A census of optical and near-infrared selected star-forming and passively evolving galaxies at redshift z∼2

Using the extensive multiwavelength data in the GOODS-North field, including our ground-based rest-frame UV spectroscopy and near-IR imaging, we construct and draw comparisons between samples of optical and near-IR selected star-forming and passively evolving galaxies at redshifts 1.4 less than or similar to z less than or similar to 2.6. We find overlap at the 70%-80% level in samples of z similar to 2 star-forming galaxies selected by their optical (U(n)GR) and near-IR (BzK) colors when subjected to common K-band limits. Deep Chandra data indicate a similar to 25% AGN fraction among near-IR selected objects, much of which occurs among near-IR bright objects (K-s < 20; Vega). Using X-rays as a proxy for the bolometric star formation rate (SFR) and stacking the X-ray emission for the remaining (non-AGN) galaxies, we find that the SFR distributions of U(n)GR, BzK, and J - K-s > 2.3 galaxies (i.e., distant red galaxies; DRGs) are very similar as a function of K-s, with K-s < 20 galaxies having [SFR] similar to 120 M. yr(-1), a factor of 2-3 higher than those with K-s > 20.5. The absence of X-ray emission from the reddest DRGs and BzK galaxies with (z - K)(AB) greater than or similar to 3 indicates that they must have declining star formation histories to explain their red colors and low SFRs. While the M/L ratio of passively evolving galaxies may be larger on average, the Spitzer IRAC data indicate that their inferred stellar masses do not exceed the range spanned by optically selected galaxies, suggesting that the disparity in current SFR may not indicate a fundamental difference between optical and near-IR selected massive galaxies (M* > 10(11) M.). We consider the contribution of optical, near-IR, and submillimeter selected galaxies to the star formation rate density (SFRD) at z similar to 2, taking into account sample overlap. The SFRD in the interval 1.4 less than or similar to z less than or similar to 2.6 of U(n)GR and BzK galaxies to K-s = 22 and DRGs to K-s = 21 is similar to 0.10 +/- 0.02 M. yr(-1) Mpc(-3). Optically selected galaxies to R = 25.5 and K-s = 22.0 account for similar to 70% of this total. Greater than 80% of radio-selected submillimeter galaxies to S-850 mu m similar to 4 mJy with redshifts 1.4 < z < 2.6 satisfy either one or more of the BX/BM, BzK, and DRG criteria.