Environmental dependence of AGN activity and star formation in galaxy clusters from Magneticum simulations

Rihtaršič, Gregor (author), Biffi, Veronica (author), Fabjan, Dunja (author), Dolag, Klaus (author)

Context. The environment inside and on the outskirts of galaxy clusters has a profound impact on the star formation rate and active galactic nucleus (AGN) activity in cluster galaxies. While the overall star formation and AGN suppression in the inner cluster regions has been thoroughly studied in the past, recent X-ray studies also indicate that conditions on the cluster outskirts may promote AGN activity. Aims. We investigate how the environment and the properties of host galaxies impact the levels of AGN activity and star formation in galaxy clusters. We aim to identify significant trends in different galaxy populations and suggest possible explanations. Methods. We studied galaxies with stellar mass log $M_∗(M_⊙)$ > 10.15 in galaxy clusters with mass $M_{500}$ > 10$^{13}$ $M_⊙$ extracted from box2b (640 comoving Mpc $h^{−1}$) of the Magneticum Pathfinder suite of cosmological hydrodynamical simulations at redshifts 0.25 and 0.90. We examined the influence of stellar mass, distance to the nearest neighbouring galaxy, cluster-centric radius, substructure membership, and large-scale surroundings on the fraction of galaxies hosting an AGN, star formation rate, and the ratio between star-forming and quiescent galaxies. Results. We find that in low-mass galaxies, AGN activity and star formation are similarly affected by the environment and decline towards the cluster centre. In massive galaxies, the impact is different; star-formation level increases in the inner regions and peaks between 0.5 and 1 $R_{500}$ with a rapid decline in the centre, whereas AGN activity declines in the inner regions and rapidly rises below $R_{500}$ towards the centre. We suggest that this increase is a result of the larger black hole masses relative to stellar masses in the cluster centre. After disentangling the contributions of neighbouring cluster regions, we find an excess of AGN activity in massive galaxies on the cluster outskirts (∼3 $R_{500}$). We also find that the local density, substructure membership, and stellar mass strongly influence star formation and AGN activity but verify that they cannot fully account for the observed radial trends.

• Language: English
• Keywords: active galaxies, star formation, active galactic nuclei, numerical methods, galaxy clusters, galaxy interactions, galaxies, large-scale structure of Universe
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 14 str.
• Numbering: Vol. 683, art. A57
• PID: 20.500.12556/RUL-154870
• UDC: 524.6
• ISSN on article: 1432-0746
• DOI: 10.1051/0004-6361/202347444
• COBISS.SI-ID: 187927811
• Publication date in RUL: 06.03.2024

Record is a part of a journal

• Title: Astronomy & astrophysics
• Shortened title: Astron. astrophys.
• Publisher: EDP Sciences
• ISSN: 1432-0746
• COBISS.SI-ID: 392577

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.