Do Most Active Galactic Nuclei Live in High Star Formation Nuclear Cusps?

الأصل · EN

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 providing a 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 and many more that have their flux dominated by a point source located at the nucleus. The inferred star formation rates (SFR) of 0.1 - 100 M yr⁻¹ using the 70 and 160 µm flux densities as SFR indicators 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 surface density [M yr⁻¹ kpc⁻²] for our sample, finding a significant fraction of these sources exceed the threshold for star formation driven winds (0.1 M yr⁻¹ kpc⁻²).