교육데이터 활용•지원 서비스

In their paper, the authors release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. The authors demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGNlike X-ray luminosities. Preselecting the library on the bases of the source properties allowed them to reach an accuracy sigma[Delta-z/(1+Z_spec)] ~ 0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. These Chandra sources are not contained in this table but are available in the HEASARC table CCOSMPHOTZ). In addition, in this study the authors released revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg² of COSMOS, and these are the sources listed in the present table. For 248 sources, their updated photometric redshift differs from the previous release by Delta-z > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band^ photometry (H_AB = 24 mag). The authors illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band. This table contains the photometric redshifts and related quantities for 1735 XMM-Newton sources over the entire 2 square degrees of the COSMOS field. Notice that in the original as-published paper no positional information was provided. The HEASARC has assumed that the source numbers used in the present catalog are in the same source numbering scheme as used by Cappelluti et al. (2009, A&A, 497, 635, the XMM-Newton Wide-Field Survey in the COSMOS Field Point-like X-ray Source Catalog, available at the HEASARC as the XMMCOSMOS table) and thus obtained the positions and (position-based) names corresponding to these X-ray sources from the latter. This table was created by the HEASARC in November 2011 based on an electronic version of Table 5 from the reference paper which was obtained from the ApJ website. This is a service provided by NASA HEASARC .