TY - UNPB
T1 - Detection of a Lensed z≈11 Galaxy in the Rest-Optical with Spitzer/IRAC and the Inferred SFR, Stellar Mass, and Physical Size
AU - Lam, Daniel
AU - Bouwens, Rychard J.
AU - Coe, Dan
AU - Zitrin, Adi
AU - Barber, Christopher
AU - Labbe, Ivo
AU - Nanayakkara, Themiya
AU - Donahue, Megan
AU - Smit, Renske
AU - Shu, Xinwen
AU - Chary, Ranga-Ram
AU - Moustakas, John
AU - Nonino, Mario
AU - Kelson, Daniel D.
AU - Broadhurst, Tom
AU - Bradley, Larry
AU - Carrasco, Mauricio
AU - Rosati, Piero
PY - 2019
Y1 - 2019
N2 - We take advantage of new 100-hour Spitzer/IRAC observations available for MACS0647-JD, a strongly
lensed z ≈ 11 galaxy candidate, to provide improved constraints on its physical properties. Probing
the physical properties of galaxies at z > 8 is challenging due to the inherent faintness of such sources
and the limited wavelength coverage available. Thanks to the high ≈2-6× lensing magnification of
the multiple images of MACS0647-JD, we can use the sensitive Spitzer/IRAC data to probe the restframe optical fluxes of MACS0647-JD and investigate its physical properties including the age and the
stellar mass. In deriving Spitzer/IRAC fluxes for MACS0647-JD, great care is taken in coping with the
impact of three bright (≈8-16 mag) stars in our field to ensure robust results. Assuming a constant star
formation rate, the age, stellar mass, and rest-frame UV slope we estimate for MACS0647-JD based on
a stack of the photometry are log10(age/yr) = 8.6+0.1
−2.1
, log10(M∗/M) = 9.1+0.2
−1.4
, and β = −1.3±0.6,
respectively. We compare our results with expectations from the EAGLE simulation and find that
MACS0647-JD has properties consistent with corresponding to the most massive and rapidly starforming galaxies in the simulation. We also find that its radius, 105±28 pc, is a factor of ≈2 smaller
than the mean size in a separate simulation project DRAGONS. Interestingly enough, the observed
size is similar to the small sizes seen in very low-luminosity z ≈ 6-10 galaxies behind lensing clusters.
Keywords: galaxies: high-redshift, galaxies: clusters: general, galaxies: clusters: individual
(MACS0647.8+7015)
AB - We take advantage of new 100-hour Spitzer/IRAC observations available for MACS0647-JD, a strongly
lensed z ≈ 11 galaxy candidate, to provide improved constraints on its physical properties. Probing
the physical properties of galaxies at z > 8 is challenging due to the inherent faintness of such sources
and the limited wavelength coverage available. Thanks to the high ≈2-6× lensing magnification of
the multiple images of MACS0647-JD, we can use the sensitive Spitzer/IRAC data to probe the restframe optical fluxes of MACS0647-JD and investigate its physical properties including the age and the
stellar mass. In deriving Spitzer/IRAC fluxes for MACS0647-JD, great care is taken in coping with the
impact of three bright (≈8-16 mag) stars in our field to ensure robust results. Assuming a constant star
formation rate, the age, stellar mass, and rest-frame UV slope we estimate for MACS0647-JD based on
a stack of the photometry are log10(age/yr) = 8.6+0.1
−2.1
, log10(M∗/M) = 9.1+0.2
−1.4
, and β = −1.3±0.6,
respectively. We compare our results with expectations from the EAGLE simulation and find that
MACS0647-JD has properties consistent with corresponding to the most massive and rapidly starforming galaxies in the simulation. We also find that its radius, 105±28 pc, is a factor of ≈2 smaller
than the mean size in a separate simulation project DRAGONS. Interestingly enough, the observed
size is similar to the small sizes seen in very low-luminosity z ≈ 6-10 galaxies behind lensing clusters.
Keywords: galaxies: high-redshift, galaxies: clusters: general, galaxies: clusters: individual
(MACS0647.8+7015)
KW - Astrophysics - Astrophysics of Galaxies
M3 - Preprint
BT - Detection of a Lensed z≈11 Galaxy in the Rest-Optical with Spitzer/IRAC and the Inferred SFR, Stellar Mass, and Physical Size
ER -