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SMCDFSCXO - Small Magellanic Cloud Deep Fields X-Ray Point Source Catalog

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Overview

This table contains the results of a pair of 100 ks Chandra observations of the Small Magellanic Cloud (SMC) to survey high-mass X-ray binaries (HMXBs), stars, and low-mass X-ray binaries (LMXBs)/cataclysmic variables down to L_x = 4.3 x 1032 erg s-1. The two SMC Deep Fields (DFs) are located in the most active star-forming region of the SMC bar, with Deep Field-1 positioned at the most pulsar-rich location identified from previous surveys. Two new pulsars were discovered in outburst, CXOU J004929.7-731058 (P = 892 s) and CXOU J005252.2-721715 (P = 326 s), and three new HMXB candidates were identified. Of the 15 Be-pulsars now known in the field, 13 were detected, with pulsations seen in 9 of them. Ephemerides demonstrate that 6 of the 10 pulsars known to exhibit regular outbursts were seen outside their periastron phase, and quiescent X-ray emission at L_X = 1033-34 erg s-1 is shown to be common. Comparison with ROSAT, ASCA, and XMM-Newton catalogs resulted in positive identification of several previously ambiguous sources. Bright optical counterparts exist for 40 of the X-ray sources, of which 33 are consistent with early-type stars (M_V < -2, B-V < 0.2), and are the subject of a companion paper to the reference paper. The results point to an underlying HMXB population density up to double that of active systems. The full catalog of 394 point sources is presented in theis table; detailed analyses of the source timing and spectral properties are available in the reference paper.

The aimpoints for these Chandra observations were as follows: DF1 had J2000.0 coordinates of 00 53 34.50 -72 26 43.2 and DF2 had J2000.0 coordinates of 00 50 41.40 -73 16 10.3.


Catalog Bibcode

2010ApJ...716.1217L

References

Exploring the Small Magellanic Cloud to the Faintest X-ray Fluxes: Source
Catalog, Timing, and Spectral Analysis
     Laycock S., Zezas A., Hong J., Drake J.J., Antoniou V.
    <Astrophys. J., 716, 1217-1240 (2010)>
    =2010ApJ...716.1217L

Provenance

This table was created by the HEASARC in August 2010 based on the electronic version of Table 2 from the reference paper which was ontained from the ApJ web site.

Parameters

Name
The name of the X-ray source using the standard prefix 'CXOU' for 'Chandra X-ray Observatory, Unregistered' and the J2000.0 equatorial source coordinates truncated to 0.1 seconds of time in RA and 1 second in Dec, e.g., 'CXOU J005252.2-721715'.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 10-6 degrees in the original table. These coordinates incorporate the full Chandra aspect solution.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 10-6 degrees in the original table. These coordinates incorporate the full Chandra aspect solution.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The 95%-confidence radius of the uncertainty in the X-ray source position, in arcseconds.

Counts
The net background-subtracted X-ray source counts in the 0.3 - 8 keV band used by the wavdetect algorithm.

Counts_Error
The standard error in the net 0.3-8 keV background-subtracted \ counts.

Off_Axis
The off-axis angle of the source, in arcminutes, calculated using the source position and the aim point of the field in which the source was detected.

SNR
The signal-to-noise ratio of the X-ray source in the 0.3-8 keV band, defined as the ratio of counts to counts_error.

SB_SNR
The soft-band (S_c: 0.5-2 keV) signal-to-noise ratio of the X-ray source.

HB_SNR
The hard-band (H_c: 2-8 keV) signal-to-noise ratio of the X-ray source

BB_SNR
The broad-band (B_c: 0.5-8 keV) signal-to-noise ratio of the X-ray source

SB_Count_Rate
The soft-band (S_c: 0.5-2 keV) count rate of the X-ray source, in counts per second (ct/s). The authors note, regarding "null", i.e. blank, values, that given the diversity of source spectra in the catalog, occasionally it was not possible to compute accurate count rate, and flux values in one or two of the three energy bands (S_c , H_c, B_c). Errors in these cases are still computed from the background annulus.

SB_Count_Rate_Error
The standard error in the soft-band count rate of the X-ray source, in counts per second (ct/s). The authors note, regarding "null", i.e. blank, values, that given the diversity of source spectra in the catalog, occasionally it was not possible to compute accurate count rate, and flux values in one or two of the three energy bands (S_c , H_c, B_c). Errors in these cases are still computed from the background annulus.

HB_Count_Rate
The hard-band (H_c: 2-8 keV) count rate of the X-ray source, in counts per second (ct/s). The authors note, regarding "null", i.e. blank, values, that given the diversity of source spectra in the catalog, occasionally it was not possible to compute accurate count rate, and flux values in one or two of the three energy bands (S_c , H_c, B_c). Errors in these cases are still computed from the background annulus.

HB_Count_Rate_Error
The standard error in the hard-band count rate of the X-ray source, in counts per second (ct/s). The authors note, regarding "null", i.e. blank, values, that given the diversity of source spectra in the catalog, occasionally it was not possible to compute accurate count rate, and flux values in one or two of the three energy bands (S_c , H_c, B_c). Errors in these cases are still computed from the background annulus.

BB_Count_Rate
The broad-band (B_c: 0.5-8 keV) count rate of the X-ray source, in counts per second (ct/s). The authors note, regarding "null", i.e. blank, values, that given the diversity of source spectra in the catalog, occasionally it was not possible to compute accurate count rate, and flux values in one or two of the three energy bands (S_c , H_c, B_c). Errors in these cases are still computed from the background annulus.

BB_Count_Rate_Error
The standard error in the broad-band count rate of the X-ray source, in counts per second (ct/s). The authors note, regarding "null", i.e. blank, values, that given the diversity of source spectra in the catalog, occasionally it was not possible to compute accurate count rate, and flux values in one or two of the three energy bands (S_c , H_c, B_c). Errors in these cases are still computed from the background annulus.

Q_25
The 25%-percentile photon energy of the X-ray source, in keV, found from a quantile analysis (see Hong et al. 2004, ApJ, 614, 508 for more details).

Q_25_Error
The standard error in the 25%-percentile photon energy of the X-ray source, in keV.

Q_50
The median (50%-percentile) photon energy of the X-ray source, in keV, found from a quantile analysis (see Hong et al. 2004, ApJ, 614, 508 for more details).

Q_50_Error
The standard error in the median (50%-percentile) photon energy of the X-ray source, in keV.

Q_75
The 75%-percentile photon energy of the X-ray source, in keV, found from a quantile analysis (see Hong et al. 2004, ApJ, 614, 508 for more details).

Q_75_Error
The standard error in the 75%-percentile photon energy of the X-ray source, in keV.

Quantile_X_Val
The quantile X-value of the X-ray source for plotting in conventional quantile parameter space (see Hong et al. 2004, ApJ, 614, 508 for more details).

Quantile_X_Val_Neg_Err
The standard error lower bound on the quantile X value of the source. Some very faint sources (<2 net counts) have null values for the standard errors in the quantile X values, as the error function becomes unbounded.

Quantile_X_Val_Pos_Err
The standard error upper bound on the quantile X alue of vthe source. Some very faint sources (<2 net counts) have null values for the standard errors in the quantile X values, as the error function becomes unbounded.

Quantile_Y_Val
The quantile Y-value of the X-ray source for plotting in conventional quantile parameter space (see Hong et al. 2004, ApJ, 614, 508 for more details).

Quantile_Y_Val_Neg_Err
The standard error lower bound on the quantile Y value of the source.

Quantile_Y_Val_Pos_Err
The standard error upper bound on the quantile Y value of the source.

Quantile_Group
The quantile-based classification of the source spectrum, used for assigning a spectral model in the flux computations. The flux values were generated using a varying spectral model, whose parameters are selected according to the quantile value for each source. This approach was introduced by Hong et al. (2009, ApJ, 706, 223) and frees the flux estimation from systematic errors inherent in assuming a single spectral model for all sources. This table also contains flux values derived for fixed power law (Gamma = 1.4) and thermal plasma (kT = 1 keV) spectral models. The quantile-based fluxes are derived from one of three power-law models that are defined by the natural groupings of sources in the quantile diagram (cf. Section 7.3 of the reference paper). For field DF1 (sources north of -73 degrees declination), the models are:

  group 1: N_H = 2.8, power law Gamma = 2.35
  group 2: N_H = 2.5, power law Gamma = 1.42
  group 3: N_H = 20.0, power law Gamma = 1.52
  
where the absorption column density N_H is in units of 1021 cm-2. For field DF2 (sources south of -73 degrees declination), the models are similar:
  group 1: N_H = 0.6, power law Gamma = 2.94
  group 2: N_H = 4.9, power law Gamma = 1.38
  group 3: N_H  = 27.0, power law Gamma = 1.91
  
where N_H is again in units of 1021 cm-2. In both fields, the algorithm identifies quantitatively similar groupings, corresponding to a very soft spectrum with typical (or sub) SMC absorption (group 1), a hard XRB-like spectrum with SMC absorption (group 2), and a heavily absorbed AGN-like spectrum (group 3). The two fixed models are provided as they will be more accurate if the nature of an individual source is known by other means.

SB_Flux_1
The soft-band (0.5-2 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using the quantile-based spectral model selected according to the quantile_group and specific deep field in which the source lies, where sources north/south of -73 degrees declination are in DF1 and DF2, respectively. In the case of unidentified sources, these quantile-based flux values should be used, whereas the fluxes calculated using a thermal plasma model, e.g., sb_flux_2, and power-law models, e.g., sb_flux_3, are appropriate when the source classification is known, e.g. from an optical counterpart.

SB_Flux_1_Error
The standard error in the soft-band X-ray source flux, in erg cm-2 s-1, calculated using the quantile-based spectral model.

HB_Flux_1
The hard-band (2-8 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using the quantile-based spectral model selected according to the quantile_group and specific deep field in which the source lies, where sources north/south of -73 degrees declination are in DF1 and DF2, respectively. In the case of unidentified sources, these quantile-based flux values should be used, whereas the fluxes calculated using a thermal plasma model, e.g., hb_flux_2, and power-law models, e.g., hb_flux_3, are appropriate when the source classification is known, e.g. from an optical counterpart.

HB_Flux_1_Error
The standard error in the hard-band X-ray source flux, in erg cm-2 s-1, calculated using the quantile-based spectral model.

BB_Flux_1
The broad-band (0.5-8 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using the quantile-based spectral model selected according to the quantile_group and specific deep field in which the source lies, where sources north/south of -73 degrees declination are in DF1 and DF2, respectively. In the case of unidentified sources, these quantile-based flux values should be used, whereas the fluxes calculated using a thermal plasma model, e.g., bb_flux_2, and power-law models, e.g., bb_flux_3, are appropriate when the source classification is known, e.g. from an optical counterpart.

BB_Flux_1_Error
The standard error in the broad-band X-ray source flux, in erg cm-2 s-1, calculated using the quantile-based spectral model.

SB_Flux_2
The soft-band (0.5-2 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a thermal-plasma model with kT = 1 keV.

SB_Flux_2_Error
The standard error in the soft-band X-ray source flux, in erg cm-2 s-1, calculated using the thermal-plasma model with kT = 1 keV.

HB_Flux_2
The hard-band (2-8 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a thermal-plasma model with kT = 1 keV.

HB_Flux_2_Error
The standard error in the hard-band X-ray source flux, in erg cm-2 s-1, calculated using the thermal-plasma model with kT = 1 keV.

BB_Flux_2
The broad-band (0.5-8 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a thermal-plasma model with kT = 1 keV.

BB_Flux_2_Error
The standard error in the broad-band X-ray source flux, in erg cm-2 s-1, calculated using the thermal-plasma model with kT = 1 keV.

SB_Flux_3
The soft-band (0.5-2 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a power-law model with spectral index Gamma = 1.4.

SB_Flux_3_Error
The soft-band (0.5-2 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a power-law model with spectral index Gamma = 1.4.

HB_Flux_3
The hard-band (2-8 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a power-law model with spectral index Gamma = 1.4.

HB_Flux_3_Error
The hard-band (2-8 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a power-law model with spectral index Gamma = 1.4.

BB_Flux_3
The broad-band (0.5 -8 keV) X-ray flux of the source, in erg cm-2 s-1, calculated using a power-law model with spectral index Gamma = 1.4.

BB_Flux_3_Error
The standard error in the broad-band X-ray source flux, in erg cm-2 s-1, calculated using a power-law model with spectral index Gamma = 1.4.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 6-Aug-2010