Stellar Masses of Luminous Compact Blue Galaxies at Redshifts z = 0.4-1.2

We present stellar mass measurements for a sample of 36 luminous compact blue galaxies (LCBGs) at redshifts z = 0.4-1.2 in the flanking fields around the Hubble Deep Field-North. The technique is based on fitting a two-component galaxy population model to multi-broadband photometry. Best-fit models are found to be largely independent of the assumed values for the initial mass function (IMF) and the metallicity of the stellar populations, but they are sensitive to the amount of extinction and the extinction law adopted. On average, the best-fit model corresponds to a LMC extinction law with E(B-V) = 0.5. Stellar mass estimates, however, are remarkably independent of the final model choice. Using a Salpeter IMF, the derived median stellar mass for this sample is 5 × 10⁹ M_☉, i.e., ~2 times smaller than previous virial mass estimates. Despite uncertainties of a factor of 2-3, our results strengthen prior claims that L* CBGs at intermediate redshifts are, on average, about 10 times less massive than a typical L* galaxy today.