CHAMPHXAGN - CHAMP (Chandra Multiwavelength Project) Hard X-Ray Emitting AGN
To construct a pure AGN sample, the authors required the rest-frame 2.0-8.0 keV luminosity (uncorrected for intrinsic absorption) to exceed 10^42 ergs s^-1, thereby excluding any sources that may contain a significant stellar or hot ISM component. The most luminous known star-forming or elliptical galaxies attain at most L_X = 10^42 ergs s^-1. Since many of the traditional optical AGN signatures are not present in obscured sources, high X-ray luminosity becomes the authors' single discriminant for supermassive black hole accretion. They believe that almost all of the NELGs and ALGs harbor accreting SMBHs based on their X-ray luminosity. They find that 90% of the identified ChaMP sources have luminosities above this threshold. These selection criteria yield a sample of 188 AGNs from 20 Chandra fields with f(2-8 keV) > 2.7 x 10-15 ergs cm^-2 s^-1, r' < 22.5, and L_X > 10^42 ergs s^-1. The authors removed five objects identified as clusters based on their extended X-ray emission.
Hard X-ray-emitting active galactic nuclei selected by the Chandra Multiwavelength Project. Silverman J.D., Green P.J., Barkhouse W.A., Kim D.-W., Aldcroft T.L., Cameron R.A., Wilkes B.J., Mossman A., Ghosh H., Tananbaum H., Smith M.G., Smith R.C., Smith P.S., Foltz C., Wik D., Jannuzi B.T. <Astrophys. J., 618, 123-138 (2005)> =2005ApJ...618..123S (SIMBAD/NED BibCode)
A running number for the X-ray source which uniquely identifies the source.
This flag parameter is set 'e' to indicate that the source fell near the chip gap, and that no spectral fitting was performed.
The designation for objects in ChaMP, as registered with the CDS Dictionary of Nomenclature of Celestial Objects, using the 'CXOMP' prefix for Chandra X-Ray Observatory Multiwavelength Project and the J2000.0 source coordinates (JHHMMSS.s+DDMMSS or JHHMMSS.s-DDMMSS).
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table.
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.1 arcseconds in the original table.
The Galactic Longitude of the X-ray source.
The Galactic Latitude of the X-ray source.
The background-subtracted counts of the X-ray source in the observed frame 2.5 - 8.0 keV band.
The uncertainty in the source counts.
The Galactic absorption-corrected observed-frame flux of the X-ray source in the 2.0 - 8.0 keV band, in units of ergs cm^-2 s^-1.
This parameter is a limit flag for the hardness ratio of the X-ray source.
The hardness ratio HR of the X-ray source, defined as HR=(H-S)/(H+S), where S are the counts in the soft band (0.3 - 2.5 keV) and H the counts in the hard band (2.5 - 8.0 keV)
The redshift of the optical counterpart to the X-ray source.
The logarithm of the rest-frame 2 - 8 keV luminosity of the X-ray source, in erg/s.
The SDSS r' filter magnitude of the optical counterpart to the X-ray source.
This parameter is a limit flag for the g'-i' color of the optical counterpart to the X-ray source.
The SDSS g'-i' color of the optical counterpart to the X-ray source.
This parameter is a limit flag for the r'-i' color of the optical counterpart to the X-ray source.
The SDSS r'-i' color of the optical counterpart to the X-ray source.
The class of the optical counterpart using classification scheme of optical spectra similar to that used in the Einstein Observatory Extended Medium-Sensitivity Survey (Stocke et al. 1991, ApJS, 76, 813). Objects with strong emission lines (equivalent widths > 5 Angstroms) are classified as either broad-line AGNs (BLAGNs; FWHM > 1000 km s^-1) or narrow emission-line galaxies (NELGs; FWHM < 1000 km s^-1). Counterparts with weak emission line or pure absorption line spectra are classified as absorption line galaxies (ALGs). Any stellar source is labeled as a STAR. For the ALGs, the authors measured the Ca II break "CONTRAST" (Stocke et al. 1991) to look for a power-law AGN component to the continuum to note potential BL Lac candidates. If the associated X-ray emission was extended, the object was further labeled as a possible cluster member.
This parameter is a limit flag for the best-fit values of log N_H for the X-ray source spectrum.
The logarithm of the best-fit absorption column density, in H atoms cm^-2. Spectral fitting was done using the CIAO Sherpa tool. For all sources, the authors fit an absorbed power law containing an intrinsic absorber with a neutral column N_H at the source redshift. Their choice of photon index (frozen at Gamma = 1.9) was based on previous studies of unabsorbed AGNs. This N_H fit provided a robust one-parameter characterization of the intrinsic spectral shape for as few as 10 counts. The authors verified by an extensive Monte Carlo simulation that the parameter uncertainties calculated with projection of confidence contours in Sherpa were reliable. Note that the spectral model contained a fixed Galactic neutral absorber appropriate for each object.
The positive error in the value of log N_H, where N_H is in H atoms cm^-2.
The negative error in the value of log N_H, where N_H is in H atoms cm^-2.
The HEASARC Browse object classification, based on the value of the broad_type parameter.