The Circumgalactic Medium of Submillimeter Galaxies. II. Unobscured QSOs within Dusty Starbursts and QSO Sightlines with Impact Parameters below 100 kpc

Hai Fu; Jacob Isbell; Caitlin M Casey; Asantha Cooray; J. Xavier Prochaska; Nick Scoville; Alan Stockton

doi:10.3847/1538-4357/aa7c63

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The Circumgalactic Medium of Submillimeter Galaxies. II. Unobscured QSOs within Dusty Starbursts and QSO Sightlines with Impact Parameters below 100 kpc

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The Circumgalactic Medium of Submillimeter Galaxies. II. Unobscured QSOs within Dusty Starbursts and QSO Sightlines with Impact Parameters below 100 kpc

Hai Fu, Jacob Isbell, Caitlin M Casey, Asantha Cooray, J. Xavier Prochaska, Nick Scoville and Alan Stockton

The Astrophysical journal, Vol.844(2), p.123

07/31/2017

DOI: 10.3847/1538-4357/aa7c63

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Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) 870 m observations of 29 bright Herschel sources near high-redshift QSOs. The observations confirm that 20 of the Herschel sources are submillimeter-bright galaxies (SMGs) and identify 16 new SMG−QSO pairs that are useful to studies of the circumgalactic medium (CGM) of SMGs. Eight out of the 20 SMGs are blends of multiple 870 m sources. The angular separations for six of the Herschel-QSO pairs are less than 10″, comparable to the sizes of the Herschel beam and the ALMA primary beam. We find that four of these six "pairs" are actually QSOs hosted by SMGs. No additional submillimeter companions are detected around these QSOs, and the rest-frame ultraviolet spectra of the QSOs show no evidence of significant reddening. Black hole accretion and star formation contribute almost equally in bolometric luminosity in these galaxies. The SMGs hosting QSOs show similar source sizes, dust surface densities, and star formation rate surface densities to those of other SMGs in the sample. We find that the black holes are growing ∼3× faster than the galaxies when compared to the present-day black hole/galaxy mass ratio, suggesting a QSO duty cycle of 30% in SMGs at . The remaining two Herschel-detected QSOs are undetected at 870 m, but each has an SMG "companion" only 9″ and 12″ away (71 and 95 kpc at z = 3). They could be either merging or projected pairs. If the former, they would represent a rare class of "wet−dry" mergers. If the latter, the QSOs would, for the first time, probe the CGM of SMGs at impact parameters below 100 kpc.

galaxies: starburst

quasars: supermassive black holes

Details

Title: Subtitle: The Circumgalactic Medium of Submillimeter Galaxies. II. Unobscured QSOs within Dusty Starbursts and QSO Sightlines with Impact Parameters below 100 kpc
Creators: Hai Fu - University of Iowa
Jacob Isbell - University of Iowa
Caitlin M Casey - University of Texas at Austin Department of Astronomy, 2515 Speedway Boulevard, Stop C1400, Austin, TX 78712, USA
Asantha Cooray - University of California Department of Physics and Astronomy, Irvine, CA 92697, USA
J. Xavier Prochaska - University of California Department of Astronomy and Astrophysics, UCO/Lick Observatory, 1156 High Street, Santa Cruz, CA 95064, USA
Nick Scoville - California Institute of Technology , MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125, USA
Alan Stockton - University of Hawaii Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
Resource Type: Journal article
Publication Details: The Astrophysical journal, Vol.844(2), p.123
DOI: 10.3847/1538-4357/aa7c63
ISSN: 0004-637X
eISSN: 1538-4357
Publisher: Institute of Physics (IOP)
Number of pages: 16
Language: English
Date published: 07/31/2017
Academic Unit: Physics and Astronomy
Record Identifier: 9984199795202771

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