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M83CXO - M 83 Chandra X-Ray Point Source Catalog

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Overview

The authors of this table have obtained a series of deep X-ray images of the nearby (4.61 Mpc) galaxy M 83 using Chandra, with a total exposure of 729 ks. Combining the new data with earlier archival observations totaling 61 ks, they find 378 point sources within the D25 contour of the galaxy. The authors find 80 more sources, mostly background active galactic nuclei (AGNs), outside of the D25 contour. Of the X-ray sources, 47 have been detected in a new radio survey of M 83 obtained using the Australia Telescope Compact Array (ATCA). Of the X-ray sources, at least 87 seem likely to be supernova remnants (SNRs), based on a combination of their properties in X-rays and at other wavelengths. The authors attempt to classify the point source population of M 83 through a combination of spectral and temporal analysis. As part of this effort, in the reference paper they carry out an initial spectral analysis of the 29 brightest X-ray sources. The soft X-ray sources in the disk, many of which are SNRs, are associated with the spiral arms, while the harder X-ray sources, mostly X-ray binaries (XRBs), do not appear to be. After eliminating AGNs, foreground stars, and identified SNRs from the sample, the authors construct the cumulative luminosity function (CLF) of XRBs brighter than 8 x 1035 erg s-1. Despite M 83's relatively high star formation rate, the CLF indicates that most of the XRBs in the disk are low mass X-ray binaries (XRBs).

The X-ray observations of M 83 in this survey were all carried out with the ACIS-S in order to maximize the sensitivity to soft X-ray sources, such as SNRs, and to diffuse emission. The nucleus of M 83 was centered in the field of the back-illuminated S3 chip to provide reasonably uniform coverage of M 83. In addition to the S3 chip, data were also obtained from chips S1, S2, S4, I2, and I3. All of the observations were made in the "very faint" mode to optimize background subtraction. Observations were spaced over a period of one year from 2010 December to 2011 December, as indicated in Table 1 of the reference paper. The only difference among observations was the roll orientation of the spacecraft and the differing exposure times. All of the observations were nominal, and yielded a total of 729 ks of useful data. In order to maximize their sensitivity and more importantly to improve their ability to identify time variable sources, the authors included in their analysis earlier Chandra observations of M 83 in 2000 and 2001 totaling 61 ks which were obtained by G. Rieke (Prop ID. 1600489) and by A. Prestwich (Prop ID. 267005758). These data were obtained in a very similar manner to that of the present survey, and increased the total exposure to 790 ks.

The authors used ACIS EXTRACT (AE) to derive net count rates from the sources in various energy bands: 0.35 - 8.0 keV (total or T), 0.35 - 1.1 keV (soft or S), 1.1 - 2.6 keV (medium or M), 2.6 - 8.0 keV (hard or H), 0.5 - 2.0 keV ("normal" soft band) and 2.0 - 8.0 keV ("normal" hard band). Their choice of these bands was based on a variety of overlapping goals. The broad 0.35 - 8.0 keV band samples the full energy range accessible to Chandra observations. The three bands S, M and H provide energy ranges intended to classify sources on the basis of their hardness ratios. The boundary at 1.1 keV, in particular, is just above the region containing strong features due to Ne and Fe seen in the spectra of most SNRs. The 0.5 - 2.0 keV and 2.0 - 8.0 keV bands are needed because number counts of active galactic nuclei (AGNs) and of X-ray binary populations are normally carried out in these bands and because the 0.5 - 2.0 keV band, encompassing the peak of the response curve, provides better statistics for some purposes than S+M. The AE count rates were used to establish which of the sources in the candidate list were statistically valid. The authors retained any source that had a probability-of-no-source < 5 x 10-6 in any one of these bands in the total data set. For their final run of AE, their list of source candidates had 847 potential sources. Of those, they find a total of 458 valid point sources, whose properties are listed in this table. Of the 458 point sources, 378 are located within the area defined by the D25 ellipse of the galaxy (which the authors take to have a major axis diameter of 12.9 arcminutes), and the remaining 80 are outside this region. There were 43 sources in the nuclear region (defined to be any source within a projected radius of 0.5 kpc from the optical nucleus).


Catalog Bibcode

2014ApJS..212...21L

References

A Deep Chandra ACIS Survey of M83
     Long K.S., Kuntz K.D., Blair W.P., Godfrey L., Plucinsky P.P.,
     Soria R., Stockdale C., Winkler P.F.
    <Astrophys. J. Suppl. Ser. 212, 21 (2014)>
    =2014ApJS..21...21L

Provenance

This table was created by the HEASARC in July 2014 based on electronic versions of Tables 3, 4 and 5 from the reference paper which were obtained from the ApJS website.

Parameters

Source_ID
A unique Chandra X-ray source identifier, e.g., 'X001', in order of increasing J2000.0 Right Ascension.

Name
The Chandra X-ray source designation. This was created by the HEASARC in the style recommended by the CDS Dictionary of Nomenclature of Celestial Objects, using the prefix of '[KB2014]' (for Long, Kuntz, Blair, 2014) and the X-ray source id, e.g., '[KB2014] X001'.

RA
The Right Ascension of the Chandra X-ray source in the selected equinox. This was given in J2000 equatorial coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the Chandra X-ray source in the selected equinox. This was given in J2000 equatorial coordinates to a precision of 0.1 arcseconds in the original table

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

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

Error_Radius
The 1-sigma positional error of the Chandra X-ray source as determined by ACIS EXTRACT (AE), in arcseconds.

Exposure
The total exposure time at the Chandra X-ray source position, in seconds (converted by the HEASARC from the ks units used in the original table).

Count_Rate
The 0.35 - 8.0 keV band (T band) count rate of the Chandra X-ray source, in ct/s (converted by the HEASARC from the ct/ks units used in the original table).

Count_Rate_Error
The uncertainty in the 0.35 - 8.0 keV band (T band) count rate of the Chandra X-ray source, in ct/s (converted by the HEASARC from the ct/ks units used in the original table).

Hardness_Ratio_1
The hardness ratio (M-S)/T of the Chandra X-ray source, where S, M and T are the photon fluxes in the soft, medium and total bands, respectively (see Overview for the definition of the energy bands).

Hardness_Ratio_1_Error
The uncertainty in the hardness ratio (M-S)/T.

Hardness_Ratio_2
The hardness ratio (H-M)/T of the Chandra X-ray source, where M, H and T are the photon fluxes in the medium, hard and total bands, respectively (see Overview for the definition of the energy bands)

Hardness_Ratio_2_Error
The uncertainty in the hardness ratio (H-M)/T.

Tb_Photon_Flux
The 0.35 - 8 keV (T band) photon flux of the Chandra X-ray source, in photon cm-2 s-1. The conversion of source counts to flux of an X-ray source depends on the assumed X-ray spectrum and, for soft sources, the absorbing column density. The authors assumed a power-law source with a photon index of -1.9 and foreground absorption column of 4 x 1020 cm-2. This choice of spectrum is appropriate for compact binaries and background AGNs, and it is typical of that chosen for other studies of the X-ray properties of normal galaxies

Tb_Photon_Flux_Error
The statistical uncertainty in the corresponding band photon flux of the Chandra X-ray source, in photon cm-2 s-1.

SB_Photon_Flux
The 0.35 - 1.1 keV (S band) photon flux of the Chandra X-ray source, in photon cm-2 s-1. The conversion of source counts to flux of an X-ray source depends on the assumed X-ray spectrum and, for soft sources, the absorbing column density. The authors assumed a power-law source with a photon index of -1.9 and foreground absorption column of 4 x 1020 cm-2. This choice of spectrum is appropriate for compact binaries and background AGNs, and it is typical of that chosen for other studies of the X-ray properties of normal galaxies

SB_Photon_Flux_Error
The statistical uncertainty in the corresponding band photon flux of the Chandra X-ray source, in photon cm-2 s-1.

MB_Photon_Flux
The 1.1 - 2.6 keV (M band) photon flux of the Chandra X-ray source, in photon cm-2 s-1. The conversion of source counts to flux of an X-ray source depends on the assumed X-ray spectrum and, for soft sources, the absorbing column density. The authors assumed a power-law source with a photon index of -1.9 and foreground absorption column of 4 x 1020 cm-2. This choice of spectrum is appropriate for compact binaries and background AGNs, and it is typical of that chosen for other studies of the X-ray properties of normal galaxies

MB_Photon_Flux_Error
The statistical uncertainty in the corresponding band photon flux of the Chandra X-ray source, in photon cm-2 s-1.

HB_Photon_Flux
The 2.6 - 8 keV (H band) photon flux of the Chandra X-ray source, in photon cm-2 s-1. The conversion of source counts to flux of an X-ray source depends on the assumed X-ray spectrum and, for soft sources, the absorbing column density. The authors assumed a power-law source with a photon index of -1.9 and foreground absorption column of 4 x 1020 cm-2. This choice of spectrum is appropriate for compact binaries and background AGNs, and it is typical of that chosen for other studies of the X-ray properties of normal galaxies

HB_Photon_Flux_Error
The statistical uncertainty in the corresponding band photon flux of the Chandra X-ray source, in photon cm-2 s-1.

Nsb_Photon_Flux
The 0.5 - 2 keV ("normal" soft band) photon flux of the Chandra X-ray source, in photon cm-2 s-1. The conversion of source counts to flux of an X-ray source depends on the assumed X-ray spectrum and, for soft sources, the absorbing column density. The authors assumed a power-law source with a photon index of -1.9 and foreground absorption column of 4 x 1020 cm-2. This choice of spectrum is appropriate for compact binaries and background AGNs, and it is typical of that chosen for other studies of the X-ray properties of normal galaxies

Nsb_Photon_Flux_Error
The statistical uncertainty in the corresponding band photon flux of the Chandra X-ray source, in photon cm-2 s-1.

Nhb_Photon_Flux
The 2 - 8 keV ("normal" hard band) photon flux of the Chandra X-ray source, in photon cm-2 s-1. The conversion of source counts to flux of an X-ray source depends on the assumed X-ray spectrum and, for soft sources, the absorbing column density. The authors assumed a power-law source with a photon index of -1.9 and foreground absorption column of 4 x 1020 cm-2. This choice of spectrum is appropriate for compact binaries and background AGNs, and it is typical of that chosen for other studies of the X-ray properties of normal galaxies

Nhb_Photon_Flux_Error
The statistical uncertainty in the corresponding band photon flux of the Chandra X-ray source, in photon cm-2 s-1.

Lx
The average 0.35 - 8 keV (T band) luminosity of the Chandra X-ray source, in erg s-1. The X-ray luminosity is calculated from the energy flux in the 0.35 - 8 keV band, assuming that it is located at the 4.61 Mpc distance of M 83. See the caveat about the reliability of the estimated luminosities for soft, relatively unabsorbed sources (such as many SNRs) which is given in Section 4.1 of the reference paper.

Lx_Error
The statistical uncertainty in the 0.35 - 8 keV luminosity of the Chandra X-ray source, in erg s-1.

Alt_Names
This field contains the names of coincident sources in the earlier X-ray surveys of Soria & Wu (2003, A&A, 410, 53: sources with 'S' prefixes) and Ducci et al. (2013, A&A, 553, A7: sources with 'D' prefixes). A source in a pre-existing catalog is assumed to be coincident if it is within 2 arcseconds of the Chandra X-ray source. If the difference in position of the Chandra X-ray source and the catalogued source is between 1 and 2 arcseconds, this is indicated with an appended colon.

Radio_Names
This field contains the names of coincident sources in the radio survey of Maddox et al. (2006, AJ, 132, 310: sources with 'M' prefixes) and the authors' own new radio survey conducted with the ATCA (the results of which are listed in Table 2 of the reference paper: sources with 'A' prefixes). A radio source is assumed to be coincident if it is within 2 arcseconds of the Chandra X-ray source. If the difference in position of the Chandra X-ray source and the catalogued source is between 1 and 2 arcseconds, this is indicated with an appended colon.

SNR_SN_Names
This field contains the names of coincident optical SNRs identified by Blair et al. (2012, ApJS, 203, 8: sources with 'B' prefixes) and Dopita et al. (2010, ApJ, 710, 964: sources with 'D' prefixes). Only nebulae having high [S II]:H-alpha ratios are included. An SNR is assumed to be coincident if it is within 2 arcseconds of the Chandra X-ray source. If the difference in position of the Chandra X-ray source and the catalogued source is between 1 and 2 arcseconds, this is indicated with an appended colon.

Spectral_Flag
This parameter contains a spectral flag for sources brighter than 500 counts, where the source spectra are characterized as having either non-thermal ('P') or thermal ('T') natures. See the text of the reference paper for more details. There are a few sources, labeled 'P/T', for which no such clear distinction could be made.

Variability_Flag
This parameter contains a variability flag where 'C' implies a "Classical" X-ray transient, and 'B' implies a source with large variations from observation to observation. A value of 'N' in this classification implies that the source is seen above the background all of the time, whereas a value of 'A' is the designation for sources that were either 'on' in the archival observations and 'off' in the new data, or vice versa. A value of 'V' refers to sources that are simply variable, while 'V*' indicates the object was variable, but the variability was not detected in the T band. See the text of the reference paper for more details..

Source_Type
The authors' attempted to classify X-ray sources in M 83. Source classifications which they regard as more tentative are followed by a '?'. The source types they used are as follows:

    AGN - Active Galactic Nucleus
    GAL - Galaxy
    NUC - Nucleus of M 83
    SNR - Supernova remnant
    SS  - Supersoft source
    Star- Foreground star
    XRB - X-ray binary
  

Notes
Additional notes on the source. More extensive commentary on a number of the sources can be found in the text of the reference paper and, for the X-ray bright sources, in the Appendix of the reference paper.

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


Contact Person

Questions regarding the M83CXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 7-Jul-2014