ALMA deep field in SSA22: Survey design and source catalog of a 20?arcmin2 survey at 1.1?mm

摘要

To search for dust-obscured star-formation activity in the early Universe, it is essential to obtain a deep and wide submillimeter/millimeter map. The advent of the Atacama Large Millimeter/submillimeter Array (ALMA) has enabled us to obtain such maps with sufficiently high spatial resolution to be free from source confusion. We present a new 1.1?mm-wave map obtained by ALMA in the SSA22 field. The field contains a remarkable proto-cluster at z?=?3.09; therefore, it is an ideal region to investigate the role of a large-scale cosmic web on dust-obscured star formation. The typical 1σ depth of our map is 73?μJy beam?1 with a |${0^{^{primeprime}_{.}}5}$| resolution. Combining the present survey with earlier, archived observations, we map an area of 20 arcmin2 (71 comoving Mpc2 at z?=?3.09). Within the combined survey area we have detected 35 sources at a signal-to-noise ratio (S/N) 5, with flux densities of S1.1mm?=?0.43–5.6 mJy, equivalent to star-formation rates of ?100–1000?M⊙?yr?1 at z?=?3.09, for a Chabrier initial mass function: 17 sources out of 35 are new detections. The cumulative number counts show an excess by a factor of three to five compared to blank fields. The excess suggests enhanced, dust-enshrouded star-formation activity in the proto-cluster on a 10 comoving Mpc scale, indicating accelerated galaxy evolution in this overdense region.