OMEGCENXMM - Omega Centauri XMM-Newton X-Ray Point Source Catalog
Omega Centauri (NGC 5139) is one of the best studied objects in
our galaxy. It is the most massive globular cluster (5.1 x 10^6 solar masses),
and is characterized by large core and half mass radii (154.88 and 250.8
arcseconds, respectively (Harris 1996, AJ, 112, 1487). The authors observed
Omega Cen with XMM-Newton on August 13th, 2001. The observation lasted 37 ks
and was performed with the medium filter. The authors detected 11 and 27 faint
X-ray sources in the core and half mass radii, respectively, searching down to
a luminosity of 1.3 x 10^31 ergs s^-1 in the 0.5 - 5 keV range (for an
assumed distance to Omega Cen of 5.3 kpc). Most sources
have bolometric X-ray luminosities between ~ 10^31 - 10^32 ergs s^-1. The bulk
of sources are hard and spectrally similar to CVs. The lack of soft faint
sources might be related to the absence of millisecond pulsars in the cluster.
The XMM-Newton observations reveal the presence of an excess of sources well
outside the core of the cluster where several RS CVn binaries have already
been found. The authors also analyzed a publicly available Chandra ACIS-I
observation performed on January 24 - 25th, 2000, to improve the XMM-Newton
source positions and to search for source intensity variations between the two
data sets. 63 XMM-Newton sources have a Chandra counterpart, and 15 sources
within the half-mass radius have shown time variability. Overall, the general
properties of the faint X-ray sources in omega Cen suggest that they are
predominantly CVs and active binaries (RS CVn or BY Dra). This table
lists all 146 X-ray sources detected in the XMM-Newton observation
above a maximum likelihood threshold in the 0.5 - 5 keV band of 12,
including the 27 sources within the half-mass radius (listed in Table 1 of
the reference paper), and the the 119 sources outside the half-mass radius
(listed in Table 2 of the reference paper). About 9 of the 27 sources within
the half-mass radius are expected to be background sources, as are ~ 65 of the
sources within 12.5 arcminutes of the cluster center, i.e., a significant
fraction of the 146 total observed X-ray sources.
For each XMM-Newton source, its position, count rate, correlation with previous
X-ray observation, and their associated errors are given. The detailed spectral
information given in Table 5 of the reference paper for 17 selected X-ray
sources is however not included in this HEASARC table.
An XMM-Newton observation of the globular cluster Omega Centauri.
Gendre B., Barret D., Webb N.A.
<Astron. Astrophys. 400, 521 (2003)>
This table was created by the HEASARC in May 2007 based on CDS
catalog J/A+A/400/521 files table1.dat, table2.dat and table3.dat.
For this table, the HEASARC has created a flag
parameter called hmr_flag which is set to 'Y' if the X-ray source lies within
the half-mass radius of the cluster, i.e, within 250.8" of the cluster center,
(such sources are listed in Table 1 of the reference paper), or to 'N' if the
X-ray source is outside the half-mass radius, (sources listed in Table 2 of
the reference paper).
The EPIC instrument by which the source was
detected. The majority of the correlated sources were detected by the PN
camera because it is more sensitive than the MOS cameras. There were however
9 sources missed by the PN, due to CCD gaps, or bad columns, or the smaller
field of view of the PN compared to the MOS; these sources are marked by
'MOS', while the remaining 137 sources are marked by 'PN'. To be precise,
of the 146 sources detected by the EPIC cameras; 59 were seen only by the PN,
9 were seen by the MOS only (and all of them were seen in MOS 1 and MOS 2),
and the remaining 78 were detected in the PN and at least one MOS camera.
A running source number which uniquely identifies the X-ray
The name of the X-ray source using the '[GBW2003]' prefix (for Gendre,
Barret, Webb, 2003) together with the X-ray source number, as recommended by
the CDS Dictionary of Nomenclature of Celestial Objects.
The Right Ascension of the XMM-Newton X-ray source in the selected
equinox. This was given in J2000.0 coordinates to a precision of 0.1 seconds
of time in the original tables.
The Declination of the XMM-Newton X-ray source in the selected
equinox. This was given in J2000.0 coordinates to a precision of 0.1
arcseconds in the original tables.
The Galactic Longitude of the XMM-Newton X-ray source.
The Galactic Latitude of the XMM-Newton X-ray source.
The statistical (90% confidence level) positional error of the
XMM-Newton X-ray source, in arcseconds.
The 0.5 - 5.0 keV band count rate of the XMM-Newton X-ray source,
The statistical error in the 0.5 - 5.0 keV band count
rate of the XMM-Newton X-ray source, in ct/s.
This flag is set to 'Y' if the X-ray source was detected
by the MOS1.
This flag is set to 'Y' if the X-ray source was detected
by the MOS2.
This flag is set to 'Y' if the X-ray source was detected in the
core of the cluster, i.e, within 154.88" of the cluster center.
This flag is set to 'Y' if the X-ray source lies within the
half-mass radius of the cluster, i.e, within 250.8" of the cluster center,
as listed in Table 1 of the reference paper, or to 'N' if the X-ray source
is outside the half-mass radius, as listed in Table 2 of the reference paper.
This parameter was created by the HEASARC.
The J2000 Right Ascension of the Chandra X-ray source
which lies within the statistical error box of the XMM-Newton X-ray source.
The J2000 Declination of the Chandra X-ray source
which lies within the statistical error box of the XMM-Newton X-ray source
The statistical positional error of the Chandra X-ray
source in the J2000 Right Ascension direction.
The statistical positional error of the Chandra
X-ray source in the J2000 Declination direction.
The ROSAT X-ray source counterpart identifier NNa of the
XMM-Newton source ([JVH94] NGC 5139 NNa in Simbad), from Johnston et al.
(1994, A&A, 289, 763) and/or Verbunt & Johnston (2000, A&A, 358, 910).
The Einstein X-ray source counterpart identifier N of the
XMM-Newton source ([HG83b] NGC 5139 N), from Hertz and Grindlay (1983, ApJ,
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