We present a spectroscopic redshift measurement of a very bright Lyman break
galaxy at z=7.7302+-0.0006 using Keck/MOSFIRE. The source was pre-selected
photometrically in the EGS field as a robust z~8 candidate with H=25.0 mag
based on optical non-detections and a very red Spitzer/IRAC 3.6-4.5
broad-band color driven by high equivalent width OIII+Hbeta line emission.
The Lyalpha line is reliably detected at >6 sigma and shows an asymmetric
profile as expected for a galaxy embedded in a relatively neutral
inter-galactic medium near the Planck peak of cosmic reionization. The line has
a rest-frame equivalent width of EW0=21+-4 A and is extended with
V_FWHM=376+89-70 km/s. The source is perhaps the brightest and most massive z~8
Lyman break galaxy in the full CANDELS and BoRG/HIPPIES surveys, having
assembled already 10^(9.9+-0.2) M_sol of stars at only 650 Myr after the Big
Bang. The spectroscopic redshift measurement sets a new redshift record for
galaxies. This enables reliable constraints on the stellar mass, star-formation
rate, formation epoch, as well as combined OIII+Hbeta line equivalent widths.
The redshift confirms that the IRAC 4.5 photometry is very likely dominated
by line emission with EW0(OIII+Hbeta)= 720-150+180 A. This detection thus adds
to the evidence that extreme rest-frame optical emission lines are a ubiquitous
feature of early galaxies promising very efficient spectroscopic follow-up in
the future with infrared spectroscopy using JWST and, later, ELTs.
Description
[1502.05399] A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE
%0 Generic
%1 oesch2015spectroscopic
%A Oesch, P. A.
%A van Dokkum, P. G.
%A Illingworth, G. D.
%A Bouwens, R. J.
%A Momcheva, I.
%A Holden, B.
%A Roberts-Borsani, G. W.
%A Smit, R.
%A Franx, M.
%A Labbe, I.
%A Gonzalez, V.
%A Magee, D.
%D 2015
%K galaxy high-z spectra
%T A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy
at z=7.730 using Keck/MOSFIRE
%U http://arxiv.org/abs/1502.05399
%X We present a spectroscopic redshift measurement of a very bright Lyman break
galaxy at z=7.7302+-0.0006 using Keck/MOSFIRE. The source was pre-selected
photometrically in the EGS field as a robust z~8 candidate with H=25.0 mag
based on optical non-detections and a very red Spitzer/IRAC 3.6-4.5
broad-band color driven by high equivalent width OIII+Hbeta line emission.
The Lyalpha line is reliably detected at >6 sigma and shows an asymmetric
profile as expected for a galaxy embedded in a relatively neutral
inter-galactic medium near the Planck peak of cosmic reionization. The line has
a rest-frame equivalent width of EW0=21+-4 A and is extended with
V_FWHM=376+89-70 km/s. The source is perhaps the brightest and most massive z~8
Lyman break galaxy in the full CANDELS and BoRG/HIPPIES surveys, having
assembled already 10^(9.9+-0.2) M_sol of stars at only 650 Myr after the Big
Bang. The spectroscopic redshift measurement sets a new redshift record for
galaxies. This enables reliable constraints on the stellar mass, star-formation
rate, formation epoch, as well as combined OIII+Hbeta line equivalent widths.
The redshift confirms that the IRAC 4.5 photometry is very likely dominated
by line emission with EW0(OIII+Hbeta)= 720-150+180 A. This detection thus adds
to the evidence that extreme rest-frame optical emission lines are a ubiquitous
feature of early galaxies promising very efficient spectroscopic follow-up in
the future with infrared spectroscopy using JWST and, later, ELTs.
@misc{oesch2015spectroscopic,
abstract = {We present a spectroscopic redshift measurement of a very bright Lyman break
galaxy at z=7.7302+-0.0006 using Keck/MOSFIRE. The source was pre-selected
photometrically in the EGS field as a robust z~8 candidate with H=25.0 mag
based on optical non-detections and a very red Spitzer/IRAC [3.6]-[4.5]
broad-band color driven by high equivalent width [OIII]+Hbeta line emission.
The Lyalpha line is reliably detected at >6 sigma and shows an asymmetric
profile as expected for a galaxy embedded in a relatively neutral
inter-galactic medium near the Planck peak of cosmic reionization. The line has
a rest-frame equivalent width of EW0=21+-4 A and is extended with
V_FWHM=376+89-70 km/s. The source is perhaps the brightest and most massive z~8
Lyman break galaxy in the full CANDELS and BoRG/HIPPIES surveys, having
assembled already 10^(9.9+-0.2) M_sol of stars at only 650 Myr after the Big
Bang. The spectroscopic redshift measurement sets a new redshift record for
galaxies. This enables reliable constraints on the stellar mass, star-formation
rate, formation epoch, as well as combined [OIII]+Hbeta line equivalent widths.
The redshift confirms that the IRAC [4.5] photometry is very likely dominated
by line emission with EW0(OIII+Hbeta)= 720-150+180 A. This detection thus adds
to the evidence that extreme rest-frame optical emission lines are a ubiquitous
feature of early galaxies promising very efficient spectroscopic follow-up in
the future with infrared spectroscopy using JWST and, later, ELTs.},
added-at = {2015-02-20T09:49:24.000+0100},
author = {Oesch, P. A. and van Dokkum, P. G. and Illingworth, G. D. and Bouwens, R. J. and Momcheva, I. and Holden, B. and Roberts-Borsani, G. W. and Smit, R. and Franx, M. and Labbe, I. and Gonzalez, V. and Magee, D.},
biburl = {https://www.bibsonomy.org/bibtex/2d9520e576a7b02874c3a54da4df826a4/miki},
description = {[1502.05399] A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE},
interhash = {d24e1679281ba9607cfa0f33930602c0},
intrahash = {d9520e576a7b02874c3a54da4df826a4},
keywords = {galaxy high-z spectra},
note = {cite arxiv:1502.05399Comment: 6 pages, 4 figures, submitted to ApJL},
timestamp = {2015-02-20T09:49:24.000+0100},
title = {A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy
at z=7.730 using Keck/MOSFIRE},
url = {http://arxiv.org/abs/1502.05399},
year = 2015
}