ALMA Deep Field in the SSA22 proto-cluster at z=3

Galaxies and nuclei in the dense environment at high redshift provide a good laboratory to investigate the accelerated, most extreme evolution of galaxies at a given epoch. The SSA22 proto-cluster at z=3.1 has known to have a 50 (comoving) Mpc-scale cosmic structure, which makes the field a suitable target in this regards. To identify dust-obscured star-formation, a contiguous 20 arcmin^2 regions at the node were observed by ALMA band 6. About 7 arcmin^2 region has 1sigma sensitivity of 25uJy/beam at 1.2mm, while the remaining ~13 region has 1sigma 60 uJy/beam at 1.1mm. In total 57 ALMA sources have been identified above 5sigma, which makes the field one of the richest field of ALMA-identified submillimeter galaxies. The follow-up spectroscopy confirmed about 20 sources as exact proto-cluster members so far. Together with high X-ray AGN fraction, our results suggest that the vigorous star formation activity and the growth of super massive black holes (SMBHs) occurred simul taneously in the densest regions at z~3. Abundant gas fueling from cosmic web is suggested from co-spatial, deep mosaic observations of ALMA band 3 (for CO(3-2)) and MUSE survey (for Lyman-alpha). We argue that we are seeing the most active historical phase of the massive galaxy population found in the core of the clusters in the present-day universe.