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astro-ph.CO2026

Euclid. A two-point correlation approach to diagnosing star-related systematics in the Euclid spectroscopic survey

Euclid Collaboration, I. Risso, B. R. Granett +298

The Euclid spectroscopic survey will measure galaxy clustering with unprecedented precision, requiring stringent control of observational and instrumental systematics. Star-related…

astro-ph.CO2026

Euclid preparation. The shape of halo profiles in CDM and non-standard cosmologies

Euclid Collaboration, L. Pizzuti, G. Y. Ferron +304

We study the shape of three-dimensional and projected dark-matter halo profiles extracted from cosmological -body simulations in CDM and non-standard cosmologies, using the \…

astro-ph.CO2026

Simulation-based tension quantification of the cosmic dipole

Mali Land-Strykowski, Harry T. J. Bevins, Oliver T. Oayda +1

The cosmic dipole measured in surveys of cosmologically distant sources consistently exceeds the expectation derived from the cosmic microwave background, posing a significant chal…

astro-ph.CO2026

Euclid preparation. First investigation of the impact of cross-contamination on spectroscopic redshift measurements with pixel-level simulations

Euclid Collaboration, F. Passalacqua, S. Anselmi +299

We present a study on simulated data focused on understanding the performance of the spectroscopic redshift measurements with the Near-Infrared Spectrometer and Photometer (NISP) i…

astro-ph.CO2026

Impact of non-Gaussian likelihood on cosmological constraints from the thermal Sunyaev--Zel'dovich power spectrum: a simulation-based inference analysis

Licong Xu, Íñigo Zubeldia, James Alvey +2

The thermal Sunyaev--Zel'dovich (tSZ) power spectrum is a sensitive probe of cosmology and cluster astrophysics, but its statistics are non-Gaussian because the signal receives a s…

astro-ph.CO2026

Euclid preparation. Three-dimensional galaxy clustering in configuration space: Three-point correlation function estimation

Euclid Collaboration, A. Veropalumbo, M. Moresco +303

Higher-order correlation functions are firmly established as a fundamental tool for the statistical analysis of clustering in modern galaxy surveys. It was demonstrated that they g…

astro-ph.CO2026

Euclid preparation. CosmoPostProcess: A simulation calibrated framework for weak lensing selection bias in richness-selected galaxy clusters

Euclid Collaboration, R. Ingrao, M. Costanzi +280

We present \texttt{CosmoPostProcess}, a simulation-based forward-modelling algorithm calibrated to reproduce Euclid optical cluster observables. Its main deliverable is a correctio…

astro-ph.CO2026

Implications of SARAS3 data for Coulomb-like interacting dark matter

Shikhar Mittal, Prakhar Bansal, Harry Bevins +1

The 21-cm signal from cosmic dawn is a potentially sensitive probe of interactions between dark matter (DM) and baryons. We investigate the implications of the SARAS3 non-detection…

astro-ph.CO2026

Towards a measurement of the primordial helium isotope ratio

Ryan J. Cooke, James W. Johnson, Pasquier Noterdaeme +4

We report the discovery of two metastable neutral helium (He I*) absorbers in the Milky Way, and use the upgraded CRyogenic InfraRed Echelle Spectrograph on the Very Large Telescop…

astro-ph.CO2026

Euclid preparation. Refining input galaxy shape distributions for shear calibration simulations

Euclid Collaboration, H. Jansen, N. Martinet +282

The Euclid Wide Survey (EWS) will cover the majority of the extragalactic sky with a resolution similar to the Hubble Space Telescope. This unprecedented data set will introduce a…

astro-ph.CO2026

Bound or blown: the fate of hot gas in galaxy groups

R. Seppi, D. Eckert, J. Schaye +14

The impact of AGN feedback on the hot gas content of galaxy groups remains a key uncertainty in galaxy formation and its connection to the large scale structure of the Universe. We…

astro-ph.CO2026

Euclid preparation. Galaxy power spectrum and bispectrum modelling

Euclid Collaboration, K. Pardede, A. Eggemeier +306

Higher-order correlation functions of the large-scale galaxy distribution offer access to information beyond that contained in standard 2-point statistics such as the power spectru…

astro-ph.CO2026★ 1 cited

Euclid. Populating a dark universe with galaxies using SciPIC

Euclid Collaboration, E. J. Gonzalez, J. Carretero +305

High-fidelity galaxy mocks are crucial for validating analysis pipelines and for cosmological inference. In this context, the Science Pipeline at PIC (SciPIC) is a pipeline specifi…

astro-ph.CO2026

Euclid preparation. Impact of redshift distribution uncertainties on the joint analysis of photometric galaxy clustering and weak gravitational lensing

Euclid Collaboration, K. A. Bertmann, A. Porredon +290

One of the mission's key projects is the so-called 32pt analysis, that is, the combination of cosmic shear, photometric galaxy clustering, and galaxy-gala…

astro-ph.CO2026★ 1 cited

Euclid preparation. Simulated galaxy catalogues for non-standard cosmological models

Euclid Collaboration, M. -A. Breton, P. Fosalba +289

Stage-IV galaxy surveys will provide the opportunity to test cosmological models and the underlying theory of gravity with unparalleled precision. In this context, it is crucial fo…

astro-ph.CO2026

FlowSN: Neural Simulation-Based Inference under Realistic Selection Effects applied to Supernova Cosmology

Benjamin M. Boyd, Kaisey S. Mandel, Matthew Grayling +10

We present FlowSN, a statistical framework using simulation-based inference (SBI) with normalising flows to account for selection effects in observational astronomy. Failure to acc…

astro-ph.CO2026

BICEP/Keck XXI: Constraints on Early-Universe Parity Violation from Multipole-Dependent Birefringence

Keck Collaboration, P. A. R. Ade, Zeeshan Ahmed +94

We present the first constraints on multipole-dependent cosmic birefringence using CMB polarization data from the BK18 dataset, which combines observations from BICEP2, Keck Array,…

astro-ph.CO2026

Time delays and stationarity in quasar light curves

Namu Kroupa, David Yallup, Will Handley

We present a fully Bayesian framework for time delay inference and stationarity tests in quasar light curves using marginalised Gaussian processes. The model separates a determinis…

astro-ph.CO2026★ 1 cited

The LOFAR sub-arcsecond view of the high-redshift radio relic in PSZ2G091.83+26.11

G. Di Gennaro, R. Timmerman, M. Hoeft +14

Enhanced inverse Compton (IC) losses at high redshift steepen diffuse radio spectra in galaxy clusters, making low-frequency (~100 MHz) observations favorable. However, low-frequen…

astro-ph.CO2026

Fast computation of temperature and polarization coupling matrices

Georgia Kiddier, Steven Gratton

We present a fast and exact method for computing CMB mode-coupling matrices based on an optimised evaluation of Wigner-3j symbols. The method exploits analytic structure in the rel…

astro-ph.CO2026

Establishing a relationship between the cosmological 21 cm power spectrum and interferometric closure phases

Pascal M. Keller, Bojan Nikolic, Nithyanandan Thyagarajan

Measurements of the cosmic 21 cm signal need to achieve a high dynamic range to isolate it from bright foreground emissions. Calibration inaccuracies can compromise the spectral fi…

astro-ph.CO2026

Euclid preparation. CIV. Impact of galaxy intrinsic alignment modelling choices on Euclid 3x2pt cosmology

Euclid Collaboration, D. Navarro-Gironés, I. Tutusaus +274

The Euclid galaxy survey will provide unprecedented constraints on cosmology, but achieving unbiased results will require an optimal characterisation and mitigation of systematic e…

astro-ph.CO2026

The Signature of Strong High-Redshift Radio Backgrounds on the Cosmic Dawn 21-cm Bispectrum

Sudipta Sikder, Rajesh Mondal, Rennan Barkana +1

Measurements from the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission 2 (ARCADE-2) reveal a strong radio background in the GHz frequency range. Since the cosm…

astro-ph.CO2026★ 4 cited

An ultra-high-resolution map of (dark) matter

Diana Scognamiglio, Gavin Leroy, David Harvey +38

Ordinary matter-including particles such as protons and neutrons-accounts for only about one sixth of all matter in the Universe. The rest is dark matter, which does not emit or ab…