Cosmology and Nongalactic Astrophysics
Inductive Biases in Field-Level Cosmological Inference from Galaxy Catalogs
James O. Baldwin, Shy Genel and Francisco Villaescusa-Navarro
We perform field-level likelihood-free inference of the matter density parameter $\Omega_m$ from simulated
galaxy catalogs using machine learning models with differing inductive biases. Using hydrodynamic simulations from CAMELS, we examine how observable choice and architecture govern cosmological information extraction. We consider
galaxy positions and line-of-sight peculiar velocities, separately and jointly, and compare permutation-invariant Deep Sets, implemented with either multilayer perceptrons (MLPs) or Kolmogorov-Arnold Networks (KANs), to graph neural networks (GNNs), which explicitly encode spatial relations. We test in-distribution and out-of-distribution (OOD) performance across simulations with different subgrid
galaxy-formation prescriptions. Deep Sets infer $\Omega_m$ from velocities alone with mean relative errors of approximately $18\%$ in-distribution and $\sim25\%$ OOD, with KANs and MLPs achieving comparable performance. In contrast, the same set-based approach does not yield useful $\sigma_8$ predictions in either in-distribution or cross-suite tests. Adding positions does not improve Deep Sets, while GNNs infer $\Omega_m$ with mean relative errors of about $10\%$ in-distribution and $10$–$17\%$ OOD. These results indicate that peculiar velocities provide the dominant source of $\Omega_m$ information for set-based models in this setting, while spatial information is most effectively used by architectures that explicitly encode
galaxy-
galaxy relations. Because the velocity inputs are exact simulated peculiar velocities, applications to survey data will require validation under realistic velocity-measurement noise, selection effects, and survey geometry.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Perturbations of Charged Black Holes with Higher-Order Interactions
Oleksandr S. Stashko, Roman A. Konoplya and Mark P. Hertzberg
We study linear gravitational perturbations and the corresponding quasinormal-mode spectra of electrically and magnetically charged black holes in the presence of higher-order corrections to the Einstein-
Hilbert action. In particular, we consider a four-derivative interaction that couples the Riemann tensor to the electromagnetic field strength in the unique (Horndeski) combination that preserves second-order equations of motion. We provide a comprehensive analysis of the stability conditions. We numerically confirm the absence of exponentially growing modes throughout the physically admissible region of parameter space where the theory remains free of pathologies. We then investigate in detail the properties of the quasinormal-mode spectra and identify several distinctive features induced by the higher-order interaction.
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Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA
TDCOSMO XXX: Spatially resolved kinematics of the deflectors in time-delay lens systems B1608+656 and SDSSJ1206+4332 from JWST-NIRSpec observation
Pritom Mozumdar, Shawn Knabel, Anowar J. Shajib et al. (+3 more)
We present spatially resolved stellar kinematics of the deflector
galaxies in two time-delay lens systems, B1608+656 and SDSS J1206+4332, measured from JWST NIRSpec integral field spectroscopy. B1608+656 is a quadruply imaged
quasar lensed by a pair of tidally interacting
galaxies, the primary deflector (G1) and a close companion (G2), for which we quantified G2's tidal influence on G1 and define a criterion identifying the region where this perturbation is negligible and standard Jeans-equation modeling remains valid. SDSS J1206+4332 is a doubly imaged
quasar whose extended host
galaxy is itself quadruply imaged by a foreground massive
galaxy (G0), accompanied by a fainter perturber (G1). For both systems, we report the first spectroscopic
redshift and velocity dispersion measurements of the perturber
galaxies. For G2 in B1608+656, we measure {\sigma}_v = 188 +/- 7 (stat.) +/- 2 (sys.) km/s at z = 0.6307, identical to the
redshift of the main deflector G1. For G1 in SDSS J1206+4332, we find {\sigma}_v = 100 +/- 21 (stat.) +/- 2 (sys.) km/s at z = 0.7403, slightly lower than the primary deflector G0. The resolved velocity maps of both primary deflectors show clear rotation signatures and we visually classify them as fast or regular rotators. The data products will be made publicly available and will be combined with time delays, lens models, and line-of-sight convergence to measure cosmological parameters in the upcoming TDCOSMO 2026 milestone publication.
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All authors Pritom Mozumdar, Shawn Knabel, Anowar J. Shajib, Tommaso Treu, Michele Cappellari, Aymeric Galan
Cosmology and Nongalactic Astrophysics
A Finely-Binned Measurement of the Connected Even-Parity Galaxy 4-Point Correlation Function of DESI Year 1 Luminous Red Galaxies
William Ortolá Leonard, Alex Krolewski, Zachary Slepian et al. (+46 more)
We present the connected even-parity
galaxy 4-Point Correlation Function (4PCF) of DESI Year 1 (Y1) Luminous Red
Galaxies (LRGs). This is one of the first measurements of the connected 4PCF on data, and shows a clear detection at $\sim$12 to 17$\sigma$ in the full-sky analysis. We test the robustness of the signal by varying three factors: hemisphere (north vs. south),
redshift range (either the full range $0.4 < z < 1.1$ or the higher-number-density interval $0.4 < z < 0.8$), and sample completeness (the full sample vs. only the most complete regions within the number density-motivated cut). Finally, we cross-correlate different patches that are spatially well-separated, and thus should have largely independent noise. This approach, at leading order, is able to remove mismatch between the covariance
matrix of the data and that of the mocks; however, in certain cases at the cost of sensitivity. We find $\sim$15$\sigma$ evidence for an even-parity 4PCF in this approach. Overall, the studies of the 4PCF presented here probe sensitively any mismatch between mock catalogs and data, and also open up the prospect of fitting a model, constraining cosmological parameters and
galaxy biases, and searching for Baryon Acoustic Oscillation (BAO) features.
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All authors William Ortolá Leonard, Alex Krolewski, Zachary Slepian, Alessandro Greco, Simon May, J. Aguilar, S. Ahlen, O. Alves, A. Aviles, F. Beutler, D. Bianchi, D. Brooks, A. Carnero Rosell, T. Claybaugh, A. de la Macorra, Biprateep Dey, S. Ferraro, J. E. Forero-Romero, E. Gaztañaga, Satya Gontcho A Gontcho, G. Gutierrez, K. Honscheid, D. Huterer, M. Ishak, S. Juneau, T. Karim, R. Kehoe, D. Kirkby, O. Lahav, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, J. A. Newman, E. Paillas, W. J. Percival, F. Prada, I. Pérez-Ràfols, C. Ravoux, R. Ruggeri, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, J. H. Silber, M. Siudek, G. Tarlé, B. A. Weaver
Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.HE
Electromagnetic Emission and Orbital Evolution of Eccentric Supermassive Black Hole Binaries in Retrograde Disks
David ONeill, Mark J. Avara, Christopher Tiede et al. (+3 more)
Circumbinary disks around supermassive black hole binaries (SMBHBs) are expected to form across a broad range of inclinations, with retrograde configurations potentially a common occurrence. Here we present the first grid-based hydrodynamical simulations of retrograde circumbinary disks around eccentric SMBHBs, solving an energy equation that balances viscous and shock heating against blackbody radiative cooling. We investigate different initial disk Mach numbers $\mathcal{M}_a \in \{10, 20, 40\}$ and consider binary eccentricities $e_\mathrm{b}\in[0.0,\,0.8]$, finding that multiple stable states exist for the same binary eccentricity and Mach number. These states differ by the sense of rotation of their minidisks; both retrograde ($\downarrow\downarrow$), both prograde ($\uparrow\uparrow$), or one of each ($\uparrow\downarrow$), a property set by the initial conditions. Our findings indicate that each state produces qualitatively distinct orbital
evolution: $\downarrow\downarrow$ and $\uparrow\downarrow$ minidisks drive circular inspirals whereas $\uparrow\uparrow$ minidisks drive eccentric inspirals with potentially observable eccentricity in the LISA band. We measure the electromagnetic emission produced by the disk, finding that a binary of mass $M_\mathrm{b}=8\times10^6\mathrm{M}_\odot$ at
redshift $z=1$ would be detectable by both current and upcoming optical and UV instruments. We demonstrate that the time- and azimuthally-averaged disk profiles are well described by 1D models, which naturally set a cavity radius within which angular momentum transport is dominated by Reynolds stresses rather than viscosity.
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All authors David ONeill, Mark J. Avara, Christopher Tiede, Daniel J. DOrazio, Zoltan Haiman, Andrew MacFadyen
Cosmology and Nongalactic Astrophysics
JZ-FMM: GPU-native differentiable N-body simulations with the Fast Multipole Method
Jens Stücker and Oskar Foldal
N-body simulations are an essential tool for modelling the
evolution of gravitating systems. Differentiable N-body simulations allow solving complicated reconstruction problems by connecting observations of evolved systems to simple informative priors on their initial conditions. While so far most reconstruction efforts focus on mildly non-linear large scale dynamics, the internal dynamics of
galaxies and clusters should exhibit rich information about their formation. The exploration of reconstruction possibilities in this highly non-linear regime naturally requires highly performant differentiable N-body simulations with small scale forces. Here, we present JZ-FMM, a GPU-native differentiable implementation of the fast multipole method for N-body simulations. We show that the GPU oriented design of tree structure, dual tree traversal and multipole translation operators improves performance over established CPU-native and hybrid N-body codes by notably more than an order of magnitude. Further, we show that gradients can be evaluated efficiently and accurately so that JZ-FMM can be used as an essential building block in future field-level reconstruction efforts. We apply the new code to the reconstruction problem of a tidally stripped satellite to show that deeply non-linear problems can indeed be solved efficiently with simulation gradients, although appropriate care must be taken to navigate the complicated optimization landscape.
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Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA
Exploring the AGN population in protoclusters: results from the TNG300 simulation and comparison with observations
A. Traina, F. Vito, A. Pillepich et al. (+7 more)
In this work, we investigate the physical properties and
cosmic evolution of
galaxies and AGN in a sample of 280 protoclusters identified in the TNG300 simulation, selected to end up in $z = 0$ clusters with $M_{200, \rm c} > 10^{14} \, {\rm M_{\odot}}$. Our goal is to provide the first statistical view of AGN activity enhancement in a uniformly defined sample of overdense environments, and to identify the physical mechanisms driving it. We identify protoclusters as the progenitors of present-day
galaxy clusters through merger-tree reconstruction and compare their
galaxy and AGN populations with a control sample of field
galaxies across the
redshift range $0 \leq z \leq 6$. We investigate
galaxy and SMBH demographics, AGN fractions, bolometric luminosity functions, and the SMBH
accretion rate density, consistently applying homogeneous selection criteria in all environments. We find that TNG300 protoclusters host systematically more massive
galaxies and SMBHs than the field by up to $1 \, {\rm dex}$ at all
redshifts, with signatures of accelerated
galaxy evolution already visible at $z \sim 3-4$. The AGN fraction increases with stellar mass in both environments and, at fixed host-
galaxy stellar mass, is broadly consistent between protoclusters and field
galaxies, indicating no strong environmental triggering of SMBH
accretion. However, when analysed as a function of
redshift, protoclusters exhibit a significant enhancement of AGN activity (by a factor $> 2$), particularly at high luminosities and early
cosmic times. We show that this enhancement primarily arises from differences in the stellar-mass distributions of
galaxies in overdense regions, where massive systems assemble earlier than in the field. Consistently, protoclusters dominate the bright end of the AGN bolometric luminosity function and contribute up to $\sim 50\%$ of the total SMBH
accretion rate density at $z \sim 6$.
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All authors A. Traina, F. Vito, A. Pillepich, A. Kapahtia, O. Cucciati, R. Gilli, F. Arrigoni-Battaia, C. Vignali, M. N. Isla Llave, V. L. Cavicchi
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th
Cosmological Collider Signals From a Triangle Loop
Zhehan Qin and Zhong-Zhi Xianyu
Triangular loop signals appear frequently in cosmological
collider models but their analytical forms remain unknown due to multiple technical challenges. Here, we determine for the first time the leading analytical cosmological
collider signals generated by a massive scalar triangle loop in inflationary bispectrum and trispectrum. Combining a directional cutting rule with partial Mellin-Barnes representations, we obtain both the local and nonlocal trispectrum signals in a soft limit and derive the leading signal in the squeezed bispectrum. Remarkably, all these signals are reproduced by the corresponding bubble diagram with a single effective pinched coupling. Signals beyond leading order and cases with arbitrary internal masses,
spins, and interactions can be generated within the same framework. Our approach also provides a systematic route to extracting analytical loop signals from general cosmological correlators.
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Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA
Overmassive No More: The Case for Little Red Dots Hosting Black Hole Seeds as Massive as Single Supermassive Stars
Wendy Q. Sun, Rohan P. Naidu, Hanpu Liu et al. (+17 more)
Little Red Dots (LRDs) display singular properties unlike any known class of AGN or
galaxies, motivating novel mass
estimators for their central engines. Inspired by their similarities to stellar phenomena, here we interpret the LRD continuum as being produced by a pseudo-photosphere. We fit tailored stellar atmosphere models to host-subtracted LRD central engines ("black hole
stars," BH*s) represented by stacks of $117$ objects. Typical BH* continuum spectra are well fit by models in a narrow range of temperatures ($T_{\rm eff}\approx4200-4800$ K), with bolometric luminosities $\approx10^{43-45}$ erg s$^{-1}$, implying pseudo-photospheric radii $\approx700-2000$ au. Based on these parameters, we explore four different approaches to deriving BH* masses: 1) using the surface
gravity from atmosphere models; 2) appealing to the resemblance to super-Eddington phenomena; 3) approximating the escape velocity from the outflowing material; and 4) exploiting the lack of variability to bound the dynamical time. For the typical BH*, all of these methods yield remarkably consistent masses of $\approx10^{4-5}\,M_\odot$, implying a highly super-Eddington luminosity of $L_{\rm{bol}}/L_{\rm{Edd}}\sim5-50$. These mass estimates place BH*s within the scatter of the local scaling relation between black hole mass and host
galaxy stellar mass, providing a self-consistent alternative to "overmassive" black holes that lie $2-3$ dex above it. Crucially, our derived masses are consistent with BH*s arising from single supermassive
stars (SMSs), whose masses cannot exceed $\approx10^{5-6}\,M_\odot$ due to general relativistic instabilities. Furthermore, for our derived $L_{\rm bol}/L_{\rm Edd}$, the sharp cutoff of the LRD luminosity function matches the maximum theoretical mass of an SMS. With LRDs, we may therefore be directly observing the birth of heavy black hole seeds.
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All authors Wendy Q. Sun, Rohan P. Naidu, Hanpu Liu, Anna de Graaff, Jenny E. Greene, Jorryt Matthee, Chris Ashall, John Chisholm, Anna-Christina Eilers, Qinyue Fei, Kasper E. Heintz, Daichi Hiramatsu, Vasily Kokorev, Joel Leja, Zhaoran Liu, Priyamvada Natarajan, Pascal A. Oesch, Robert A. Simcoe, Alberto Torralba, Andrea Weibel
Cosmology and Nongalactic Astrophysics
From quantum fluctuations to galaxy power spectrum multipoles
Nhat-Minh Nguyen
These notes trace large-scale structure from primordial
curvature perturbations generated by inflationary
quantum fluctuations to
galaxy power-spectrum multipoles. Three core lectures develop the linear matter power spectrum, spherical and anisotropic collapse,
galaxy bias,
redshift-space distortions, the Kaiser model, and multipole
estimators with Gaussian covariance. The extension develops nonlinear bias and the one-loop effective field theory model used in full-shape analyses. Derivations are explicit; appendices collect longer calculations and solutions. The core lectures assume undergraduate-level cosmology; the extension assumes familiarity with perturbation theory.
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Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA
A Spectral Framework for Testing the Quasi-Star Hypothesis in Little Red Dots I: Weighing LRDs by Their Super-Eddington Luminosity Ratios—No Signs of Overmassive Black Holes
Olivia Curtis, Nikko J. Cleri, Jakob M. Helton et al. (+2 more)
We present a spectral test of the quasi-
star hypothesis for Little Red Dots (LRDs) whereby a black hole grows inside a stellar-like envelope. We use Prospector to fit host
galaxies and TLUSTY photospheres to 5 LRDs that show strong molecular or atomic absorption. We approximate each object's electron-scattered Eddington luminosity ratio, $\phi \equiv \kappa_{\rm es}\sigma T_{\rm eff}^{4}/(gc)$, and we use MESA-QUEST to simulate their envelopes. All 5 are super-Eddington at $\phi = {87}$–$299$, with the caveat that the largest sources sit at the edge of our atmosphere grid and beyond our simulations. We derive envelope masses between $700$–${15{,}000}\,M_\odot$, where quasi-
star theory requires the black hole to be less than a third of that. GN-28074 falls 5 decades below its published virial mass estimate, alleviating the overmassive black hole problem. Their black holes double every $\sim0.05$–${0.2}$~Myr and can produce intermediate-mass black holes in $\lesssim30$~Myr. Our 3 water-absorbing objects have cold components that are $2$–$3$~dex denser than their hot components, which we interpret as the water forming in cold dense clouds. We then extend our measurements to 82 archival LRDs, finding that the population has super-Eddington photospheres and wind speeds that increase with $\phi$, which implies that LRDs evolve from massive sources with slow winds to having more eruptive winds as they mature and shed their outer envelopes. We thus constrain the Eddington ratios and masses of LRDs and show self-consistently that quasi-
stars may be the central engines powering LRDs.
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All authors Olivia Curtis, Nikko J. Cleri, Jakob M. Helton, Joel Leja, Jason T. Wright
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Reconstructing sign-switching dark energy histories: Scalar-field regularity, conditional potential comparison, and representative dynamics
Shahnawaz A. Adil, Özgür Akarsu, Mariam Bouhmadi-López et al. (+3 more)
Phenomenologically similar sign-switching dark-energy histories need not have comparable scalar-field realizations. We reconstruct minimally coupled scalars with fixed kinetic sign for three prescribed histories: the error-function model (ECDM), the compact smooth-step model (SSCDM), and the ladder-like model (L$\Lambda$CDM). Continuous negative-to-positive density crossings select the phantom branch. ECDM yields a smooth on-shell potential at every finite
redshift; its equation-of-state pole at the density zero is only a ratio singularity. Exact SSCDM has a regular trajectory but a $C^1$, non-$C^2$ endpoint potential, $V-V_e\propto|\phi-\phi_e|^{4/3}$. Its non-Lipschitz force permits delayed departures from frozen plateaus, so the reconstructed potential and plateau data do not uniquely generate the prescribed history. The exact Ladder requires distributional kinetic stress and has no ordinary classical realization in the adopted one-field action. In conditional synthetic comparisons, the sigmoid–Gaussian family ranks highest for ECDM and the generalized
axion-like family for SSCDM, although the fitted
axion exponents $n<1/2$ imply a divergent endpoint force. Representative regular forward solutions exhibit negative-to-positive scalar-density crossings, with the potential zero preceding the density zero. In a closure test, unretuned
evolution of the top-ranked ECDM template tracks the target approximately, $\max|\Delta\widetilde\Omega_\phi|\simeq0.16$. Closure fails structurally for compact SSCDM: no potential with a locally Lipschitz force can reproduce its exact finite-duration frozen plateaus from exactly frozen initial data. Field-map existence, invertibility, and endpoint regularity must be assessed before interpreting a phenomenological history as scalar dynamics. The phantom action is used only as a homogeneous effective proxy.
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All authors Shahnawaz A. Adil, Özgür Akarsu, Mariam Bouhmadi-López, Beñat Ibarra-Uriondo, Nihan Kat{\i}rc{\i}, J. Alberto Vázquez
Cosmology and Nongalactic Astrophysics
Sizing the Universe with DESI Galaxy Sizes: Plain Fundamentals of Fundamental-Plane Lensing
Kun Xu, Jiaqi Wang, Ravi K. Sheth et al. (+44 more)
Weak gravitational
lensing provides a powerful way to map
cosmic structure, but most current measurements rely on
galaxy shape distortions from deep imaging surveys and are affected by systematics such as intrinsic
alignments, photometric-
redshift uncertainties and shape-measurement biases. Here we present a spectroscopic
galaxy-
galaxy lensing magnification measurement using Fundamental-Plane (FP) size residuals, $\delta_r\equiv\Delta\log_{10}R_\mathrm{e}$, from 3.26 million DESI luminous red
galaxy (LRG) sources behind DESI Bright
Galaxy Survey lenses. The FP-like relation predicts the intrinsic sizes of LRGs from
lensing-invariant quantities, including velocity dispersion $\sigma_0$ and surface brightness $I_\mathrm{e}$, with a scatter of about 0.06-0.07 dex.
Lensing magnifies LRG sizes, giving the direct convergence response $\delta_r(\kappa)=\kappa/\ln 10$, but we show that the full
lensing response is modified by magnification bias, because fitting $R_\mathrm{e}$ with $I_\mathrm{e}$ inevitably induces a magnitude dependence in $\bar{\delta}_r(m)$. After calibrating this response, we recover surface-density profiles with uncertainties comparable to those from individual Stage-III shear surveys using 5-20 million higher-
redshift sources. The corresponding excess surface-density profiles agree with shear-based measurements. We further show that the
estimator is robust to size-measurement uncertainties, with a convergence multiplicative bias only $\simeq -0.2$ times the size bias. FP
lensing therefore provides a clean, spectroscopic and complementary probe of
cosmic structure.
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All authors Kun Xu, Jiaqi Wang, Ravi K. Sheth, J. Aguilar, S. Ahlen, F. Beutler, D. Bianchi, D. Brooks, A. Carnero Rosell, T. Claybaugh, A. de la Macorra, P. Doel, J. E. Forero-Romero, E. Gaztañaga, G. Gutierrez, K. Honscheid, C. Howlett, M. Ishak, J. Jimenez, S. Juneau, R. Kehoe, D. Kirkby, O. Lahav, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, J. A. Newman, W. J. Percival, F. Prada, I. Pérez-Ràfols, C. Ravoux, G. Rossi, R. Ruggeri, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, H. Seo, J. Silber, M. Siudek, G. Tarlé, B. A. Weaver, H. Zou
Cosmology and Nongalactic Astrophysics
Differential Polarization Calibration: A Consistency Test for Cosmic Birefringence
Anto I. Lonappan, Brian Keating and Kam Arnold
The
cosmic microwave background birefringence angle $\beta$ is exactly degenerate with a common instrumental polarization-angle offset. The Minami–Komatsu(MK) likelihood separates these quantities using Galactic foreground polarization, so its inferred detector angles merit a diagnostic that does not reuse the foreground-$EB$ model. We develop a birefringence-blind differential
estimator from antisymmetric and symmetric cross-spectra and apply it for the first time as an explicit consistency test of a foreground-assisted birefringence analysis. For a map pair, the common rotation cancels identically and the
estimator measures $\Delta\alpha_{ij}=\alpha_i-\alpha_j$; combining all pairs in a gauge-fixed network reconstructs the observable detector-dependent calibration pattern. Applied to eight Planck NPIPE detector-set maps, the differential reconstruction agrees with the MK pattern, giving $\chi^2=8.18$ for seven degrees of freedom (PTE=0.32), with all shared-data residuals below $1.8\sigma$. Because both reconstructions use the same maps, this is an independent
estimator and modeling route rather than an independent-data confirmation. The agreement therefore strengthens confidence in the calibration foundation of the MK-inferred $\beta$ without providing an independent absolute measurement of it. A conditional common-mode reconstruction gives $\beta=0.37\pm0.12^\circ$. The differential test uses existing data and can serve as a validation layer for future $EB$-based birefringence analyses.
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Cosmology and Nongalactic Astrophysics
Baryonification IV: Constraining baryonic feedback with X-ray gas fractions
Jozef Bucko, Andrina Nicola, Aurel Schneider et al. (+8 more)
Baryonic feedback redistributes gas around dark matter
halos, suppressing the matter power spectrum at scales now probed by weak
lensing surveys. X-ray observations directly trace this hot gas, and are one of the main probes of its distribution and properties. We present a forward-modelling framework, built on the baryonification model, linking the three-dimensional gas density and temperature profiles of groups and clusters to observed X-ray surface brightness and luminosity profiles on one side, and to matter power spectrum suppression on the other. We validate the model against independent three-dimensional density reconstructions from the literature, and examine our temperature and
metallicity treatment in the group-scale regime. Applying this framework to the SZ-selected CHEX-MATE and X-ray-selected eFEDs samples, we measure gas fractions across the group-to-cluster mass range while accounting for X-ray selection effects, with the first published gas fractions based on CHEX-MATE data. Combining both samples, we derive a joint constraint on the hot gas fraction retained by groups and clusters as a function of mass and on the baryonic suppression of the matter power spectrum. We find $f_{\rm gas} = 0.029 \pm 0.006$ at $M_{500c} = 3\times 10^{13}M_\odot$, $f_{\rm gas} = 0.078 \pm 0.004$ at $M_{500c} = 3\times 10^{14}M_\odot$, and suppression of 6% at $k=1\,h/\rm Mpc$ and 23% at $k=5\,h/\rm Mpc$. Our findings are consistent with recent kinematic Sunyaev-Zel'dovich results, hinting at strong feedback. We also show that the $L_X$-$M$ relation is degenerate with feedback strength, and that different feedback scenarios produce distinct X-ray profile shapes that map onto the same $L_X$-$M$ point. This work is a first step toward extending the framework to forward-model diffuse X-ray emission at the map level for simulation-based inference in upcoming wide-area X-ray surveys such as eROSITA.
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All authors Jozef Bucko, Andrina Nicola, Aurel Schneider, Michael Kovač, Sambit K. Giri, Robert Reischke, Esra Bulbul, Nicolas Clerc, Ang Liu, Iacopo Bartalucci, Alexandre Refregier
Cosmology and Nongalactic Astrophysics
Mitigating baryonic effects in weak lensing with higher-order statistics
Andreas Tersenov, Sacha Guerrini, Jean-Luc Starck et al. (+1 more)
Weak gravitational
lensing is a premier cosmological probe, but its small-scale statistical power is compromised by baryonic feedback. Higher-order statistics capture non-Gaussian information that the power spectrum misses, yet their sensitivity to feedback remains a concern for Stage IV surveys. We quantify how unmodeled feedback biases the cosmological parameters inferred from the angular power spectrum (PS), starlet peak counts, and the starlet $\ell_1$-norm, and we determine the scale cuts needed to remove that bias. We also test the Bernardeau-Nishimichi-Taruya (BNT) transform as a strategy for more precise scale cuts. Our analysis is based on the cosmoGRID V1 suite, which imprints feedback on dark matter convergence maps with a baryon correction model, and on simulation-based inference with neural posterior estimation, carried out across footprints ranging from Stage III-like to the full sky. We find that biases grow with survey area, exceeding $2\sigma$ for all three statistics at Stage IV-like footprints, and removing them costs a substantial fraction of the signal. Restricted to these “baryon-safe” scales, the starlet $\ell_1$-norm still reaches a figure of merit almost twice that of the PS. The BNT transform localizes the baryonic sensitivity to the lowest transformed
redshift bin and improves the PS figure of merit by a factor of $\sim$1.4, while its linear mixing of shape noise inflates the contours of the map-based higher-order statistics. Higher-order statistics therefore deliver a substantial gain over the power spectrum with no baryonic modeling at all, and an even larger one as modeling improves.
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All authors Andreas Tersenov, Sacha Guerrini, Jean-Luc Starck, Martin Kilbinger
Cosmology and Nongalactic Astrophysics
A Two-Dimensional Test of Cosmological Parity Violation with the 3-Point Correlation Function
William Ortolá Leonard and Zachary Slepian
Searches for parity violation (PV) in the Universe's large-scale structure have recently been carried out using parity-odd modes of the
galaxy 4-Point Correlation Function (4PCF). Here, we introduce a new
estimator for a 3-Point Correlation Function (3PCF) that is sensitive to PV. The construction exploits the handedness of triangles formed on 2D spherical shells, where mirror-image configurations cannot be related by proper rotations within the surface. By dotting the oriented area vector with an externally-defined normal vector to the shell, we obtain sensitivity to PV. We present a discrete
estimator for this statistic and also show how to correct for the survey geometry. This parity-odd 3PCF provides a complementary test of PV in
galaxy surveys and a potential cross-check of PV 4PCF measurements.
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Cosmology and Nongalactic Astrophysics
TILING I: Field-level Bayesian reconstruction of cosmological initial conditions during the epoch of reionization
Nikolaos Triantafyllou, Andrei Mesinger, Steven Murray et al. (+1 more)
Reconstructing the initial conditions (ICs) of the matter field for an observed volume gives a complete picture of that region's temporal
evolution. IC reconstruction is common at low
redshifts but largely unexplored during the epoch of reionization (EoR; $z\gtrsim 5$), partly due to difficulties modeling inhomogeneous
cosmic radiation fields. Yet the EoR spans half the observable Universe, offering unmatched potential for astrophysics and cosmology. Here we quantify how well upcoming
galaxy and 21cm observations can constrain ICs during the EoR. We develop $\tt TILING$ ($\bf T$omographic $\bf I$nference of $\bf L$inear $\bf I$Cs via $\bf N$etwork $\bf G$rafting): a hybrid machine learning pipeline that first produces a point estimate of the ICs, which then improves a score-based
diffusion network for generating posterior samples. We train $\tt TILING$ on mock
galaxy maps at varying UV magnitude limits, plus corresponding 21cm maps at varying noise levels and foreground "wedge" contamination. For fiducial survey choices, we achieve accurate IC reconstruction (posterior mean cross-correlation coefficients >0.8 and power spectrum errors under a few percent) down to $\text{k}\lesssim 0.2 \text{cMpc}^{-1}$. While 21cm interferometry aids recovery of IC power spectra, most constraining power, especially for IC
Fourier phases, comes from
galaxy maps, underscoring the need for complementary observations when interpreting the 21cm signal. We show how $\tt TILING$ can recover 21cm power spectrum modes excised by foreground contamination. Our framework can also: (i) guide follow-up observations of sub-volumes of interest; (ii) reconstruct
galaxy evolution and reionization morphology for specific volumes; and (iii) isolate the contribution to reionization from the vast majority of
galaxies unobservable by optical/IR
telescopes like $\it JWST$. Our code is publicly available.
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All authors Nikolaos Triantafyllou, Andrei Mesinger, Steven Murray, Samuel Gagnon-Hartman
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Breaking binary formation mechanism degeneracies with gravitational wave clustering
Nicola Bellomo, Michele Bosi, Sarah Libanore et al. (+4 more)
Thanks to the almost 400 gravitational wave events detected, we are currently able to grasp the fundamental features of black hole mass,
spin, and distance distributions. However, such a fast increase in the precision of the measurements does not necessarily correspond to a better theoretical understanding of gravitational wave sources, especially in current scenarios where the number of free parameters is significantly larger than the number of inferred properties of the black hole population. In this work, we showcase how the landscape of theoretical models can be chipped away by complementary data-analysis strategies, in particular by studying the statistical properties of gravitational wave anisotropic distribution. Specifically, we show how gravitational wave clustering is sensitive to two unique features of each binary formation mechanism: the time-delay distribution and the properties of the binary hosts. First, we consider a model-agnostic scenario and show the impact that different time-delay distributions have on the gravitational wave bias. Then, we consider a realistic scenario where gravitational wave events are sourced either by isolated binary
evolution or dynamical processes in globular clusters, and study how the gravitational wave bias is unique sensitive to the specific properties of the environment. In both scenarios, we show how the cross-correlation between
galaxy and gravitational wave catalogs is able to distinguish between models with different time delays or with different binary sub-populations originated in specific formation channels.
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All authors Nicola Bellomo, Michele Bosi, Sarah Libanore, Michele Liguori, Michela Mapelli, Federico Semenzato, Stefano Torniamenti
Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA
Small-Scale Clustering of Primordial Black Holes: The Little Red Dot Mass Function and the High-Redshift Galaxy Tension
Borui Zhang, Wei-Xiang Feng and Haipeng An
Supermassive black holes (SMBHs) in "little red dots" (LRDs) discovered by the James Webb Space
Telescope (JWST) may result from runaway mergers of primordial black holes (PBHs) in clusters—through long-short mode coupling on small scales in the early Universe. In this framework, we derive the SMBH mass function, together with the compactness and overmassive features of LRDs. We also estimate that the dense gas residing in PBH clusters is consistent with LRD observations. In addition, SMBHs formed from PBH clusters can help accelerate
galaxy formation at high
redshifts, thus alleviating tension with $\Lambda$CDM cosmology.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
A Vector-Like Lepton Interpretation of the High-Energy Nuclear Recoil Candidate in LUX-ZEPLIN
Fatemeh Elahi and Pedro Schwaller
The LUX-ZEPLIN (LZ) experiment has recently reported a nuclear-recoil candidate at $E_R=248\pm23_{\rm stat}\pm23_{\rm sys}\,{\rm keV}$ in an exposure of $2.84\,{\rm tonne\,yr}$. At this unusually high recoil energy, the
spin-independent (SI) xenon response is strongly suppressed, motivating dark matter interactions with a harder recoil spectrum. We show that elastic
spin-dependent (SD) scattering through the nonrelativistic operator $\mathcal O_4=\mathbf S_{\rm DM}\cdot\mathbf S_N$ provides a simple realization of such a spectrum. We consider singlet-doublet Majorana dark matter, for which a diagonal $Z$ coupling generates the required SD interaction. The accompanying
Higgs-mediated SI interaction would generically produce too many low-energy recoils, but can be suppressed along a
Higgs blind spot while retaining a nonzero $Z$ coupling. We find a region of the
Higgs blind spot that simultaneously predicts an $\mathcal O(1)$ event rate in the LZ high-recoil window and reproduces the observed thermal relic abundance. The same SD interaction leads to solar capture, allowing this region to be tested independently with solar-
neutrino searches. Current IceCube limits already probe part of the LZ-compatible thermal parameter space, while a viable region remains. Additional xenon exposure and improved solar-
neutrino searches can therefore provide complementary tests of this interpretation.
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Cosmology and Nongalactic Astrophysics
Optical Depths from the Thermal Sunyaev-Zel'dovich Effect with ACT DR6 and DESI DR1 Spectroscopic Galaxies and Optically-Selected Clusters
J. E. Moore, C. Popik, Y. Gong et al. (+66 more)
We present stacked thermal Sunyaev-Zel'dovich (tSZ) effect measurements for three samples of
galaxy groups and clusters: those traced by the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1) luminous red
galaxies (LRG) and the DESI DR1 Bright
Galaxy Sample (BGS), and an eROMaPPer optically-selected sample from the DESI Legacy Imaging Survey. We use the latest Atacama Cosmology
Telescope DR6 (ACT)+Planck component-separated internal linear combination (ILC) Compton-$y$ maps and ACT+Planck coadded 90, 150, and 220 GHz temperature maps to extract the tSZ signal within a $\sim2'$ disk aperture for sources binned by luminosity, richness, or mass. We measure the average tSZ signal with high statistical significance, with signal-to-noise ratios surpassing 38 for LRG, 27 for BGS, and 39 for the eROMaPPer sample using the 90 GHz ACT DR6+Planck map. We conduct a detailed study of systematics and foregrounds such as dust and
cosmic infrared background (CIB) contamination, which remain a core challenge for tSZ analysis. For the LRG and BGS samples, we find that dust and
radio source emission dominate the tSZ signal at scales near and below the disk aperture radius. Large-scale ($R>4'$) contamination from the CIB is less significant. We mitigate these contaminants to isolate the tSZ signal and use a combination of simulated and real measurements to develop Compton-$y-$optical depth ($\bar y-\bar \tau$) scaling relations to infer optical depths, which are found to be in agreement with values measured using the pairwise kinematic SZ effect for the same tracer samples. The $\bar y-\bar \tau$ scaling relation for the eROMaPPer sample is the first such relationship to be derived directly from SZ measurements.
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All authors J. E. Moore, C. Popik, Y. Gong, Y-H. Hsu, E. M. Vavagiakis, N. Battaglia, R. Bean, D. Gruen, P. Gallardo, B. Hadzhiyska, G. Ockert, J. Aguilar, S. Ahlen, A. Aviles, F. Beutler, D. Bianchi, J. R. Bond, D. Brooks, E. Bulbul, A. Carnero Rosell, E. Chaussidon, T. Claybaugh, J. Comparat, A. de la Macorra, Biprateep Dey, P. Doel, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, Satya Gontcho A Gontcho, G. Gutierrez, K. Honscheid, M. Ishak, S. Juneau, T. Karim, R. Kehoe, M. Kluge, A. Kremin, A. Kusiak, O. Lahav, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, T. Mroczkowski, S. Nadathur, J. A. Newman, M. D. Niemack, H. E. Noriega, E. Paillas, W. J. Percival, F. Prada, I. Pérez-Ràfols, C. Ravoux, B. Ried Guachalla, G. Rossi, R. Ruggeri, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, J. Silber, M. Siudek, G. Tarlé, B. A. Weaver, E. J. Wollack, H. Zou
Cosmology and Nongalactic Astrophysics
Why Azimuthal Averaging Works in Halo Lensing: Symmetry and Power Counting for Nonlinear Shear and Magnification
Keiichi Umetsu
Cluster weak-
lensing analyses often compress two-dimensional
lensing fields into azimuthally averaged radial profiles and evaluate nonlinear observables from the averaged convergence and shear. However, the ring average of a nonlinear observable generally differs from the mean-field prediction formed from the averaged fields. This difference, divided by the mean-field prediction, defines the fractional residual. For a complete ring, the difference begins at second order in angular fluctuations. For centered elliptical
halos, rotational
symmetry makes the shape contribution even in signed ellipticity, while the leading miscentering dipole is orthogonal to the shape quadrupole. We test these predictions using projected triaxial NFW
halos at six mass-
redshift grid points spanning $3\leq M_{200\mathrm c}/(10^{14}\,h^{-1}M_\odot)\leq20$ and $0.2\leq z_l\leq0.5$, for $z_s=1$. For the reference offset model, centering offsets follow a Rayleigh distribution with scale $0.05r_{200\mathrm c}$. For $0.366\leq R/r_{200\mathrm c}\leq1$, where at least $95\%$ of each population satisfies a conservative subcriticality criterion, we calculate the median of the fractional residuals across the retained
halos for each population and radius. The largest population-median magnitudes are $0.90\%$ for reduced shear, $0.0093\%$ for inverse magnification, $0.64\%$ for magnification, and $0.18\%$ across the two magnification-bias cases $\mu^{\alpha-1}$ ($\alpha=0.3, 1.4$). In the paired calculation at $z_s=2$, the maximum magnitude increases for every observable, consistent with weak-
lensing power counting. Across both source planes and the common radial domain, every population median remains below $2\%$ in magnitude. This accuracy follows from first-order cancellation, rotational
symmetry, and harmonic orthogonality, with further weak-
lensing suppression of the remaining nonlinear terms.
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Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA
Weak cool core, weak turbulence: XRISM, XMM-Newton and Chandra spectroscopy of the core of Abell 1413
Egemen Gormez and Murat Hudaverdi
We present the first XRISM spectroscopy of the core of Abell 1413 (z = 0.143), combining 104.7 ks of Resolve with archival XMM-Newton and Chandra spectra of a matched sky region. A1413 is hot, massive and relaxed but lacks a strong cool core (t_cool = 6.4 Gyr), a regime in which the low
turbulence reported to date has been tested only once, in A3571. The Resolve spectrum requires a single velocity-broadened component with kT = 7.06 (+0.33, -0.43) keV and a line-of-sight velocity dispersion sigma_v = 170 (+25, -24) km/s (M_3D = 0.217). The bulk velocity relative to the brightest cluster
galaxy, v_bulk = -24 +/- 26 (z_ICM) +/- 71 (z_BCG) km/s, is limited by the optical
redshift rather than by Resolve, and disfavours coherent line-of-sight sloshing. The non-thermal pressure fraction, 2.5 +/- 0.7 per cent, implies a hydrostatic mass bias b < 2.5 per cent, comparable to the strong cool-core cluster A2029 (2.6 +/- 0.3 per cent) and, at matched sampling scale, if anything below it. With A3571 (1.3 +/- 0.3 per cent), to which A1413 rescales within 0.2 sigma, two weak cool cores now show that this quiescence does not require central cooling. The resolved Fe-K He-alpha complex gives Fe = 0.38 +/- 0.03 (stat) +/- 0.04 (sys) solar; Ni/Fe, separated from Fe K-beta for the first time, is solar, as is the pattern as a whole. The Ne, Mg and Si lines that set Ne/Fe, Mg/Fe and Si/Fe lie below 2 keV, where our instruments disagree by 10-20 per cent; we therefore do not regard the SNIa fraction as constrained.
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