X-Ray Detected Active Galactic Nuclei in Dwarf Galaxies At 0 < Z < 1

Authors

K. Pardo, Princeton University
A. D. Goulding, Princeton University
J. E. Greene, Princeton University
R. S. Somerville, Rutgers University
E. Gallo, University of Michigan-Ann Arbor
R. C. Hickox, Dartmouth College

Document Type

Article

Publication Date

11-9-2016

Publication Title

The Astrophysical Journal

Department

Department of Physics and Astronomy

Abstract

We present a sample of accreting supermassive black holes (SMBHs) in dwarf galaxies at z\lt 1. We identify dwarf galaxies in the NEWFIRM Medium Band Survey with stellar masses of {M}_\star \lt 3× {10}⁹ {M}_⊙ that have spectroscopic redshifts from the DEEP2 survey and lie within the region covered by deep (flux limit of ˜ 5× {10}^-17{--}6× {10}^-16 {erg} {{cm}}^-2 {{{s}}}^-1) archival Chandra X-ray data. From our sample of 605 dwarf galaxies, 10 exhibit X-ray emission consistent with that arising from active galactic nucleus (AGN) activity. If black-hole mass scales roughly with stellar mass, then we expect that these AGNs are powered by SMBHs with masses of ˜ {10}⁵{--}{10}⁶ {M}_⊙ and typical Eddington ratios of ˜ 5 % . Furthermore, we find an AGN fraction consistent with extrapolations of other searches of ˜ 0.6 % {--}3 % for {10}⁹ {M}_⊙ ≤slant {M}_\star ≤slant 3× {10}⁹ {M}_⊙ and 0.1\lt z\lt 0.6. Our AGN fraction is in good agreement with a semi-analytic model, suggesting that, as we search larger volumes, we may use comparisons between observed AGN fractions and models to understand seeding mechanisms in the early universe.

DOI

10.3847/0004-637X/831/2/203

Dartmouth Digital Commons Citation

Pardo, K.; Goulding, A. D.; Greene, J. E.; Somerville, R. S.; Gallo, E.; and Hickox, R. C., "X-Ray Detected Active Galactic Nuclei in Dwarf Galaxies At 0 < Z < 1" (2016). Dartmouth Scholarship. 2140.
https://digitalcommons.dartmouth.edu/facoa/2140