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M33CHASE: Help

M33CHASE - M 33 Chandra ACIS Survey (ChASeM33) Source Catalog


Overview

The Chandra ACIS Survey of M 33 (ChASeM33) Source Catalog contains some overview results from a deep survey of the nearest face-on spiral galaxy. The 1.4 Ms survey covers the galaxy out to an angular radius R ~ 18'(~4 kpc). These data provide the most intensive, high spatial resolution assessment of the X-ray source populations available for the confused inner regions of M33. Mosaic images of the ChASeM33 observations show several hundred individual X-ray sources as well as soft diffuse emission from the hot interstellar medium. Bright, extended emission surrounds the nucleus and is also seen from the giant H II regions NGC 604 and IC 131. Fainter extended emission and numerous individual sources appear to trace the inner spiral structure.

The initial source catalog contained herein, arising from ~2/3 of the expected survey data, includes 394 sources significant at the 3-sigma confidence level or greater, down to a limiting luminosity (absorbed) of ~ 1.6 x 10^35 ergs s^-1 (0.35 - 8.0 keV energy band). The hardness ratios of the sources separate those with soft, thermal spectra such as supernova remnants from those with hard, nonthermal spectra such as X-ray binaries and background active galactic nuclei. Emission extended beyond the Chandra point-spread function is evident in 23 of the 394 sources. Cross-correlation of the ChASeM33 sources against previous catalogs of X-ray sources in M 33 results in matches for the vast majority of the brighter sources and shows 28 ChASeM33 sources within 10" of supernova remnants identified by prior optical and radio searches. This brings the total number of such associations to 31 out of 100 known supernova remnants in M33.


Catalog Bibcode

2008ApJS..174..366P

References

Chandra ACIS Survey of M33 (ChASeM33): A First Look
   Plucinsky, P.P., Williams, B., Long, K.S., Gaetz, T.J., Sasaki, M.,
   Pietsch, W., Tullmann, R., Smith, R.K., Blair, W.P., Helfand, D.,
   Hughes, J.P., Winkler, P.F., de Avillez, M., Bianchi, L., Breitschwerdt, D.,
   Edgar, R.J., Ghavamian, P., Grindlay, J., Haberl, F., Kirshner, R.,
   Kuntz, K., Mazeh, T., Pannuti, T.G., Shporer, A., Thilker, D.A.
  <Astrophys. J., Suppl. Ser., 174, 366-378 (2008)>
  =2008ApJS..174..366P

Provenance

This table was created by the HEASARC in February 2008 based on elecetronic versions of Tables 2 and 3 of the reference paper obtained from the electronic ApJS web site.

Parameters

Source_Number
This parameter is a unique source number identifying ChASeM33 sources. Sources are listed in order of increasing J2000 right ascension.

Name
The preferred designation for the X-ray source, using the ChASeM33 prefix (Chandra ACIS Survey of M 33) registered by the authors, followed by the source number.

Extent_Flag
This flag parameter is set to 'E' to indicate that the source is extended, i.e., shows evidence of spatial extent beyonf the local PSF. There are 23 such extended sources.

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.

Error_Radius
The positional error of the X-ray source, in arcsecnds.

Counts
The net background-subtracted X-ray source counts calculated using ACIS Extract in the 0.35 - 8.0 keV band. Only source candidates with 3-sigma or more signifance were retained for the source catalog.

Count_Rate
The X-ray source count rate (0.35 - 8.0 keV band), in ct/s. Pileup can affect the derived values for this parameter, notice. These values should thus be treated with caution for the bright X-ray sources.

Count_Rate_Error
The error in the X-ray source count rate (0.35 - 8.0 keV band), in ct/s.

Photon_Flux
The absorbed photon flux (0.35 - 8.0 keV band) of the X-ray source, in photons/s/cm^2. The photon flux is computed from the sum of the photon fluxes in the 0.35 - 1.1, 1.1 - 2.6,and 2.6 - 8.0 keV bands. The photon fluxes are computed using the net counts in the band, the mean effective area in the band, and the exposure. The mean effective area for each band is computed assuming a flat spectrum. Pileup can affect the derived values for this parameter, notice. These values should thus be treated with caution for the bright X-ray sources.

Photon_Flux_Error
The error in the photon flux (0.35-8.0 keV band), in photons/s/cm^2.

Hardness_Ratio_1
The X-ray source hardness ratio HR1 defined as (M-S)/(S+M+H), constructed using a definition similar to that described in Prestwich et al. (2003, ApJ, 595, 719) from the X-ray source background-subtracted fluxes for the soft (S), medium (M), and hard (H) bands. In this case, the energy ranges for the S, M and H bands are 0.35 - 1.1 keV, 1.1 - 2.6 keV, and 2.6 - 8 keV, respectively. Pileup can affect the derived values for this parameter, notice. These values should thus be treated with caution for the bright X-ray sources.

Hardness_Ratio_1_Error
The error in the hardness ratio HR1, The uncertainties for the hardness ratios were estimated by propagating the flux errors assuming Gaussian statistics.

Hardness_Ratio_2
The X-ray source hardness ratio HR2 defined as (H-M)/(S+M+H), constructed using a definition similar to that described in Prestwich et al. (2003, ApJ, 595, 719) from the X-ray source background-subtracted fluxes for the soft (S), medium (M), and hard (H) bands. In this case, the energy ranges for the S, M and H bands are 0.35 - 1.1 keV, 1.1 - 2.6 keV, and 2.6 - 8 keV, respectively. Pileup can affect the derived values for this parameter, notice. These values should thus be treated with caution for the bright X-ray sources.

Hardness_Ratio_2_Error
The error in the hardness ratio HR2, The uncertainties for the hardness ratios were estimated by propagating the flux errors assuming Gaussian statistics.

Alt_Name_1
The name of the XMM-Newton X-ray source, if any, lieing within 7 arcseconds (the 3-sigma positional uncertainty for the weakest XMM-Newton sources) of the ChASeM33 source from the Pietsch et al. (2004, A&A, 426, 11) source list, using the source designation recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

Alt_Name_2
The name of the XMM-Newton X-ray source, if any, lieing within 7 arcseconds (the 3-sigma positional uncertainty for the weakest XMM-Newton sources) of the ChASeM33 source from the Misanovic et al. (2004, A&A, 448, 1247) source list, using the source designation recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

Alt_Name_3
The name of the counterpart Chandra X-ray source in the Grimm et al. (2005, ApJS, 161, 271) source list, using the source designation recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

Comments
Other identifications and or comments about the source, where the SNRs are from Gordon et al. (1998, ApJS, 117, 89), and the UIT sources are from Massey et al. (1996, ApJ, 469, 629). Ref. (e) is Hatzidimitriou et al. (2006, A&A, 451, 835), ref. (f) is Pietsch et al. (2006, ATel, 905, 1), and ref. (g) is Williams et al. (2007, private communication).


Contact Person

Questions regarding the M33CHASE database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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