Cosmology and Nongalactic Astrophysics
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- [1] arXiv:2406.12976 [pdf, html, other]
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Title: Large Blue Spectral Index From a Conformal Limit of a Rotating Complex ScalarComments: 52 pages of main text, 13 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
One well known method of generating a large blue spectral index for axionic isocurvature perturbations is through a flat direction not having a quartic potential term for the radial partner of the axion field. In this work, we show how one can obtain a large blue spectral index even with a quartic potential term associated with the Peccei-Quinn symmetry breaking radial partner. We use the fact that a large radial direction with a quartic term can naturally induce a conformal limit which generates an isocurvature spectral index of 3. We point out that this conformal representation is intrinsically different from both the ordinary equilibrium axion scenario or massless fields in Minkowski spacetime. Another way to view this limit is as a scenario where the angular momentum of the initial conditions slows down the radial field or as a superfluid limit. Quantization of the non-static system in which derivative of the radial field and the derivative of the angular field do not commute is treated with great care to compute the vacuum state. The parametric region consistent with axion dark matter and isocurvature cosmology is discussed.
- [2] arXiv:2406.12979 [pdf, html, other]
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Title: Removal of interloper contamination to line-intensity maps using correlations with ancillary tracers of the large-scale structureComments: 11 pages (+1 page appendices + references), 4 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Line-intensity mapping (LIM) offers an approach to obtain three-dimensional maps of the large-scale structure by collecting the aggregate emission from all emitters along the line of sight. The procedure hinges on reconstructing the radial positions of sources by relating the observed frequency to the rest-frame frequency of a target emission line. However, this step is hindered by `interloper-line' emission from different cosmological volumes that redshifts into the same observed frequency. In this work, we propose a model-independent technique to remove the contamination of line interlopers using their statistical correlation with external tracers of the large-scale structure, and identify the weights that minimize the variance of the cleaned field. Furthermore, we derive expressions for the resulting power spectra after applying our cleaning procedure, and validate them against simulations. We find that the cleaning performance improves as the correlation between the line interlopers and the external tracer increases, resulting in a gain in the signal-to-noise ratio of up to a factor 6 (2) for the auto- (cross-)power spectrum in idealized scenarios. This approach has the advantage of being model-independent, and is highly complementary to other techniques, as it removes large-scale clustering modes instead of individually masking the brightest sources of contamination.
- [3] arXiv:2406.12985 [pdf, html, other]
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Title: CMB Spectral Distortions: A Multimessenger Probe of the Primordial UniverseComments: 8 pages, contribution to the 2024 Cosmology session of the 58th Rencontres de MoriondSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
The frequency spectrum of the cosmic microwave background (CMB) is a relatively untapped source of data which can allow us to peer beyond the surface of last scattering. Small deviations away from a perfect blackbody shape will encode valuable information about the state of the primordial Universe which may not be accessible by other means. Here, we briefly review some key science goals of CMB spectral distortions, with an emphasis on how future generations of experiments can be used in tandem with complementary observational probes to perform model discrimination of exotic physics scenarios. We focus here on synergies between spectral distortions, gravitational waves, and 21cm cosmology.
- [4] arXiv:2406.13056 [pdf, html, other]
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Title: Mildly boosted dark matter annihilation and reconciling indirect galactic signalsComments: 6 pages, 3 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
The galactic center excess is a possible non-gravitational observation of dark matter; however, the canonical dark matter model (thermal freeze-out) is in conflict with other gamma-ray observations, in particular those made of the Milky Way's satellite dwarf galaxies. Here we consider the effects of a two-component dark matter model which results in minimally boosted particles that must remain bound to their host galaxy in order to produce an observational signal. This leads to a signal that is heavily dependent on galactic scale and can help reconcile the differences in the galactic center and dwarf galaxy measurements under the dark matter paradigm.
- [5] arXiv:2406.13079 [pdf, html, other]
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Title: Predicting the 21 cm field with a Hybrid Effective Field Theory approachComments: 14 pages, 11 figures, submitted to PRDSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
A detection of the 21 cm signal can provide a unique window of opportunity for uncovering complex astrophysical phenomena at the epoch of reionization and placing constraints on cosmology at high redshifts, which are usually elusive to large-scale structure surveys. In this work, we provide a theoretical model based on a quadratic bias expansion capable of recovering the 21 cm power spectrum with high accuracy sufficient for upcoming ground-based radio interferometer experiments. In particular, we develop a hybrid effective field theory (HEFT) model in redshift space that leverages the accuracy of $N$-body simulations with the predictive power of analytical bias expansion models, and test it against the Thesan suite of radiative transfer hydrodynamical simulations. We make predictions of the 21 cm brightness temperature field at several distinct redshifts, ranging between $z = 6.5$ and 11, thus probing a large fraction of the reionization history of the Universe ($x_{\rm HI} = 0.3 \sim 0.9$), and compare our model to the `true' 21 cm brightness in terms of the correlation coefficient, power spectrum and modeling error. We find percent-level agreement at large and intermediate scales, $k \lesssim 0.5 h/{\rm Mpc}$, and favorable behavior down to small scales, $k \sim 1 h/{\rm Mpc}$, outperforming pure perturbation-theory-based models. To put our findings into context, we show that even in the absence of any foreground contamination the thermal noise of a futuristic HERA-like experiment is comparable with the theoretical uncertainty in our model in the allowed `wedge' of observations, providing further evidence in support of using HEFT-based models to approximate a range of cosmological observables.
- [6] arXiv:2406.13388 [pdf, html, other]
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Title: Suppression without Thawing: Constraining Structure Formation and Dark Energy with Galaxy ClusteringComments: 9 pages, 2 figures, to be submitted to PRLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present a new perturbative full-shape analysis of BOSS galaxy clustering data, including the full combination of the galaxy power spectrum and bispectrum multipoles, baryon acoustic oscillations, and cross-correlations with the gravitational lensing of cosmic microwave background measured from \textit{Planck}. Assuming the $\Lambda$CDM model, we constrain the matter density fraction $\Omega_m = 0.3154\pm 0.0089$, the Hubble constant $H_0=68.34\pm 0.77\,\mathrm{km}\,\mathrm{s}^{-1}\mathrm{Mpc}^{-1}$, and the mass fluctuation amplitude $\sigma_8=0.686\pm 0.027$ (equivalent to $S_8 = 0.704\pm 0.031$). Cosmic structure at low redshifts appears suppressed with respect to the Planck $\Lambda$CDM concordance model at $4.5\sigma$. We explore whether this tension can be explained by the recent DESI preference for dynamical dark energy (DDE): the BOSS data combine with DESI BAO and PantheonPlus supernovae competitively compared to the CMB, yielding no preference for DDE, but the same $\sim 10\%$ suppression of structure, with dark energy being consistent with a cosmological constant at 68\% CL. Our results suggest that either the data contains residual systematics, or more model-building efforts may be required to restore cosmological concordance.
- [7] arXiv:2406.13480 [pdf, html, other]
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Title: Neutron stars and Pulsar timing arrays as Axion giant gyroscopesComments: 6 pages, 2 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
We consider the three-dimensional rotating motions of neutron stars blown by the "axion wind". Neutron star precession and spin can change from the magnetic moment coupling to the oscillating axion background field, in analogy to the gyroscope motions with a driving force and the laboratory Nuclear Magnetic Resonance(NMR) detections of the axion. This effect modulates the pulse arrival time of the pulsar timing arrays. It shows up as a signal on the timing residual and two-point correlation function on the recent data of Nanograv and PPTA. The current measurement of PTAs can thus cast constraints on the axion-nucleon coupling as g_{ann} ~ 10^{-12}{GeV}^{-1}.
- [8] arXiv:2406.13519 [pdf, html, other]
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Title: Strongly lensed supernovae: lessons learnedComments: Invited review in connection with the "Multi-messenger Gravitational Lensing" workshop hosted by the Royal Society in Manchester, March 11-12, 2024Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Since a few years, we have finally entered the era of discoveries of multiply-imaged gravitationally lensed supernovae. To date, all cluster lensed supernovae have been found from space, while those deflected by individual galaxies were identified with wide-field ground-based surveys through the magnification of "standard candles" method, i.e., without the need of spatially resolving the individual images. We review the challenges in identifying these extremely rare events, as well as the unique opportunities they offer for time-delay cosmography and the study of the properties of the deflecting bodies acting as lenses.
- [9] arXiv:2406.13667 [pdf, html, other]
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Title: Matter Power Spectra in Modified Gravity: A Comparative Study of Approximations and $N$-Body SimulationsBenjamin Bose, Ashim Sen Gupta, Bartolomeo Fiorini, Guilherme Brando, Farbod Hassani, Tessa Baker, Lucas Lombriser, Baojiu Li, Cheng-Zong Ruan, Cesar Hernandez-Aguayo, Luis Atayde, Noemi FruscianteComments: 20 pages, 4 figures, 4 tablesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Testing gravity and the concordance model of cosmology, $\Lambda$CDM, at large scales is a key goal of this decade's largest galaxy surveys. Here we present a comparative study of dark matter power spectrum predictions from different numerical codes in the context of three popular theories of gravity that induce scale-independent modifications to the linear growth of structure: nDGP, Cubic Galileon and K-mouflage. In particular, we compare the predictions from full $N$-body simulations, two $N$-body codes with approximate time integration schemes, a parametrised modified $N$-body implementation and the analytic halo model reaction approach. We find the modification to the $\Lambda$CDM spectrum is in $2\%$ agreement for $z\leq1$ and $k\leq 1~h/{\rm Mpc}$ over all gravitational models and codes, in accordance with many previous studies, indicating these modelling approaches are robust enough to be used in forthcoming survey analyses under appropriate scale cuts. We further make public the new code implementations presented, specifically the halo model reaction K-mouflage implementation and the relativistic Cubic Galileon implementation.
- [10] arXiv:2406.13736 [pdf, html, other]
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Title: Constraining cosmological parameters using void statistics from the SDSS surveyComments: 22 pages, 18 figures. All data sets are made publicly available in this https URLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We identify voids as maximal non-overlapping spheres within the haloes of the Uchuu simulation and three smaller halo simulation boxes with smaller volume and different $\sigma_{8}$ values, and galaxies with redshift in the range $0.02<z<0.132$ and absolute magnitude in the $r-$band $M_{r}<-20.5$ of 32 Uchuu-SDSS simulated lightcones the seventh release of \textit{The Sloan Digital Sky Survey} (SDSS DR7) survey. We compute the Void Probability Function and the abundance of voids larger than $r$ predicted by the theoretical framework used in this work and we check that it predicts successfully both void functions for the halo simulation boxes. Next, we asses the potential of this theoretical framework to constrain cosmological parameters using Uchuu-SDSS void statistics, and we calculate the confidence levels using Monte Carlo Markov Chain techniques to infer the values of $\sigma_{8}$, $\Omega_{\rm m}$ and H$_{0}$ from the SDSS sample used. The constraints we obtain from the SDSS survey sample used. The results are: $\sigma_{8}=1.028^{+0.273}_{-0.305}$, $\Omega_{\rm m}=0.296^{+0.110}_{-0.102}$, H$_{0}=83.43\pm^{+29.27}_{-27.70}$, $\Gamma=0.1947^{+0.0578}_{-0.0516}$ and S$_{8}$=1.017$^{+0.363}_{-0.359}$. If we combine these constraints with KiDS-1000+DESY3, we get $\sigma_{8}=0.858^{+0.040}_{-0.040}$, $\Omega_{\rm m}=0.257\pm^{+0.023}_{-0.020}$, H$_{0}=74.17^{+4.66}_{-4.66}$ and S$_{8}$=0.794$^{+0.016}_{-0.016}$. The combined uncertainties are approximately a factor 2-3 smaller than only-Weak-Lensing uncertainties. This is a consequence of the orientation of the confidence level contours of SDSS voids and Weak Lensing in the plane $\sigma_{8}-\Omega_{\rm m}$, which are almost orthogonal (abridged).
- [11] arXiv:2406.13747 [pdf, html, other]
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Title: Cosmological tests with bright and dark standard sirensComments: Contribution to the 2024 Cosmology session of the 58th Rencontres de MoriondSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Gravitational waves (GWs) are signals that propagate across large distances in the Universe, and thus, they bring information on the cosmic history. GW sources are at the same time distance indicators and tracers of the matter field. Events generated by binary systems can be divided into bright standard sirens, when followed by electromagnetic transients from which the redshift of the source can be measured, and the more numerous dark standard sirens, when counterparts are not available. In this proceeding, I will discuss some methods for testing the cosmological model using either bright or dark sirens and their combinations with other cosmological probes, focusing on some of my own recent contributions.
- [12] arXiv:2406.13887 [pdf, html, other]
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Title: Dark Matter and General Relativistic Instability in Supermassive StarsComments: 11 pages, 2 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We calculate the extent to which collisionless dark matter impacts the stability of supermassive stars $(M\gtrsim10^4\,M_\odot)$. We find that, depending on the star's mass, a dark matter content in excess of ${\sim}1\%$ by mass throughout the entire star can raise the critical central density for the onset general relativistic instability, in some cases by orders of magnitude. We consider implications of this effect for the onset of nuclear burning and significant neutrino energy losses.
- [13] arXiv:2406.14152 [pdf, html, other]
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Title: Clocking the End of Cosmic InflationComments: 24 pages, 2 figures, uses jcappubSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
Making observable predictions for cosmic inflation requires determining when the wavenumbers of astrophysical interest today exited the Hubble radius during the inflationary epoch. These instants are commonly evaluated using the slow-roll approximation and measured in e-folds $\Delta N=N-N_\mathrm{end}$, in reference to the e-fold $N_\mathrm{end}$ at which inflation ended. Slow roll being necessarily violated towards the end of inflation, both the approximated trajectory and $N_\mathrm{end}$ are determined at, typically, one or two e-folds precision. Up to now, such an uncertainty has been innocuous, but this will no longer be the case with the forthcoming cosmological measurements. In this work, we introduce a new and simple analytical method, on top of the usual slow-roll approximation, that reduces uncertainties on $\Delta N$ to less than a tenth of an e-fold.
- [14] arXiv:2406.14475 [pdf, html, other]
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Title: The feasibility of weak lensing and 21cm intensity mapping cross-correlation measurementsComments: 15 pages, 15 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
One of the most promising probes to complement current standard cosmological surveys is the HI intensity map, i.e. the distribution of temperature fluctuations in neutral hydrogen. In this paper we present calculations of the 2-point function between HI (at redshift $z$ < 1) and lensing convergence ($\kappa$). We also construct HI intensity maps from N-body simulations, and measure 2-point functions between HI and lensing convergence. HI intensity mapping requires stringent removal of bright foregrounds, including emission from our galaxy. The removal of large-scale radial modes during this HI foreground removal will reduce the HI-lensing cross-power spectrum signal, as radial modes are integrated to find the convergence; here we wish to characterise this reduction in signal. We find that after a simple model of foreground removal, the cross-correlation signal is reduced by $\sim$50-70\%; we present the angular and redshift dependence of the effect, which is a weak function of these variables. We then calculate S/N of $\kappa$HI detection, including cases with cut sky observations, and noise from radio and lensing measurements. We present Fisher forecasts based on the resulting 2-point functions; these forecasts show that by measuring $\kappa\Delta$$T_\mathrm{HI}$ correlation functions in a sufficient number of redshift bins, constraints on cosmology and HI bias will be possible
- [15] arXiv:2406.14519 [pdf, html, other]
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Title: ForSE+: Simulating non-Gaussian CMB foregrounds at 3 arcminutes in a stochastic way based on a generative adversarial networkComments: Published in A&A. Comments welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present ForSE+, a Python package that produces non-Gaussian diffuse Galactic thermal dust emission maps at arcminute angular scales and that has the capacity to generate random realizations of small scales. This represents an extension of the ForSE (Foreground Scale Extender) package, which was recently proposed to simulate non-Gaussian small scales of thermal dust emission using generative adversarial networks (GANs). With the input of the large-scale polarization maps from observations, ForSE+ has been trained to produce realistic polarized small scales at 3' following the statistical properties, mainly the non-Gaussianity, of observed intensity small scales, which are evaluated through Minkowski functionals. Furthermore, by adding different realizations of random components to the large-scale foregrounds, we show that ForSE+ is able to generate small scales in a stochastic way. In both cases, the output small scales have a similar level of non-Gaussianity compared with real observations and correct amplitude scaling as a power law. These realistic new maps will be useful, in the future, to understand the impact of non-Gaussian foregrounds on the measurements of the cosmic microwave background (CMB) signal, particularly on the lensing reconstruction, de-lensing, and the detection of cosmological gravitational waves in CMB polarization B-modes.
- [16] arXiv:2406.14554 [pdf, html, other]
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Title: Neutrino mass bounds from DESI 2024 are relaxed by Planck PR4 and cosmological supernovaeComments: 5 pages, 3 figures, 2 tables, plus appendicesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
The recent DESI 2024 Baryon Acoustic Oscillations (BAO) measurements combined with the CMB data from the Planck 18 PR3 dataset and the Planck PR4+ACT DR6 lensing data, with a prior on the sum of the neutrino masses $\sum m_\nu>0$, leads to a strong constraint, $\sum m_\nu<0.072$ eV, which would exclude the inverted neutrino hierarchy and put some tension on even the standard hierarchy. We show that actually this bound gets significantly relaxed when combining the new DESI measurements with the HiLLiPoP+LoLLiPoP likelihoods, based on the Planck 2020 PR4 dataset, and with supernovae datasets. We note that the fact that neutrino masses are pushed towards zero, and even towards negative values, is known to be correlated with the so-called $A_L$ tension, a mismatch between lensing and power spectrum measurements in the Planck PR3 data, which is reduced by HiLLiPoP+LoLLiPoP to less than 1$\sigma$. We find $\sum m_\nu<0.1$ eV and $\sum m_\nu<0.12$ eV, with the supernovae Pantheon+ and DES-SN5YR datasets respectively. The shift caused by these datasets is more compatible with the expectations from neutrino oscillation experiments, and both the normal and inverted hierarchy scenarios remain now viable, even with the $\sum m_\nu>0$ prior. Finally, we analyze neutrino mass bounds in an extension of $\Lambda$CDM that addresses the $H_0$ tension, with extra fluid Dark Radiation, finding that in such models bounds are further relaxed and the posterior probability for $\sum m_\nu$ begins to exhibit a peak at positive values.
New submissions for Friday, 21 June 2024 (showing 16 of 16 entries )
- [17] arXiv:2406.12887 (cross-list from physics.ins-det) [pdf, html, other]
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Title: Scintillating low-temperature calorimeters for direct dark matter searchComments: 20 pages, 11 figuresSubjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The lack of an unambiguous signal for thermally produced dark matter particles in direct detection, indirect detection, and collider searches calls for broadening the search strategies by probing a wider range of dark matter masses with different detection techniques. One of the most common approaches is to search for nuclear recoils induced by dark matter particles scattering off the target material's nuclei. Low-temperature detectors have proven to provide the required performance to probe dark matter masses from 100 MeV/c$^2$ to 100 GeV/c$^2$ via this channel. Using scintillation light as an ancillary channel is a powerful tool for particle identification and background suppression at the keV-recoil energy scale. The CRESST-III experiment, employing scintillating cryogenic detectors with highly sensitive transition edge sensors and multi-target absorber crystals, achieved unprecedented sensitivities to explore sub-GeV dark matter masses. COSINUS, instead, is a new experiment exploiting the phonon-light technique using sodium iodide crystals with the scope to clarify the long-lasting dark matter claim of the DAMA/LIBRA collaboration. This article reviews the principle of scintillating low-temperature calorimeters with emphasis on the benefits and challenges of this technique for direct dark matter searches in light of the current status and future developments.
- [18] arXiv:2406.12956 (cross-list from hep-ph) [pdf, html, other]
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Title: Cold Darkogenesis: Dark Matter and Baryon Asymmetry in Light of the PTA SignalComments: 5 + 4 pages, 3 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex); High Energy Physics - Theory (hep-th)
We build upon the intriguing possibility that the recently reported nano-Hz gravitational wave signal by Pulsar Timing Array (PTA) experiments is sourced by a strong first-order phase transition from a nearly conformal dark sector. The phase transition has to be strongly supercooled to explain the signal amplitude, while the critical temperature has to be in the $\cal{O}$(GeV) range, as dictated by the peak frequency of the gravitational wave spectrum. However, the resulting strong supercooling exponentially dilutes away any pre-existing baryon asymmetry and dark matter, calling for a new paradigm of their productions. We then develop a mechanism of cold darkogenesis that generates a dark asymmetry during the phase transition from the textured dark $SU(2)_{\rm D}$ Higgs field. This dark asymmetry is transferred to the visible sector via neutron portal interactions, resulting in the observed baryon asymmetry. Furthermore, the mechanism naturally leads to the correct abundance of asymmetric dark matter, with self-interaction of the scale that is of the right order to solve the diversity problem in galactic rotation curves. Collider searches for mono-jets and dark matter direct detection experiments can dictate the viability of the model.
- [19] arXiv:2406.12958 (cross-list from hep-th) [pdf, html, other]
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Title: Unimodular Quadratic Gravity and the Cosmological ConstantComments: 6 pagesSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Unimodular gravity addresses the old cosmological constant (CC) problem, explaining why such constant is not at least as large as the largest particle mass scale, but classically it is indistinguishable from ordinary gravity. Conversely, quantum physics may give us a way to distinguish the two theories. Thus, here the unimodular constraint is imposed on a non-perturbative and background-independent quantum version of quadratic gravity, which was recently formulated. It is shown that unimodularity does lead to different predictions for some inflationary quantum observables. Unimodular gravity per se does not solves the new CC problem (why the CC has the observed value?) even in this realization. To address this issue a multiverse made by different eras in a single big bang is considered and the observed scale of dark energy is explained anthropically.
- [20] arXiv:2406.12970 (cross-list from hep-ph) [pdf, html, other]
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Title: Warm and Fuzzy Dark Matter: Free Streaming of Wave Dark MatterComments: 16 pages, 11 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Wave or fuzzy dark matter that is produced with relativistic wavenumbers exhibits free streaming effects analogous to warm or hot particle dark matter with relativistic momenta. Axions produced after inflation provide such a warm or mildly relativistic candidate, where the enhanced suppression and observational bounds are only moderately stronger than that from wave propagation of initially cold axions. More generally, the free streaming damping also impacts isocurvature fluctuations from generation in causally disconnected patches. As coherent spatial fluctuations free stream away they leave incoherent and transient superpositions in their wakes. These multiple wave momentum streams are the wave analogue of particle phase space fluctuations or directional collisionless damping of massive neutrinos or hot dark matter. The observable impact on both adiabatic and isocurvature fluctuations of fuzzy dark matter can differ from their cold dark matter counterparts due to free streaming depending on how warm or hot is their momentum distribution.
- [21] arXiv:2406.13055 (cross-list from nucl-th) [pdf, html, other]
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Title: Self-consistent strong screening applied to thermonuclear reactionsComments: 16 pages, 5 figures, typeset using LATEX default style in AASTeX631Subjects: Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Plasma Physics (physics.plasm-ph)
Self-consistent strong plasma screening around light nuclei is implemented in the Big Bang nucleosynthesis (BBN) epoch to determine the short-range screening potential, $e\phi(r)/T \geq 1$, relevant for thermonuclear reactions. We numerically solve the non-linear Poisson-Boltzmann equation incorporating Fermi-Dirac statistics adopting a generalized screening mass to find the electric potential in the cosmic BBN electron-positron plasma for finite-sized $^4$He nuclei as an example. Although the plasma follows Boltzmann statistics at large distances, Fermi-Dirac statistics is necessary when work performed by ions on electrons is comparable to their rest mass energy. While strong screening effects are generally minor due to the high BBN temperatures, they can enhance the fusion rates of high-$Z>2$ elements while leaving fusion rates of lower-$Z\le 2$ elements relatively unaffected. Our results also reveal a pronounced spatial dependence of the strong screening potential near the nuclear surface. These findings about the electron-positron plasma's role refine BBN theory predictions and offer broader applications for studying weakly coupled plasmas in diverse cosmic and laboratory settings.
- [22] arXiv:2406.13082 (cross-list from gr-qc) [pdf, other]
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Title: The Hanbury-Brown and Twiss effect in inflationary cosmological perturbationsSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
The simplest model of inflation is based around an inflaton field that starts in a coherent false vacuum state with a positive cosmological constant, rolls slowly to the true vacuum and relaxes to it via reheating. We examine whether the scale of the transition from coherence to chaoticity can be examined via the Hanbury-Brown and Twiss (HBT) effect, in parallel with analogous problems of heavy ion physics (the ``pion laser'' and the thermalizing glasma).
We develop an ansatz which contains a definition of ''chaoticity'' which parallels that of the usual setups where HBT is used.
However, we also discuss the differences between the inflationary setup and more mainstream uses of HBT and conclude that these are more significant than the similarities, making the use of the developed methodology uncertain. - [23] arXiv:2406.13132 (cross-list from gr-qc) [pdf, html, other]
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Title: Cosmic slowing down of acceleration with the Chaplygin-Jacobi gas as a dark fluidComments: 16 pages, 5 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
A particular generalization of the Chaplygin inflationary model, using the formalism of Hamilton-Jacobi and elliptic functions, results in a more general non-linear Chaplygin-type equation of state (Chaplygin-Jacobi model). We investigate the implementation of this model as a dark energy (DE) fluid to explain the recent acceleration of the universe. Unlike $\Lambda$CDM and other Chaplygin-like fluids, where the final fate of the universe is an eternal de Sitter (dS) phase, the dynamics of this model allow for the possibility of a decelerating phase in the future, following the current accelerating phase. In other words, a transient acceleration arises, accounting for the recently claimed slowing down phenomenon. This Chaplygin-Jacobi model shows important differences compared to the standard and generalized Chaplygin gas models. Additionally, we perform a Markov Chain Monte Carlo (MCMC) analysis using several datasets, including Type Ia Supernovae (SnIa), Cosmic Chronometers (CC), and Fast Radio Bursts (FRBs), to examine the observational viability of the model. Our results indicate that a transient phase of accelerated expansion is not excluded by current observations.
- [24] arXiv:2406.13394 (cross-list from gr-qc) [pdf, html, other]
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Title: Gravitational Wave Birefringence from Fuzzy Dark MatterComments: 7 pagesSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Gravitational wave (GW) birefringence is a remarkable phenomenon that can be used to test the parity violation in gravity. By coupling the fuzzy dark matter (FDM) scalar to the gravitational Chern-Simons term, we explore the GW birefringence effects in the FDM background. In particular, in light of the highly oscillating granular FDM structure at the galactic scale, we are led to investigating the GW propagation in the Chern-Simons gravity over the general nontrivial scalar profile, which is a natural extension of previous studies on the homogeneous and isotropic configurations. As a result, it is found that GWs of both circularly polarized modes propagate in the straight line with the speed of light, and does not show any velocity birefringence. However, when considering the imaginary part of the dispersion relation, GWs exhibit the amplitude birefringence in which one circular polarization is enhanced while the other suppressed. Due to its local nature, the FDM-induced amplitude birefringence only depends on the GW frequency without any reliance on the GW event distance. More importantly, the birefringence factor shows a periodic time variation with the period reflecting the FDM scalar mass, which is the smoking gun for testing this new birefringence mechanism. Finally, we also study the extra-galactic FDM contribution to the GW birefringence, which is shown to be suppressed by the cosmological DM density and thus subdominant compared with the galactic counterpart.
- [25] arXiv:2406.13479 (cross-list from astro-ph.HE) [pdf, html, other]
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Title: Is Lensing Amplitude Anomaly in the Cosmic Microwave Background the Evidence of Extremely Low Frequency Primordial Gravitational Wave?Comments: 3 pages, 2 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Trajectories of photons of cosmic microwave background (CMB) from the surface of last scattering to us could be deflected by extremely low frequency primordial gravitational wave (PGW). With large scale structure (LSS) producing a smoothing of the acoustic peaks in the power spectrum of the CMB anisotropies through weak lensing, the presence of extremely low frequency PGW could enhance the effect of weak lensing on CMB due to the coupling of extremely low frequency PGW and LSS, thus, give rise to much more smoothing of the spectrum. This may be an natural explanation for the lensing amplitude anomaly observed by Planck, meaning that lensing amplitude anomaly may be the evidence of extremely low frequency PGW.
- [26] arXiv:2406.13521 (cross-list from gr-qc) [pdf, html, other]
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Title: Gravitational-wave background in bouncing models from semi-classical, quantum and string gravityIdo Ben-Dayan, Gianluca Calcagni, Maurizio Gasperini, Anupam Mazumdar, Eliseo Pavone, Udaykrishna Thattarampilly, Amresh VermaComments: 1+33 pages, 4 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We study the primordial spectra and the gravitational-wave background (GWB) of three models of semi-classical, quantum or string gravity where the big bang is replaced by a bounce and the tensor spectrum is blue-tilted: ekpyrotic universe with fast-rolling Galileons, string-gas cosmology with Atick-Witten conjecture and pre-big-bang cosmology. We find that the ekpyrotic scenario does not produce a GWB amplitude detectable by present or third-generation interferometers, while the string-gas model is ruled out for producing too large a signal. In contrast, the GWB of the pre-big-bang scenario falls within the sensitivity window of both LISA and Einstein Telescope, where it takes the form of a single or a broken power law depending on the choice of parameters. The latter will be tightly constrained by both detectors.
- [27] arXiv:2406.13554 (cross-list from astro-ph.GA) [pdf, html, other]
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Title: The emergence of the Star Formation Main Sequence with redshift unfolded by JWSTP. Rinaldi, R. Navarro-Carrera, K. I. Caputi, E. Iani, G. Ostlin, L. Colina, S. Alberts, J. Alvarez-Marquez, M. Annunziatella, L. Boogaard, L. Costantin, J. Hjorth, D. Langeroodi, J. Melinder, T. Moutard, F. WalterComments: 15 pages, 4 figures. Submitted to ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We investigate the correlation between stellar mass (M*) and star formation rate (SFR) across the stellar mass range log10(M*/Msun)~6-11. We consider almost 50,000 star-forming galaxies at z~3-7, leveraging data from COSMOS/SMUVS, JADES/GOODS-SOUTH, and MIDIS/XDF. This is the first study spanning such a wide stellar mass range without relying on gravitational lensing effects. We locate our galaxies on the SFR-M* plane to assess how the location of galaxies in the star-formation main sequence (MS) and starburst (SB) region evolves with stellar mass and redshift. We find that the two star-forming modes tend to converge at log10(M*/Msun) < 7, with all galaxies found in the SB mode. By dissecting our galaxy sample in stellar mass and redshift, we show that the emergence of the star-formation MS is stellar-mass dependent: while in galaxies with log10(M*/Msun) > 9 the MS is already well in place at z = 5-7, for galaxies with log10(M*/Msun)~7-8 it only becomes significant at z<4. Overall, our results are in line with previous findings that the SB mode dominates amongst low stellar-mass galaxies. The earlier emergence of the MS for massive galaxies is consistent with galaxy downsizing.
- [28] arXiv:2406.13613 (cross-list from astro-ph.GA) [pdf, html, other]
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Title: Einasto gravitational potentials have difficulty to hold spherically symmetric stellar systems with coresJorge Sanchez Almeida (1 and 2) ((1) Instituto de Astrofisica de Canarias, Tenerife, Spain, (2) Departamento de Astrofisica, Universidad de La Laguna, Tenerife, Spain)Comments: RNAAS complementing our previous paper Sanchez Almeida et al. (2023, ApJ, 954, 153; doi: https://doi.org/10.3847/1538-4357/ace534)Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
It was known that an ideal spherically symmetric stellar system with isotropic velocities and an inner core cannot reside in a Navarro, Frenk, and White (NFW) gravitational potential. The incompatibility can be pinned down to the radial gradient of the NFW potential in the very center of the system, which differs from zero. The gradient is identically zero in an Einasto potential, also an alternative representation of the dark matter (DM) halos created by the kind of cold DM (CDM) defining the current cosmological model. Here we show that, despite the inner gradient being zero, stellar cores are also inconsistent with Einasto potentials. This result may have implications to constrain the nature of DM through interpreting the stellar cores often observed in dwarf galaxies.
- [29] arXiv:2406.13732 (cross-list from astro-ph.GA) [pdf, html, other]
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Title: On the dark matter content of ultra-diffuse galaxiesComments: 9 pages, 6 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
I compare the dark matter content within stellar half-mass radius expected in a $\Lambda$CDM-based galaxy formation model with existing observational estimates for the observed dwarf satellites of the Milky Way and ultra-diffuse galaxies (UDGs). The model reproduces the main properties and scaling relations of dwarf galaxies, in particular their stellar mass-size relation. I show that the model also reproduces the relation between the dark matter mass within the half-mass radius, $M_{\rm dm}(<r_{1/2})$, and stellar mass exhibited by the observed dwarf galaxies. The scatter in the $M_{\rm dm}(<r_{1/2})-M_\star$ relation is driven primarily by the broad range of sizes of galaxies of a given stellar mass. I also show the $M_{\rm dm}(<r_{1/2})$ of UDGs are within the range expected in the model for their stellar mass, but they tend to lie above the median relation due to their large sizes. The upper limits on $M_{\rm dm}(<r_{1/2})$ for the dark matter deficient UDGs are also consistent with the range of dark matter masses expected in the model. The most dark matter-deficient galaxies of a given size correspond to halos with the smallest concentrations and the largest ratios of $M_\star/M_{\rm 200c}$. Conversely, the most dark matter-dominated galaxies are hosted by the highest concentration halos with the smallest $M_\star/M_{\rm 200c}$ ratios. The model indicates that the scatter between $M_{\rm dm}(<r_{1/2})$ and $M_{\rm 200c}$ is large, which renders inference of the virial mass from $M_{\rm dm}(<r_{1/2})$ uncertain and dependent on specific assumptions about the halo mass profile. Results presented in this paper indicate that dark matter-deficient UDGs may represent a tail of the expected dark matter profiles, especially if the effect of feedback on these profiles is taken into account.
- [30] arXiv:2406.14089 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: The Simons Observatory: Alarms and Detector Quality MonitoringDavid V. Nguyen, Sanah Bhimani, Nicholas Galitzki, Brian J. Koopman, Jack Lashner, Laura Newburgh, Max Silva-Feaver, Kyohei YamadaComments: 14 pages, 6 figures, 2 tables. To be presented at SPIE Astronomical Telescopes + Instrumentation 2024Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The Simons Observatory (SO) is a group of modern telescopes dedicated to observing the polarized cosmic microwave background (CMB), transients, and more. The Observatory consists of four telescopes and instruments, with over 60,000 superconducting detectors in total, located at ~5,200 m altitude in the Atacama Desert of Chile. During observations, it is important to ensure the detectors, telescope platforms, calibration and receiver hardware, and site hardware are within operational bounds. To facilitate rapid response when problems arise with any part of the system, it is essential that alerts are generated and distributed to appropriate personnel if components exceed these bounds. Similarly, alerts are generated if the quality of the data has become degraded. In this paper, we describe the SO alarm system we developed within the larger Observatory Control System (OCS) framework, including the data sources, alert architecture, and implementation. We also present results from deploying the alarm system during the commissioning of the SO telescopes and receivers.
- [31] arXiv:2406.14101 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: Peculiar Velocity Reconstruction From Simulations and Observations Using Deep Learning AlgorithmsSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
In this paper, we introduce a Unet model of deep learning algorithms for reconstructions of the 3D peculiar velocity field, which simplifies the reconstruction process with enhanced precision. We test the adaptability of the Unet model with simulation data under more realistic conditions, including the redshift space distortion (RSD) effect and halo mass threshold. Our results show that the Unet model outperforms the analytical method that runs under ideal conditions, with a 16% improvement in precision, 13% in residuals, 18% in correlation coefficient and 27% in average coherence. The deep learning algorithm exhibits exceptional capacities to capture velocity features in non-linear regions and substantially improve reconstruction precision in boundary regions. We then apply the Unet model trained under SDSS observational conditions to the SDSS DR7 data for observational 3D peculiar velocity reconstructions.
- [32] arXiv:2406.14157 (cross-list from gr-qc) [pdf, html, other]
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Title: Exact solutions for differentially rotating galaxies in general relativityComments: 5 pages, 2 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
A class of stationary axisymmetric solutions of Einstein's equations for isolated differentially rotating dust sources is presented. The low-energy asymptotic regime is extracted, requiring a self-consistent coupling of quasilocal energy and angular momentum. The Raychaudhuri equation reduces to a balance equation, with two important limits. These limits can be interpreted empirically for rotationally supported configurations such as galaxies. The net energy including quasilocal kinetic contributions vanishes on the inner vortex surface, and the outer rotosurface. These new geometrical objects potentially shed light on virialization. Whether or not abundant collisionless dark matter exists, the new solutions suggest that the phenomenology of galactic rotation curves be fundamentally reconsidered, for consistency with general relativity.
Cross submissions for Friday, 21 June 2024 (showing 16 of 16 entries )
- [33] arXiv:2101.09862 (replaced) [pdf, html, other]
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Title: Constraints on the minimally extended varying speed of light model using the Pantheon+ datasetComments: version 2 to match the version accepted by the Universe. 24 pages, 2 figures, 4 tablesJournal-ref: Universe 2024, 10(6), 268Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
In the context of the minimally extended varying speed of light (meVSL) model, both the absolute magnitude and the luminosity distance of type Ia supernovae (SNe Ia) deviate from those predicted by general relativity (GR). Using data from the Pantheon$+$ survey, we assess the plausibility of various dark energy models within the framework of meVSL. Both the constant equation of state (EoS) of the dark energy model ($\omega$CDM) and the Chevallier-Polarski-Linder (CPL) parameterization model ($\omega = \omega_0 + \omega_a (1-a)$) indicate potential variations in the cosmic speed of light at the 1-$\sigma$ confidence level. For $\Omega_{\m0} = 0.30, 0.31$, and 0.32 with $(\omega_0 \,, \omega_a) = (-1 \,, 0)$, the 1-$\sigma$ range of $\dot{c}_0/c_0 \, (10^{-13} \, \text{yr}^{-1}) $ is (-8.76 \,, -0.89), (-11.8 \,, 3.93), and (-14.8 \,, -6.98), respectively. Meanwhile, the 1-$\sigma$ range of $\dot{c}_0/c_0 (10^{-12} \, \text{yr}^{-1}) $ for CPL dark energy models with $-1.05 \leq \omega_{0} \leq -0.95$ and $0.28 \leq \Omega_{\m0} \leq 0.32$, is (-6.31\,, -2.98). The value of $c$ at $z = 3$ can exceed that of the present by $0.2 \sim 3$ \% for $\omega$CDM models and $5 \sim 13$ \% for CPL models. Additionally, for viable models except for the CPL model with $\Omega_{\m0} = 0.28$, we find $-25.6 \leq \dot{G}_0/G_0 \, (10^{-12} \, \text{yr}^{-1}) \leq -0.36$. For this particular model, we obtain an increasing rate of the gravitational constant within the range $1.65 \leq \dot{G}_0/G_0 \, (10^{-12} \, \text{yr}^{-1}) \leq 3.79$. We obtained some models that do not require dark matter energy density through statistical interpretation. However, this is merely an effect of the degeneracy between model parameters and energy density and does not imply that dark matter is unnecessary.
- [34] arXiv:2206.08327 (replaced) [pdf, html, other]
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Title: The BOSS bispectrum analysis at one loop from the Effective Field Theory of Large-Scale StructureComments: JCAP version, 23+18 pages, 6 figures, 5 tablesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
We analyze the BOSS power spectrum monopole and quadrupole, and the bispectrum monopole and quadrupole data, using the predictions from the Effective Field Theory of Large-Scale Structure (EFTofLSS). Specifically, we use the one loop prediction for the power spectrum and the bispectrum monopole, and the tree level for the bispectrum quadrupole. After validating our pipeline against numerical simulations as well as checking for several internal consistencies, we apply it to the observational data. We find that analyzing the bispectrum monopole to higher wavenumbers thanks to the one-loop prediction, as well as the addition of the tree-level quadrupole, significantly reduces the error bars with respect to our original analysis of the power spectrum at one loop and bispectrum monopole at tree level. After fixing the spectral tilt to Planck preferred value and using a Big Bang Nucleosynthesis prior, we measure $\sigma_8=0.794\pm 0.037$, $h = 0.692\pm 0.011$, and $\Omega_m = 0.311\pm 0.010$ to about $4.7\%$, $1.6\%$, and $3.2\%$, at $68\%$ CL, respectively. This represents an error bar reduction with respect to the power spectrum-only analysis of about $30\%$, $18\%$, and $13\%$ respectively. Remarkably, the results are compatible with the ones obtained with a power-spectrum-only analysis, showing the power of the EFTofLSS in simultaneously predicting several observables. We find no tension with Planck.
- [35] arXiv:2209.02741 (replaced) [pdf, html, other]
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Title: Probing ultralight scalar, vector and tensor dark matter with pulsar timing arraysComments: 6 pages, 3 figures, accepted by PLBSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
Pulsar timing arrays (PTAs) are sensitive to oscillations in the gravitational potential along the line-of-sight due to ultralight particle pressure. We calculate the probing power of PTAs for ultralight bosons across all frequencies, from those larger than the inverse observation time to those smaller than the inverse distance to the pulsar. We show that since the signal amplitude grows comparably to the degradation in PTA sensitivity at frequencies smaller than inverse observation time, the discovery potential can be extended towards lower masses by over three decades, maintaining high precision. We demonstrate that, in the mass range $10^{-26} -10^{-23}$ eV, existing 15-year PTA data can robustly detect or rule out an ultralight component down to $O(1 - 10)\%$ of the total dark matter. Non-detection, together with other bounds in different mass ranges, will imply that ultralight scalar/axion can comprise at most $1-10\%$ of dark matter in the $10^{-30}\!-\!10^{-17}$ eV range. With 30 years of observation, current PTAs can extend the reach down to $0.1-1 \%$, while next-generation PTAs such as SKA can attain the $0.01-0.1\%$ precision. We generalize the analysis and derive predictions for ultralight spin-1 vector (i.e. dark photon) and spin-2 tensor dark components.
- [36] arXiv:2303.14156 (replaced) [pdf, html, other]
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Title: Non-Gaussianity in rapid-turn multi-field inflationComments: 33 pages, 9 figuresJournal-ref: JCAP 03 (2024) 014Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
We show that theories of inflation with multiple, rapidly turning fields can generate large amounts of non-Gaussianity. We consider a general theory with two fields, an arbitrary field-space metric, and a potential that supports sustained, rapidly turning field trajectories. Our analysis accounts for non-zero field cross-correlation and does not fix the power spectra of curvature and isocurvature perturbations to be equal at horizon crossing. Using the $\delta N$ formalism, we derive a novel, analytical formula for bispectrum generated from multi-field mixing on super-horizon scales. Rapid-turn inflation can produce a bispectrum with several potentially large contributions that are not necessarily of the local shape. We exemplify the applicability of our formula with a fully explicit model and show that the new contributions indeed can generate a large amplitude of local non-Gaussianity, $f_{\rm NL}^{\rm loc}\sim {\cal O}(1)$. These results will be important when interpreting the outcomes of future observations.
- [37] arXiv:2307.11409 (replaced) [pdf, html, other]
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Title: Direct signatures of the formation time of galaxiesComments: PRD version, extended discussion, 5+3 pages, 1 figure, ancillary file includedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We show that it is possible to directly measure the formation time of galaxies using large-scale structure. In particular, we show that the large-scale distribution of galaxies is sensitive to whether galaxies form over a narrow period of time before their observed times, or are formed over a time scale on the order of the age of the Universe. Along the way, we derive simple recursion relations for the perturbative terms of the most general bias expansion for the galaxy density, thus fully extending the famous dark-matter recursion relations to generic tracers.
- [38] arXiv:2310.06120 (replaced) [pdf, html, other]
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Title: XLSSC 122 caught in the act of growing up: Spatially resolved SZ observations of a z=1.98 galaxy clusterJ. van Marrewijk, L. Di Mascolo, A. S. Gill, N. Battaglia, E. S. Battistelli, J. R. Bond, M. J. Devlin, P. Doze, J. Dunkley, K. Knowles, A. Hincks, J. P. Hughes, M. Hilton, K. Moodley, T. Mroczkowski, S. Naess, B. Partridge, G. Popping, C. Sifón, S. T. Staggs, E. J. WollackSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
How protoclusters evolved from sparse galaxy overdensities to mature galaxy clusters is still not well understood. In this context, detecting and characterizing the hot ICM at high redshifts (z~2) is key to understanding how the continuous accretion from and mergers along the filamentary large-scale structure impact the first phases of cluster formation. We study the dynamical state and morphology of the z=1.98 galaxy cluster XLSSC 122 with high-resolution observations (~5") of the ICM through the SZ effect. Via Bayesian forward modeling, we map the ICM on scales from the virial radius down to the core of the cluster. To constrain such a broad range of spatial scales, we employ a new technique that jointly forward-models parametric descriptions of the pressure distribution to interferometric ACA and ALMA observations and multi-band imaging data from the 6-m, single-dish Atacama Cosmology Telescope. We detect the SZ effect with $11\sigma$ in the ALMA+ACA observations and find a flattened inner pressure profile that is consistent with a non-cool core classification with a significance of $>3\sigma$. In contrast to the previous works, we find better agreement between the SZ effect signal and the X-ray emission as well as the cluster member distribution. Further, XLSSC 122 exhibits an excess of SZ flux in the south of the cluster where no X-ray emission is detected. By reconstructing the interferometric observations and modeling in the uv-plane, we obtain a tentative detection of an infalling group or filamentary-like structure that is believed to boost and heat up the ICM while the density of the gas is low. In addition, we provide an improved SZ mass of $M_{500,\mathrm{c}} = 1.66^{+0.23}_{-0.20} \times 10^{14} \rm M_\odot$. Altogether, the observations indicate that we see XLSSC 122 in a dynamic phase of cluster formation while a large reservoir of gas is already thermalized.
- [39] arXiv:2311.07557 (replaced) [pdf, html, other]
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Title: Backreaction of axion-SU(2) dynamics during inflationComments: 25 pages, 13 figures, 2 tablesJournal-ref: JCAP04(2024)018Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
We consider the effects of backreaction on axion-SU(2) dynamics during inflation. We use the linear evolution equations for the gauge field modes and compute their backreaction on the background quantities numerically using the Hartree approximation. We show that the spectator chromo-natural inflation attractor is unstable when back-reaction becomes important. Working within the constraints of the linear mode equations, we find a new dynamical attractor solution for the axion field and the vacuum expectation value of the gauge field, where the latter has an opposite sign with respect to the chromo-natural inflation solution. Our findings are of particular interest to the phenomenology of axion-SU(2) inflation, as they demonstrate the instability of the usual trajectory due to large backreaction effects. The viable parameter space of the model becomes significantly altered, provided future non-Abelian lattice simulations confirm the existence of the new dynamical attractor. In addition, the backreaction effects lead to characteristic oscillatory features in the primordial gravitational wave background that are potentially detectable with upcoming gravitational wave detectors.
- [40] arXiv:2312.16147 (replaced) [pdf, html, other]
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Title: Causal bounds on cosmological angular correlationSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
We test the hypothesis that angular correlations of gravitationally-induced temperature anisotropy in the cosmic microwave background (CMB) vanish over a range of large angular separations constrained by causality. Standard conformal geometry is used to show that if primordial quantum fluctuations generate physical correlations of gravitational potential only within compact causal diamonds bounded by inflationary horizons, the angular correlation function $C(\Theta)$ of gravitationally-induced CMB anisotropy should exactly vanish over a significant range of angular separation around $\Theta= 90^\circ$. This geometrical causal symmetry is shown to be consistent with CMB correlations in all-sky maps from the WMAP and Planck satellites, after accounting for the unmeasured dipole component and systematic measurement errors. Most significantly, the even-parity component of correlation $C_{even}(\Theta)$ is shown to be much closer to zero than previously documented, and orders of magnitude less than standard expectations. This occurrence is extremely unlikely in standard cosmological realizations based on a quantum field model: within the computed causal shadow, $\Theta= \pi/2 \pm \arcsin(1/4)$, or $75.52^\circ\lesssim\Theta\lesssim 104.48^\circ$, standard realizations are shown to produce residual correlations as small as those in the Planck maps with probabilities that range from $\simeq 10^{-4.3}$ to $\simeq 10^{-2.8}$. These results could signify that primordial quantum geometrical fluctuations obey a causal symmetry not included in the standard quantum field model.
- [41] arXiv:2401.07079 (replaced) [pdf, html, other]
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Title: A New Solution for the Observed Isotropic Cosmic Birefringence Angle and its Implications for the Anisotropic Counterpart through a Boltzmann ApproachAlessandro Greco (Physics and Astronomy Dept. and INFN, Padova, ITALY), Nicola Bartolo (Physics and Astronomy Dept. and INFN and INAF, Padova, ITALY), Alessandro Gruppuso (INAF and INFN, Bologna, ITALY, and Physics and Earth Science Dept., Ferrara, ITALY)Comments: 20 pages, 5 figures. Added short commentsSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Cosmic Birefringence (CB) is a phenomenon in which the polarization of the Cosmic Microwave Background (CMB) radiation is rotated as it travels through space due to the coupling between photons and an axion-like field. We look for a solution able to explain the result obtained from the \textit{Planck} Public Release 4 (PR4), which has provided a hint of detection of the CB angle, $\alpha=(0.30\pm0.11)^{\circ}$. In addition to the solutions, already present in the literature, which need a non-negligible evolution in time of the axion-like field during recombination, we find a new region of the parameter space which allows for a nearly constant time evolution of such a field in the same epoch. The latter reinforces the possibility to employ the commonly used relations connecting the observed CMB spectra with the unrotated ones, through trigonometric functions of the CB angle. However, if the homogeneous axion field sourcing isotropic birefringence is almost constant in time during the matter-dominated era, this does not automatically implies that the same holds true also for the associated inhomogeneous perturbations. For this reason, in this paper we present a full generalized Boltzmann treatment of this phenomenon, that is able, for the first time to our knowledge to deal with the time evolution of anisotropic cosmic birefringence (ACB). We employ this approach to provide predictions of ACB, in particular for the set of best-fit parameters found in the new solution of the isotropic case. If the latter is the correct model, we expect an ACB spectrum of the order of $(10^{-15}\div10^{-32})$ deg$^2$ for the auto-correlation, and $(10^{-7}\div10^{-17})$ $\mu $K$\cdot\,$deg for the cross-correlations with the CMB $T$ and $E$ fields, depending on the angular scale.
- [42] arXiv:2402.16635 (replaced) [pdf, html, other]
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Title: Cosmic Type Ia SN rate and constraints on SN Ia progenitorsComments: Accepted for publication in A&ASubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Type Ia supernovae play a key role in the evolution of galaxies by polluting the interstellar medium with a fraction of iron peak elements larger than that released in the core collapse supernova events. Their light-curve, moreover, is widely used in cosmological studies as it constitutes a reliable distance indicator at extra-galactic scales. Among the mechanisms proposed to explain the Type Ia SNe, the single and double degenerate channels are thought to be the dominant ones, which imply a different distribution of time delays between the progenitor formation and the explosion. In this paper, we aim at determining the dominant mechanism by comparing a compilation of Type Ia SN rates with those computed from various cosmic star formation histories coupled with different delay time distribution functions, and evaluating the relative contributions of both channels. By using a least-squares fitting procedure, we model the observations of Type Ia SN rates assuming different combinations of three recent cosmic star formation rates and seven delay time distributions. The goodness of these fits are statistically quantified by the chi-squared test. For two of the three cosmic star formation rates, the single degenerate scenario provides the most accurate explanation for the observations, while a combination of 34% single degenerate and 66% double degenerate delay time distributions is more plausible for the remaining tested cosmic star formation rates. The wide double degenerate scenario mechanism slightly under-predicts the observations at redshift z>1, unless the cosmic SFR flattens in that regime. On the contrary, although the purely close double degenerate scenario can be ruled out, we cannot rule out a mixed scenario with single and double degenerate progenitors.
- [43] arXiv:2403.04316 (replaced) [pdf, html, other]
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Title: Testing scale-invariant inflation against cosmological dataComments: 39 pages, 4 figures, 1 table. v2: additional references added, clarified some aspects of the analysis with regards to reheating and convergence of the results, clarified differences with respect to earlier results. Version accepted for publication in JCAPSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
There is solid theoretical and observational motivation behind the idea of scale-invariance as a fundamental symmetry of Nature. We consider a recently proposed classically scale-invariant inflationary model, quadratic in curvature and featuring a scalar field non-minimally coupled to gravity. We go beyond earlier analytical studies, which showed that the model predicts inflationary observables in qualitative agreement with data, by solving the full two-field dynamics of the system -- this allows us to corroborate previous analytical findings and set robust constraints on the model's parameters using the latest Cosmic Microwave Background (CMB) data from Planck and BICEP/Keck. We demonstrate that scale-invariance constrains the two-field trajectory such that the effective dynamics are that of a single field, resulting in vanishing entropy perturbations and protecting the model from destabilization effects. We derive tight upper limits on the non-minimal coupling strength, excluding conformal coupling at high significance. By explicitly sampling over them, we demonstrate an overall insensitivity to initial conditions. We argue that the model \textit{predicts} a minimal level of primordial tensor modes set by $r \gtrsim 0.003$, well within the reach of next-generation CMB experiments. These will therefore provide a litmus test of scale-invariant inflation, and we comment on the possibility of distinguishing the model from Starobinsky and $\alpha$-attractor inflation. Overall, we argue that scale-invariant inflation is in excellent health, and possesses features which make it an interesting benchmark for tests of inflation from future CMB data.
- [44] arXiv:2404.17334 (replaced) [pdf, html, other]
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Title: From infinite to infinitesimal: Using the Universe as a dataset to probe Casimir corrections to the vacuum energy from fields inhabiting the dark dimensionComments: figures, tables, and references added; conclusions unchangedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
Promptly after high-resolution experiments harbinger the field of precision cosmology low- and high-redshift observations abruptly gave rise to a tension in the measurement of the present-day expansion rate of the Universe ($H_0$) and the clustering of matter ($S_8$). The statistically significant discrepancies between the locally measured values of $H_0$ and $S_8$ and the ones inferred from observations of the cosmic microwave background assuming the canonical $\Lambda$ cold dark matter (CDM) cosmological model have become a new cornerstone of theoretical physics. $\Lambda_s$CDM is one of the many beyond Standard Model setups that have been proposed to simultaneously resolve the cosmological tensions. This setup relies on an empirical conjecture, which postulates that $\Lambda$ switched sign (from negative to positive) at a critical redshift $z_c \sim 2$. We reexamine a stringy model that can describe the transition in the vacuum energy hypothesized in $\Lambda_s$CDM. The model makes use of the Casimir forces driven by fields inhabiting the incredible bulk of the dark dimension scenario. Unlike the $\Lambda_s$CDM setup the model deviates from $\Lambda$CDM in the early universe due to the existence of relativistic neutrino-like species. Using the Boltzmann solver CLASS in combination with MontePython we confront predictions of the stringy model to experimental data (from the Planck mission, Pantheon+ supernova type Ia, BAO, and KiDS-1000). We show that the string-inspired model provides a satisfactory fit to the data and can resolve the cosmological tensions.
- [45] arXiv:2404.18579 (replaced) [pdf, html, other]
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Title: Dark energy in light of recent DESI BAO and Hubble tensionComments: 8 pages, 4 figureSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Recently, Dark Energy Spectroscopic Instrument (DESI) collaboration based on their first year data has reported a $\gtrsim 3\sigma$ evidence for an evolving dark energy (DE) against the cosmological constant (CC), so the standard $\Lambda$CDM model. However, it is necessary to access the impact of DESI data on the state equation $w_0$-$w_a$ of DE in the Hubble-tension-free cosmologies, where $w_0$ and $w_a$ is the parameters of state equation of DE. In this paper, using recent DESI BAO measurements combined with Planck CMB and Pantheon Plus dataset, we perform the Monte Carlo Markov Chain (MCMC) analysis for the $w_0w_a$CDM model with possible pre-recombination resolutions of the Hubble tension. It is found that though $w_0>-1$ and $w_a<0$ are still preferred, the CC is also $<2\sigma$ consistent, while the bestfit Hubble constant $H_0$ are higher than those with pre-DESI BAO data but without the further exacerbation of $S_8$ tension. According to our results, the resolutions of Hubble tension are likely to suppress the \textit{preference} of DESI for the evolving DE, thus the claim of ruling out the CC needs to be more cautious regarding not only the recent observational data but also the cosmological tensions.
- [46] arXiv:2405.01950 (replaced) [pdf, other]
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Title: Probabilistic Lagrangian bias estimators and the cumulant bias expansionComments: 26 pages, 16 figures, submitted to A&ASubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
The spatial distribution of galaxies is a highly complex phenomenon currently impossible to predict deterministically. However, by using a statistical $\textit{bias}$ relation, it becomes possible to robustly model the average abundance of galaxies as a function of the underlying matter density field. Understanding the properties and parametric description of the bias relation is key to extract cosmological information from future galaxy surveys. Here, we contribute to this topic primarily in two ways: (1) We develop a new set of probabilistic estimators for bias parameters using the moments of the Lagrangian galaxy environment distribution. These estimators include spatial corrections at different orders to measure bias parameters independently of the damping scale. We report robust measurements of a variety of bias parameters for haloes, including the tidal bias and its dependence with spin at a fixed mass. (2) We propose an alternative formulation of the bias expansion in terms of "cumulant bias parameters" that describe the response of the logarithmic galaxy density to large-scale perturbations. We find that cumulant biases of haloes are consistent with zero at orders $n > 2$. This suggests that: (i) previously reported bias relations at order $n > 2$ are an artefact of the entangled basis of the canonical bias expansion; (ii) the convergence of the bias expansion may be improved by phrasing it in terms of cumulants; (iii) the bias function is very well approximated by a Gaussian -- an avenue which we explore in a companion paper.
- [47] arXiv:2405.01951 (replaced) [pdf, other]
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Title: Gaussian Lagrangian Galaxy BiasComments: 21 pages, 12 figures, submitted to A&ASubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Understanding $\textit{galaxy bias}$ -- that is the statistical relation between matter and galaxies -- is of key importance for extracting cosmological information from galaxy surveys. While the bias function $f$ -- that is the probability of forming galaxy in a region with a given density field -- is usually approximated through a parametric expansion, we show here, that it can also be measured directly from simulations in a non-parameteric way. Our measurements show that the Lagrangian bias function is very close to a Gaussian for halo selections of any mass. Therefore, we newly introduce a Gaussian bias model with several intriguing properties: (1) It predicts only strictly positive probabilities $f > 0$ (unlike expansion models), (2) It has a simple analytic renormalized form and (3) It behaves gracefully in many scenarios where the classical expansion converges poorly. We show that the Gaussian bias model describes the galaxy environment distribution $p(\delta | \mathrm{g})$, the scale dependent bias function $f$ and the renormalized bias function $F$ of haloes and galaxies generally equally well or significantly better than a second order expansion with the same number of parameters. We suggest that a Gaussian bias approach may enhance the range of validity of bias schemes where the canonical expansion converges poorly and further, that it may make new applications possible, since it guarantees the positivity of predicted galaxy densities.
- [48] arXiv:2406.09379 (replaced) [pdf, html, other]
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Title: The Stability of the BAO Linear Point under Modified GravityComments: 9 pages, 5 figures, submitted to Physical Review D, v2Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Baryon Acoustic Oscillations (BAOs) are crucial in cosmological analysis, providing a standard ruler, as well as constraints on dark energy. In General Relativity models, the BAO Linear Point - the midpoint between the dip and the peak in the correlation function - has been shown to be rather robust to evolution and redshift space distortions. We show that this remains true even when the gravity model is not General Relativity, at least for $f(R)$ and DGP gravity models which have the same expansion history as the standard $\Lambda$CDM. For the Linear Point to be able to distinguish between modified gravity (MG) and $\Lambda$CDM, survey volumes of order tens of cubic Gpc are required.
- [49] arXiv:2301.05679 (replaced) [pdf, html, other]
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Title: Effective speed of cosmological perturbationsComments: The first version of this paper was submitted to JCAP on February 7th 2023, and the first report was received on January 14th 2024. This is a revised version based on the first referee reportJournal-ref: Phys.Dark Univ. 45 (2024) 101549Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We derive an effective equation and action for comoving curvature perturbations and gravitational waves (GWs) in terms of a time, momentum and polarization dependent effective speed, encoding the effects of the interaction among metric perturbations or with other fields, such as dark energy and dark matter. The structure of the effective actions and equations is the same for scalar and tensor perturbations, and the effective actions can be written as the Klein-Gordon action in terms of an appropriately defined effective metric, dependent on the effective speed. The effective action reproduces, and generalizes to higher order in perturbations, results obtained for GWs in the effective field theory of inflation and dark energy, or for curvature perturbations in systems with multiple scalar fields, encoding in the effective speed the effects of both entropy and anisotropy. The effective approach can also be applied to the solutions of theories with field equations different from the Einstein equations, by defining an appropriate effective energy-momentum tensor. As an example, we show that for a minimally coupled scalar field in general relativity, the effective speeds of curvature perturbations and gravitational waves are frequency and polarization dependent, due to their coupling in the action beyond the quadratic order.
- [50] arXiv:2311.12259 (replaced) [pdf, other]
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Title: Analytical models of supermassive black holes in galaxies surrounded by dark matter halosComments: revtex4-2, no figures. Version to appear in Phys. Lett. B 855 (2024) 138797Journal-ref: Phys. Lett. B 855 (2024) 138797Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
In this Letter, we present five analytical models in closed forms, each representing a supermassive black hole (SMBH) located at the center of a galaxy surrounded by dark matter (DM) halo. The density profile of the halo vanishes inside twice the Schwarzschild radius of the hole and satisfies the weak, strong, and dominant energy conditions. The spacetime are asymptotically flat, and the difference among the models lies in the slopes of the density profiles in the spike and regions far from the center of the galaxy. Three of them represent cusp models, whereas the other two represent core models. With the well-known (generalized) Newman-Janis algorithm, rotating SMBHs with DM halos can be easily constructed from these models.
- [51] arXiv:2402.05720 (replaced) [pdf, html, other]
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Title: Measurements of the Low-Acceleration Gravitational Anomaly from the Normalized Velocity Profile of Gaia Wide Binary Stars and Statistical Testing of Newtonian and Milgromian TheoriesComments: 36 pages, 27 figures, 4 tables, ApJ, revised (Sections 2.1 & 3.4 expanded, Appendix B added)Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Low-acceleration gravitational anomaly is investigated with a new method of exploiting the normalized velocity profile $\tilde{v}\equiv v_p/v_c$ of wide binary stars as a function of the normalized sky-projected radius $s/r_{\rm{M}}$ where $v_p$ is the sky-projected relative velocity between the pair, $v_c$ is the Newtonian circular velocity at the sky-projected separation $s$, and $r_{\rm{M}}$ is the MOND radius. With a Monte Carlo method Gaia observed binaries and their virtual Newtonian counterparts are probabilistically distributed on the $s/r_{\rm{M}}$ versus $\tilde{v}$ plane and a logarithmic velocity ratio parameter $\Gamma$ is measured in the bins of $s/r_{\rm{M}}$. With three samples of binaries covering a broad range in size, data quality, and implied fraction of hierarchical systems including a new sample of 6389 binaries selected with accurate distances and radial velocities, I find a unanimous systematic variation from the Newtonian flat line. With $\Gamma=0$ at $s/r_{\rm{M}}\lesssim 0.15$ or $s\lesssim 1$~kilo astronomical units (kau), I get $\Gamma=0.068\pm 0.015$ (stat) $_{-0.015}^{+0.024}$ (syst) for $s/r_{\rm{M}} \gtrsim 0.7$ or $s\gtrsim 5$~kau. The gravitational anomaly (i.e.\ acceleration boost) factor given by $\gamma_g = 10^{2\Gamma}$ is measured to be $\gamma_g = 1.37_{-0.09}^{+0.10}$ (stat) $_{-0.09}^{+0.16}$ (syst). With a reduced $\chi^2$ test of Newtonian and Milgromian nonrelativistic theories, I find that Newtonian gravity is ruled out at $5.8\sigma$ ($\chi^2_\nu=9.4$) by the new sample (and $9.2\sigma$ by the largest sample used). The Milgromian AQUAL theory is acceptable with $0.5\lesssim \chi^2_\nu\lesssim 3.1$. These results agree well with earlier results with the "acceleration-plane analysis" for a variety of samples and the "stacked velocity profile analysis" for a pure binary sample.
- [52] arXiv:2404.03779 (replaced) [pdf, html, other]
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Title: Primordial black holes and induced gravitational waves in non-singular matter bouncing cosmologyComments: Accepted at JCAPSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We present a novel model-independent generic mechanism for primordial black hole formation within the context of non-singular matter bouncing cosmology. In particular, considering a short duration transition from the matter contracting phase to the Hot Big Bang expanding Universe, we find naturally enhanced curvature perturbations on very small scales which can collapse and form primordial black holes. Interestingly, the primordial black hole masses that we find can lie within the observationally unconstrained asteroid-mass window, potentially explaining the totality of dark matter. Remarkably, the enhanced curvature perturbations, collapsing to primordial black holes, can induce as well a stochastic gravitational-wave background, being potentially detectable by future experiments, in particular by SKA, PTAs, LISA and ET, hence serving as a new portal to probe the potential bouncing nature of the initial conditions prevailed in the early Universe.
- [53] arXiv:2404.13025 (replaced) [pdf, html, other]
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Title: Gravitational wave probes of Barrow cosmology with LISA standard sirensComments: 26 pages, 5 figuresJournal-ref: Journal of Cosmology and Astroparticle Physics (2024)Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We study the Barrow cosmological model, which proposes that quantum gravity effects create a complex, fractal structure for the universe's apparent horizon. We leverage the thermodynamics - gravity conjecture. By applying the Clausius relation to the apparent horizon of the Friedmann - Lemaître - Robertson - Walker universe within this framework, we derive modified field equations where the Barrow entropy is linked to the horizon. We assess the Barrow cosmology against current observations - cosmic microwave background , supernovae , and baryon acoustic oscillations data - and include projections for future Laser Interferometer Space Antenna (LISA) standard sirens (SS). Our numerical results suggest a modest improvement in the Hubble tension for Barrow cosmology with phantom dark energy behavior, compared to the standard cosmological model. Furthermore, incorporating simulated LISA SS data alongside existing observational constraints tightens the limitations on cosmological parameters, particularly the deformation exponent.
- [54] arXiv:2405.09609 (replaced) [pdf, html, other]
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Title: Open star clusters and their asymmetrical tidal tailsPavel Kroupa (Bonn, Prague), Jan Pflamm-Altenburg (Bonn), Sergij Mazurenko (Bonn), Wenjie Wu (Bonn), Ingo Thies (Bonn), Vikrant Jadhav (Bonn), Tereza Jerabkova (Garching)Comments: 22 pages, 14 figures, 1 table, LaTeX, ApJ, in press; replaced version contains minor corrections for consistency with published versionSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Stars that evaporate from their star cluster by the energy equipartition process end up either in a leading or a trailing tidal tail. In Newtonian gravitation and for open star clusters in the Solar vicinity, the tidal threshold, or prah, for escape is symmetrical, such that the leading and trailing tails are equally populated. The data by six independent teams that applied the convergent point method to map out the tidal tails of four open clusters (the Hyades, the Praesepe, Coma Berenices and COIN-Gaia13) using Gaia DR2 and DR3 are here applied to test for the expected symmetry. All tidal tails contain more stars in the leading tail. The combined confidence amounts to an 8 sigma falsification of the prah symmetry. The same test using Milgromian dynamics leads to consistency with the data. More effort needs to be exerted on this matter, but the data indicate with high confidence that the tidal prah of an open star cluster is asymmetrical with the corresponding confidence that Newtonian gravitation is falsified. Open star clusters depopulate more rapidly in Milgromian than in Newtonian dynamics and the COIN-Gaia13 cluster is here found to be nearly completely dissolved. In view of these results, the wide-binary star test and the Keplerian Galactic rotation curve finding are briefly discussed.