CEA astronomers identify signatures of AGN feedback

Active galactic nuclei (AGN) are super massive black holes accreting gas. During this process they releases large amounts of radiation and launch fast winds throughout their host galaxies. It has been argued that these effects can influence the star formation in the galaxies and are a vital part of galaxy evolution. This phenomenon is called AGN feedback. However, most of the evidence for AGN feedback is from cosmological simulations and astronomers have not yet found a conclusive observational evidence.

We used the largest sample of AGN observed with ALMA at 870 μm and results from two different flavours of the EAGLE hydrodynamical simulation to find the signature of the AGN feedback. Using the ALMA observations we measured the specific star formation rate (sSFR – star formation rate divided by stellar mass of the galaxies) for AGN in redshift range between 1.5 and 3.2 and with stellar mass above 2x10¹⁰ M_⊙. We also calculated the sSFR for two different flavours of the EAGLE hydrodynamical simulation; one with AGN feedback (reference model) and one without (no AGN model). We find good agreement between the observations and that predicted by the EAGLE reference model. However, the no AGN model predicts much shallower trend of sSFR with stellar mass and narrower spread of values by factor of ~2. We concluded that the signature of AGN feedback is a broader spread of sSFR values for all galaxies (not just those hosting AGN)

Link to the original research paper: arxiv.org/abs/1712.02708

Contacts from CEA, Durham:

Jan Scholtz

David Alexander

David Rosario

Stuart McAlpine

Mark Swinbank