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CHAMPLANE - Chandra Multiwavelength Plane Survey Optical ID Catalog

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Overview

The authors have carried out optical and X-ray spectral analyses on a sample of 136 candidate optical counterparts of X-ray sources found in five Galactic bulge fields included in their Chandra Multiwavelength Plane (ChaMPlane) Survey. They used a combination of optical spectral fitting and quantile X-ray analysis to obtain the hydrogen column density toward each object, and a three-dimensional dust model of the Galaxy to estimate the most probable distance in each case. They present the discovery of a population of stellar coronal emission sources, likely consisting of pre-main-sequence, young main-sequence, and main-sequence stars, as well as a component of active binaries of RS CVn or BY Dra type. They identify one candidate quiescent low-mass X-ray binary with a subgiant companion, but note that this object may also be an RS CVn system. They report the discovery of 3 new X-ray-detected cataclysmic variables (CVs) in the direction of the Galactic center (at distances <~2 kpc). This number is in excess of predictions made with a simple CV model based on a local CV space density of <~10-5 pc-3, and a scale height of ~200 pc. They discuss several possible reasons for this observed excess in their paper.

Catalog Bibcode

2008ApJ...685..463K

References

Investigating ChaMPlane X-Ray Sources in the Galactic Bulge with Magellan
LDSS2 Spectra
	Koenig, X., Grindlay, J.E., van den Berg, M., Laycock, S., Zhao, P.,
        Hong, J., Schlegel, E.M.
       <Astrophys. J. 685, 463 (2008)>
       =2008ApJ...685..463K

Provenance

This table was created by the HEASARC in October 2008 based on the version of Table 5 from the paper which was obtained from the electronic ApJ web site.

Parameters

Field_ID
The CXO field name in which the source was detected. The observational details of these fields (e.g., field centers, exposures, numbers of detected sources) are given in Table 1 of the reference paper.

Name
The ChaMPlane IAU-style optical source (ChOPS) identification. Those desiring to find detailed X-ray counterpart properties can readily search the ChaMPlane online X-ray database at http://hea-www.harvard.edu/ChaMPlane/database_xray.html using the optical source ID for coordinates.

RA
The Right Ascension of the optical source counterpart to the Chandra X-ray source in the selected equinox. This was created from the IAU-style name for the counterpart, which was in J2000.0 equatorial coordinates and was given to a precision of 0.01 seconds of time.

Dec
The Declination of the optical source counterpart to the Chandra X-ray source in the selected equinox. This was created from the IAU-style name for the counterpart, which was in J2000.0 equatorial coordinates and was given to a precision of 0.1 arcseconds.

LII
The Galactic Longitude of the optical source counterpart to the Chandra X-ray source.

BII
The Galactic Latitude of the optical source counterpart to the Chandra X-ray source.

Spect_Type
The spectral type classification of the optical source counterpart to the Chandra X-ray source. Effective temperatures and adopted photometry for each spectral type 'bin' are given in Table 4 of the reference paper.

Broad_Type
An additional classification of the source type, where 'q' means quiescent low-mass X-ray binary (qLMXB_ candidate, 'by' means BY Dra candidate, 'rs' means RS CVn candidate, 'tt' means T Tauri, and 'cv' means cataclysmic variable (CV).

Counts
The background-subtracted net counts of the X-ray source in the B_X band (0.3-8.0 keV).

Counts_Flag
This flag parameter is set to 'L' to indicate when a source has an X-ray signal-to-noise ratio less than 3.

Counts_Error
The uncertainty in the X-ray source counts.

NH_Limit
This limit parameter is set to '<' or '>' to indicate when the associated parameter is an upper or lower limit, respectively.

NH
The hydrogen column density in units of atoms cm-2, as derived from the authors' fitting technique or quantile analysis. The true value may be higher by 2 x 1021 cm-2, as discussed in Section 3.1 of the reference paper.

NH_Flag
This flag parameter is set to 'd' to indicate objects with unknown ('?') spectral type and CVs, for which have the nh values were estimated from a quantile color-color diagram (QCCD) analysis.

NH_Error
The uncertainty in the hydrogen column density, in units of atoms cm-2.

Fx_Over_Fr_Limit
This limit parameter is set to '<' or '>' to indicate when the associated parameter is an upper or lower limit, respectively.

Fx_Over_Fr
The logarithm of the ratio f_x/f_R, of the unabsorbed flux in the S_C band (0.5-2.0 keV) for the X-ray source to the unreddened optical R-band flux (in ergs cm-2 s-1 (1000 Angstroms)-1) of the optical counterpart, adopting a 1.0 keV MEKAL X-ray spectral model.

Fx_Over_Fr_Error
The uncertainty in f_x/f_R (in the same units).

Distance_Limit
This limit parameter is set to '<' or '>' to indicate when the associated parameter is an upper or lower limit, respectively.

Distance
The estimated distance to the source, in kpc. The uncertainty in this parameter is ~60%.

Abs_Vmag_Limit
This limit parameter is set to '<' or '>' to indicate when the associated parameter is an upper or lower limit, respectively

Abs_Vmag
The absolute visual (V-band) magnitude of the optical counterpart to the X-ray source.

Abs_Vmag_Error
The uncertainty in the absolute V-band magnitude.

Log_Lx_Limit
This limit parameter is set to '<' or '>' to indicate when the associated parameter is an upper or lower limit, respectively

Log_Lx
The logarithm of the X-ray luminosity, log L_x, in the S_C band (ergs s-1).

Log_Lx_Error
The uncertainty in Log L_x (in the same units).

Rmag
The apparent R-band magnitude of the optical counterpart to the X-ray source.

Rmag_Error
The uncertainty in the apparent R-band magnitude.

Num_Opt_Matches
The number of optical matches found within the 95% confidence (2 sigma) error circle of the X-ray source.

XO_Error_Radius
The combined 95% X-ray and optical position error circle, in arcseconds, used to search for optical matches.

Offset
The positional offset between the X-ray centroid and optical position, in arcseconds.

Random_Match_Prob
The random match probability of finding an optical counterpart, given the error circle size and the measured local optical projected surface density. Specifically, this is the expected number of optical sources that should fall in an error circle of this size by chance, given the observed surface density of stars within 1 of the X-ray position on the Mosaic image.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 29-Oct-2008