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Extracting the Star Formation Histories of SSA22 Protocluster AGN with Lightning

Presentation #101.22 in the session AGN & Quasars — iPoster Session.

Published onJun 29, 2022
Extracting the Star Formation Histories of SSA22 Protocluster AGN with Lightning

It has been widely noted that high redshift overdensities (protoclusters) host a larger fraction of active galactic nuclei (AGN) than mean density fields, but the source of AGN fraction enhancement in protoclusters remains ambiguous. Since AGN coevolve with their host galaxy, constraining the star formation histories (SFH) of protocluster AGN host galaxies may shed light on the cause of the protocluster AGN fraction enhancement by exposing differences between the evolution of the protocluster and field AGN host populations. Our previous work has suggested that the galaxy population in the z = 3.1 SSA22 protocluster is more massive by a factor of ~2 than the field population at the same redshift. We speculated that this increase in the average mass of protocluster galaxies could lead to the observed AGN fraction enhancement, though our sample excluded AGN hosts due to the difficulty of simultaneously modeling AGN and stellar population emission. Here, we present updates to our spectral energy distribution (SED) fitting code, Lightning, to incorporate physically-based X-ray to infrared (IR) AGN models, and we use Lightning to extract SFHs for 9 X-ray detected AGN in the SSA22 protocluster by fitting their X-ray to IR SEDs. We compare the extracted protocluster SFHs and host galaxy properties to samples of X-ray detected AGN in the Chandra deep fields.


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