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GC47TUCCX2 - 47 Tuc Globular Cluster Chandra X-Ray Point Source Catalog (2017 Version)

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Overview

The authors combined Chandra ACIS observations of the globular cluster 47 Tucanae (47 Tuc) from 2000, 2002, and 2014-2015 to create a deeper X-ray source list and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. This work combined 180 ks of new Chandra ACIS data on 47 Tuc with 370 ks of archival data and used improved algorithms to generate a new source catalog, finding 81 new sources for a total of 370 within the half-mass region (2.79 arcsec) of the cluster. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. The authors associated five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. (2001, CDS Cat. <J/ApJ/559/1060>).

See also the related 2005 source catalog.


Catalog Bibcode

2017MNRAS.472.3706B

References

Chandra studies of the globular cluster 47 Tucanae: a deeper X-ray source
catalogue, five new X-ray counterparts to millisecond radio pulsars and new
constraints to r-mode instability window.
    Bhattacharya S., Heinke C.O., Chugunov A.I., Freire P.C.C., Ridolfi A.,
    Bogdanov S.
   <Mon. Not. R. Astron. Soc., 472, 3706-3721 (2017)>
   =2017MNRAS.472.3706B

Provenance

This table was created by the HEASARC in September 2020 based upon the CDS Catalog J/MNRAS/472/3706 files table2.dat, table4.dat, and table5.dat.

Parameters

Source_Number
The WAVDETECT (W) detection number of the X-ray source. Because of the iterative nature of source list construction over several papers (Grindlay et al. 2001, 2002; Edmonds et al. 2003a, 2003b; Heinke et al. 2005), the W numbering scheme does not follow clear patterns and has holes (numbers that do not correspond to real sources within the chosen field). The W numbers for five sources, which have been resolved into multiple sources, and six sources which were previously identified but were not detected in this analysis, have been omitted.

Name
The name for the X-ray source using the 'CXOGlb' prefix (for Chandra X-Ray Observatory, Globular Cluster) and the J2000.0 equatorial coordinates (JHHHMMSSs-DDMMSS), as registered with the CDS Dictionary of Nomenclature of Celestial Objects.

Alt_Name
An alternative X-ray source designation as recommended by the CDS Dictionary of Nomenclature of Celestial Objects using the '[GHE2001] W' prefix as first used in Grindlay et al. (2001, Science, 292, 2290) and the X-ray (W) source_number.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.001 seconds of time in the reference paper. The X-ray positions were aligned to the international celestial reference frame using the radio-timing positions of 19 out of the 23 millisecond pulsars (MSPs) with well-constrained positions in 47 Tuc. Section 3.3 of the reference paper contains more detailed description of the astrometric corrections.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.001 arcseconds in the reference paper. The X-ray positions were aligned to the international celestial reference frame using the radio-timing positions of 19 out of the 23 millisecond pulsars (MSPs) with well-constrained positions in 47 Tuc. Section 3.3 of the reference paper contains more detailed description of the astrometric corrections.

LII
The Galactic Longitude of the X-ray source. This parameter was added by the HEASARC and is calculated from the J2000.0 coordinates.

BII
The Galactic Latitude of the X-ray source. This parameter was added by the HEASARC and is calculated from the J2000.0 coordinates.

Error_Radius
The positional error of the X-ray source based on the 95% error circle calculated using the empirical formula derived by Heinke et al. (2005, ApJ, 625, 796H) from applying wavdetect on simulated data.

PSF_Fraction
The fraction of the 1.5-keV point-spread function (PSF) enclosed by the extraction region for the X-ray source.

Exposure
The exposure time for the X-ray source, in seconds (s). The HEASARC calculated the value of this parameter using the fractional exposure times given in Table 2 of the reference paper (CDS table table2.dat) and the nominal on-axis exposure times of 540,000 ks.

SB_Counts
The background-subtracted counts in the X-ray source in the 0.5 - 2 keV energy band.

SB_Counts_Neg_Err
The lower limit 1-sigma (68% confidence) error in the background-subtracted 0.5 - 2 keV counts.

SB_Counts_Pos_Err
The upper limit 1-sigma (68% confidence) error in the background-subtracted 0.5 - 2 keV counts.

Counts
The background-subtracted counts in the X-ray source in the 0.5 - 6 keV energy band.

Counts_Neg_Err
The lower limit 1-sigma (68% confidence) error in the background-subtracted 0.5 - 6 keV counts.

Counts_Pos_Err
The upper limit 1-sigma (68% confidence) error in the background-subtracted 0.5 - 6 keV counts.

Lx
The 0.5 - 6.0 keV luminosity of the X-ray source, in erg/s. Photon fluxes were computed from the recorded counts, effective apertures, exposure times, and effective area functions for each source. Assuming a 2-keV VMEKAL spectrum (chosen to describe the faint sources which are likely dominated by chromospherically active binaries and CVs, both of which have X-ray spectra well represented by this model, see e.g., Heinke et al. 2005, ApJ, 625, 796H], and accounting for Galactic absorption with the TBABS model (Wilms, Allen & McCray, 2000), to the combined spectrum. The authors use the known cluster absorbing column, distance, and metal abundances to convert the photon cm-2 s-1 conversion for the different flux bands and subsequently use these conversions to calculated the 0.5 - 6.0 keV luminosity.

Lx_Neg_Err
The lower limit 1-sigma (68% confidence) error in the 0.5 - 6.0 keV luminosity, in erg/s.

Lx_Pos_Err
The upper limit 1-sigma (68% confidence) error in the 0.5 - 6.0 keV luminosity, in erg/s.

Note_Flag
Additional note concerning the X-ray source, which is coded as follows:

        c  -- source appears to be confused
        m  -- source which has been added manually
        X# -- ROSAT source number.
  

Radio_Name
The milli-second pulsar (MSP) radio detection name (e.g. 47 Tuc E = MSP-E).

Radio_Name_2
The second MSP radio detection name, if two possibilities.

Radio_RA_Offset
The deviation between the X-ray and radio positions in right ascension, given in arcseconds.

Radio_RA_Offset_2
The deviation between the X-ray and radio positions in right ascension, given in arcseconds, for the second MSP match if there are two possibilities (e.g., radio_name_2).

Radio_Dec_Offset
The deviation between the X-ray and radio positions in declination, given in arcseconds.

Radio_Dec_Offset_2
The deviation between the X-ray and radio positions in declination, given in arcseconds, for the second MSP match if there are two possibilities (e.g., radio_name_2).

Rel_Offset_Limit
The limit flag (e.g., "<") for the rel_offset parameter, which gives the total deviation in position between the X-ray and radio positions divided by the X-ray position error.

Rel_Offset
The total deviation in position between the X-ray and radio positions divided by the X-ray position error (i.e., error_radius).

AGB2001_Name
The name based on the Albrow et al. (2001, CDS Cat. J/ApJ/559/1060) designation, which is an optical HST study, for chromospherically active binaries.

HST_RA_Offset
The deviation between the Chandra X-ray and HST positions in declination, given in arcseconds.

HST_Dec_Offset
The deviation between the Chandra X-ray and HST positions in declination, given in arcseconds.

Source_Type
The source type, taken from Albrow et al. (2001, CDS Cat. J/ApJ/559/1060).

Period
The variability period, in days, taken from Albrow et al., 2001, CDS Cat. J/ApJ/559/1060).


Contact Person

Questions regarding the GC47TUCCX2 database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 16-Sep-2020 22:45:14 EDT