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HCGXRBS - X-Ray Observations of Compact Group Galaxies

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Overview

This catalog presents the study of a sample of 15 compact groups (CGs) observed with Chandra/ACIS, Swift/UVOT and Spitzer/IRAC-MIPS for which archival data exist, allowing the authors to obtain SFRs, stellar masses, sSFRs and X-ray fluxes and luminosities for individual, off-nuclear point sources, which they summed to obtain total X-ray luminosities originating in off-nuclear point sources in a galaxy.

Details on the Swift and Spitzer observations and data for systems in this sample can be found in Tzanavaris et al. (2010ApJ...716..556T) and Lenkic et al. (2016MNRAS.459.2948L). For Chandra/ACIS observations, see Tzanavaris et al. (2014ApJS..212....9T) and Desjardins et al. (2013ApJ...763..121D; 2014ApJ...790..132D).

The authors obtained total galaxy X-ray luminosities, LX, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of the galaxies, they found that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, they found that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the +/- 1 sigma scatter of the Mineo et al. LX-star formation rate (SFR) correlation or have higher LX than predicted by this correlation for their SFR. These "excesses" may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies were found to be consistent with the Boroson et al. LX-stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual effects such as AGN activity or hot gas. Assuming non-nuclear sources are low- or high-mass XRBs, the authors used appropriate XRB luminosity functions to estimate the probability that stochastic effects can lead to such extreme LX values. They found that, although stochastic effects do not in general appear to be important, for some galaxies there is a significant probability that high LX values can be observed due to strong XRB variability.


Catalog Bibcode

2016ApJ...817...95T

References

Exploring X-ray binary populations in compact group galaxies with Chandra.
    Tzanavaris P., Hornschemeier A.E., Gallagher S.C., Lenkic L.,
    Desjardins T.D., Walker L.M., Johnson K.E., Mulchaey J.S.
   <Astrophys. J., 817, 95 (2016)>
   =2016ApJ...817...95T

Provenance

This table was created by the HEASARC in May 2019 based upon the CDS Catalog J/ApJ/817/95 file table3.dat

Parameters

Name
The source name is of the form 'HCG/RSCG' to designate the catalog origin, followed by the numbers that refer to the compact group identification and the number(s) indicating the galaxy or galaxies within the group. The catalog origin designation 'HCG' refers to the catalog Hickson et al. 1992 VII/213; 'RSCG' refers to the Redshift Survey Compact Groups, Barton et al (1996AJ....112..871B). The RSCG subsample is a part of a larger sample selected by Walker et al (2012AJ....143...69W) to have properties similar to those of HCGs. In this analysis the term "galaxy" or "galaxy region" refers to the Kron apertures the authors used for defining galaxy boundaries within the Spitzer/IRAC 3.6 micron image, which in some cases include more than one letter-designated galaxy. Therefore, e.g., the letter designation "HCG 31ACE" means that these authors treat the compact group galaxies HCG 31A, HCG 31C and HCG 31E as a single source in their analysis.

Morph_Type
The morphological Hubble type based on the best-fitting SED template.

RA
The Right Ascension of the field in the selected equinox. This parameter was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table. These are not coordinates of the galaxy nucleus. They are coordinates of the first nonnuclear X-ray point source within the galaxy. This is still adequate for galaxy identification.

Dec
The declination of the field in the selected equinox. This parameter was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table. These are not coordinates of the galaxy nucleus. They are coordinates of the first nonnuclear X-ray point source within the galaxy. This is still adequate for galaxy identification.

LII
The Galactic Longitude of the field.

BII
The Galactic Latitude of the field.

SFR
The star formation rate (in solar mass/yr) of the compact group galaxy, based on ultraviolet (from Swift uvw2) and infrared (from Spitzer MIPS 24 micron) photometry, as described in Lenkic et al. (2016).

SFR_Error
The uncertainty in star formation rate of the compact group galaxy.

Mass
The stellar mass (in solar mass units) of the compact group galaxy based on Spitzer IRAC 3.6 and 4.5 micron photometry, as described in Lenkic et al. (2016).

Mass_Error
The uncertainty in stellar mass.

Lx
The total X-ray luminosity (in the 0.5-8.0 keV Chandra band) from point sources within the galaxy region.

Lx_Pos_Err
The upper uncertainty for the total X-ray luminosity (in the 0.5-8.0 keV Chandra band) from point sources within the galaxy region.

Lx_Neg_Err
The lower uncertainty for the total X-ray luminosity (in the 0.5-8.0 keV Chandra band) from point sources within the galaxy region.

Num_Detections
The number of detected point sources within the galaxy region.

Lx_Fraction
The fraction of the total luminosity that is contributed by a central source, if a central source is present. (Where no central source is detected, the value is 0.)

Fx_Max
The upper limit for the 0.5-8.0 keV flux in erg/s/cm2.

Lx_Max
The upper limit for the 0.5-8.0 keV luminosity in erg/s.

CG_Prob
The probability that a source within the galaxy boundaries belongs to the CG galaxy instead of a background AGN. Using the flux limits, fx_max, and the expected log N- log S distribution of AGN from Cappelluti et al. (2009), the authors estimate the number of expected background AGN that would be detected within the galaxy region. Therefore, this probability is measured by subtracting the number of expected background AGN from the number of observed sources and dividing by the total number of observed sources.

H1_Prob
The probability of measuring a total galaxy luminosity that is greater than or equal to the observed value, given the luminosity detection limit for the galaxy and the Gilfanov et al. (2004) or Mineo et al. (2012) X-ray binary luminosity functions.

H2_Prob
The probability of measuring a total galaxy luminosity that is greater than or equal to the observed value, given the luminosity detection limit for the galaxy and the Gilfanov et al. (2004) or Mineo et al. (2012) X-ray binary luminosity functions, and assuming a range in luminosity for the individual point sources of two orders of magnitude to account for variability.


Contact Person

Questions regarding the HCGXRBS database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Tuesday, 14-May-2019 17:47:09 EDT