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Massive black holes in nuclear star clusters: Investigation with SRG/eROSITA X-ray data by Hoyer, Nils; Arcodia, Riccardo; Bonoli, Silvia; Merloni, Andrea; Neumayer, Nadine; Zhang, Yi; Comparat, Johan is a scholarly article available to read on EtoBox.

What is Massive black holes in nuclear star clusters: Investigation with SRG/eROSITA X-ray data about?

Massive black holes (MBHs) are typically hosted in the centres of massive galaxies but they appear to become rarer in lower mass galaxies, where nuclear star clusters (NSCs) frequently appear instead. The transition region, where both an MBH and NSC can co-exist, has been poorly studied to date and only a few dozen galaxies are known to host them. One avenue for detecting new galaxies with both an MBH and NSC is to look for accretion signatures of MBHs. Here, we use new SRG/eROSITA all-sky survey eRASS:4 data to search for X-ray signatures of accreting MBHs in NSCs, while also investigating their combined occupation fraction. We find significant detections for 18 galaxies (~8.3%), including one ultra-luminous X-ray source; however, only three galaxies (NGC2903, 4212, and 4639) have X-ray luminosities that are higher than the expected value from X-ray binaries, indicative of the presence of an MBH. In addition, the X-ray luminosity of six galaxies (NGC2903, 3384, 4321, 4365, 4639, and 4701) differs from previous studies and could indicate the presence of a variable active galactic nucleus. The combined occupation fraction of accreting MBHs and NSCs becomes non-zero for galaxy masses

Author

Hoyer, Nils; Arcodia, Riccardo; Bonoli, Silvia; Merloni, Andrea; Neumayer, Nadine; Zhang, Yi; Comparat, Johan

Published

2024

Language

EN