J/ApJ/634/272 X-ray sources in NGC 4261 (Giordano+, 2005)
The trail of discrete X-ray sources in the early-type galaxy NGC 4261:
anisotropy in the globular cluster distribution?
Giordano L., Cortese L., Trinchieri G., Wolter A., Colpi M., Gavazzi G.,
Mayer L.
<Astrophys. J., 634, 272-280 (2005)>
=2005ApJ...634..272G 2005ApJ...634..272G (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources
Keywords: binaries: close - galaxies: elliptical and lenticular, cD -
globular clusters: general - X-rays: binaries - X-rays: galaxies
Abstract:
Chandra images of the elliptical galaxy NGC 4261 have revealed an
anisotropy in the spatial distribution of the off-nuclear X-ray
sources, interpreted by Zezas et al. (2003ApJ...599L..73Z 2003ApJ...599L..73Z) as evidence
of an association with a young stellar population. Our independent
analysis of archive X-ray (Chandra) and optical (INT and HST)
observations confirms the anisotropy of the X-ray sources but conducts
to a different interpretation for their origin.
Description:
NGC 4261 was observed by Chandra with the Advanced CCD Imaging
Spectrometer (ACIS-S3 CCD) on 2000 May 6 for a total exposure of
37,210s. We have used archive observations of the INT and the HST Wide
Field Planetary Camera 2 (WFPC2) for a systematic search of the
optical counterparts of the X-ray sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 59 54 List of sources detected in the field of NGC 4261
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2006)
B/int : Isaac Newton Telescope Wide Field Survey (CASU 2002)
B/chandra : The Chandra Archive Log (CXC, 1999-)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [GCT2005] Source number
3 A1 --- f_[GCT2005] [*] Indicates the source appears in Fig. 6
5- 6 I2 h RAh Hour of Right Ascension (J2000.0)
8- 9 I2 min RAm Minute of Right Ascension (J2000.0)
11- 15 F5.2 s RAs Second of Right Ascension (J2000.0)
17 A1 --- DE- Sign of the Declination (J2000.0)
18- 19 I2 deg DEd Degree of Declination (J2000.0)
21- 22 I2 arcmin DEm Arcminute of Declination (J2000.0)
24- 28 F5.2 arcsec DEs Arcsecond of Declination (J2000.0)
30- 36 F7.2 10-4ct/s CR 0.3-7.0keV count rate (10-4/s) (1)
38- 42 F5.2 10-4ct/s e_CR Error in CR
44- 50 F7.2 10+31W Lx X-ray luminosity (0.2-10keV)
in units of 1038erg/s (2)
52- 59 A8 --- CPT Counterpart (3)
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Note (1): Count rates are in the full 0.3-7.0keV band, as given by WAVDETECT.
Note (2): X-ray luminosities are calculated assuming a power-law spectrum with
a photon index of 1.7, a Galactic line-of-sight column density of
NH=5.8x1020/cm2 and a distance of 32Mpc.
Note (3): Indicates the association with a globular cluster (GC) in the HST
field, a candidate globular cluster (GCC) from the INT list, or the
name of the foreground/background galaxy. The question mark indicates
that no optical coverage is available.
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History:
From electronic version of the journal
(End) Marianne Brouty [CDS] 08-Aug-2006