SPITZERULTRA FAINT SURVEY PROGRAM (SURFS UP). II. IRAC-DETECTED LYMAN-BREAK GALAXIES AT 6 ≲z≲ 10 BEHIND STRONG-LENSING CLUSTERS

Kuang-Han Huang, Maruša Bradač, Brian C. Lemaux, R. E. Ryan, Jr., Austin Hoag, Marco Castellano, Ricardo Amorín, Adriano Fontana, Gabriel B. Brammer, Benjamin Cain, L. M. Lubin, Emiliano Merlin (+6 others)
2016 Astrophysical Journal  
We study the stellar population properties of the IRAC-detected $6 \lesssim z \lesssim 10$ galaxy candidates from the Spitzer UltRa Faint SUrvey Program (SURFS UP). Using the Lyman Break selection technique, we find a total of 16 new galaxy candidates at $6 \lesssim z \lesssim 10$ with $S/N \geq 3$ in at least one of the IRAC $3.6\mu$m and $4.5\mu$m bands. According to the best mass models available for the surveyed galaxy clusters, these IRAC-detected galaxy candidates are magnified by factors
more » ... agnified by factors of $\sim 1.2$--$5.5$. We find that the IRAC-detected $6 \lesssim z \lesssim 10$ sample is likely not a homogeneous galaxy population: some are relatively massive (stellar mass as high as $4 \times 10^9\,M_{\odot}$) and evolved (age $\lesssim 500$ Myr) galaxies, while others are less massive ($M_{\text{stellar}}\sim 10^8\,M_{\odot}$) and very young ($\sim 10$ Myr) galaxies with strong nebular emission lines that boost their rest-frame optical fluxes. We identify two Ly$\alpha$ emitters in our sample from the Keck DEIMOS spectra, one at $z_{\text{Ly}\alpha}=6.76$ (in RXJ1347) and one at $z_{\text{Ly}\alpha}=6.32$ (in MACS0454). We show that IRAC $[3.6]-[4.5]$ color, when combined with photometric redshift, can be used to identify galaxies likely with strong nebular emission lines within certain redshift windows.
doi:10.3847/0004-637x/817/1/11 fatcat:icewruxhbnghbjianpnh3elvue