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RASSDSSAGN - ROSAT All-Sky Survey and SDSS DR5 Sample of X-Ray Emitting AGN

HEASARC
Archive

Overview

This table contains further results of a program aimed at yielding ~ 104 fully characterized optical identifications of ROSAT X-ray sources. The program employs X-ray data from the ROSAT All Sky Survey (RASS) and both optical imaging and spectroscopic data from the Sloan Digital Sky Survey (SDSS). RASS/SDSS data from 5740 deg2 of sky spectroscopically covered in SDSS Data Release 5 (DR5) provide an expanded catalog of 7000 confirmed quasars and other active galactic nuclei (AGN) that are probable RASS identifications. Again, in this expanded catalog the identifications as X-ray sources are statistically secure, with only a few percent of the SDSS AGNs likely to be randomly superposed on unrelated RASS X-ray sources. Most identifications continue to be quasars and Seyfert 1 galaxies with 15 < m < 21 and 0.01 < z < 4, but the total sample size has grown to include very substantial numbers of even quite rare AGN, e.g., it now includes several hundreds of candidate X-ray-emitting BL Lac objects and narrow-line Seyfert 1 galaxies. In addition to exploring rare subpopulations, such a large total sample may be useful when considering correlations between the X-ray and the optical and may also serve as a resource list from which to select the ``best'' object (e.g., the X-ray-brightest AGN of a certain subclass at a preferred redshift or luminosity) for follow-up X-ray spectral or alternate detailed studies.

Much more information on the SDSS is available at the project's web site at http://www.sdss.org/.


Catalog Bibcode

2007AJ....133..313A

References

A large, uniform sample of X-Ray-Emitting Active Galactic Nuclei from the
ROSAT All-Sky and Sloan  Digital Sky Surveys: the Data Release 5 Sample.
    Anderson S.F., Margon B., Voges W., Plotkin, R.M., Syphers, D.,
    Haggard, D., Collinge, M.J., Meyer, J., Strauss, M.A., Agueros M.A.,
    Hall P.B., Homer, L., Ivezic Z., Richards, G.T., Richmond M.W.,
    Schneider, D.P., Stinson, G., Vanden Berk, D.E., York D.G.
   <Astron. J., 133, 313-329 (2007)>
   =2007AJ....133..313A

Provenance

This table was created by the HEASARC in February 2007 based on the combination of the electronic versions of tables 1 through 6 from the above reference which were obtained from the electronic AJ website. It replaces a previous version containing the results presented by Anderson et al. (2003, AJ, 126, 2209) which were based on a cross-correlation of the RASS with optical data from very early on in the SDSS program, e.g., extending back to the 'Early Data Release' before SDSS photometric calibrations were complete.

HEASARC Implementation

As noted in the Provenance section, the HEASARC created this table by combining the contents from 6 separate tables from the original publication:
 Table       No. of       Table Description
             Entries
     1        6224        Observed Parameters of Broad-Line RASS/SDSS AGN
     2        6224        Derived Parameters of Broad-Line RASS/SDSS AGN
     3         515        Observed Parameters of RASS/SDSS AGN Having
                             Narrower Permitted Emission
     4         515        Derived Parameters of RASS/SDSS AGN Having
                             Narrower Permitted Emission
     5         266        Observed Parameters of RASS/SDSS BL Lac Candidates
     6         266        Derived Parameters of RASS/SDSS BL Lac Candidates
As can be seen, these 6 tables are actually 3 pairs of tables, each pair containing the observed and derived parameters for a specific group of objects, broad-line RASS/SDSS AGN (Tables 1 and 2), RASS/SDSS AGN having narrower permitted emission (Tables 3 and 4), and RASS/SDSS BL Lac candidates (Tables 5 and 6). In order to preserve these distinctions, the HEASARC has created a new parameter object_type which is set to 1 for the first group, 2 for the second group, and 3 for the third group.

Parameters

RASS_Name
The RASS X-Ray source designation using the recommended '1RXS J' prefix and based on the J2000 equatorial coordinates of the X-ray source.

Name
The SDSS designation of the suggested quasar/AGN counterpart to the X-ray source based on its J2000 optical position.

RA
The Right Ascension of the SDSS optical counterpart in the selected equinox. This was given in J2000 equatorial coordinates to a precision of 0.01 seconds of time in the original catalog.

Dec
The Declination of the SDSS optical counterpart in the selected equinox. This was given in J2000 equatorial coordinates to a precision of 0.1 arcseconds in the original catalog.

LII
The Galactic Longitude of the optical counterpart.

BII
The Galactic Latitude of the optical counterpart.

Umag
The uniform DR5 optical PSF photometric magnitude in the SDSS u-band (e.g., Fukugita et al. 1996, AJ, 111, 1748) in the asinh AB system (Lupton et al. 1999, AJ, 118, 1406).

Gmag
The uniform DR5 optical PSF photometric magnitude in the SDSS g-band (e.g., Fukugita et al. 1996, AJ, 111, 1748) in the asinh AB system (Lupton et al. 1999, AJ, 118, 1406).

Rmag
The uniform DR5 optical PSF photometric magnitude in the SDSS r-band (e.g., Fukugita et al. 1996, AJ, 111, 1748) in the asinh AB system (Lupton et al. 1999, AJ, 118, 1406).

Imag
The uniform DR5 optical PSF photometric magnitude in the SDSS i-band (e.g., Fukugita et al. 1996, AJ, 111, 1748) in the asinh AB system (Lupton et al. 1999, AJ, 118, 1406).

Zmag
The uniform DR5 optical PSF photometric magnitude in the SDSS z-band (e.g., Fukugita et al. 1996, AJ, 111, 1748) in the asinh AB system (Lupton et al. 1999, AJ, 118, 1406).

G0mag
The extinction-corrected g-band PSF magnitude, corrected according to the reddening maps of Schlegel et al. (1998, ApJ, 500, 525), g*0.

Optical_Morphology
The value of the SDSS imaging morphology parameter, a commonly used and reliable SDSS measure of optical morphology (see Stoughton 2002, AJ, 123, 485 for more details); a value of 6 indicates a stellar/unresolved optical morphology, while a value of 3 indicates an extended/resolved, i.e., galaxy, morphology.

Redshift
The redshift as measured from the SDSS spectra. The authors visually reexamined all spectra to confirm their nature, as well as to verify the spectroscopic pipeline redshifts.

RASS_Count_Rate
The RASS X-ray source count rate (in ct/s) in the 0.1 - 2.4 keV broad band, corrected for vignetting.

RASS_Exposure
The RASS exposure time (in s) for the X-ray source.

RASS_Hardness_Ratio_1
The RASS hardness ratio 1 of the X-ray source, HR1 = (B-A)/(B+A), where A is the PHA 11-41 channel counts and B is the PHA 52-201 channel counts; see Voges at al. (1999, A&A, 349, 389) for more information.

RASS_Hardness_Ratio_2
The RASS hardness ratio 2 of the X-ray source, HR2 = (D-C)/(D+C), where C is the PHA 52-90 channel counts and D is the PHA 91-201 channel counts; see Voges at al. (1999, A&A, 349, 389) for more information.

RASS_Detect_Likelihood
The X-ray source detection likelihood, being a maximum likelihood measure of source significance.

RASS_Flux
The X-ray flux in the 0.1 - 2.4 keV band, as observed, i.e., without corrections for absorption in the Galaxy, in erg/s/cm2. The authors used the HEASARC's PIMMS (Portable Interactive Multi-Mission Simulator) software to convert RASS count rates into X-ray fluxes, assuming a power-law X-ray spectrum with an X-ray energy index alpha_x of 1.5 typical of (low-redshift) quasars in the RASS PSPC bandpass.

RASS_Corr_Flux
The X-ray flux (in erg/s/cm2) in the 0.1 - 2.4 keV band, corrected for absorption within the Galaxy, with an absorbing column estimated from the NH column density measures of the Stark et al. (1992, ApJS, 79, 77) 21-cm maps.

Log_Lx_Broad
The logarithm of the inferred broadband (0.1 - 2.4 keV) X-Ray luminosity (in erg/s), adopting values of H_0 = 70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7. In converting from corrected broad-band X-ray flux to luminosity, the authors assumed an X-ray power-law spectrum with an energy index alpha_x = 1.5.

Log_L_Opt
The logarithm of the inferred monochromatic UV/optical luminosity (in erg/s/Hz) at a frequency corresponding to rest-frame 2500 Angstroms, adopting values of H_0 = 70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7. In converting from corrected optical g-band flux to luminosity, the authors assumed an optical power-law spectrum with an energy index alpha_o = 0.5.

Log_Lx_2keV
The logarithm of the inferred monochromatic soft X-ray luminosity at 2 keV (in erg/s/Hz), adopting values of H_0 = 70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7.

Alpha_Ox
The slope of a hypothetical power law (in energy), alpha_ox, from the UV/optical to the X-ray, i.e., connecting 2500 Angstroms and 2 keV.

Comments
This field contains brief comments, e.g., noting selected objects that are radio sources, listing an alternate name (shortened, if needed to the first 20 characters) taken from the NASA/IPAC Extragalactic Database for about 10% of the quasars, and noting the ~1.5% of the cases for which two of the catalogued AGN fell within the same RASS error circle (the latter are denoted by "ambigID" in the comments, and 8 such cases involve AGN pair at similar redshifts).

Object_Type
This HEASARC database table has been created from the merger of 6 separate tables from the orginal reference. These 6 tables are actually 3 pairs of tables, each pair containing the observed and derived parameters for a specific group of objects. Broad-Line RASS/SDSS AGN are listed in Tables 1 and 2, RASS/SDSS AGN having narrower permitted emission in Tables 3 and 4, and RASS/SDSS BL Lac candidates in Tables 5 and 6 of the published paper. In order to preserve these distinctions, the HEASARC has created the parameter object_type which is set to 1 for the first group, 2 for the second group, and 3 for the third group. Thus, setting object_type = 1 in a parameter search will recover all of the entries from Table 1 and 2 of the published paper.


Contact Person

Questions regarding the RASSDSSAGN database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 27-Apr-2009