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CHAMPLANEX - ChaMPlane Galactic Bulge and Center X-Ray Source Catalog

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Overview

This table contains the Chandra Multiwavelength Plane (ChaMPlane) Survey catalog of X-ray point sources in the window and four Galactic bulge fields, specifically all source detections with net counts >= 1 in the 0.3-8 keV broad band. In the reference paper, the authors present the log N-log S and spatial distributions of X-ray point sources in seven Galactic bulge (GB) fields within 4 degrees of the Galactic center (GC). They compare the properties of 1159 X-ray point sources discovered in their deep (100 ks) Chandra observations of three low extinction Window fields near the GC with the X-ray sources in the other GB fields centered around Sgr B2, Sgr C, the Arches Cluster, and Sgr A* using Chandra archival data. To reduce the systematic errors induced by the uncertain X-ray spectra of the sources coupled with field-and-distance-dependent extinction, they classify the X-ray sources using quantile analysis and estimate their fluxes accordingly. The result indicates that the GB X-ray population is highly concentrated at the center, more heavily than the stellar distribution models. It extends out to more than 1.4 degrees from the GC, and the projected density follows an empirical radial relation inversely proportional to the offset from the GC. They also compare the total X-ray and infrared surface brightness using the Chandra and Spitzer observations of the regions. The radial distribution of the total infrared surface brightness from the 3.6-micron band images appears to resemble the radial distribution of the X-ray point sources better than that predicted by the stellar distribution models. Assuming a simple power-law model for the X-ray spectra, the closer to the GC, the intrinsically harder the X-ray spectra appear, but adding an iron emission line at 6.7 keV in the model allows the spectra of the GB X-ray sources to be largely consistent across the region. This implies that the majority of these GB X-ray sources can be of the same or similar type. Their X-ray luminosity and spectral properties support the idea that the most likely candidate is magnetic cataclysmic variables (CVs), primarily intermediate polars (IPs). Their observed number density is also consistent with the majority being IPs, provided the relative CV to star density in the GB is not smaller than the value in the local solar neighborhood.

Catalog Bibcode

2009ApJ...706..223H

References

Radial Distribution of X-Ray Point Sources Near the Galactic Center
    Hong. J., van den Berg M., Grindlay J.E., Laycock S.
   <Astrophys. J. 706, 223-237 (2009)>
   =2009ApJ...706..223H

Provenance

This table was created by the HEASARC in January 2010, based on the electronic version of Table 2 from the reference paper, which was obtained from the Astrophysical Journal web site.

Parameters

Name
The Chandra X-ray source designation as recommended by the authors and the Dictionary of Nomenclature of Celestial Objects using the 'CXOPS' prefix for Chandra X-ray Observatory Plane Survey and the J2000.0 equatorial coordinates, e.g., 'CXOPS J174337.4-292027'.

Field_Name_Code
The Chandra field designation as described in Table 1 of the reference paper, using the following abbreviations:

  Arches        - Arches Cluster
  BW            - Baade's Window
  LW            - Limiting Window
  SgrA*         - Sgr A* field
  SgrB2         - Sgr B2 field
  SgrC          - Sgr C field
  Stacked_SgrA* - 14 Stacked Sgr A* pointings
  SW            - Stanek's Window
  

RA
The Right Ascension of the Chandra source in the selected equinox. This was given in J2000.0 coordinates to a precision of 1 microdegree (3.6 mas).

Dec
The Declination of the Chandra source in the selected equinox. This was given in J2000.0 coordinates to a precision of 1 microdegree (3.6 mas).

LII
The Galactic Longitude of the Chandra source.

BII
The Galactic Latitude of the Chandra source.

Error_Radius
The 95% confidence Chandra X-ray source positional error, in arcseconds, calculated by an empirical formula using MARX simulations, viz., equation (5) in Hong et al. (2005, ApJ, 635, 907).

Off_Axis
The offset of the X-ray source position from the aimpoint of the Chandra observation, in arcminutes.

FB_Counts
The net source counts in the 0.3-8.0 keV (B_X) energy band found using aperture photometry. For sources that fall near other sources, the authors carefully revised the aperture of the source regions by excluding overlapping sections to minimize the contamination from neighboring sources.

FB_Counts_Error
The statistical error in the net source counts in the 0.3-8.0 keV B_X band.

SB_Counts
The net source counts in the 0.5-2.0 keV (the conventional soft or S_c) energy band found using aperture photometry. For sources that fall near other sources, the authors carefully revised the aperture of the source regions by excluding overlapping sections to minimize the contamination from neighboring sources.

SB_Counts_Error
The statistical error in the net source counts in the 0.5-2.00 keV S_c band.

HB_Counts
The net source counts in the 2.0-8.0 keV (the conventional hard or H_c) energy band found using aperture photometry. For sources that fall near other sources, the authors carefully revised the aperture of the source regions by excluding overlapping sections to minimize the contamination from neighboring sources.

HB_Counts_Error
The statistical error in the net source counts in the 2.0-8.0 keV H_c band.

HB_SNR
The signal-to-noise ratio (snr) of the Chandra point source in the 2.0-8.0 keV band. Source with snr values greater than or equal to 3.0 are included in the log N - log S plot in Figure 5 of the reference paper.

Median_Energy
The median energy E_50 of the source photons, in keV.

Median_Energy_Error
The error in the source photons median energy, in keV.

Quantile_Y_Val
The y-value of the source in the quantile diagram (cf. Figure 2 in the reference paper), defined as y = 3(E_25 - 0.3 keV)/(E_75 - 0.3 keV), where the energy quantile E_x corresponds to the energy below which x% of the counts are detected.

Quantile_Y_Val_Neg_Err
The negative error in the y-value of the quantile diagram.

Quantile_Y_Val_Pos_Err
The positive error in the y-value of the quantile diagram.

Quantile_Group
The group in the quantile diagram - the plot of x = log_10[(E_50 - 0.3 keV)/(8.0 keV - E_50)] versus y = 3(E_25 - 0.3 keV)/(E_75 - 0.3 keV) - to which the source belongs: 1, 2 or 3 (referred to as G1, G2 , G3 in the reference paper). The way in which the division of the quantile diagram into 3 groups was done is depicted in Figure 2 of the reference paper.

HB_Flux
The unabsorbed source flux in the 2.0-8.0 keV band, in erg cm-2 s-1. This is calculated based on a simple power law plus 6.6 keV Fe emission line (PL + Fe) spectral model using quantile analysis as discussed in Section 3 of the reference paper. The flux estimates in the other bands are not included due to their large uncertainties.

HB_Flux_Error
The statistical error in the unabsorbed source flux in the 2.0-8.0 keV band, in erg cm-2 s-1.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 24-May-2012