The Far-IR View of an Ultra-Hard X-ray Selected Sample of AGN

Type Conference Paper
Names Thomas Shimizu, M. Melendez, R. Mushotzky, A. J. Barger, L. L. Cowie
Proceedings Title American Astronomical Society
Conference Name AAS Meeting #223, #150.20
Date January 1, 2014
Library Catalog
Abstract We present early results of the Herschel PACS (70 and 160 μm) and SPIRE (250, 350, and 500 μm) survey of 313 low redshift (z < 0.05), ultra-hard X-ray (14-195 keV) selected AGN from the 58 month Swift/BAT catalog. Selection of AGN from ultra-hard X-rays avoids bias from obscuration that are unavoidable at other wavelengths (eg optical, infrared, and radio) providing the most complete sample of AGN to study the connection between nuclear activity and star formation in host galaxies. With the high angular resolution of PACS, we find that ~35% and ~20% of the sources are 'point-like' at 70 and 160 μm respectively with another 20% that have their flux dominated by a point source located at the nucleus. The inferred star formation rates (SFR) of 0.1 - 100 Msun yr-1 using the 70 and 160 μm flux densities and the calibration of Calzettti et al (2010) are consistent with those inferred from Spitzer NeII fluxes, but we find that 11.25 μm PAH data give ~3x lower SFR. Using GALFIT to measure the size of the FIR emitting regions, we determined the SFR density [Msun yr-1 kpc-2] for our sample, finding a significant fraction to exist above the threshold for star formation driven winds (0.1 Msun yr-1 kpc-2, Heckman 2001). Analysis of the SPIRE colors (250/350 and 350/500) also reveals evidence for the presence of nonthermal synchrotron emission from a radio jet significantly affecting the FIR emission at long wavelengths and altering the shape of the spectral energy distribution (SED). We also will present the broad band Herschel 70-500m SEDS for our sample and include archival Spitzer, WISE, FIRST and NVSS data to extend the SED down to near-IR and up to radio wavelengths. The SEDs will be fit using multiple models to attempt to determine the AGN contribution to the FIR (indirect or direct) and ultimately its effect on nuclear star formation.
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