Journal Article

On the stellar masses of IRAC detected Lyman Break Galaxies at <i>z</i>∼ 3

G. E. Magdis, D. Rigopoulou, J.-S. Huang and G. G. Fazio

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 401, issue 3, pages 1521-1531
Published in print January 2010 | ISSN: 0035-8711
Published online January 2010 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2009.15779.x
On the stellar masses of IRAC detected Lyman Break Galaxies at z∼ 3

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We present results of a large survey of the mid-infrared (mid-IR) properties of 248 Lyman Break Galaxies (LBGs) with confirmed spectroscopic redshift using deep Spitzer/Infrared Array Camera (IRAC) observations in six cosmological fields. By combining the new mid-IR photometry with optical and near-infrared observations, we model the spectral energy distributions (SEDs) employing a revised version of the Bruzual and Charlot synthesis population code that incorporates a new treatment of the thermal-pulsating asymptotic giant branch phase (CB07). Our primary aim is to investigate the impact of the AGB phase in the stellar masses of the LBGs, and compare our new results with previous stellar mass estimates. We investigate the stellar mass of the LBG population as a whole and assess the benefits of adding longer wavelengths to estimates of stellar masses for high-redshift galaxies. Based on the new CB07 code, we find that the stellar masses of LBGs are smaller on an average by a factor of ∼1.4 compared to previous estimates. LBGs with 8 and/or 24 μm detections show higher masses (M*∼ 1011 M) than LBGs faint in the IRAC bands (M*∼ 109 M). The ages of these massive LBGs are considerably higher than the rest of the population, indicating that they have been star forming for at least ∼1 Gyr. We also show how the addition of the IRAC bands improves the accuracy of the estimated stellar masses and reduced the scatter on the derived mass-to-light ratios. In particular, we present a tight correlation between the 8 μm IRAC band (rest-frame K for galaxies at z∼ 3) and the stellar mass. We calculate the number density of massive (M* > 1011 M) LBGs and find it to be Φ= (1.12 ± 0.4) × 10−5 Mpc−3, ∼1.5 times lower than that found by previous studies. Finally, based on ultraviolet-corrected star formation rates (SFRs), we investigate the SFR–stellar mass correlation at z∼ 3, find it similar to the one observed at other redshifts and show that our data place the peak of the evolution of the specific SFR at z∼ 3.

Keywords: Catalogues; galaxies: high-redshift; early Universe

Journal Article.  9819 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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