TY - JOUR
T1 - CANDELS
T2 - The Evolution of Galaxy Rest-Frame Ultraviolet Colors from z = 8 to 4
AU - Finkelstein, Steven L.
AU - Papovich, Casey
AU - Salmon, Brett
AU - Finlator, Kristian
AU - Dickinson, Mark
AU - Ferguson, Henry C.
AU - Giavalisco, Mauro
AU - Koekemoer, Anton M.
AU - Reddy, Naveen A.
AU - Bassett, Robert
AU - Conselice, Christopher J.
AU - Dunlop, James S.
AU - Faber, S. M.
AU - Grogin, Norman A.
AU - Hathi, Nimish P.
AU - Kocevski, Dale D.
AU - Lai, Kamson
AU - Lee, Kyoung-Soo
AU - McLure, Ross J.
AU - Mobasher, Bahram
AU - Newman, Jeffrey A.
PY - 2011/10/1
Y1 - 2011/10/1
N2 - We study the evolution of galaxy rest-frame ultraviolet (UV) colors in
the epoch 4 <z <8. We use new wide-field near-infrared data in
GOODS-S from the CANDELS, HUDF09 and ERS programs to select galaxies via
photometric redshift measurements. Our sample consists of 2812 candidate
galaxies at z > 3.5, including 113 at z = 7 to 8. We fit the observed
spectral energy distribution to a suite of synthetic stellar population
models, and measure the value of the UV spectral slope (beta) from the
best-fit model spectrum. The median value of beta evolves significantly
from -1.82 (+0.00,-0.04) at z = 4, to -2.37 (+0.26,-0.06) at z = 7.
Additionally, we find that faint galaxies at z = 7 have beta = -2.68
(+0.39,-0.24) (~ -2.4 after correcting for observational bias); this is
redder than previous claims in the literature, and does not require
"exotic" stellar populations to explain their colors. This evolution can
be explained by an increase in dust extinction, with the timescale
consistent with low-mass AGB stars forming the bulk of the dust. We find
no significant (<2-sigma) correlation between beta and M_UV when
measuring M_UV at a consistent rest-frame wavelength of 1500 A. This is
particularly true at bright magnitudes, though our results do show
evidence for a weak correlation at faint magnitudes when galaxies in the
HUDF are considered separately, hinting that dynamic range in sample
luminosities may play a role. We do find a strong correlation between
beta and the stellar mass at all redshifts, in that more massive
galaxies exhibit redder colors. The most massive galaxies in our sample
have red colors at each redshift, implying that dust can build up
quickly in massive galaxies, and that feedback is likely removing dust
from low-mass galaxies at z > 7. Thus the stellar-mass - metallicity
relation, previously observed up to z ~ 3, may extend out to z = 7 - 8.
AB - We study the evolution of galaxy rest-frame ultraviolet (UV) colors in
the epoch 4 <z <8. We use new wide-field near-infrared data in
GOODS-S from the CANDELS, HUDF09 and ERS programs to select galaxies via
photometric redshift measurements. Our sample consists of 2812 candidate
galaxies at z > 3.5, including 113 at z = 7 to 8. We fit the observed
spectral energy distribution to a suite of synthetic stellar population
models, and measure the value of the UV spectral slope (beta) from the
best-fit model spectrum. The median value of beta evolves significantly
from -1.82 (+0.00,-0.04) at z = 4, to -2.37 (+0.26,-0.06) at z = 7.
Additionally, we find that faint galaxies at z = 7 have beta = -2.68
(+0.39,-0.24) (~ -2.4 after correcting for observational bias); this is
redder than previous claims in the literature, and does not require
"exotic" stellar populations to explain their colors. This evolution can
be explained by an increase in dust extinction, with the timescale
consistent with low-mass AGB stars forming the bulk of the dust. We find
no significant (<2-sigma) correlation between beta and M_UV when
measuring M_UV at a consistent rest-frame wavelength of 1500 A. This is
particularly true at bright magnitudes, though our results do show
evidence for a weak correlation at faint magnitudes when galaxies in the
HUDF are considered separately, hinting that dynamic range in sample
luminosities may play a role. We do find a strong correlation between
beta and the stellar mass at all redshifts, in that more massive
galaxies exhibit redder colors. The most massive galaxies in our sample
have red colors at each redshift, implying that dust can build up
quickly in massive galaxies, and that feedback is likely removing dust
from low-mass galaxies at z > 7. Thus the stellar-mass - metallicity
relation, previously observed up to z ~ 3, may extend out to z = 7 - 8.
U2 - 10.1088/0004-637X/756/2/164
DO - 10.1088/0004-637X/756/2/164
M3 - Article
SN - 0004-637X
VL - 756
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 164
ER -