THE CIRCUMGALACTIC MEDIUM OF SUBMILLIMETER GALAXIES. I. FIRST RESULTS FROM A RADIO-IDENTIFIED SAMPLE

• Published in: The Astrophysical journal 2016-11, Vol.832 (1), p.52
• Main Authors: Fu, Hai, Hennawi, J. F., Prochaska, J. X., Mutel, R., Casey, C., Cooray, A., Kereš, D., Zhang, Z.-Y., Clements, D., Isbell, J., Lang, C., McGinnis, D., Micha owski, M. J., Mooley, K., Perley, D., Stockton, A., Thompson, D.
• Format: Article
• Language: English
• Subjects: Absorbers; Absorption; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COVERINGS; Far infrared radiation; GALAXIES; galaxies: halos; Gas absorption; Halos; INFRARED SPECTRA; Infrared spectroscopy; intergalactic medium; INTERGALACTIC SPACE; METALS; Near infrared radiation; Near infrared spectroscopy; QUASARS; quasars: absorption lines; RED SHIFT; Space telescopes; Spectrum analysis; Stars & galaxies
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/832/1/52

ABSTRACT We present the first results from an ongoing survey to characterize the circumgalactic medium (CGM) of massive high-redshift galaxies detected as submillimeter galaxies (SMGs). We constructed a parent sample of 163 SMG-QSO pairs with separations less than ∼36″ by cross-matching far-infrared-selected galaxies from Herschel with spectroscopically confirmed QSOs. The Herschel sources were selected to match the properties of the SMGs. We determined the sub-arcsecond positions of six Herschel sources with the Very Large Array and obtained secure redshift identification for three of those with near-infrared spectroscopy. The QSO sightlines probe transverse proper distances of 112, 157, and 198 kpc at foreground redshifts of 2.043, 2.515, and 2.184, respectively, which are comparable to the virial radius of the ∼1013 M halos expected to host SMGs. High-quality absorption-line spectroscopy of the QSOs reveals systematically strong H i Ly absorption around all three SMGs, with rest-frame equivalent widths of ∼2-3 . However, none of the three absorbers exhibit compelling evidence for optically thick H i gas or metal absorption, in contrast to the dominance of strong neutral absorbers in the CGM of luminous z ∼ 2 QSOs. The low covering factor of optically thick H i gas around SMGs tentatively indicates that SMGs may not have as prominent cool gas reservoirs in their halos as the coeval QSOs and that they may inhabit less massive halos than previously thought.