J/ApJ/578/405 Neutron stars in NGC 5139 (Rutledge+, 2002)
A possible transient neutron star in quiescence
in the globular cluster NGC 5139.
Rutledge R.E., Bildsten L., Brown E.F., Pavlov G.G., Zavlin V.E.
<Astrophys. J. 578, 405 (2002)>
=2002ApJ...578..405R 2002ApJ...578..405R
ADC_Keywords: Clusters, globular ; Pulsars ; X-ray sources
Keywords: Galaxy: globular clusters: individual (NGC 3139) - stars: neutron
Description:
The Chandra/ACIS-I detectors observed NGC 5139 in imaging mode for two
continuous periods (2000 January 24 02:15-09:46 and January 25
04:33-17:24 TT) for a total exposure of ∼68.6ks. We combined the two
observations and analyzed them as one. We searched for point sources
using CELLDETECT, using only the 0.1-2.5keV energy range, excluding
regions less than 16 pixels from the detector edges and keeping only
sources with signal-to-noise ratio (S/N)>5.0. We find 40 X-ray point
sources over the four ACIS-I chips and chip S2 of ACIS-S, which are
numbered in order of decreasing S/N in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 90 40 Chandra X-Ray Sources in the Field of NGC 5139
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- RBB2002b Sequential number
3 A1 --- n_RBB2002b [c] Note on RBB2002b (1)
5- 8 F4.1 --- S/N Signal-to-noise ratio
10- 11 I2 h RAh Right ascension (J2000)
13- 14 I2 min RAm Right ascension (J2000)
16- 21 F6.3 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 34 F5.2 arcsec DEs Declination (J2000)
36- 39 F4.2 arcsec e_RAs ? rms uncertainty on position (2)
41- 44 F4.2 arcsec e_DEs ? rms uncertainty on position (2)
46- 49 F4.2 --- Delta/rC Off-axis in radius core units (3)
51- 56 F6.2 --- chi2 ? Reduced chi2 statistic
58 I1 --- dof ? Degree of freedom
59 A1 --- n_chi2 [d] d: Object not spectrally analyzed (4)
61- 65 E5.0 --- Prob(chi2) ? Prob(chi2)
66 A1 --- n_Prob(chi2) [n] n: not analysed (no Prob(chi2) value)
68- 69 I2 eV kTeff ? Best fit kTeff value
71 I1 eV e_kTeff ? rms uncertainty on kTeff
73- 76 F4.1 ph/ks Counts Counts (0.1-2.5keV)
78- 80 F3.1 ph/ks e_Counts rms uncertainty on Counts
82- 84 A3 --- Type Type of source (5)
86 I1 --- Ref ? References (6)
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Note (1): c: X-ray CELLDETECT positional uncertainty possibly incorrect
by up to 10" because of large off-axis angle and low S/N.
Note (2): Statistical uncertainty in RA/DE (or both). Systematic positional
uncertainty is ±0.15" (see text).
Note (3): Radius core (rC) = 156" (Djorgovski & Meylan, 1993,
ASP Conf. Ser. 50, Structure and Dynamics of Globular Clusters, ed. S.
G. Djorgovski & G. Meylan (San Francisco: ASP), 376).
Note (4): No chi2, dof and Prob(chi2) values (see text).
Note (5): Types:
qNS = quiescent transient neutron star
CV = cataclysmic variable
Note (6): References:
(1) Cool et al., 1995ApJ...438..719C 1995ApJ...438..719C
(2) present work
(3) Carson et al., 2000ApJ...532..461C 2000ApJ...532..461C
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History:
From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 09-Dec-2002