Active galactic nuclei activity and mass assembly in the dense environment of xdcpj0044.0-2033
Abstract
The evolution of galaxies and their central black holes is mainly linked to the presence of cold molecular gas and, therefore, the environment in which these objects are located may influence their evolution. Indeed, observations and models point out a possible accelerated formation of galaxies and evolution of black holes in overdense environment in which processes as galaxy-galaxy mergers can affect the transportation of cold gas and influence star formation and other internal features. The ideal laboratories for studying the evolution of Active Galactic Nuclei (AGNs), galaxies and their properties are galaxy clusters at different redshift. Particularly, we can roughly identify a transition epoch at 1.5 < z < 2.5, when nuclear activity and star formation are at their peak. In our work, we presented a multi-wavelength study of a region of 24 kpc x 24 kpc located ∼157 kpc from the center of the galaxy cluster XDCPJ0044.0-2033 at z>1.5, around an X-ray point-like source for which we have photometric and spectroscopic multi-wavelength observations. Particularly, we performed sources identification and photometric analysis on high resolution Hubble Space Telescope (HST) images in F105W-, F140W- and F160W-band and spectroscopic analysis of the Near-Infrared (NIR) KMOS data in H and YJ bands. Finally, we analyzed Chandra ACIS-S X-ray data associated to the X-ray point-like emission. We find that the analyzed region hosts up to 9 different sources, 6 of them confirmed to be cluster members with redshift ranging from 1.5728 to 1.5762. These sources form two different complexes at a projected distance of ∼13 kpc. Moreover, one of these two complexes has a negative velocity shift of ∼300 km/s with respect to the other, indicating that they will probably merge. One of these sources shows the presence of a broad Hα emission line and is associated to the X-ray point-like emission, so we classify it as a Type-1, slightly obscured, broad line AGN. This AGN hosts a relatively massive black hole (M _{BH}∼10 7 M _{Sun}) which is highly accreting (λ _{Edd}∼ 0.4). The discovered super complex of galaxies at z∼1.6 represents the progenitors of local massive galaxies: we are witnessing the galaxy mass assembly in one of the densest region of a galaxy cluster at z∼1.6, which is thought to be a crucial formation epoch, when both star formation and nuclear activity are at their peak. Also, the presence of an AGN is interesting for the AGN-host galaxy co-evolution scenario.
- Publication:
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44th COSPAR Scientific Assembly. Held 16-24 July
- Pub Date:
- July 2022
- Bibcode:
- 2022cosp...44.2344L