A MULTI-WAVELENGTH VIEW OF THE STAR FORMATION ACTIVITY AT z ∼ 3

We present a multi-wavelength, UV-to-radio analysis for a sample of massive (M-* similar to 10(10) M-circle dot) IRAC-and MIPS 24 mu m detected Lyman break galaxies (LBGs) with spectroscopic redshifts z similar to 3 in the GOODS-North field. For LBGs without individual 24 mu m detections, we employ stacking techniques at 24 mu m, 1.1 mm, and 1.4 GHz to construct the average UV-to-radio spectral energy distribution and find it to be consistent with that of a luminous infrared galaxy with L-IR = 4.5+(1.1)(2.3) x 10(11) L-circle dot and a specific star formation rate of 4.3 Gyr(-1) that corresponds to a mass doubling time similar to 230 Myr. On the other hand, when considering the 24 mu m detected LBGs we find among them galaxies with L-IR > 10(12) L-circle dot, indicating that the space density of z similar to 3 UV-selected ultra-luminous infrared galaxies (ULIRGs) is similar to(1.5 +/- 0.5) x 10(-5) Mpc(-3). We compare measurements of star formation rates from data at different wavelengths and find that there is tight correlation (Kendall's tau > 99.7%) and excellent agreement between the values derived from dust-corrected UV, mid-IR, millimeter, and radio data for the whole range of L-IR up to L-IR similar to 10(13) L-circle dot. This range is greater than that for which the correlation is known to hold at z similar to 2, possibly due to the lack of significant contribution from polycyclic aromatic hydrocarbons to the 24 mu m flux at z similar to 3. The fact that this agreement is observed for galaxies with L-IR > 10(12) L-circle dot suggests that star formation in UV-selected ULIRGs, as well as the bulk of star formation activity at this redshift, is not embedded in optically thick regions as seen in local ULIRGs and submillimeter-selected galaxies at z = 2.