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SMCWINGCXO - Small Magellanic Cloud Wing Survey Chandra X-Ray Point Source Catalog

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Overview

The authors have detected 523 X-ray sources in a survey of the Small Magellanic Cloud (SMC) Wing with the Chandra X-ray Observatory. By cross-correlating the X-ray data with optical and near-infrared catalogues, they have found 300 matches. Using a technique that combines X-ray colours and X-ray to optical flux ratios, they have been able to assign preliminary classifications to 265 of the objects. The identifications include 4 pulsars, 1 high-mass X-ray binary (HMXB) candidate, 34 stars and 185 active galactic nuclei (AGN). In addition, the authors have classified 32 sources as hard AGN which are likely absorbed by local gas and dust, and 9 soft AGN whose nature is still unclear. Considering the abundance of HMXBs discovered so far in the Bar of the SMC the number that have been detected in the Wing is low.

Observations in the Wing of the SMC were made from 2005 July to 2006 March with Chandra. The survey consisted of 20 fields, with exposure times ranging from 8.6 - 10.3 ks. X-ray parameters for 523 sources detected in the Wing of the SMC with Chandra are presented. For each source equatorial coordinates, positional error, net counts (total counts minus background counts) in the 0.5 - 8.0 keV band, signal-to-noise of the detection and source flux in the 0.5 - 8.0 keV band are given. The median, compressed median and normalized quartile ratio of the photon energy distribution, determined using quantile analysis, are given for sources with three or more counts. For the sources that have optical counterparts the V- and R-band magnitudes, B-V colour, X-ray to optical flux ratios based on the V- and R-band magnitudes, and a preliminary classification for the sources are given.


Catalog Bibcode

2008MNRAS.383..330M

References

The Chandra Small Magellanic Cloud Wing Survey - the search for X-ray binaries.
    McGowan K.E., Coe M.J., Schurch M.P.E., McBride V.A., Galache J.L.,
    Edge W.R.T., Corbet R.H.D., Laycock S., Buckley D.A.H.
   <Mon. Not. R. Astron. Soc., 383, 330-338 (2008)>
   =2008MNRAS.383..330M    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in June 2008 based on the CDS Catalog J/MNRAS/383/330 file table2.dat.

Parameters

Source_Number
A unique identification number for each X-ray source in the catalog, in order of increasing J2000.0 Right Ascension.

Name
The name for the X-ray source using the '[MCS2008]' prefix (for McGowan, Coe, Schurch 2008) and the value of the source number parameter, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects, e.g., '[MCS2008] 5'.

RA
The Right Ascension of the Chandra source in the selected equinox as taken from the wavelet analysis (see Section 2.1 of the reference paper). The RA was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the Chandra source in the selected equinox as taken from the wavelet analysis (see Section 2.1 of the reference paper). The Declination was given in J2000.0 coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the Chandra source.

BII
The Galactic Latitude of the Chandra source.

Error_Radius
The positional error of the X-ray source, in arcseconds. This was calculated by taking into account the properties of the telescope optics and the source brightness (see Hong et al. 2005, ApJ, 635, 907). The positional error given corresponds to the 95% confidence region, combined in quadrature with the boresight error (~0.7 arcseconds at 95% confidence).

Counts
The net counts for the X-ray source, being the total source counts (background-subtracted) in the 0.5 - 8.0 keV energy band.

SNR
The signal-to-noise ratio of the X-ray source detection as given by the wavelet algorithm.

Flux
The X-ray flux of the Chandra source in the 0.5 - 8.0 keV energy band, in erg/s/cm^2. This was determined by converting the source count rate into a flux employing the absorbed power-law spectrum discussed in section 2 of the reference paper.

Median_Energy
For sources that have 3 or more X-ray counts, this is the median energy E_med of the photon energy distribution including background subtraction, in keV (see Section 4 of the reference paper for more details).

Compressed_Median
For sources that have 3 or more X-ray counts, this is the compressed median of the photon energy distribution including background subtraction, defined as log10 (m/(1-m)), where m = Q_50 is the normalized median energy or 50% quartile value given by m = (E_med - 0.5)/(8.0 - 0.5), E_med is the median energy in keV, and 0.5 keV and 8.0 keV are the lower and upper limits to the energy range considered (see Section 4 of the reference paper for more details).

Energy_Quartile_Ratio
The normalized quartile ratio of the photon energy distribution, 3 x (Q_25/Q_75), where Q_25 and Q_75 are the 25% and 75% quartile normalized energy values, respectively. In general, the quantile Q_x is defined as (E_x% - E_lo)/(E_hi - E_lo), where E_x% is the energy below which the net counts are x% of the total counts, and E_lo and E_hi are the lower and upper limits to the energy range considered (0.5 and 8.0 keV, respectively, in this case): see Section 4 of the reference paper for more details.

Vmag
The magnitude (apparent) of the optical counterpart to the Chandra X-ray source in the V filter.

Rmag
The magnitude (apparent) of the optical counterpart to the Chandra X-ray source in the R filter.

BV_Color
The B-V color index of the optical counterpart to the Chandra X-ray source.

Fx_Hard_Over_Fv
The ratio of the hard (2 - 10 keV) X-ray flux f_hard to the V-band flux f_V, where f_V = 8 x 10^-6 x 10^(-V/2.5) erg s^-1 cm^-2, and V is the apparent visual magnitude. This ratio is useful for distinguishing between HMXBs and stars in the magnitude range 12 < V < 18: see Section 6 of the reference paper for more details.

Log_Fx_Soft_Over_Fr
The log of the ratio of the soft (0.5 - 2 keV) X-ray flux f_soft to the R-band flux f_R, where log (f_soft/f_R) = log(f_soft) + 5.50 + R/2.5 and R is the apparent R magnitude. This ratio is useful for classifying AGN: see Section 6 of the reference paper for more details.

Source_Type
A broad classification of the source, based on the X-ray to optical flux ratios combined with the X-ray quantile analyses, where the sources are classified as follows:

             star = star
              AGN = AGN
            AGN h = hard AGN
            AGN s = soft AGN
           pulsar = pulsar
            HMXB? = HMXB candidate
              unc = sources with optical matches that were not able to be
                     classified
  

Class
The HEASARC Browse object classification, based on the value of the source_type parameter.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 3-Jun-2008