Journal article
A Long Stream of Metal-Poor Cool Gas around a Massive Starburst Galaxy at z = 2.67
The Astrophysical journal, Vol.908(2), 188
02/01/2021
DOI: 10.3847/1538-4357/abdb32
Abstract
We present the first detailed dissection of the circumgalactic medium (CGM) of massive starburst galaxies at z > 2. Our target is a submillimeter galaxy (SMG) at z = 2.674 that has a star formation rate of 1200 M⊙ yr−1 and a molecular gas reservoir of 1.3 × 1011 M⊙. We characterize its CGM with two background QSOs at impact parameters of 93 kpc and 176 kpc. We detect strong H i and metal-line absorption near the redshift of the SMG toward both QSOs, each consisting of three main subsystems spanning over 1500 km s−1. The absorbers show remarkable kinematic and metallicity coherence across a separation of ∼86 kpc. In particular, the cool gas in the CGM of the SMG exhibits high H i column densities (${\rm{log}}({N}_{{\rm{H}}{\rm\small{I}}}/{{\rm{cm}}}^{-2})=20.2,18.6$), a low metallicity ([M/H] ≈ −2.0), and nearly the same radial velocity (δv ∼ −300 km s−1). While the H i column densities match previous results on the massive halos hosting QSOs, the metallicity is lower by more than an order of magnitude, making it an outlier in the line width−metallicity relation of damped Lyα absorbers. The large physical extent, the velocity coherence, the high surface densities, and the low metallicity are all consistent with the cool, inflowing, and near-pristine gas streams predicted to penetrate hot massive halos at z > 1.5. We estimate a total gas accretion rate of ∼100 M⊙ yr−1 from three such streams. At this rate, it takes only a gigayear to acquire the molecular gas reservoir of the central starburst.
Details
- Title: Subtitle
- A Long Stream of Metal-Poor Cool Gas around a Massive Starburst Galaxy at z = 2.67
- Creators
- Hai Fu - University of IowaRui XueJ. Xavier Prochaska - University of California, Santa CruzAlan StocktonSam PonnadaMarie Wingyee Lau - University of California, RiversideAsantha Cooray - University of California, IrvineDesika Narayanan - University of Florida
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.908(2), 188
- DOI
- 10.3847/1538-4357/abdb32
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Grant note
- DOI: 10.13039/100000001, name: National Science Foundation, award: AST-1614326
- Language
- English
- Date published
- 02/01/2021
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984429053402771
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