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Physics Astrophysics Cosmology and Nongalactic Astrophysics

astro-ph.CO Watch Cosmology and Nongalactic Astrophysics

Wednesday 7 October

Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA

Mass Proxy Quality of Halo Properties in IllustrisTNG and FLAMINGO Simulations: II. Galaxies, Stars, and Black Holes

Eddie Aljamal, August E. Evrard, Arya Farahi et al. (+1 more)

We study the stellar, black hole, and satellite galaxy populations of group- and cluster-scale halos in the IllustrisTNG, TNG-Cluster, and FLAMINGO cosmological hydrodynamical simulations. We characterize the mass-conditioned scaling relations, covariance, conditional likelihoods, and mass proxy quality (MPQ) of integral properties within $R_{\rm 500c}$: total stellar mass ($M_{\star,\,\rm tot}$), brightest central galaxy stellar mass ($M_{\star,\,\rm BCG}$), intracluster light mass ($M_{\star,\,\rm ICL}$), total black hole mass ($M_{\rm BH}$), satellite occupation ($N_{\rm sat}$), and satellite velocity dispersion ($\sigma_{\rm sat,\,1D}$), at $z\in \{0,0.5,1,2\}$. While normalization differences of up to a factor of two emerge among simulations, many properties exhibit remarkably similar mass-localized slopes, intrinsic scatters, and MPQs across halo samples and redshifts. Correlations among stellar, satellite, and gas properties are generally consistent in sign and their dependence on halo mass and redshift, whereas those involving $M_{\rm BH}$ and $N_{\rm sat}$ show greater variation, particularly in TNG-Cluster. Conditional likelihoods are nearly lognormal for many properties, including $M_{\star,\,\rm tot}$, $N_{\rm sat}$, and $\sigma_{\rm sat,\,1D}$, while $M_{\star,\,\rm BCG}$ and $M_{\star,\,\rm ICL}$ are negatively skewed. Among the properties considered here, total stellar mass is the best mass proxy, with a halo mass scatter of $7$-$14\%$, followed by $N_{\rm sat}$ with a mass scatter of $9$-$18\%$. The consistent correlation behavior of $M_{\star,\,\rm ICL}$ highlights its potential for next-generation observational studies. Finally, $\sigma_{\rm sat,\,1D}$ exhibits highly consistent scaling, with mass-independent slope and scatter and a largely neutral correlation structure, suggesting that it is relatively insensitive to astrophysical complexity.
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All authors Eddie Aljamal, August E. Evrard, Arya Farahi, Dylan Nelson

Cosmology and Nongalactic Astrophysics

Debiasing Local Cluster Infall Reveals $\boldsymbol{H_0}$: Application to the Virgo Cluster

Bastien Carreres, David Benisty, Jenny Wagner et al. (+3 more)

Galaxy recession velocities are commonly used to measure the Hubble constant, $H_0$, with peculiar velocities treated as random noise. Around massive clusters, however, these motions can be predicted by the gravitational potential of the central halo, allowing them to be modeled rather than averaged over. Past analyses relied on analytic approximations for the distance-infall-velocity relation, whose accuracy has not been tested using realistic cosmological simulations. We use halos from the IllustrisTNG simulation to quantify the bias and precision of several commonly used Hubble-flow models. We find that widely used fitting functions systematically underestimate $H_0$, whereas the full analytical solution reduces but does not eliminate these biases. We develop a simulation-based method to infer $H_0$ and apply it to TRGB distance samples around the Virgo Cluster. We find $H_0=74.4\pm 2.9$ and $73.4\pm 3.9$ km s$^{-1}$ Mpc$^{-1}$ (stat) for the minor and the major infall models, respectively. Correcting for the bias calibrated on TNG halos, these measurements raise the value of $H_0$ to $81.6 \pm 7.8$ and $87.3 \pm 8.8$ km s$^{-1}$ Mpc$^{-1}$ (stat+sys), where the minor infall model has the smallest bias from the Virgo mocks. We show that statistical errors are dominated by the residual velocity scatter around the infall model, while systematic errors are dominated by the transformation to the structure's comoving frame and halo population variance. These results establish a framework for interpreting cluster infall measurements and explain trends in previous $H_0$ inferences.
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All authors Bastien Carreres, David Benisty, Jenny Wagner, Avery Erlenbach, Dan Scolnic, Adam Riess

Cosmology and Nongalactic Astrophysics

Primordial black holes

V.I. Dokuchaev, Yu.N. Eroshenko, V.V. Nikulin et al. (+3 more)

Primordial black holes, whose formation in the early Universe was first hypothesized by Ya.B.~Zel'dovich and I.D.~Novikov in 1966 (the text of this pioneering article is provided in Appendix II to this review), have attracted increasing attention in recent years. Modern astronomical data across the electromagnetic spectrum, together with observations of gravitational waves and cosmic neutrinos, have revealed a number of unique astrophysical phenomena that may be related to primordial black holes formed in the pre-stellar cosmological epoch. This review describes various models of primordial black hole formation, as well as methods for testing these models with astronomical and astrophysical observations. In particular, we discuss in detail the formation of primordial black holes and their clusters through the collapse of closed domain walls and through effects associated with extra spatial dimensions of the Universe.
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All authors V.I. Dokuchaev, Yu.N. Eroshenko, V.V. Nikulin, K.A. Postnov, S.G. Rubin, V.D. Stasenko

Cosmology and Nongalactic Astrophysics

Feedback-Conditional 3D Reconstruction of Cosmic Baryons with Flow Matching

Maryam Hussaini, Aizhan Akhmetzhanova, Carolina Cuesta-Lazaro et al. (+1 more)

The complex relationship between galaxies and diffuse gas at large scales depends strongly on astrophysical feedback and cosmology. The dispersion measure (DM) of Fast Radio Bursts (FRBs) is a column of cosmic baryon density and is dominated by the intergalactic medium, which is not necessarily captured by traditional halo model prescriptions. We introduce a generative model to reconstruct 3D gas density fields from galaxy surveys, including redshift space distortions. The probabilistic model is trained on the CAMELS50 simulation suite (IllustrisTNG) and learns to predict the posterior distribution of gas fields conditioned on stellar mass-weighted galaxy density, cosmological parameters, the minimum stellar mass threshold for the galaxy sample, and the baryon suppression power spectrum as a measure of baryonic feedback. Our method uses the 3D gas reconstruction to estimate per-sightline FRB DMs and their posteriors. We validate the model on test boxes by showing agreement between predicted and true DM across individual lines of sight and the overall DM distribution. The model generalizes to a box size $\sim$\,4$^3$ times larger in volume than the training boxes and can cover the volumes spanned by cosmological FRB sightlines. The model's 3D gas density predictions vary with input power spectrum and feedback scenarios, offering an inference path to constrain feedback models from FRBs and other probes such as X-rays, the SZ effect, and weak lensing.
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All authors Maryam Hussaini, Aizhan Akhmetzhanova, Carolina Cuesta-Lazaro, Liam Connor

Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.HE

The Origin of the Fermi Halo-like Emission: A New Model of the Fermi Bubbles

Ilias Cholis, Leo Qiyuan Hu and Yi-Ming Zhong

We study the gamma-ray sky at high latitudes for energies between 0.3 and 900 GeV. We search for a contribution in the high-latitude sky and in the region of the Galactic Stellar Halo that would be beyond known astrophysical emissions, i.e., the galactic diffuse emission, the isotropic mostly extragalactic gamma-ray background, the Fermi Bubbles, Loop I, the contribution from the Galactic Center Excess, and the known point and extended gamma-ray sources detected by the Fermi-LAT Collaboration. We perform a sequence of template fits to the Fermi gamma-ray data, testing different regions of interest of the galactic sky, utilizing a large set of alternative galactic diffuse emission models, and implementing alternative fitting schemes to assess the impact of increased modeling complexity of the gamma-ray sky. We find that the halo-like emission recently reported by Totani (2025) is real, but it is likely due to emission from the Fermi Bubbles rather than dark matter annihilation in the Galactic halo. We provide new templates for the Fermi Bubbles, including an updated model for the Flat Bubbles and a detailed model of their substructures, the Cocoons and the Inner Bubbles. In combination, these components account for the previously reported halo-like emission. We also estimate the associated fluxes and spectral properties of the Flat Bubbles, the Inner Bubbles, and the Cocoons. This updated model for the Fermi Bubbles provides new input toward understanding their origin.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th

General Spin-1 Dynamics During Inflation: Microcausality Constraints and Cosmological Collider Signals

Trevor Cheung, Carlos Duaso-Pueyo, David Stefanyszyn et al. (+1 more)

We construct the general theory of a spin-1 field propagating on an inflationary background consistent with scale invariance, rotations, Bunch-Davies conditions and microcausality. Our Boostless Proca theory generalises the usual massive Proca theory to a Lagrangian with 5 free parameters: 4 corresponding to parity-even terms and a single parity-odd term. We impose three degrees of freedom from the outset and find that microcausality, the statement that field operators vanish outside the lightcone, requires the kinetic terms to be gauge invariant. We couple this spin-1 state to the inflaton and study the signatures it imprints on cosmological correlators. We find no new signals for the bispectrum meaning that the known signals are the most general thereby providing a very clean model-independent probe of new physics in this leading form of non-Gaussianity. For the trispectrum and higher-point functions, the boostless Proca theory produces new shapes with all 5 parameters in principle measurable.
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All authors Trevor Cheung, Carlos Duaso-Pueyo, David Stefanyszyn, Dong-Gang Wang

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Matter-Antimatter Asymmetry from Dirac-Majorana Flip-Flop

Debasish Borah, Arnab Dasgupta, Debalina Nandy et al. (+2 more)

The observed matter-antimatter asymmetry can be generated dynamically via leptogenesis, where a non-zero lepton asymmetry is generated first and then gets converted into baryon asymmetry via sphalerons. Creation of non-zero lepton asymmetry typically requires lepton number violation (LNV) which, within the seesaw framework, results in the Majorana nature of light neutrinos. With no signs of LNV at terrestrial experiments, we propose a novel leptogenesis scenario where LNV occurs at high temperatures while zero-temperature physics is consistent with the pure Dirac nature of neutrinos. In a concrete model of this "Dirac-Majorana flip-flop", the right chiral parts of Dirac neutrinos initially acquire a large Majorana mass in the early Universe when a singlet scalar field with two units of lepton number acquires a non-zero vacuum expectation value (VEV), thereby facilitating leptogenesis from out-of-equilibrium decay of heavy Majorana fermions. At lower temperatures, the VEV of the scalar singlet gets restored to zero to be consistent with lepton number conservation. A first-order VEV-restoring phase transition can lead to observable gravitational waves, while light Dirac neutrinos can generate detectable dark radiation at cosmic microwave background experiments.
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All authors Debasish Borah, Arnab Dasgupta, Debalina Nandy, Indrajit Saha, Harman Singh

Cosmology and Nongalactic Astrophysics

Primordial black holes as a natural consequence of scale-invariance

TaeHun Kim and Wan-Il Park

We show that a scale-invariant $U(1)$ gauge theory can naturally realize large curvature perturbations around the end of thermal inflation, seeding the formation of primordial black holes (PBHs). The allowed nonminimal gravitational interaction $\xi$ of the Higgs field induces a Hubble-scale negative mass-squared term for positive $\xi \sim \mathcal{O}(1)$, and triggers a second order phase transition that ends thermal inflation while keeping the extra $e$-folds small. This sharp contrast to the minimally coupled case allows the gauge coupling to be much smaller than unity. It turns out that field fluctuations are dominated by thermal fluctuations around the onset of the phase transition, and sufficiently amplified to produce an appreciable amount of PBHs with a wide range of possible masses. The associated scalar-induced gravitational waves (GWs) are accompanied by cosmic-string induced GWs coming from the breaking of the $U(1)$ symmetry. As a result, the generated PBH population can have a correlated GW signature relevant to pulsar timing arrays, space-based interferometers, or ground-based detectors.
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Cosmology and Nongalactic Astrophysics

Interpretation of Nanohertz Gravitational Waves via Cosmic Strings in Post-BBN Matter and Kination Domination

Raymond T. Co, Siu Cheung Lam and Taegyu Lee

Recent pulsar timing array (PTA) observations have reported evidence for a common low frequency signal consistent with a stochastic gravitational wave background. In this work, we investigate the cosmic string interpretation of this signal in a non-standard cosmological history between big bang nucleosynthesis and recombination, featuring an early matter-dominated era followed by a kination phase. Previous studies have shown that kination can significantly modify the cosmic-string-induced gravitational wave spectrum, generating characteristic features in the nanohertz range and producing a shape consistent with current PTA data. Building on this, we perform separate Bayesian analyses of the NANOGrav 15-year and EPTA DR2 New+ datasets to quantify the extent to which such a cosmological history is favored by the data. We find substantial evidence for a transient period of matter and kination domination over the standard cosmological history within a cosmic-string interpretation of the gravitational-wave signal, with a Bayes factor $3.63^{+0.22}_{-0.21}$ from the NANOGrav 15-year dataset, while leaving the inferred cosmic-string tension nearly unchanged. This cosmic-string-dominated scenario is particularly relevant if the contribution from supermassive black hole binaries (SMBHBs) is small, as hinted at by astrophysical population simulations. Compared with a scenario where gravitational waves are produced purely by SMBHBs, cosmic-string interpretations with and without an additional contribution from SMBHBs, across both expansion histories and datasets, reveal no significant preference.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Impact of site-dependent noise configurations on Einstein Telescope science at low frequency

Francesco Crescimbeni, Matteo Di Giovanni, Davide Rozza et al. (+9 more)

We investigate how site-dependent Newtonian noise configurations affect the scientific performance of the Einstein Telescope (ET), a third-generation gravitational-wave observatory. We compare the baseline triangular and 2L detector geometries, with arm lengths of 10km and 15km, respectively, under three site-dependent noise scenarios constructed from measurements in the Euregio Meuse-Rhine region, Lausitz, and Sardinia. The differences among the adopted sensitivities are concentrated mainly below 10Hz and thus have the greatest impact on science cases that rely on the early inspiral of light objects, or on massive systems whose characteristic frequencies lie in the low-frequency band. We quantify these effects for four ET science cases: (1) detection and parameter estimation of intermediate-mass black-hole binaries; (2) post-Newtonian tests of General Relativity based on the early inspiral; (3) black-hole ringdown spectroscopy with massive remnants; and (4) early-warning and sky-localization capabilities for binary neutron-star mergers. Using Bayesian parameter estimation, we find that improved low-frequency sensitivity can significantly enhance ET's scientific performance across all four cases. Within the configurations considered here, a 2L network in which at least one of the two L-shaped interferometers attains a noise level comparable to that assumed for the Sardinian site generally provides better performance than the triangular configurations. Conversely, strong degradation of the sensitivity below 10Hz can substantially reduce, and in some regimes offset, the scientific gains expected from increasing the arm length from 10km to 15km. These results highlight the importance of site selection and low-frequency noise mitigation, alongside network geometry, for fully realizing ET's scientific potential in the largely unexplored frequency band below 10Hz.
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All authors Francesco Crescimbeni, Matteo Di Giovanni, Davide Rozza, Andrea Contu, Alessandro Cardini, Domenico D'Urso, Carlo Giunchi, Luca Naticchioni, Marco Olivieri, Mike Lindner, Andreas Rietbrock, Paolo Pani

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

A weakly modelled view of the joint compact-binary mass plane: population structure and spectral-siren cosmology

Viola De Renzis, Alessandro Agapito and Michele Mancarella

We introduce a flexible mixture model for the joint source-frame component-mass distribution of compact binaries, inferred simultaneously with cosmology, together with a framework that identifies structures in the reconstructed density, quantifying their posterior stability, local prominence, and cosmological relevance. Applied to GWTC-5.0, the workflow clarifies several familiar and emergent structures. The $\sim35~M_\odot$ feature is classified as a clear near-equal-mass peak despite an ambiguous interpretation in the primary-mass projection. A weaker unequal-mass concentration near $(21,12)~M_\odot$ is recovered frequently but with lower prominence. A tentative joint transition near $60~M_\odot$ appears at mildly unequal masses, with a more robust manifestation in the primary-mass projection. For cosmology, the two-dimensional mass model constraint on $H_0$ is $33\%$ narrower than a model that flexibly reconstructs only the primary mass, and only $\sim~10\%$ wider than analyses based on strongly parameterized one-dimensional spectral structure. At the feature level, we show that the $\sim10~M_\odot$ and $\sim35~M_\odot$ concentrations depend on $H_0$ mainly through a common scale which captures the entire $\sim~(1+z)$ cosmological rescaling of both masses; the intermediate unequal-mass feature instead retains residual dependence in the orthogonal mass-ratio direction. More generally, we argue that population prominence, formal inclusion in an astrophysical feature catalogue, and cosmological relevance need not coincide. These results suggest that a genuinely two-dimensional view may be required to fully exploit spectral-siren information. Our workflow provides a reproducible way to detect population structure and identify which aspects of its geometry are associated with spectral-siren constraints. The feature finder is directly applicable to other population reconstructions.
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Cosmology and Nongalactic Astrophysics

Constraints on Primordial Oscillatory Features from the Power Spectrum and Bispectrum of Redshift-Space Galaxy Clustering in DESI DR1

Shi-Fan Chen, Anton Chudaykin, Mikhail M. Ivanov et al. (+2 more)

We constrain oscillatory features in the primordial power spectrum using the public DESI DR1 galaxy and quasar clustering data. Our analysis is based on a custom pipeline for the redshift-space power spectrum and bispectrum of the six main DESI DR1 tracers, modeled with the Lagrangian effective field theory,which provides a principled resummation of the non-linear damping of the features. We consider oscillations that are linear and logarithmic in wavenumber, and, for the first time, consistently include the galaxy bispectrum in the search. We also study the dependence of the results on the background cosmology, which is important given the tension between the DESI BAO and Planck data within the baseline cosmological model. Marginalizing over $\Lambda$CDM parameters, we bound the amplitude of linear and logarithmic oscillations to $A_{\rm lin}<0.033$ and $A_{\rm log}<0.035$ respectively (at 95$\%~$CL) across the frequency ranges $\omega_{\rm lin}^{\rm phys}\in(20,800)~{\rm Mpc}$ and $\omega_{\rm log}\in(2.5,80)$. The constraints reach percent-level precision away from the frequencies degenerate with the baryon acoustic oscillations (BAO). Fixing to the Planck 2018 cosmology, the bounds tighten to $A_{\rm lin}<0.024$ and $A_{\rm log}<0.031$, but in this case we also find a $\simeq 3\sigma$ global preference for a logarithmic feature with $\omega_{\rm log}\simeq 15$, dominated by the LRG2 sample, whose local wavelength matches the apparent BAO scale at wavenumbers best constrained by DESI. Since the preference for this feature disappears once the cosmological parameters are varied, we expect that it is a manifestation of the known distance-scale tension between the DESI and Planck data rather than a primordial signal. Our analysis thus emphasizes the importance of cosmology marginalization in searches for primordial features.
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All authors Shi-Fan Chen, Anton Chudaykin, Mikhail M. Ivanov, Oliver H. E. Philcox, Mario Ballardini

Cosmology and Nongalactic Astrophysics

Angular Baryon Acoustic Oscillations with DESI DR1

Anya Paopiamsap, Juan Mena-Fernández, Héctor Gil-Marín et al. (+1 more)

We present the angular BAO analysis using DESI DR1 data as a complementary approach to DESI's primary 3D BAO analysis. We perform the analysis using the two-point angular correlation function $w(\theta)$ in tomographic redshift shells of $\delta z = 0.02, 0.05$, spanning the redshift range $0.4 < z < 2.1$ using the DESI tracers: LRG1, LRG2, LRG3+ELG1, ELG2 and QSO. The main benefit is that it requires no fiducial cosmology to convert redshifts into distances and yields a direct measurement of the transverse dilation parameter $\alpha_{\perp}(z)$. We fit each tracer with a single shared $\alpha_{\perp}(z)$ using templates constructed in a fiducial cosmology and a mock-based covariance from 1000 EZmock realisations. We measure $\alpha_\perp$ to $2.5$ – $4.2\%$ precision in each tracer bin. Compared to the $D_M/r_{\rm d}$ measurements obtained from the DESI DR1 3D analysis for the same tracers, our results are consistent within the statistical precision. We find no evidence for a shift in the transverse BAO scale between the 2D and 3D analyses. Flat $\Lambda$CDM fits to $\alpha_\perp(z)$ alone give $\Omega_{\rm m} = 0.198^{+0.045}_{-0.068}$, $1.6\sigma$ below the DESI 3D value, and the pull is dominated by the $z =1.49$ QSO bin, whose $\alpha_\perp(z=1.49)=1.058\pm0.028$ sits $\sim 2\sigma$ above the fiducial. Restricting to LRGs and ELGs only, our $\Omega_{\rm m}$ and $H_0 r_{\rm d}$ agree with the 3D transverse-only fit over the same bins to better than $0.1\sigma$. With an additional BBN prior, the full 2D sample gives $H_0 = 63.9^{+1.9}_{-3.3}\, {\rm km\,s^{-1}\,Mpc^{-1}}$. This pipeline is implementable on forthcoming DESI data releases, where the increase in volume and sampling density will determine if the QSO offset persists and will also tighten 2D BAO constraints.
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All authors Anya Paopiamsap, Juan Mena-Fernández, Héctor Gil-Marín, Licia Verde

Cosmology and Nongalactic Astrophysics

Effective Neutrino Mass and Apparent Phantom Crossing

Gabriel Rodrigues, Jamerson Rodrigues, Simony Santos da Costa et al. (+1 more)

Recent cosmological constraints on the sum of neutrino masses have reached, and in some analyses fallen below, the minimum value implied by the normal mass ordering, suggesting a possible tension with neutrino-oscillation measurements. We investigate whether this discrepancy can be alleviated in a mass-varying-neutrino (MaVaN) cosmology in which a canonical pseudo-Nambu-Goldstone boson (pNGB) drives late-time cosmic acceleration and controls the masses of massive neutrinos through an exponential coupling. Using current cosmic microwave background, baryon acoustic oscillation, and type Ia supernova data, we reconstruct the neutrino-mass evolution and show that the cosmologically inferred effective neutrino mass can fall below the present-day normal-ordering floor while remaining consistent with oscillation constraints. The same interaction produces a distinctive late-time signature, with 96% of the posterior expansion histories exhibiting a crossing of the apparent phantom divide, $w_{\rm app}=-1$, at $z_{\rm cross}=0.90^{+0.28}_{-0.13}$ at 68% C.L. The underlying scalar field nevertheless remains canonical, with $w_\phi \geq -1$. Our results therefore show that neutrino mass variation can simultaneously alleviate the apparent neutrino-mass tension and generate the phantom-crossing behavior favored by current cosmological data, without introducing a phantom field or violating the null energy condition.
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All authors Gabriel Rodrigues, Jamerson Rodrigues, Simony Santos da Costa, Jailson Alcaniz

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Phenomenology of axion-meson mixing and scattering processes

Noé Duarte-González

We study the mixing between a generic axion-like particle (ALP) and the light pseudoscalar mesons within chiral perturbation theory ($\chi$PT), and its consequences for low-energy scattering and decay processes. Starting from the most general ALP effective Lagrangian, we derive the ALP-meson kinetic and mass mixing induced at leading order in the ALP decay constant and isospin breaking for arbitrary ALP masses. As a result, we obtain the physical ALP mass to $\mathcal{O}(F^2/f_a^2)$, recovering the QCD-axion limit and finding that any ALP with a vanishing bare mass shares the QCD-axion mass. We provide a compact parameterization of every four-body amplitude involving pseudoscalar mesons and an arbitrary number of ALPs. As an illustration, we show the $K\bar{K}\to P^0a$ scattering. The framework applies for general ALP masses and couplings and consistently incorporates isospin breaking, essential for otherwise forbidden processes.
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Cosmology and Nongalactic Astrophysics

Cosmic Birefringence from Large Lepton Asymmetry

Kentaro Kasai and Ippei Obata

Cosmic birefringence, the rotation of the polarization plane of CMB photons, provides an intriguing probe of physics beyond the Standard Model. In this paper, we investigate a vector Chern-Simons coupling between the neutrino current and photons as a possible origin of isotropic cosmic birefringence. Firstly, we perform the first analysis of anisotropic cosmic birefringence induced by the neutrino current. We find that the anisotropic signal sourced by lepton-number isocurvature fluctuations can be important on large scales, whereas on small scales, the anisotropic signal induced by gravitational effects becomes dominant comparing with the axion-like particle (ALP) scenario. Secondly, we show that a large lepton asymmetry generated through the Affleck-Dine mechanism can successfully account for the observed isotropic birefringence, and discuss its possible connection to the recently reported low helium-4 abundances in Subaru EMPRESS and Atacama Cosmology Telescope (ACT).
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Cosmology and Nongalactic Astrophysics

LazyTB: Extended LTB-solutions with Multiple Interacting Fluids

Kimmo Kainulainen, Enrico D. Schiappacasse, Linda Tenhu et al. (+1 more)

We present a low entry barrier numerical code LazyTB that solves the Einstein equations in the ADM-formulation for a general spherically symmetric problem with an arbitrary number of fluids with user defined equations of state and optional interactions between the fluids mediated by drag-vectors. We present the ADM equations in terms of carefully chosen dimensionless variables that avoid some numerical instabilities by analytic cancellation of potentially diverging terms. We demonstrate the code by applying it to a number of examples including the standard LTB model, a model with radiation and dark matter, a polytropic dark energy model with a non-vanishing sound speed and a model with coupled interacting dark matter and dark energy. We also implement a suite of diagnostic tools, including ray-tracing algorithms, that allow extracting physical observables such as luminosity distances for observers at arbitrary locations from the simulations. The code is built to be easy to extend also beyond the late-universe applications considered in the examples of this paper. LazyTB is available at https://github.com/ollijvaisanen/LazyTB.
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All authors Kimmo Kainulainen, Enrico D. Schiappacasse, Linda Tenhu, Olli Väisänen

Cosmology and Nongalactic Astrophysics

Scalar Perturbations and Induced Gravitational Waves from First-Order Phase Transitions in Lattice Simulations

Yuan-Jie Li, Jing Liu, Zhuan Ning et al. (+2 more)

Cosmological first-order phase transitions can generate curvature perturbations through inhomogeneous quantum tunneling, as studied previously on superhorizon scales. In this work, we for the first time conduct three-dimensional lattice simulations that incorporate scalar metric perturbations and radiation perturbations, covering a range from bubble wall scales to super-horizon scales. We obtain the precise scalar perturbation power spectrum and the probability density function of energy density perturbations. Furthermore, we simulate the gravitational-wave energy spectra generated by each source during the first-order phase transition, including the scalar field itself, scalar metric perturbations, and the energy density and velocity perturbations of radiation. For gravitational waves, the contribution from other sources can exceed $1/3$ of that from the scalar field at superhorizon scales. Additionally, we compare the effects of different values of the transition strength and rate on the results. This paper provides more accurate numerical results for research aimed at detecting or constraining first-order phase transitions via gravitational waves and curvature perturbations.
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All authors Yuan-Jie Li, Jing Liu, Zhuan Ning, Xiang-Xi Zeng, Zong-Kuan Guo

Tuesday 6 October

Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.HE

An All-Sky Search for Moving Gamma-Ray Sources with Fermi-LAT

Dou Lai and James Unwin

Nearby compact gamma-ray sources can move appreciably during the Fermi-LAT mission and thus evade searches that assume a stationary sky. Compact dark matter halos, dark matter spikes around primordial black holes (PBH), and evaporating PBH provide potential examples. We perform a novel all-sky search for steady point sources moving at 0.25 deg/yr-0.8deg/yr in ten years of 1-100 GeV Fermi-LAT data. For a transverse speed of 200 km/s, this angular range probes distances of roughly $3.0\times10^3$ AU to $9.7\times10^3$ AU. We find 577 candidate tracks, consistent with $533\pm27.0$ tracks in time-scrambled skies. We place a model-independent 90% upper limit of 80.8 recovered signal tracks. At peak calibrated sensitivity, this corresponds to fewer than 123 steady, full-sky sources with an incident $E^{-2}$ photon spectrum. We give the calibrated detection efficiency of the search to steady point sources and use it to derive illustrative constraints on both evaporating PBHs and PBHs surrounded by annihilating dark matter halos.
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Cosmology and Nongalactic Astrophysics

The Impact of Galaxy Catalogue Completeness with GLADE+ on Dark Siren Cosmology: A Line-of-Sight Prior Analysis of GWTC-3 Events

Juan Esteban Rivera, Antonio Enea Romano, Rachel Gray et al. (+2 more)

Cosmological parameters can be estimated from dark sirens, gravitational waves events without electromagnetic counterpart, by using inference methods which estimate statistically the source redshift from galaxy catalogs. We study the effects of applying different apparent magnitude cuts to the GLADE+ catalog, analyzing events from the third LIGO-Virgo-KAGRA gravitational wave transient catalog (GWTC-3), consisting of 42 binary black holes, 3 neutron star black hole systems and the event GW190425 associated to a binary neutron star coalescence. We find that the inclusion of fainter galaxies has no significant effects on the joint analysis of almost all the events, while for some single well localized event, the effects can be more important, in particular for the event GW190814. To understand why inclusion of fainter galaxies in general has negligible impact on the estimation of cosmological parameters, we compare the redshift of the events with the redshift distribution of dimmer galaxies, and find that most of them are not located in redshift proximity of the events, explaining the limited impact of their inclusion. The event, GW190814 is an exception, as its distance localization, converted into redshift, overlaps with fainter galaxies, unlike what happens for other events, which are farther away. These results show the importance of event localization and catalog depth in determining the impact of catalog completeness on cosmological parameters estimation. To check quantitatively what is the information gained by adding fainter galaxies we have analyzed its impact on the line of sight prior calculation. Based on the results for GW190814 we expect that fainter galaxies will play a more significant role in the estimation of cosmological parameters also for the joint analysis of multiple events, when deeper catalogs will be available.
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All authors Juan Esteban Rivera, Antonio Enea Romano, Rachel Gray, Sergio Vallejo-Peña, Riccardo Sturani

Cosmology and Nongalactic Astrophysics · Cross-listed from physics.comp-ph

Convergence of Roberts flow dynamos in Eulerian and Lagrangian codes

Nikyta Shchutskyi, Axel Brandenburg and Matthieu Schaller

Standard benchmark tests for numerical magnetohydrodynamics codes focus on one- and two-dimensional problems that ignore the possibility of dynamos, i.e., an exponential instability converting kinetic energy into magnetic energy. They also tend to ignore magnetic helicity conservation that can have dramatic effects in periodic domains. The existence of magnetic diffusion is crucial for dynamos, as was exemplified by the impossibility of finding dynamo solutions when using Euler potentials, which is a perfectly valid approach in the absence of magnetic diffusion. The Roberts flows~I, II, III, and IV are two-dimensional flows that support three-dimensional dynamos, all of which are also large-scale dynamos in the sense that their planar averages are of significant strengths, even though flow~II is pointwise non-helical. Here we demonstrate the numerical convergence properties of solutions obtained using discretisation schemes of second, sixth, and tenth order in the mesh width in the Pencil Code, compare the results with the SPH-based SWIFT code, and present a list of averaged quantities that facilitate their use in characterising the solutions as benchmarks. In addition, we present a procedure to obtain two-dimensional time-independent magnetic field visualisation for all Roberts flows, and perform per-pixel comparison between the Pencil and SWIFT codes. The rich combination of features makes Roberts flows an excellent dynamo benchmark for the direct numerical simulations of magnetohydrodynamics equations.
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Cosmology and Nongalactic Astrophysics

Measuring the Clustering of tSZ-Selected Galaxy Clusters with SPT-3G

E. S. Martsen, D. Anbajagane, L. E. Bleem et al. (+96 more)

We present a measurement of the spatial clustering of galaxy clusters selected via the thermal Sunyaev-Zel'dovich (tSZ) signal. Using a cluster catalog derived from five years of SPT-3G Main field survey data, we define a sample spanning $0.25 < z < 1.1$, as well as two subsamples spanning $0.25 < z < 0.67$ and $0.67 < z < 1.1$. We detect cluster clustering at $12.8\sigma$, the highest significance detection in a tSZ-selected sample to date. We detail our analytic modeling and theoretical covariance models, including validations performed on synthetic data created from numerical simulations. The measurements and inference pass a variety of null tests, and show minimal sensitivity to common spatially varying systematics that impact optical clustering measurements, such as depth, stellar density, and extinction. We use our pipeline to place constraints on the halo bias of our sample, $b_{\rm{h}} = 5.30\pm{0.24}$, and the normalization of our mass-observable relation, $\rm{lnA}_{sz} = 0.43^{+0.17}_{-0.21}$. We also demonstrate the useful synergies between cluster clustering and abundance measurements, which manifest in the breaking of high-dimensional parameter degeneracies. Samples of clusters selected using the tSZ effect serve as a unique probe of clustering that is insensitive to common systematics, relative to conventional galaxy datasets, and the detection significance of this measurement will increase substantially with existing data from the SPT-3G Ext-10k survey and upcoming data from SPT-3G+ and the Simons Observatory.
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All authors E. S. Martsen, D. Anbajagane, L. E. Bleem, B. A. Benson, E. Anderes, A. J. Anderson, B. Ansarinejad, M. Archipley, L. Balkenhol, D. R. Barron, P. S. Barry, K. Benabed, A. N. Bender, F. Bianchini, S. Bocquet, F. R. Bouchet, E. Camphuis, M. G. Campitiello, J. E. Carlstrom, J. Carron, C. L. Chang, P. M. Chichura, A. Chokshi, T.-L. Chou, A. Coerver, T. M. Crawford, C. Daley, T. de Haan, K. R. Dibert, M. A. Dobbs, M. Doohan, D. Dutcher, C. Feng, K. R. Ferguson, N. C. Ferree, K. Fichman, A. Foster, N. Frontiere, S. Galli, A. E. Gambrel, A. K. Gao, F. Ge, S. Gradis, F. Guidi, S. Guns, N. W. Halverson, E. Hivon, G. P. Holder, W. L. Holzapfel, J. C. Hood, A. Hryciuk, N. Huang, T. Jhaveri, F. Kéruzoré, A. R. Khalife, M. Klein, L. Knox, K. Kornoelje, C.-L. Kuo, P. Larsen, K. Levy, Y. Li, A. E. Lowitz, C. Lu, G. P. Lynch, T. J. Maccarone, A. S. Maniyar, F. Menanteau, M. Millea, J. Montgomery, Y. Nakato, T. Natoli, Y. Omori, A. Ouellette, Z. Pan, P. Paschos, K. A. Phadke, K. Prabhu, W. Quan, M. Rahimi, A. Rahlin, C. L. Reichardt, M. Rouble, J. E. Ruhl, A. C. Silva Oliveira, A. Simpson, J. A. Sobrin, A. A. Stark, J. Stephen, C. Tandoi, C. Trendafilova, J. D. Vieira, A. G. Vieregg, A. Vitrier, Y. Wan, N. Whitehorn, W. L. K. Wu, M. R. Young, J. A. Zebrowski

Cosmology and Nongalactic Astrophysics

The BUFFALO Survey : The Subhalo Mass Function for Abell 2744 with Strong+Weak Gravitational Lensing

Nency R. Patel, Mathilde Jauzac, Anna Niemiec et al. (+16 more)

We present a combined strong and weak gravitational lensing mass model of the massive merging galaxy cluster Abell 2744 (z = 0.308). The mass reconstruction combines strong-lensing constraints in the cluster core with weak-lensing measurements derived from deep imaging with the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST), enabling a reconstruction of the projected mass distribution from the core to the cluster outskirts. Using the resulting mass map, we identify cluster substructures and construct the subhalo mass function (SHMF) for Abell 2744. To interpret the observed substructure population, we apply identical detection methods to projected mass maps of massive galaxy clusters from the BAryons and HAloes of MAssive Systems (BAHAMAS) simulations. We observe a systematic excess of detected substructures in Abell 2744 compared to BAHAMAS. We interpret this excess as likely reflecting Abell 2744's exceptionally disturbed dynamical state, characterised by complex ongoing mergers, rather than tension with $\Lambda$Cold Dark Matter ($\Lambda$CDM) or self-interacting dark matter (SIDM) predictions. Although confirming this interpretation will require extending the analysis to a larger sample of clusters spanning a range of dynamical states.
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All authors Nency R. Patel, Mathilde Jauzac, Anna Niemiec, Guillaume Mahler, David Lagattuta, David Harvey, Johannes Schwinn, Andrew Robertson, Lukas J. Furtak, Sownak Bose, Alastair Edge, Anton Koekemoer, Jose Diego, Andreas Faisst, Eric Jullo, Marceau Limousin, Richard Massey, Derek Perera, Sut-Ieng Tam

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

An early $Z'$ dominance: dark matter, gravitational waves & collider probes

Basabendu Barman, Nayan Das, Partha Kumar Paul et al. (+1 more)

In the minimal anomaly-free gauged B$-$L extension of the Standard Model (SM), we consider a scenario in which the energy density of the new Abelian gauge boson dominates the Universe prior to big bang nucleosynthesis (BBN), resulting in an early matter-dominated (EMD) era. Taking one of the three right-handed neutrinos to be a decaying dark matter (DM) candidate, we investigate its production during this EMD phase. We show that the region of parameter space consistent with the relic abundance lies within the projected sensitivity of several gravitational wave (GW) experiments, where the GW signal arises from cosmic strings formed during the spontaneous breaking of the gauged B$-$L symmetry. We further constrain the viable parameter space using bounds from collider experiments, beam dump experiments, BBN, and ultra high energy neutrino observations, demonstrating the complementarity of multi-messenger probes in exploring physics beyond the SM as well as non-standard cosmological histories prior to BBN.
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All authors Basabendu Barman, Nayan Das, Partha Kumar Paul, Narendra Sahu

Cosmology and Nongalactic Astrophysics

Full-Shape Analysis of the Redshift-Space Galaxy Trispectrum in the EFTofLSS

Beatriz Tucci and Oliver H. E. Philcox

The effective field theory of large-scale structure (EFTofLSS) program for spectroscopic galaxy surveys has been remarkably successful for cosmological inference from the galaxy power spectrum and bispectrum. However, a full-shape cosmological analysis including the galaxy trispectrum has not yet been performed. In this work, we develop the tree-level EFTofLSS model of the galaxy trispectrum, including all relevant ingredients: galaxy bias, stochasticity, infrared resummation, Fingers-of-God (FoG) counterterms, Alcock-Paczynski distortions, binning effects, and covariance. We validate the model by performing cosmological inference using the one-loop galaxy power spectrum, tree-level bispectrum, and tree-level trispectrum measured from dark-matter halos in 25 AbacusSummit $N$-body simulations, whose large effective volume ($V=200h^{-3}\text{Gpc}^3$) allows us to test the precision of our model and determine scale cuts in both real-space and redshift-space. We also study the cosmological information content of the galaxy trispectrum in a DESI-like volume, finding that its inclusion can improve constraints e.g., on $\omega_{\rm cdm}$ by up to $15\%$. We further find that the maximum scale cut can be extended to $k_{\max}=0.12h\mathrm{Mpc}^{-1}$ depending on the tracer, thanks to our improved treatment of FoG effects. This provides a path towards using the three-dimensional large-scale structure to constrain new-physics scenarios with distinctive signatures in the trispectrum, in particular primordial non-Gaussianity.
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Cosmology and Nongalactic Astrophysics

Mitigating prior-volume effects in galaxy clustering by adopting Mpc over Mpc/h units

Andrea Pezzotta, Alejandro Pérez-Fernández, Giosuè Gambardella et al. (+4 more)

We investigate prior-volume effects in Bayesian analyses of galaxy clustering based on state-of-the-art models, such as the EFT and the VDG$_\infty$ model. We show that these effects are largely driven by imposing priors on the model parameters defined in ${\rm Mpc}/h$ units, thereby introducing a spurious correlation with the Hubble parameter $h$, and that they can be strongly mitigated by adopting a more physically motivated formulation in ${\rm Mpc}$ units. We test this approach using a set of synthetic data vectors designed to reproduce the clustering signal expected in a Stage-IV survey across a range of cosmological models, including $\Lambda$CDM, $K$CDM, $w$CDM, and $w_0w_a$CDM. We find that the resulting constraints are largely free from shifts induced during the marginalisation process, even in the challenging $w_0w_a$CDM runs, reducing discrepancies with the fiducial values from several standard deviations to well within $1\sigma$. The performance of this approach is comparable to that of alternative mitigation strategies, such as the adoption of invariant priors or the reparametrisation of nuisance parameters in terms of growth and geometrical amplitudes. For the latter, we find that using $\sigma_{12}$ in place of the commonly adopted $\sigma_8$ to describe the amplitude of density fluctuations improves the performance of the reparametrisation technique, even at high redshifts, where constraints on the dark-energy equation of state are weaker. We further show that these conclusions hold with the inclusion of additional BAO constraints, and for data sets with reduced statistical power. These results add to the benefits of working with ${\rm Mpc}$ units, avoiding an explicit dependence on $h$, with direct relevance for the analyses of Stage-IV galaxy surveys.
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All authors Andrea Pezzotta, Alejandro Pérez-Fernández, Giosuè Gambardella, Ariel G. Sánchez, Alexander Eggemeier, Martin Crocce, Benjamin Camacho-Quevedo

Cosmology and Nongalactic Astrophysics

Halo Mass Function Constraints on Early Galaxy and AGN Populations in the JWST Era

Elan Yogeswaren and Robert Schaefer

The discovery by the James Webb Space Telescope (JWST) of massive galaxies and luminous active galactic nuclei (AGN) at high redshift provides an increasingly sensitive test of the connection between cosmological structure formation and the astrophysical processes that make dark matter halos observable. We develop a framework connecting the linear matter power spectrum to the mass variance, peak height, halo mass function (HMF), cumulative halo abundance, and observable galaxy and AGN populations. We use the Sheth-Tormen (ST) HMF as the baseline and compare it with an illustrative Bolshoi-Klypin-calibrated modification (KST) to quantify the sensitivity of predictions to the calibration of the HMF against cosmological N-body simulations. We apply the framework to three complementary tests: the baryonic and stellar mass reservoir available to massive galaxies, the abundance of halos capable of hosting luminous AGN, and the rest frame ultraviolet luminosity function of high redshift galaxies. Because the most massive systems occupy the rare, high peak tail of the halo distribution, modest changes in inferred host mass, baryonic conversion efficiency, black-hole occupation or duty cycle, and HMF calibration can produce large changes in predicted abundances. The ST-KST comparison shows that uncertainty in the high redshift halo population can materially affect the inferred host supply, particularly toward large z (10). Comparison with representative JWST massive galaxy, AGN, and UV luminosity function measurements demonstrates that matching the properties of an individual source is not sufficient for population consistency; the corresponding host halos must also exist in adequate numbers. Current observations provide increasingly stringent quantitative stress tests of both cosmological halo abundances and the baryonic and black hole physics at cosmic dawn.
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Cosmology and Nongalactic Astrophysics

When, Why, and How CMB Compression Fails

Davide Pedrotti, William Giarè, Hanyu Cheng et al. (+1 more)

We test when compressed CMB likelihoods can be reliably used to constrain new physics beyond $\Lambda$CDM, formulating concrete criteria for when, why, and how CMB compression fails. We derive our conclusions by exploring a broad set of models that modify different aspects of the cosmological evolution, including late-time dark-energy dynamics, non-standard late-time dark-matter evolution through interactions or decay, and dark-matter models with persistently non-standard redshift evolution. For each case, we compare the results obtained from data combinations based on the full Planck-CMB likelihood with their counterparts based on a compressed CMB likelihood calibrated in $\Lambda$CDM. We find that the compression remains accurate for late-time dark-energy extensions that preserve the dark-matter background evolution and do not introduce significant additional perturbative effects. By contrast, modifying the dark-matter evolution breaks the mapping between the present-day matter density and the matter density at the epochs relevant to the CMB, causing the compressed constraints to fail even when the modification acts exclusively at late times. In these cases, the compressed likelihood can drastically alter the geometry of the multidimensional posterior distributions, shifting their centers, producing strongly anisotropic deformations, reordering principal modes, and generating genuine mixing and rotation of their eigendirections. These multidimensional distortions propagate into substantially incorrect marginalized constraints on cosmological parameters, with differences between the full and compressed analyses reaching nearly an order of magnitude in some of the cases studied here.
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All authors Davide Pedrotti, William Giarè, Hanyu Cheng, Eleonora Di Valentino

Cosmology and Nongalactic Astrophysics

Boosted Odds: Lower-Point Probes of Parity Violation with Momentum Fields

Yong Sheng Yap, William R. Coulton, Jiamin Hou et al. (+1 more)

Parity-violating initial conditions are uniquely compelling signatures of inflationary dynamics beyond the single-field slow-roll paradigm, and their effects on the distribution of late-time observables can be easily separated from that of gravitational nonlinearities and galaxy formation physics. In this work, we propose using the momentum field, $\mathbf{p} = (1+\delta)\mathbf{v}$, and, in particular, the density-density-momentum bispectrum as a novel probe of primordial parity violation. This class of bispectra greatly complements traditional searches using four-point statistics of the density field, furnishing new observables that can be sensitive to parity-violating physics. At the same time, its lower dimensionality substantially reduces the complexity associated with analysing high-dimensional data vectors and their covariance. We show that the sensitivity of the density-density-momentum bispectrum to parity violation effects persists even if we can only observe the projection of the momentum field along the line-of-sight. We perform a Fisher forecast for the parity-violating amplitude of the ultra-squeezed template in the cross bispectrum of kinetic Sunyaev-Zel'dovich (kSZ) anisotropies and galaxy clustering, and we find that our approach give competitive constraints when compared to existing methods. Our method can be easily co-opted to existing pipelines to study parity violation and, as the galaxy-galaxy-kSZ bispectrum is a key cosmological probe, take advantage of the significant existing efforts dedicated to mitigating systematics and covariance modelling.
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All authors Yong Sheng Yap, William R. Coulton, Jiamin Hou, Steven Gratton

Cosmology and Nongalactic Astrophysics

Stochastic effect on ultralight dark matter searches with astronomical polarized sources

Kyohei Yamada

Ultralight axion-like particles (ALP) are the well-motivated candidates for the dark matter. In the standard halo model, the ultralight galactic dark matter behaves as a stochastic Gaussian random field, and the polarization angle of the linearly polarized light propagating through the field stochastically oscillates proportional to the field difference between the observer and the source. The statistics of this signal depend on the source size and its distance from the observer relative to the ALP Compton length and coherence length, and therefore on the ALP mass. We present a unified statistical framework for the polarization-oscillation searches with light sources of arbitrary size and distance. We classify the statistics of the stochastic oscillation amplitude into four distinct regimes and provide a seamless description including the transitional regimes between them. Our framework reproduces the signal models in previously known cases including the laboratory-scale searches and searches using pulsars and the cosmic microwave background. We provide a likelihood prescription that incorporates the stochasticity of the signal, and show that uncertainties in source distance must be carefully accounted for, as they can alter the resulting constraints on the ALP-photon coupling by up to a factor of three. Our results provide a consistent basis for interpreting and comparing a broad range of ALP searches with astronomical polarized sources.
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