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M101CXO - M 101 Chandra X-Ray Point Source Catalog

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Overview

A deep (98.2ks) Chandra Cycle 1 observation has revealed a wealth of discrete X-ray sources as well as diffuse emission in the nearby face-on spiral galaxy M 101. From this rich data set, the authors have created a catalog of the 110 sources from the S3 chip which were detected with a significance of greater than 3-sigma. This detection threshold corresponds to a flux of ~ 10^-16 ergs/cm^2/s and a luminosity of ~ 10^36 ergs/s for a distance to M 101 of 7.2 Mpc. The sources display a distinct correlation with the spiral arms of M101 and include a variety of X-ray binaries, supersoft sources, supernova remnants, and other objects of which only ~27 are likely to be background sources.

The 29 brightest sources have enough flux (greater than 100 counts) to perform at least crude spectral modeling using the HEASARC XSPEC model fitting program. Most of the sources could be satisfactorily fitted with a simple absorbed power-law spectrum model; however, eight of the softest sources were better fitted by an absorbed blackbody model.


Catalog Bibcode

2001ApJ...561..189P

References

Chandra X-ray sources in M101.
    Pence W.D., Snowden S.L., Mukai K., Kuntz K.D.
    <Astrophys. J. 561, 189 (2001)>
    =2001ApJ...561..189P (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in July 2007 based on CDS Catalog J/ApJ/561/189 files table1.dat and table4.dat.

Parameters

Source_Number
A running X-ray source number in order of increasing J2000.0 Right Ascension.

Name
The preferred designation for the X-ray source using the '[PSM2001]' prefix (for Pence, Mukai and Snowden 2001) and the source number, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

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.

Source_Region
The X-ray events located within a circular region around each of the 110 X-ray sources were used to calculate the count rate within standard energy bands and to generate spectra and light curves for each source. The radius of the region was chosen as a function of the distance of the source from the optical axis so as to enclose greater than 95% of the source flux as predicted from the model PSFs and verified by numerical experiments on the brightest sources. The area of the source region is given in units of the 0.49 arcsecond Chandra CCD pixels.

SB1_Counts
The net background-subtracted source counts in the S1 (0.125 - 0.8 keV) band, where the energy ranges for the first set of bands (S1, M1, and H1) were selected to produce roughly equal count rates in each band for the typical sample of sources seen in M 101.

Mb1_Counts
The net background-subtracted source counts in the M1 (0.8 - 1.3 keV) band, where the energy ranges for the first set of bands (S1, M1, and H1) were selected to produce roughly equal count rates in each band for the typical sample of sources seen in M 101.

HB1_Counts
The net background-subtracted source counts in the H1 (1.3 - 8.0 keV) band, where the energy ranges for the first set of bands (S1, M1, and H1) were selected to produce roughly equal count rates in each band for the typical sample of sources seen in M 101.

SB2_Counts
The net background-subtracted source counts in the S2 (0.125 - 0.5 keV) band, where the energy ranges for the second set of bands (S2, M2, and H2) were chosen to be a more standard set of astrophysically relevant energy ranges so as to facilitate the comparison of these results with those from previous X-ray missions.

Mb2_Counts
The net background-subtracted source counts in the M2 (0.5 - 2.0 keV) band, where the energy ranges for the second set of bands (S2, M2, and H2) were chosen to be a more standard set of astrophysically relevant energy ranges so as to facilitate the comparison of these results with those from previous X-ray missions.

HB2_Counts
The net background-subtracted source counts in the H2 (2.0 - 8.0 keV) band, where the energy ranges for the second set of bands (S2, M2, and H2) were chosen to be a more standard set of astrophysically relevant energy ranges so as to facilitate the comparison of these results with those from previous X-ray missions.

SB2_Flux
The S2 (0.125 - 0.5 keV) band flux for the X-ray source, in erg cm^-2 s^-1. The ratio between the total net X-ray counts and the model X-ray flux in the S2, M2, and H2 bands for the 29 brightest sources was used to derive a mean counts-to-flux conversion factor that could be applied to the fainter sources to estimate their fluxes. Figure 8 in the reference paper shows the flux-per-count ratio plotted as a function of the hardness ratio, HR2, for each source. The adopted multiplication factor for the S2 counts to convert from total net counts in the 98.2 ks exposure into a flux units of ergs cm^-2 s^-1, is (2.37 +/- 0.39) x 10^-17. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

Mb2_Flux
The M2 (0.5 - 2.0 keV) band flux for the X-ray source, in erg cm^-2 s^-1. The ratio between the total net X-ray counts and the model X-ray flux in the S2, M2, and H2 bands for the 29 brightest sources was used to derive a mean counts-to-flux conversion factor that could be applied to the fainter sources to estimate their fluxes. Figure 8 in the reference paper shows the flux-per-count ratio plotted as a function of the hardness ratio, HR2, for each source. The adopted multiplication factor for the M2 counts (which has a slight dependence on the hardness ratio of the source) to convert from total net counts in the 98.2 ks exposure into a flux units of ergs cm^-2 s^-1, is [(3.5 + 0.9 x HR2) +/- 0.24] x 10^-17, where HR2 is the hardness ratio as defined below. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

HB2_Flux
The H2 (2.0 - 8.0 keV) band flux for the X-ray source, in erg cm^-2 s^-1. The ratio between the total net X-ray counts and the model X-ray flux in the S2, M2, and H2 bands for the 29 brightest sources was used to derive a mean counts-to-flux conversion factor that could be applied to the fainter sources to estimate their fluxes. Figure 8 in the reference paper shows the flux-per-count ratio plotted as a function of the hardness ratio, HR2, for each source. The adopted multiplication factor for the H2 counts, to convert from total net counts in the 98.2 ks exposure into a flux units of ergs cm^-2 s^-1, is (1.89 +/- 0.34) x 10^-16. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

Spectral_Index
The spectral index of the best-fit simple absorbed power-law spectrum model for the 21 bright sources for which this model gave a satisfactory fit.

Bb_Kt
The temperature, in keV, of the best-fit absorbed blackbody spectral model for the 8 of the bright sources whose softer spectra were better fitted by this model

NH
The best-fit absorbing Hydrogen column density for the 29 brighter sources for which spectral fits were performed.

Reduced_Chi_Squared
The reduced Chi^2^ value of the best-fit spectral model for the 29 brighter sources for which spectral fits were performed.

Model_Sb2_Flux
The S2 (0.125 - 0.5 keV) band flux for the X-ray source, obtained from the best-fit spectral model, in erg cm^-2 s^-1. This is given only for the 29 brighter sources for which spectral fits were performed. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

Model_Mb2_Flux
The M2 (0.5 - 2.0 keV) band flux for the X-ray source, obtained from the best-fit spectral model, in erg cm^-2 s^-1. This is given only for the 29 brighter sources for which spectral fits were performed. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

Model_Hb2_Flux
The H2 (2.0 - 8.0 keV) band flux for the X-ray source, obtained from the best-fit spectral model, in erg cm^-2 s^-1. This is given only for the 29 brighter sources for which spectral fits were performed. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

SB2_Log_Lx
The X-ray luminosity in the S2 energy band, in erg s^-1, assuming the quoted model NH absorption and assuming a distance of 7.2 Mpc to M 101. This is given only for the 29 brighter sources for which spectral fits were performed. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

Mb2_Log_Lx
The X-ray luminosity in the M2 energy band, in erg s^-1, assuming the quoted model NH absorption and assuming a distance of 7.2 Mpc to M 101. This is given only for the 29 brighter sources for which spectral fits were performed. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.

HB2_Log_Lx
The X-ray luminosity in the H2 energy band, in erg s^-1, assuming the quoted model NH absorption and assuming a distance of 7.2 Mpc to M 101. This is given only for the 29 brighter sources for which spectral fits were performed. The X-ray flux and luminosity values (but not the net counts values) quoted in this paper have been corrected for several instrumental effects, as discussed in Section 8 of the reference paper.


Contact Person

Questions regarding the M101CXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 19-Jul-2007