Abstract

How Prevalent are Dust Obscured AGN at z=1-2?: Predictions for MIRI/JWST Samples

Allison Kirkpatrick (Yale)

Alexandra Pope, UMass Anna Sajina, Tufts Eric Roebuck, Tufts

The buildup of stellar and black hole mass peaked during z=1-3, making this a key epoch in the era of JWST. IR luminous galaxies dominate the stellar growth during this period, and many are harboring a hidden active galactic nucleus (AGN), feedback from which may quench star formation. I quantify the contribution of AGN heating to the infrared emission of 343 IR luminous galaxies from z=0.5-2.8 using Spitzer mid-IR spectroscopy, available for every source, providing an unique opportunity for predicting the demographics of samples selected with MIRI/JWST. I classify sources as star forming galaxies, AGN, or composites based on the presence of mid-IR continuum emission due to a dusty torus. I quantify the percentage of AGN sources at different flux thresholds as a function of wavelength and find that obscured AGN comprise >40% of even the faintest samples. The composites are a separate class of galaxy which show a true mix of star formation and obscured AGN activity, and mid-IR emission alone can predict total IR luminosity of the AGN in composite systems, important for calculating correct star formation rates. I use my spectroscopic sample to calibrate new color selection diagnostics well suited for JWST, and I use my diagnostics to find previously unidentified AGN and composites in a large sample of main sequence, quiescent, and quenching galaxies from CANDELS. I find that dust obscured AGN and composites are preferentially located on the main sequence, indicating my IR selection techniques are ideal for finding luminous AGN in star forming galaxies prior to quenching.

Talk