NWAYAWGROS - AllWISE Counterparts and Gaia Matches to ROSAT/2RXS X-Ray Sources

Overview

This table contains the 132,254 AllWISE counterparts and/or Gaia matches to 106,573 X-ray sources detected in the ROSAT 2RXS survey with Galactic latitude |b| > 15 degrees. These are the brightest X-ray sources in the sky, but their position uncertainties and the sparse multi-wavelength coverage until now rendered the identification of their counterparts a demanding task with uncertain results. New all-sky multi-wavelength surveys of sufficient depth, like AllWISE and Gaia, and a new Bayesian statistics-based algorithm, NWAY, allow us, for the first time, to provide reliable counterpart associations.

NWAY extends previous distance- and sky density-based association methods and, using one or more priors (e.g. colors, magnitudes), weights the probability that sources from two or more catalogs are simultaneously associated on the basis of their observable characteristics. Here, counterparts have been determined using a Wide-field Infrared Survey Explorer (WISE) color-magnitude prior. A reference sample of 4,524 XMM/Chandra and Swift X-ray sources demonstrates a reliability of 94.7 per cent for 2RXS sources. Combining the results of this work and of the matching of XMM-Newton Slew Survey, Version 2 (XMMSL2) sources also reported in this study (the results of the latter are available as the HEASARC's database table NWAYAWGXMM) with Chandra-COSMOS data, the authors propose a new separation between stars and AGN in the X-ray/WISE flux-magnitude plane, that is valid over six orders of magnitude. The authors also release the NWAY code and its user manual. NWAY was extensively tested with XMM-COSMOS data.

Using two different sets of priors, the authors find an agreement of 96 per cent and 99 per cent with published Likelihood Ratio methods. Their results were achieved faster and without any follow-up visual inspection. With the advent of deep and wide area surveys in X-rays (e.g. SRG/eROSITA, Athena/WFI) and radio (ASKAP/EMU, LOFAR, APERTIF, etc.), NWAY will provide a powerful and reliable counterpart identification tool.

For all the available options, see the NWAY manual at https://github.com/JohannesBuchner/nway/raw/master/doc/nway-manual.pdf.

Catalog Bibcode

2018MNRAS.473.4937S

References

Finding counterparts for all-sky X-ray surveys with NWAY:
a Bayesian algorithm for cross-matching multiple catalogues.
    Salvato M., Buchner J., Budavari T., Dwelly T., Merloni A.. Brusa M.,
    Rau A., Fotopoulou S., Nandra K.
    <Mon. Not. R. Astron. Soc. 473, 4937 (2018)>
    =2018MNRAS.473.4937S        (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in February 2018 based on the CDS catalog J/MNRAS/473/4937 file 2rxswg.dat.

Parameters

Name
The 2RXS catalog X-ray source Designation from Boller et al. (2016, A&A, 588, A103, available as the RASS2RXS table in the HEASARC database).

RA
The Right Ascension of the 2RXS catalog X-ray source in the selected equinox. This was given in J2000.0 decimal degrees in the original table.

Dec
The Declination of the 2RXS catalog X-ray source in the selected equinox. This was given in J2000.0 decimal degrees in the original table.

LII
The Galactic Longitude of the 2RXS catalog X-ray source.

BII
The Galactic Latitude of the 2RXS catalog X-ray source.

Error_Radius
The positional error of the 2RXS catalog X-ray source, in arcseconds.

Detect_Likelihood
The 2RXS X-ray source detection likelihood, taken from Boller et al. (2016, A&A, 588, A103, available as the RASS2RXS table in the HEASARC database).

Source_Extent
The 2RXS X-ray source extent, in image pixels, from Boller et al. (2016, A&A, 588, A103, available as the RASS2RXS table in the HEASARC database).

Extent_Likelihood
The likelihood that the 2RXS X-ray source is extended, from Boller et al. (2016, A&A, 588, A103, available as the RASS2RXS table in the HEASARC database)

Flux
The 2RXS X-ray source flux, in erg s^-1 cm^-2, computed as in Dwelly et al. (2017, MNRAS, 469, 1065).

Flux_Error
The uncertainty in the 2RXS X-ray source flux, in erg s^-1 cm^-2, computed as in Dwelly et al. (2017, MNRAS, 469, 1065).

AllWISE_Name
The WISE All-Sky Release Catalog (AllWISE) IR source Designation, from Cutri et al. (2013, CDS Cat. II/328).

AllWISE_RA
The Right Ascension of the WISE All-Sky Release Catalog (AllWISE) IR source in the selected equinox. This was given in J2000.0 decimal degrees in the original table.

AllWISE_Dec
The Declination of the WISE All-Sky Release Catalog (AllWISE) IR source in the selected equinox. This was given in J2000.0 decimal degrees in the original table.

AllWISE_Error_Radius
The positional error of the WISE All-Sky Release Catalog (AllWISE) IR source, in arcseconds.

W1_Mag
The AllWISE W1 ([3.4] um) magnitude of the AllWISE infrared source.

W1_Mag_Error
The uncertainty in the AllWISE magnitude in the W1 band.

W2_Mag
The AllWISE W2 ([4.6] um) magnitude of the AllWISE infrared source.

W2_Mag_Error
The uncertainty in the AllWISE magnitude in the W2 band.

W3_Mag
The AllWISE W3 ([12] um) magnitude of the AllWISE infrared source.

W3_Mag_Error
The uncertainty in the AllWISE magnitude in the W3 band.

W4_Mag
The AllWISE W4 ([22] um) magnitude of the AllWISE infrared source.

W4_Mag_Error
The uncertainty in the AllWISE magnitude in the W4 band.

W1_SNR
The signal-to-noise ratio of the AllWISE source in the W1 band.

W2_SNR
The signal-to-noise ratio of the AllWISE source in the W2 band.

W3_SNR
The signal-to-noise ratio of the AllWISE source in the W3 band.

W4_SNR
The signal-to-noise ratio of the AllWISE source in the W4 band.

AllWISE_Flags
The reliability flag of the AllWISE source, taken from Cutri et al. (2013, CDS Cat. II/328).

AllWISE_ROSAT_Offset
The angular separation between the positions of the X-ray Source and the AllWISE candidate counterpart, in arcseconds.

Dist_Bayesfactor
The logarithm of the ratio between the prior and posterior probabilities that the counterpart is really associated withe the X-ray source. based on distance matching (see Appendix B of the reference paper for more details).

Dist_Post
The distance posterior probability comparing this association versus no association, as in Budavari and Szalay (2008, ApJ, 679, 301: see also Appendix B of the reference paper for more details).

Bias
The probability weighting (bias_ALLW_COLOURMAG_PIX) introduced by the AllWISE prior, where a value of 1 indicates no change (see Appendix B of the reference paper for more details).

Prob_Single
The probability p_single is the same as the dist_post parameter, but weighted by the AllWISE color-magnitude prior.

Prob_Any
The probability p_any that there is a correct counterpart for the specified X-ray source among the listed associations. The lower the value of p_any, the lower is the confidence that a reliable counterpart was found. See Section 4.2 of the reference paper.

Prob_I
The relative probability of the specific match (p_i) to the X-ray source, if one exists. The p_i values add up to unity for each X-ray source.

Match_Flag
The quality of the X-ray to WISE association, coded as follows:

      1 = most probable "best" match, if existing;
      2 = almost as good solutions.

For this work, the authors defined match_flag = 2 if p_i/p_i(match_flag = 1) > 0.5. A selection of match_flag = 1 selects the best counterpart for each X-ray source.

Group_ID
If the 2RXS source has only one possible AllWISE counterpart, the values of the group_id and number_matches parameters are left blank. Otherwise, the number_matches parameter value (GroupSize) indicates the number of possible counterparts while the GroupID value is the same integer for the group. A sort on the GroupID value, will rank the first non-unique match group together, followed by all the rows in the second non-unique group, etc.

Number_Matches
The number of possible All-WISE counterparts (GroupSize) for a given X-ray source.

OneRXS_Name
The X-ray source designation in the 1RXS catalogs of Voges et al. (1999 and 2000) Voges et al. (1999, Cat. CDS IX/10) and Voges et al. (2000, CDS Cat. IX/29), available as the HEASARC database tables RASSBSC and RASSFSC.

TwoMASS_ID
The 2MASS identifier as listed in the AllWISE catalog.

Jmag
The 2MASS magnitude in the J band of the infrared counterpart, as given in the AllWISE Catalog.

Jmag_Error
The uncertainty in the 2MASS magnitude in the J band of the infrared counterpart, as reported in the AllWISE catalog.

Hmag
The 2MASS magnitude in the H band of the infrared counterpart, as given in the AllWISE catalog.

Hmag_Error
The uncertainty in the 2MASS magnitude in the H band of the infrared counterpart, as reported in the AllWISE catalog.

Kmag
The 2MASS magnitude in the K band of the infrared counterpart, as given in the AllWISE catalog.

Kmag_Error
The uncertainty in the 2MASS magnitude in the K band of the infrared counterpart, as reported in the AllWISE catalog.

Gaia_Name
The solution identification of the optical counterpart from the original Gaia DR1 catalog (see Fabricius et al. (2016, A&A, 595, A3 for more details).

Gaia_RA
The Gaia Right Ascension of the optical counterpart in the selected equinox. This was given in J2000.0 decimal degrees in the original table.

Gaia_Dec
The Gaia Declination of the optical counterpart in the selected equinox. This was given in J2000.0 decimal degrees in the original table.

Gaia_PM_RA
The proper motion in Right Ascension of the optical counterpart, in milliarcseconds per year, as measured by Gaia.

Gaia_PM_RA_Error
The uncertainty in the proper motion in Right Ascension of the optical counterpart, in milliarcseconds per year, as measured by Gaia.

Gaia_PM_Dec
The proper motion in Declination of the optical counterpart, in milliarcseconds per year, as measured by Gaia.

Gaia_PM_Dec_Error
The uncertainty in the proper motion in Declination of the optical counterpart, in milliarcseconds per year, as measured by Gaia.

Gaia_G_Band_Flux
The Gaia G-band mean flux of the optical counterpart, in electrons per second.

Gaia_G_Band_Flux_Error
The uncertainty in the Gaia G-band mean flux of the optical counterpart, in electrons per second.

Gaia_Gmag
The Gaia G-band mean magnitude of the optical counterpart.

Contact Person

Questions regarding the NWAYAWGROS database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:32:28 EDT