The Subaru-XMM-Newton Deep Survey (SXDS). VIII. Multi-wavelength identification, optical/NIR spectroscopic properties, and photometric redshifts of X-ray sources

Masayuki Akiyama, Yoshihiro Ueda, Mike G. Watson, Hisanori Furusawa, Tadafumi Takata, Chris Simpson, Tomoki Morokuma, Toru Yamada, Kouji Ohta, Fumihide Iwamuro, Kiyoto Yabe, Naoyuki Tamura, Yuuki Moritani, Naruhisa Takato, Masahiko Kimura, Toshinori Maihara, Gavin Dalton, Ian Lewis, Hanshin Lee, Emma Curtis-LakeEdward Macaulay, Frazer Clarke, John D. Silverman, Scott Croom, Masami Ouchi, Hitoshi Hanami, Jorge Díaz Tello, Tomohiro Yoshikawa, Naofumi Fujishiro, Kazuhiro Sekiguchi

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


We report on the multi-wavelength identification of the X-ray sources found in the Subaru-XMM-Newton Deep Survey (SXDS) using deep imaging data covering the wavelength range between the far-UV and mid-IR (MIR). We select a primary counterpart of each X-ray source by applying the likelihood ratio method to R-band, 3.6 μm, near-UV, and 24 μm source catalogs as well as matching catalogs of active galactic nucleus (AGN) candidates selected in 1.4 GHz radio and i-band variability surveys. Once candidates for Galactic stars, ultra-luminous X-ray sources in a nearby galaxy, and clusters of galaxies are removed there are 896 AGN candidates in the sample. We conduct spectroscopic observations of the primary counterparts with multi-object spectrographs in the optical and NIR; 65% of the X-ray AGN candidates are spectroscopically identified. For the remaining X-ray AGN candidates, we evaluate their photometric redshift with photometric data in 15 bands. Utilizing the multi-wavelength photometric data of the large sample of X-ray-selected AGNs, we evaluate the stellar masses, M, of the host galaxies of the narrow-line AGNs. The distribution of the stellar mass is remarkably constant from z = 0.1 to 4.0. The relation between M and 2-10 keV luminosity can be explained with strong cosmological evolution of the relationship between the black hole mass and M. We also evaluate the scatter of the UV-MIR spectral energy distribution (SED) of the X-ray AGNs as a function of X-ray luminosity and absorption by the nucleus. The scatter is compared with galaxies which have redshift and stellar mass distribution matched with the X-ray AGN. The UV-NIR (near-IR) SEDs of obscured X-ray AGNs are similar to those of the galaxies in the matched sample. In the NIR-MIR range, the median SEDs of X-ray AGNs are redder, but the scatter of the SEDs of the X-ray AGN broadly overlaps that of the galaxies in the matched sample.

Original languageEnglish
Article number82
JournalPublications of the Astronomical Society of Japan
Issue number5
Publication statusPublished - 2015 Jun 30


  • X-rays: galaxies
  • catalogs
  • galaxies: active
  • quasars: general
  • surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'The Subaru-XMM-Newton Deep Survey (SXDS). VIII. Multi-wavelength identification, optical/NIR spectroscopic properties, and photometric redshifts of X-ray sources'. Together they form a unique fingerprint.

Cite this