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SA57XMM: Help

SA57XMM - Selected Area 57 XMM-Newton X-Ray Source Catalog


Overview

The maximum number density of Active Galactic Nuclei (AGNs), as deduced from X-ray studies, occurs at z >= 1, with lower luminosity objects peaking at smaller redshifts. Optical studies lead to a different evolutionary behaviour, with a number density peaking at z ~ 2 independently of the intrinsic luminosity, but this result is limited to active nuclei brighter than the host galaxy. A selection based on optical variability can detect low luminosity AGNs (LLAGNs), where the host galaxy light prevents the identification by non-stellar colours. The authors collected X-ray data in a field where there existed an optically-selected sample of "variable galaxies", i.e. variable objects with diffuse appearance, in order to investigate the X-ray and optical properties of the population of AGNs, particularly of low luminosity ones, where the host galaxy is visible. They observed a field of ~ 0.2 deg^2 in the Selected Area 57, for 67 ks with XMM-Newton. They correlated the list of detected X-ray sources with a photographic survey of SA 57, complete to B_J ~ 23 and with the available spectroscopic data. They obtained a catalog of 140 X-ray sources to limiting fluxes of 5 x 10^-16 and 2 x 10^-15 erg/cm^2/s in the 0.5 - 2 keV and 2 - 10 keV bands, respectively, 98 of which are identified in the optical bands. The X-ray detection of part of the variability-selected candidates confirms their AGN nature. Diffuse variable objects populate the low luminosity side of the sample. Only 25/44 optically-selected QSOs are detected in X-rays. 15% of all QSOs in the field have X/O < 0.1. Additional information on the likely optical counterparts of 98 of the X-ray sources is available in the reference paper, e.g., in Table 3.

Catalog Bibcode

2007A&A...469.1211T

References

An X-ray Survey in SA 57 with XMM-Newton.
    Trevese D., Vagnetti F., Puccetti S., Fiore F., Tomei M., Bershady M.A.
   <Astron. Astrophys. 469, 1211 (2007)>
   =2007A&A...469.1211T

Provenance

This table was created by the HEASARC in September 2007 based on CDS table J/A+A/469/1211 file table2.dat.

Description

The authors obtained a 67 ks XMM-Newton pointing of the SA 57 region centered at (RA, Dec) = (13:08:28, +29:23:07) (J2000). The X-ray observations were performed on January 2005. Source detection was performed on co-added PN + MOS1 + MOS2 images accumulated in four energy bands: 0.5 - 10 keV, 0.5 - 2 keV, 2 - 10 keV, and 5 - 10 keV. The source detections and the X-ray photometry were performed using the PWXDetect code (Pillitteri et al. 2006, A&A, 450, 993) based on wavelet transform of the count rate image. The authors adopted a significance level threshold corresponding to a probability of 2 x 10^-5 that a local maximum is generated by a Poisson fluctuation of the background counts. The limiting fluxes in the four bands are approximately: 10^-15, 5 x 10^-16, 2 x 10^-15, and 10^-14 erg/cm^2/s, respectively. The result of this selection is a sample of 140 sources, detected in at least one band.

Parameters

Source_Number
A running X-ray source number in order of increasing J2000.0 Declination which uniquely identifies the X-ray source.

Name
The name for the x-ray source using the 'SA57X' prefix (for Selected Area 57 X-ray source) and the source number, as used in the reference paper.

Source_Flag
This flag parameter is set to the following non-blank values to indicate the following note on specific X-ray source detections:

   c = At the same position an extended source is detected, corresponding to the
       galaxy cluster ZwCl 1305.4+29, not considered in the present analysis
   d = This source is only detected in the 5-10 keV band, with
       flux = 3.48 x 10^-14 erg/cm^2/s
  

RA
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.

Dec
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.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Flux
The X-ray flux of the source, in erg/cm^2/s, in the 0.5 - 10 keV band.

Flux_Flag
This flag parameter is set to 'b' to indicate that the object was not detected in the 0.5 - 10 keV band, but that the quoted value was computed using the measured fluxes in other bands.

SB_Flux
The X-ray flux of the source, in erg/cm^2/s, in the 0.5 - 2 keV band.

SB_Flux_Flag
This flag parameter is set to 'b' to indicate that the object was not detected in the 0.5 - 2 keV band, but that the quoted value was computed using the measured fluxes in other bands.

SB_Flux_Limit
This flag parameter is set to '<' to indicate that the corresponding flux is an upper limit, not a detection.

HB_Flux
The X-ray flux of the source, in erg/cm^2/s, in the 2 - 10 keV band.

HB_Flux_Flag
This flag parameter is set to 'b' to indicate that the object was not detected in the 2 - 10 keV band, but that the quoted value was computed using the measured fluxes in other bands.

HB_Flux_Limit
This flag parameter is set to '<' to indicate that the corresponding flux is an upper limit, not a detection.

Opt_Id_Rank
This flag parameter indicates the reliability of the optical counterpart identification, as follows:

        U = none identified
        I = identified
        M = marginal identification
        A = ambiguous identification
  

Contact Person

Questions regarding the SA57XMM database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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