The SSA22 H I Tomography Survey (SSA22-HIT). I. Data Set and Compiled Redshift Catalog
Ouchi, Masami; Hennawi, Joseph F.; Inoue, Akio K.; Sugahara, Yuma; Tamura, Yoichi; Schlegel, David J.; Prochaska, J. Xavier; Tejos, Nicolas; Yamada, Toru; Iwata, Ikuru; Mukae, Shiro; Mawatari, Ken; Kashikawa, Nobunari; Umehata, Hideki; Matsuda, Yuichi; Yamanaka, Satoshi; Lee, Khee-Gan; Hayashino, Tomoki; Otsuka, Takuya
Japan, United States, Chile, Germany
Abstract
We conducted a deep spectroscopic survey, named SSA22-HIT, in the SSA22 field with the DEep Imaging MultiObject Spectrograph (DEIMOS) on the Keck telescope, designed to tomographically map high-z H I gas through analysis of Lyα absorption in background galaxies' spectra. In total, 198 galaxies were spectroscopically confirmed at 2.5 < z < 6 with a few low-z exceptions in the 26 × 15 arcmin2 area, of which 148 were newly determined in this study. Our redshift measurements were merged with previously confirmed redshifts available in the 34 × 27 arcmin2 area of the SSA22 field. This compiled catalog containing 730 galaxies of various types at z > 2 is useful for various applications, and it is made publicly available. Our SSA22-HIT survey has increased by approximately twice the number of spectroscopic redshifts of sources at z > 3.2 in the observed field. From a comparison with publicly available redshift catalogs, we show that our compiled redshift catalog in the SSA22 field is comparable to those among major extragalactic survey fields in terms of a combination of wide area and high surface number density of objects at z > 2. About 40% of the spectroscopically confirmed objects in SSA22-HIT show reasonable quality of spectra in the wavelengths shorter than Lyα when a sufficient amount of smoothing is adopted. Our data set enables us to make the H I tomographic map at z ≳ 3, which we present in a parallel study.