%0 Generic %1 furusawa2016constraint %A Furusawa, Hisanori %A Kashikawa, Nobunari %A Kobayashi, Masakazu A. R. %A Dunlop, James S. %A Shimasaku, Kazuhiro %A Takata, Tadafumi %A Sekiguchi, Kazuhiro %A Naito, Yoshiaki %A Furusawa, Junko %A Ouchi, Masami %A Nakata, Fumiaki %A Yasuda, Naoki %A Okura, Yuki %A Taniguchi, Yoshiaki %A Yamada, Toru %A Kajisawa, Masaru %A Fynbo, Johan P. U. %A Fevre, Olivier Le %D 2016 %K emitters evolution lya redshift %T A New Constraint on the Ly$\alpha$ Fraction of UV Very Bright Galaxies at Redshift 7 %U http://arxiv.org/abs/1604.02214 %X We study the extent to which very bright (-23.0 < MUV < -21.75) Lyman-break selected galaxies at redshifts z~7 display detectable Lya emission. To explore this issue, we have obtained follow-up optical spectroscopy of 9 z~7 galaxies from a parent sample of 24 z~7 galaxy candidates selected from the 1.65 sq.deg COSMOS-UltraVISTA and SXDS-UDS survey fields using the latest near-infrared public survey data, and new ultra-deep Subaru z'-band imaging (which we also present and describe in this paper). Our spectroscopy has yielded only one possible detection of Lya at z=7.168 with a rest-frame equivalent width EW_0 = 3.7 (+1.7/-1.1) Angstrom. The relative weakness of this line, combined with our failure to detect Lya emission from the other spectroscopic targets allows us to place a new upper limit on the prevalence of strong Lya emission at these redshifts. For conservative calculation and to facilitate comparison with previous studies at lower redshifts, we derive a 1-sigma upper limit on the fraction of UV bright galaxies at z~7 that display EW_0 > 50 Angstrom, which we estimate to be < 0.23. This result may indicate a weak trend where the fraction of strong Lya emitters ceases to rise, and possibly falls between z~6 and z~7. Our results also leave open the possibility that strong Lya may still be more prevalent in the brightest galaxies in the reionization era than their fainter counterparts. A larger spectroscopic sample of galaxies is required to derive a more reliable constraint on the neutral hydrogen fraction at z~7 based on the Lya fraction in the bright galaxies.

@misc{furusawa2016constraint, abstract = {We study the extent to which very bright (-23.0 < MUV < -21.75) Lyman-break selected galaxies at redshifts z~7 display detectable Lya emission. To explore this issue, we have obtained follow-up optical spectroscopy of 9 z~7 galaxies from a parent sample of 24 z~7 galaxy candidates selected from the 1.65 sq.deg COSMOS-UltraVISTA and SXDS-UDS survey fields using the latest near-infrared public survey data, and new ultra-deep Subaru z'-band imaging (which we also present and describe in this paper). Our spectroscopy has yielded only one possible detection of Lya at z=7.168 with a rest-frame equivalent width EW_0 = 3.7 (+1.7/-1.1) Angstrom. The relative weakness of this line, combined with our failure to detect Lya emission from the other spectroscopic targets allows us to place a new upper limit on the prevalence of strong Lya emission at these redshifts. For conservative calculation and to facilitate comparison with previous studies at lower redshifts, we derive a 1-sigma upper limit on the fraction of UV bright galaxies at z~7 that display EW_0 > 50 Angstrom, which we estimate to be < 0.23. This result may indicate a weak trend where the fraction of strong Lya emitters ceases to rise, and possibly falls between z~6 and z~7. Our results also leave open the possibility that strong Lya may still be more prevalent in the brightest galaxies in the reionization era than their fainter counterparts. A larger spectroscopic sample of galaxies is required to derive a more reliable constraint on the neutral hydrogen fraction at z~7 based on the Lya fraction in the bright galaxies.}, added-at = {2016-04-11T17:52:28.000+0200}, author = {Furusawa, Hisanori and Kashikawa, Nobunari and Kobayashi, Masakazu A. R. and Dunlop, James S. and Shimasaku, Kazuhiro and Takata, Tadafumi and Sekiguchi, Kazuhiro and Naito, Yoshiaki and Furusawa, Junko and Ouchi, Masami and Nakata, Fumiaki and Yasuda, Naoki and Okura, Yuki and Taniguchi, Yoshiaki and Yamada, Toru and Kajisawa, Masaru and Fynbo, Johan P. U. and Fevre, Olivier Le}, biburl = {https://www.bibsonomy.org/bibtex/2d10bc733c4e76d9f4271130055554077/miki}, description = {[1604.02214] A New Constraint on the Ly$\alpha$ Fraction of UV Very Bright Galaxies at Redshift 7}, interhash = {182c3e1ae8aeef81b46a2af354393a78}, intrahash = {d10bc733c4e76d9f4271130055554077}, keywords = {emitters evolution lya redshift}, note = {cite arxiv:1604.02214Comment: 20 pages, 7 figures, accepted for publication in ApJ}, timestamp = {2016-04-11T17:52:28.000+0200}, title = {A New Constraint on the Ly$\alpha$ Fraction of UV Very Bright Galaxies at Redshift 7}, url = {http://arxiv.org/abs/1604.02214}, year = 2016 }