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Nuclear activity is more prevalent in star-forming galaxies

Rosario, D.J.; Santini, P.; Lutz, D.; Netzer, H.; Bauer, F.E.; Berta, S.; Magnelli, B.; Popesso, P.; Alexander, D.M.; Brandt, W.N.; Genzel, R.; Maiolino, R.; Mullaney, J.R.; Nordon, R.; Saintonge, A.; Tacconi, L.; Wuyts, S.

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D.J. Rosario

P. Santini

D. Lutz

H. Netzer

F.E. Bauer

S. Berta

B. Magnelli

P. Popesso

W.N. Brandt

R. Genzel

R. Maiolino

J.R. Mullaney

R. Nordon

A. Saintonge

L. Tacconi

S. Wuyts


We explore the question of whether low and moderate luminosity active galactic nuclei (AGNs) are preferentially found in galaxies that are undergoing a transition from active star formation (SF) to quiescence. This notion has been suggested by studies of the UV-optical colors of AGN hosts, which find them to be common among galaxies in the so-called Green Valley, a region of galaxy color space believed to be composed mostly of galaxies undergoing SF quenching. Combining the deepest current X-ray and Herschel/PACS far-infrared (FIR) observations of the two Chandra Deep Fields with redshifts, stellar masses, and rest-frame photometry derived from the extensive and uniform multi-wavelength data in these fields, we compare the rest-frame U - V color distributions and star formation rate distributions of AGNs and carefully constructed samples of inactive control galaxies. The UV-to-optical colors of AGNs are consistent with equally massive inactive galaxies at redshifts out to z ~ 2, but we show that such colors are poor tracers of SF. While the FIR distributions of both star-forming AGNs and star-forming inactive galaxies are statistically similar, we show that AGNs are preferentially found in star-forming host galaxies, or, in other words, AGNs are less likely to be found in weakly star-forming or quenched galaxies. We postulate that, among X-ray-selected AGNs of low and moderate accretion luminosities, the supply of cold gas primarily determines the accretion rate distribution of the nuclear black holes.

Journal Article Type Article
Publication Date Jul 1, 2013
Deposit Date Sep 13, 2013
Publicly Available Date Dec 23, 2013
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 771
Issue 1
Article Number 63
Keywords Galaxies, Active, Evolution, Star formation, Infrared, Surveys, X-rays.
Public URL


Published Journal Article (1.5 Mb)

Copyright Statement
© 2013. The American Astronomical Society. All rights reserved. Printed in the U.S.A.

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