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Hubble Space Telescope/Advanced Camera for Surveys Morphology of Lyα Emitters at Redshift 5.7 in the COSMOS Field

Taniguchi, Y. and Murayama, T. and Scoville, N. Z. and Sasaki, S. S. and Nagao, T. and Shioya, Y. and Saito, T. and Ideue, Y. and Nakajima, A. and Matsuoka, K. and Sanders, D. B. and Mobasher, B. and Aussel, H. and Capak, P. and Salvato, M. and Koekemoer, A. and Carilli, C. and Cimatti, A. and Ellis, R. S. and Garilli, B. and Giavalisco, M. and Ilbert, O. and Impey, C. D. and Kitzbichler, M. G. and Le Fevre, O. and McCracken, H. J. and Scarlata, C. and Schinnerer, E. and Smolcic, V. and Tribiano, S. and Trump, J. R. (2009) Hubble Space Telescope/Advanced Camera for Surveys Morphology of Lyα Emitters at Redshift 5.7 in the COSMOS Field. Astrophysical Journal, 701 (2). pp. 915-944. ISSN 0004-637X.

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We present detailed morphological properties of Lyα emitters (LAEs) at z ≈ 5.7 in the COSMOS field based on Hubble Space Telescope Advanced Camera for Surveys (ACS) data. The ACS imaging in the F814W filter covered 85 LAEs of the 119 LAEs identified in the full two square degree field, and 47 LAEs of them are detected in the ACS images. Nearly half of them are spatially extended with a size larger than 0.15 arcsec (~0.88 kpc at z = 5.7) and up to 0.4 arcsec (~2.5 kpc at z = 5.7). The others are nearly unresolved compact objects. Two LAEs show double-component structures indicating interaction or merging of building components to form more massive galaxies. By stacking the ACS images of all the detected sources, we obtain a Sersic parameter of n ~ 0.7 with a half-light radius of 0.13 arcsec (0.76 kpc), suggesting that the majority of ACS detected LAEs have not spheroidal-like but disk-like or irregular light profiles. Comparing ACS F814W magnitudes (I _(814)) with Subaru/Suprime-Cam magnitudes in the NB816, i', and z' bands, we find that the ACS imaging in the F814W band mainly probes UV continuum rather than Lyα line emission. UV continuum sizes tend to be larger for LAEs with larger Lyα emission regions as traced by the NB816 imaging. The nondetection of 38 LAEs in the ACS images is likely due to the fact that their surface brightness is too low both in the UV continuum and Lyα emission. Estimating I_(814) for the ACS-undetected LAEs from the z' and NB816 magnitudes, we find that 16 of these are probably LAEs with a size larger than 0.15 arcsec in UV continuum. All these results suggest that our LAE sample contains systematically larger LAEs in UV continuum size than those previously studied at z ~ 6.

Item Type:Article
Related URLs:
URLURL TypeDescription
Scoville, N. Z.0000-0002-0438-3323
McCracken, H. J.0000-0002-9489-7765
Schinnerer, E.0000-0002-3933-7677
Additional Information:© 2009 American Astronomical Society. Print publication: Issue 2 (2009 August 20); received 2008 November 3, accepted for publication 2009 June 15; published 2009 July 28. We thank both the Subaru and HST staff for their invaluable help, and all members of the COSMOS team.We also thank the anonymous referee for his/her useful comments. This work was in part financially supported by JSPS (15340059 and 17253001).
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)15340059
Japan Society for the Promotion of Science (JSPS)17253001
Subject Keywords:cosmology: observations; early universe; galaxies: evolution; galaxies: formation; galaxies: high-redshift
Record Number:CaltechAUTHORS:20090831-141027603
Persistent URL:
Official Citation:Hubble Space Telescope/Advanced Camera for Surveys Morphology of Lyα Emitters at Redshift 5.7 in the COSMOS Field Y. Taniguchi, T. Murayama, N. Z. Scoville, S. S. Sasaki, T. Nagao, Y. Shioya, T. Saito, Y. Ideue, A. Nakajima, K. Matsuoka, D. B. Sanders, B. Mobasher, H. Aussel, P. Capak, M. Salvato, A. Koekemoer, C. Carilli, A. Cimatti, R. S. Ellis, B. Garilli, M. Giavalisco, O. Ilbert, C. D. Impey, M. G. Kitzbichler, O. Le Fevre, H. J. McCracken, C. Scarlata, E. Schinnerer, V. Smolcic, S. Tribiano, and J. R. Trump 2009 ApJ 701 915-944 doi: 10.1088/0004-637X/701/2/915
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15495
Deposited By: Jason Perez
Deposited On:11 Sep 2009 22:17
Last Modified:18 May 2017 22:46

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