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A Long Stream of Metal-poor Cool Gas around a Massive Starburst Galaxy at z = 2.67

Fu, Hai and Xue, R. and Prochaska, J. X. and Stockton, A. and Ponnada, S. and Lau, M. W. and Cooray, A. and Narayanan, D. (2021) A Long Stream of Metal-poor Cool Gas around a Massive Starburst Galaxy at z = 2.67. Astrophysical Journal, 908 (2). Art. No. 188. ISSN 1538-4357.

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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 (log(N_(HI)/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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemData
Fu, Hai0000-0001-9608-6395
Xue, R.0000-0001-7689-9305
Prochaska, J. X.0000-0002-7738-6875
Lau, M. W.0000-0001-9755-9406
Cooray, A.0000-0002-3892-0190
Narayanan, D.0000-0002-7064-4309
Additional Information:© 2021. The American Astronomical Society. Received 2020 December 23; revised 2021 January 7; accepted 2021 January 11; published 2021 February 24. We thank D. Kereš and J. Hennawi for discussions. This work is partially supported by the National Science Foundation (NSF) grant AST-1614326. D. N. acknowledges support from NSF AST-1909153. The National Radio Astronomy Observatory is a facility of the NSF operated under cooperative agreement by Associated Universities, Inc. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2015.1.00131.S, ADS/JAO. ALMA#2018.1.00548.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. Facilities: Herschel, ALMA, Gemini/GNIRS, VLT/X-shooter, Keck/LRIS, Sloan, KiDS, VISTA.
Funding AgencyGrant Number
Subject Keywords:Starburst galaxies; Circumgalactic medium
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Starburst galaxies (1570); Circumgalactic medium (1879)
Record Number:CaltechAUTHORS:20210312-123707863
Persistent URL:
Official Citation:Hai Fu et al 2021 ApJ 908 188
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108412
Deposited By: Tony Diaz
Deposited On:12 Mar 2021 21:53
Last Modified:12 Mar 2021 21:53

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