Title: The stellar populations of Lyman Break Galaxies at z~5 in the GOODS-N
Author(s): K. Yabe, K. Ohta (Kyoto Univ.), I. Iwata (NAOJ, Okayama), M. Sawicki (St. Mary's Univ., Canada), N. Tamura, K. Aoki (NAOJ, Hawaii), M. Akiyama, T. Ichikawa, M. Kajisawa (Tohoku Univ.), and MOIRCS team

Abstract: We present results of SED fitting analysis for Lyman Break Galaxies (LBGs) at z~5 in the GOODS-N/MODS region. We used deep imaging data including U (KPNO MOSAIC), B, V, R, Ic, z' (Subaru S-Cam), J, H, K (Subaru MOIRCS), 3.6, and 4.5 micron (Spitzer IRAC). We subtracted neighboring objects with GALFIT to avoid severe contamination in the IRAC images and obtained the sample of ~130 LBGs at z~5. By using the deepest NIR and the large sample, we constructed the observed SEDs and improved the results by Yabe et al. (2009).
Resulting stellar masses range from 10^8 to 10^11 Msun with median value of ~3x10^9 Msun. The median stellar age, color excess, and star formation rate are 24 Myr, 0.25 mag, and 120 Msun/yr, respectively. We compare the results with those of LBGs at z=2-3. The stellar masses of LBGs at a fixed UV luminosity increase from z~5 to z=2-3. The stellar ages of the LBGs at z~5 are younger and the color excesses are larger than those of LBGs at z=2-3. The star formation rates are higher than the z=2-3 LBGs. We suggest that the LBGs at z~5 are undergoing intense star formation making them dusty and they are dominated by younger stellar populations than in the case of z=2-3 LBGs. By using the resulting stellar masses, we also derived the stellar mass function and the stellar mass density at z~5.