Redshift evolution of the baryon and gas fraction in simulated groups and clusters of galaxies

¹ Dipartimento di Fisica e Astronomia, Università di Bologna, Via Gobetti 92/3, 40121 Bologna, Italy
e-mail: matteo.angelinelli2@unibo.it
² INAF, Osservatorio di Astrofisica e Scienza dello Spazio, via Piero Gobetti 93/3, 40121 Bologna, Italy
³ INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
⁴ Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr.1, 81679 München, Germany
⁵ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85741 Garching, Germany
⁶ Hamburger Sternwarte, University of Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
⁷ Istituto di Radio Astronomia, INAF, Via Gobetti 101, 40121 Bologna, Italy
⁸ INAF, Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34143 Trieste, Italy
⁹ IFPU, Institute for Fundamental Physics of the Universe, Via Beirut 2, 34014 Trieste, Italy

Received: 23 December 2022
Accepted: 11 May 2023

Abstract

We study the redshift evolution of the baryon budget in a large set of galaxy clusters from the Magneticum suite of smoothed particle hydrodynamical cosmological simulations. At high redshifts (z ≳ 1), we obtain ‘closed-box’ (i.e. baryon mass fraction f_bar = Ω_bar/Ω_tot) systems independently of the mass of the systems on radii greater than 3R_500, c, whereas at lower redshifts, only the most massive halos can be considered closed box. Furthermore, in the innermost regions (r < R_500, c), the baryon fraction shows a general decrease with redshift, and for less massive objects we observe a much more prominent decrease than for massive halos (f_bar × Ω_tot/Ω_bar = Y_bar decreases by ∼4% from z ∼ 2.8 to z ∼ 0.2 for massive systems and by ∼15% for less massive objects in the same redshift range). The gas depletion parameter Y_gas = f_gas/(Ω_bar/Ω_tot) shows a steeper and highly scattered radial distribution in the central regions (0.5R_500, c ≤ r ≤ 2R_500, c) of less massive halos with respect to massive objects at all redshifts, while on larger radii (r ≥ 2R_500, c) the gas fraction distributions are independent of the masses or the redshifts. We divide the gas content of halos into the hot and cold phases. The hot, X-ray-observable component of the gas accurately traces the total amount of gas at low redshifts (e.g., for z ∼ 0.2 at R_500, c, in the most massive subsample, that is, 4.6 × 10¹⁴ ≤ M_500, c/M_⊙ ≤ 7.5 × 10¹⁴ and least massive subsample, that is, 6.0 × 10¹³ ≤ M_500, c/M_⊙ ≤ 1.9 × 10¹⁴, we obtain Y_gas ∼ 0.75 and 0.67, Y_hot ∼ 0.73 and 0.64, and Y_cold ∼ 0.02 and 0.02, respectively). On the other hand, at higher redshifts, the cold component provides a non-negligible contribution to the total amount of baryons in our simulated systems, especially in less massive objects (e.g., for z ∼ 2.8 at R_500, c, in the most massive subsample, that is, 2.5 × 10¹³ ≤ M_500, c/M_⊙ ≤ 5.0 × 10¹³ and least massive subsample, that is, 5.8 × 10¹² ≤ M_500, c/M_⊙ ≤ 9.7 × 10¹², we obtain Y_gas ∼ 0.63 and 0.64, Y_hot ∼ 0.50 and 0.45, and Y_cold ∼ 0.13 and 0.18, respectively). Moreover, the behaviour of the baryonic, entire-gas, and hot-gas-phase depletion parameters as functions of radius, mass, and redshift are described by some functional forms for which we provide the best-fit parametrization. The evolution of metallicity and stellar mass in halos suggests that the early (z > 2) enrichment process is dominant, while more recent star-formation processes make negligible contributions to the enrichment of the gas metallicity. In addition, active galactic nuclei (AGN) play an important role in the evolution of the baryon content of galaxy clusters. Therefore, we investigate possible correlations between the time evolution of AGN feedback and the depletion parameters in our numerical simulations. Interestingly, we demonstrate that the energy injected by the AGN activity shows a particularly strong positive correlation with Y_bar, Y_cold, and Y_star and a negative correlation with Y_hot and Z_Tot. On the other hand, Y_gas shows a less prominent level of negative correlation, a result which is highly dependent on the mass of the halos. These trends are consistent with previous theoretical and numerical works, meaning that our results, combined with findings derived from current and future X-ray observations, represent possible proxies with which to test the AGN feedback models used in different suites of numerical simulations.