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A Massive Molecular Gas Reservoir in the z = 5.3 Submillimeter Galaxy AzTEC-3

Riechers, Dominik A. and Capak, Peter L. and Carilli, Christopher L. and Cox, Pierre and Neri, Roberto and Scoville, Nicholas Z. and Schinnerer, Eva and Bertoldi, Frank and Yan, Lin (2010) A Massive Molecular Gas Reservoir in the z = 5.3 Submillimeter Galaxy AzTEC-3. Astrophysical Journal Letters, 720 (2). L131-L136. ISSN 2041-8205. doi:10.1088/2041-8205/720/2/L131.

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We report the detection of CO J = 2→1, 5→4, and 6→5 emission in the highest-redshift submillimeter galaxy (SMG) AzTEC-3 at z = 5.298, using the Expanded Very Large Array and the Plateau de Bure Interferometer. These observations ultimately confirm the redshift, making AzTEC-3 the most submillimeter-luminous galaxy in a massive z ≃ 5.3 protocluster structure in the COSMOS field. The strength of the CO line emission reveals a large molecular gas reservoir with a mass of 5.3 × 10^(10)(α_(CO)/0.8) M_☉ sun, which can maintain the intense 1800 M_☉ sun yr^(–1) starburst in this system for at least 30 Myr, increasing the stellar mass by up to a factor of six in the process. This gas mass is comparable to "typical" z ~ 2 SMGs and constitutes ≳80% of the baryonic mass (gas+stars) and 30%-80% of the total (dynamical) mass in this galaxy. The molecular gas reservoir has a radius of <4 kpc and likely consists of a "diffuse", low-excitation component, containing (at least) 1/3 of the gas mass (depending on the relative conversion factor αCO), and a "dense", high-excitation component, containing ~2/3 of the mass. The likely presence of a substantial diffuse component besides highly excited gas suggests different properties between the star-forming environments in z > 4 SMGs and z > 4 quasar host galaxies, which perhaps trace different evolutionary stages. The discovery of a massive, metal-enriched gas reservoir in an SMG at the heart of a large z = 5.3 protocluster considerably enhances our understanding of early massive galaxy formation, pushing back to a cosmic epoch where the universe was less than 1/12 of its present age.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Riechers, Dominik A.0000-0001-9585-1462
Capak, Peter L.0000-0003-3578-6843
Carilli, Christopher L.0000-0001-6647-3861
Cox, Pierre0000-0003-2027-8221
Neri, Roberto0000-0002-7176-4046
Scoville, Nicholas Z.0000-0002-0438-3323
Schinnerer, Eva0000-0002-3933-7677
Bertoldi, Frank0000-0002-1707-1775
Yan, Lin0000-0003-1710-9339
Additional Information:© 2010 American Astronomical Society. Received 2010 June 28; accepted 2010 July 30; published 2010 August 16. We thank Josh Younger for the SMA image of AzTEC-3, Christian Henkel for the original version of the LVG code, and the referee for a helpful report. D.R. acknowledges support from NASA through Hubble Fellowship grant HST-HF-51235.01 awarded by STScI, operated by AURA for NASA, under contract NAS 5-26555. The IRAM PdBI is supported by INSU/CNRS (France),MPG (Germany), and IGN (Spain). The EVLA is a facility of NRAO, operated by AUI, under a cooperative agreement with the NSF.
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASANAS 5-26555
NASA Hubble FellowshipHST-HF-51235.01
Subject Keywords:cosmology: observations; galaxies: active; galaxies: formation; galaxies: high-redshift; galaxies: starburst; radio lines: galaxies
Issue or Number:2
Classification Code:PACS: 98.54.Ep; 98.62.Ai; 98.62.Qz; 95.85.Bh; 98.62.Py; 98.62.Bj
Record Number:CaltechAUTHORS:20100927-105114318
Persistent URL:
Official Citation:Dominik A. Riechers et al 2010 ApJ 720 L131 doi: 10.1088/2041-8205/720/2/L131
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20157
Deposited On:27 Sep 2010 23:18
Last Modified:08 Nov 2021 23:57

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