Optically faint massive Balmer Break Galaxies at z>3 in the CANDELS/GOODS fields

We present a sample of 33 Balmer Break Galaxies (BBGs) selected as dropouts in the deepest HST/F160W images of the two CANDELS/GOODS fields (i.e., $H\gtrsim27.3$ mag) but relatively bright in Spitzer/IRAC ($[3.6],[4.5] 10^{3}\,\rm{M}_\odot/yr$). The rest of BBGs, 15%, shows slightly suppressed SFRs and mass-weighted ages older than 500 Myr, which indicates that they are either post-starbursts or quiescent galaxies. Only 2 galaxies are X-ray detected AGN, but we cannot discard the presence of obscured AGN in the rest of sources. Our sample of BBGs accounts for 7% of the total number density of $\log(\rm{M}/\rm{M}_\odot) >10$ galaxies at $z>3$, but it is a significant contributor (30%) to the general population of $\log(\rm{M}/\rm{M}_\odot)>11$ galaxies at $4 11$ galaxies in the local Universe was assembled in the first 1.5 Gyr after the Big Bang.