[C II] Line Emission in Massive Star-forming Galaxies at z = 4.7
Abstract
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [C II] 157.7 μm fine structure line and thermal dust continuum emission from a pair of gas-rich galaxies at z = 4.7, BR1202-0725. This system consists of a luminous quasar host galaxy and a bright submillimeter galaxy (SMG), while a fainter star-forming galaxy is also spatially coincident within a 4'' (25 kpc) region. All three galaxies are detected in the submillimeter continuum, indicating FIR luminosities in excess of 10^(13) L_☉ for the two most luminous objects. The SMG and the quasar host galaxy are both detected in [C II] line emission with luminosities L_([CII]) = (10.0 ± 1.5) × 10^9 L_☉ and L_([CII]) = (6.5 ± 1.0) × 10^9 L_☉, respectively. We estimate a luminosity ratio L_([CII])/L_(FIR) = (8.3 ± 1.2) × 10^(–4) for the starburst SMG to the north and L [C II]/L FIR = (2.5 ± 0.4) × 10–4 for the quasar host galaxy, in agreement with previous high-redshift studies that suggest lower [C II]-to-FIR luminosity ratios in quasars than in starburst galaxies. The third fainter object with a flux density S_(340GHz) = 1.9 ± 0.3 mJy is coincident with a Lyα emitter and is detected in HST ACS F775W and F814W images but has no clear counterpart in the H band. Even if this third companion does not lie at a redshift similar to BR1202-0725, the quasar and the SMG represent an overdensity of massive, infrared luminous star-forming galaxies within 1.3 Gyr of the big bang.
Additional Information
© 2012 American Astronomical Society. Received 2012 April 24; accepted 2012 May 16; published 2012 June 4. We thank the referee for helpful suggestions based on the original manuscript. This work was co-funded under the Marie Curie Actions of the European Commission (FP7-COFUND). We thank all those involved in the ALMA project for making these observations possible. This Letter makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00006.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada) and NSC and ASIAA(Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. D.R. acknowledges support from NASA through a Spitzer Space Telescope grant. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.Attached Files
Published - Wagg2012p18836Astrophys_J_Lett.pdf
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Additional details
- Eprint ID
- 32474
- Resolver ID
- CaltechAUTHORS:20120716-111911487
- Marie Curie Fellowship
- NASA Spitzer Space Telescope
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2012-07-16Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field