The SRG/eROSITA All-Sky Survey

Constraints on f (R) gravity from cluster abundances

¹ Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany
² Universität Innsbruck, Institut für Astro- und Teilchenphysik, Technikerstr. 25/8, 6020 Innsbruck, Austria
³ IRAP, Université de Toulouse, CNRS, UPS, CNES, 31028 Toulouse, France
⁴ Argelander-Institut für Astronomie (AIfA), Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁵ Universitäts-Sternwarte, LMU Munich, Scheinerstr. 1, 81679 München, Germany
⁶ Arnold Sommerfeld Center for Theoretical Physics, LMU Munich, Theresienstr. 37, 80333 München, Germany
⁷ Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, 1290 Versoix, Switzerland
⁸ Department of Physics, National Cheng Kung University, 70101 Tainan, Taiwan
⁹ Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
¹⁰ McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
¹¹ Subaru Telescope, National Astronomical Observatory of Japan, 650 N Aohoku Place Hilo, HI 96720, USA
¹² Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Nagoya 464-8602, Japan
¹³ Institute for Advanced Research, Nagoya University, Nagoya 464-8601, Japan
¹⁴ Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo, Chiba 277-8583, Japan

^★ Corresponding author; eartis@mpe.mpg.de

Received: 13 February 2024
Accepted: 30 September 2024

Abstract

The evolution of the cluster mass function traces the growth of the linear density perturbations and can be utilized to constrain the parameters of cosmological and alternative gravity models. In this context, we present new constraints on potential deviations from general relativity by investigating the Hu-Sawicki parametrization of the f (R) gravity with the first Spectrum Roentgen Gamma (SRG)/eROSITA All-Sky Survey (eRASS1) cluster catalog in the western Galactic hemisphere in combination with the overlapping Dark Energy Survey Year-3, KiloDegree Survey, and Hyper Suprime-Cam data for weak lensing mass calibration. For the first time, we present constraints obtained from cluster abundances only. When we consider massless neutrinos, we find a strict upper limit of log |f_R0| < −4.31 at a 95% confidence level. Massive neutrinos suppress structure growth at small scales, and thus have the opposite effect of f (R) gravity. We consequently investigate the joint fit of the mass of the neutrinos with the modified gravity parameter. We obtain log |f_R0| < −4.08 jointly with ∑ m_ν < 0.49 eV at a 95% confidence level, which is tighter than the limits in the literature utilizing cluster counts only. At log |f_R0| = −6, the number of clusters is not significantly changed by the theory. Consequently, we do not find any statistical deviation from general relativity in the study of eRASS1 cluster abundance. Deeper surveys with eROSITA, increasing the number of detected clusters, will further improve constraints on log |f_R0| and investigate alternative gravity theories.