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NGC4649CX2 - NGC 4649 Chandra X-Ray Point Source Catalog 2

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Overview

This table contains the main X-ray source catalog for the Chandra monitoring observations of the 16.5-Mpc distant elliptical galaxy, NGC 4649. The galaxy has been observed with Chandra ACIS-S3 in six separate pointings, reaching a total exposure of 299 ks. There are 501 X-ray sources detected in the 0.3-8.0 keV band in the merged observation or in one of the six individual observations; 399 sources are located within the D25 ellipse. The observed 0.3-8.0 keV luminosities of these 501 sources range from 9.3 x 1036 erg s-1 to 5.4 x 1039 erg s-1. The 90% detection completeness limit within the D25 ellipse is 5.5 x 1037 erg s-1. Based on the surface density of background active galactic nuclei (AGNs) and the detection completeness, we expect ~ 45 background AGNs among the catalog sources (~ 15 within the D25 ellipse). There are nine sources with luminosities greater than 1039 erg s-1, which are candidates for ultraluminous X-ray sources. The nuclear source of NGC 4649 is a low-luminosity AGN, with an intrinsic 2.0-8.0 keV X-ray luminosity of 1.5 x 1038 erg s-1. The X-ray colors suggest that the majority of the catalog sources are low-mass X-ray binaries (LMXBs). The authors find that 164 of the 501 X-ray sources show long-term variability, indicating that they are accreting compact objects, and discover four transient candidates and another four potential transients. They also identify 173 X-ray sources (141 within the D25 ellipse) that are associated with globular clusters (GCs) based on Hubble Space Telescope and ground-based data; these LMXBs tend to be hosted by red GCs. Although NGC 4649 has a much larger population of X-ray sources than the structurally similar early-type galaxies, NGC 3379 and NGC 4278, the X-ray source properties are comparable in all three systems.

This HEASARC table contains the main Chandra source catalog of the basic properties of the 501 X-ray detected sources (Table 3 in the reference paper which includes both sources detected in the merged X-ray image as well as a number only detected in the individual observations), and also the information on source counts, hardness ratios and soft and hard X-ray colors in the merged observation for the same 501 X-ray detected sources (Table 4 in the reference paper). It does not contain the information on source counts, hardness ratios and soft and hard X-ray colors for these same sources in the six individual observations that were contained in Tables 5 - 10 of the reference paper.


Catalog Bibcode

2013ApJS..204...14L

References

Deep Chandra Monitoring Observations of NGC 4649.
I. Catalog of Source Properties
    Luo B., Fabbiano G., Strader J., Kim D.-W., Brodie J.P., Fragos T.,
    Gallagher J.S., King A., Zezas A.
   <Astrophys. J. Suppl., Volume 204, Issue 2, article id. 14, 15 pp. (2013).>
   =2013ApJS..204...14L

Provenance

This table was created by the HEASARC in March 2013 based on the electronic version of Tables 3 and 4 from the reference paper which were obtained from the ApJS website..

Parameters

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

Name
The name of the X-ray source using the 'CXOU' prefix (for Chandra X-ray Observatory, Unregistered) and the truncated J2000.0 equatorial coordinates, in the style recommended by the CDS Dictionary of Nomenclature of Celestial Objects, e.g., 'CXOU JHHMMSS.S+DDMMSS'.

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

Dec
The Declination of the Chandra X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10-6 degrees in the original table.

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

BII
The Galactic Latitude of the Chandra X-ray source

Radial_Distance
The radial distance of the Chandra X-ray source from the nucleus of NGC 4649 situated at RA(J2000) = 12h 43m 39.97s, Dec(J2000) = +11o 33' 09.7", in units of arcminutes.

Error_Radius
The source positional uncertainty at the 95% confidence level, in units of arcseconds (see Section 3.1 of the reference paper for more details).

Log_Lx_Limit
This parameter is set to '<' if the associated parameter is a 3-sigma upper limit rather than a detection.

Log_Lx
The logarithm of the observed full-band (FB: 0.3-8.0 keV) luminosity of the Chandra X-ray source, in units of erg s-1 (or 3-sigma upper limit thereof if log_lx_limit = '<'), assuming a distance of 16.5 Mpc to NGC 4649.

Variability_Flag
The long-term variability flag (see Section 3.6 of the reference paper). The source is labeled as variable ('V'), non-variable ('N'), a transient candidate ('TC'), or a potential transient candidate('PTC'). All transient candidates are variable.

Variability_Significance
The maximum statistical significance of the FB flux variation between any two observations (see Section 3.6 of the reference paper)). It is set to null if the source is not covered by at least two observations or is not detected in at least one observation.

Positional_Flag
The positional flag. The source may be located within the D25 ellipse of NGC 4649 ('1'), within the D25 ellipse of the smaller companion galaxy NGC 4647 ('2'), within both D25 ellipses ('3'), or outside the ellipses ('0').

Opt_Ctrpart_Flag
The optical counterpart flag. The source may have a reliable HST GC counterpart ('1'; 157 sources), a probable HST GC counterpart ('2'; 4 sources), a ground-based GC counterpart ('3'; 12 sources), a background AGN counterpart ('4'; 17 sources), a counterpart that is an unusual dwarf galaxy ('5'; 1 source), a counterpart that is the nucleus of NGC 4649 ('6'; 1 source), a counterpart that is a foreground star ('7'; 2 sources), or it has a high chance (> 50%) of being associated with the companion galaxy NGC 4647 ('8'; 35 sources), it has a less significant chance of being associated with NGC 4647 ('9'; 8 sources), or it is associated with NGC 4649 but has no counterpart ('0'; 264 sources).

GC_Identifier
The GC identifier from Strader et al. (2012, ApJ, 760, 87) or from Lee et al. (2008, ApJ, 674, 857; starting with the letter 'L') for the 173 X-ray sources with a GC counterpart.

Counts_Limit
This parameter is set to '<' if the associated parameter is a 3-sigma upper limit rather than a detection.

Counts
The net full-band (FB: 0.3-8.0 keV) counts CFB for the Chandra X-ray source.

Counts_Neg_Err
The lower 1-sigma uncertainty in the net 0.3-8 keV counts for the Chandra X-ray source.

Counts_Pos_Err
The upper 1-sigma uncertainty in the net 0.3-8 keV counts for the Chandra X-ray source.

SB_Counts_Limit
This parameter is set to '<' if the associated parameter is a 3-sigma upper limit rather than a detection.

SB_Counts
The net soft-band (SB: 0.3-2 keV) counts CSB for the Chandra X-ray source.

SB_Counts_Neg_Err
The lower 1-sigma uncertainty in the net soft-band (SB: 0.3-2 keV) counts.

SB_Counts_Pos_Err
The upper 1-sigma uncertainty in the net soft-band (SB: 0.3-2 keV) counts.

HB_Counts_Limit
This parameter is set to '<' if the associated parameter is a 3-sigma upper limit rather than a detection.

HB_Counts
The net hard-band (HB: 2-8 keV) counts CHB for the Chandra X-ray source.

HB_Counts_Neg_Err
The lower 1-sigma uncertainty in the net hard-band (HB: 2-8 keV) counts for the Chandra X-ray source.

HB_Counts_Pos_Err
The upper 1-sigma uncertainty in the net hard-band (HB: 2-8 keV) counts for the Chandra X-ray source.

SB1_Counts_Limit
This parameter is set to '<' if the associated parameter is a 3-sigma upper limit rather than a detection.

SB1_Counts
The net 0.3-1 keV (SB1) counts CSB1 for the Chandra X-ray source.

SB1_Counts_Neg_Err
The lower 1-sigma uncertainty in the net 0.3-1 keV counts for the Chandra X-ray source.

SB1_Counts_Pos_Err
The upper 1-sigma uncertainty in the net 0.3-1 keV counts for the Chandra X-ray source.

SB2_Counts_Limit
This parameter is set to '<' if the associated parameter is a 3-sigma upper limit rather than a detection.

SB2_Counts
The net 1-2 keV (SB2) counts CSB2 for the Chandra X-ray source.

SB2_Counts_Neg_Err
The lower 1-sigma uncertainty in the net 1-2 keV counts for the Chandra X-ray source.

SB2_Counts_Pos_Err
The upper 1-sigma uncertainty in the net 1-2 keV counts for the Chandra X-ray source.

Hardness_Ratio
The hardness ratio HR = (CHB-CSB)/(CHB+CSB) of the X-ray source.

Hardness_Ratio_Neg_Err
The lower 1-sigma uncertainty in the X-ray hardness ratio.

Hardness_Ratio_Pos_Err
The upper 1-sigma uncertainty in the X=ray hardness ratio.

Soft_Color
The soft X-ray color SC = (CSB2-CSB1)/C_FB) of the X-ray source.

Soft_Color_Neg_Err
The lower 1-sigma Uncertainty in the soft X-ray color of the X-ray source.

Soft_Color_Pos_Err
The upper 1-sigma Uncertainty in the soft X-ray color of the X-ray source.

Hard_Color
The hard X-ray color HC = (CHB-CSB2)/C_FB) of the X-ray source.

Hard_Color_Neg_Err
The lower 1-sigma Uncertainty in the hard X-ray color of the X-ray source.

Hard_Color_Pos_Err
The upper 1-sigma Uncertainty in the hard X-ray color of the X-ray source.


Contact Person

Questions regarding the NGC4649CX2 database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 19-Mar-2013