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|Title:||The assembly of `normal' galaxies at z ̃ 7 probed by ALMA||Authors:||Maiolino, R.
|Issue Date:||2015||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||452||Issue:||1||First Page:||54||Abstract:||We report new deep observations obtained with the Atacama Large Millimetre Array (ALMA) aimed at investigating the [C II]158 μm line and continuum emission in three spectroscopically confirmed Lyman break galaxies at 6.8 < z ≤ 7.1, i.e. well within the re-ionization epoch. With star formation rates of SFR ̃ 5-15M<SUB>☉</SUB> yr<SUP>- 1</SUP> these systems are much more representative of the high-z galaxy population than other systems targeted in the past by millimetre observations. For the galaxy with the deepest observation we detect [C II] emission at redshift z = 7.107, fully consistent with the Ly α redshift, but spatially offset by 0.7 arcsec (4 kpc) from the optical emission. At the location of the optical emission, tracing both the Ly α line and the far-UV continuum, no [C II] emission is detected in any of the three galaxies, with 3σ upper limits significantly lower than the [C II] emission observed in lower redshift galaxies. These results suggest that molecular clouds in the central parts of primordial galaxies are rapidly disrupted by stellar feedback. As a result, [C II] emission mostly arises from more external accreting/satellite clumps of neutral gas. These findings are in agreement with recent models of galaxy formation. Thermal far-infrared continuum is not detected in any of the three galaxies. However, the upper limits on the infrared-to-UV emission ratio do not exceed those derived in metal- and dust-poor galaxies.||Acknowledgments:||We are grateful to the UK ARC node for assistance in the preparation of the ALMA observations, for providing the calibrated data. We are grateful to the UK ARC node, to the central ESO ARC node and to Leonardo Testi for helpful discussions on the data analysis and for their tips on the proper use of the casa software. We also thank Marijn Franx and Padelis Papadopoulos for useful comments. We thank Ilse De Looze for providing the data from her sample of galaxies. We are grateful to Kazuaki Ota, for providing the infrared and UV data on low metallicity galaxies and for comments on the paper. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2012.1.00719.S and ADS/JAO.ALMA#2012.A.00040.S; which can be retrieved from the ALMA data archive: https://almascience.eso.org/alma-data/archive . 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.||URI:||http://hdl.handle.net/20.500.12386/23265||URL:||https://academic.oup.com/mnras/article/452/1/54/1747703||ISSN:||0035-8711||DOI:||10.1093/mnras/stv1194||Bibcode ADS:||2015MNRAS.452...54M||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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