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J/ApJ/738/129        XMM-Newton X-ray sources in NGC 6553       (Guillot+, 2011)

Discovery of a candidate quiescent low-mass X-ray binary in the globular cluster NGC 6553. Guillot S., Rutledge R.E., Brown E.F., Pavlov G.G., Zavlin V.E. <Astrophys. J., 738, 129 (2011)> =2011ApJ...738..129G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Binaries, X-ray ; Stellar distribution Keywords: globular clusters: individual: NGC 6553 - stars: neutron - X-rays: binaries Abstract: This paper reports the search for quiescent low-mass X-ray binaries (qLMXBs) in the globular cluster (GC) NGC 6553 using an XMM-Newton observation designed specifically for that purpose. We spectrally identify one candidate qLMXB in the core of the cluster, based on the consistency of the spectrum with a neutron star H-atmosphere model at the distance of NGC 6553. Specifically, the best-fit radius found using the three XMM European Photon Imaging Camera spectra is RNS=6.3+2.3-0.8 km (for MNS=1.4 M) and the best-fit temperature is kTeff=136+21-34 eV. Both physical parameters are in accordance with typical values of previously identified qLMXBs in GC and in the field, i.e., RNS∼5-20 km and kTeff=50-150 eV. A power-law (PL) component with a photon index Γ=2.1+0.5-0.8 is also required for the spectral fit and contributes ∼33% of the total flux of the X-ray source. A detailed analysis supports the hypothesis that the PL component originates from nearby sources in the core, unresolved with XMM. The analysis of an archived Chandra observation provides marginal additional support to the stated hypothesis. Finally, a catalog of all the sources detected within the XMM field of view is presented here. Description: NGC 6553 was observed with XMM-Newton on 2006 October 6 at 01:41:44 UT, using the three EPIC cameras, for an exposure time of 20.4 ks, with the medium filter. The Chandra X-ray Observatory observed the GC for 5.25 ks, on 2008 October 30 at 01:38:12 UT, with the ACIS-S detector (Garmire et al. 2003, Proc. SPIE, 4851, 28) in VERY-FAINT mode. Objects: ------------------------------------------------ RA (ICRS) DE Designation(s) ------------------------------------------------ 18 09 15.68 -25 54 27.9 NGC 6553 = GCl 88 ------------------------------------------------ File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 56 43 X-ray Sources Detected in the XMM Observation of NGC 6553 table2.dat 93 43 Spectral Results of X-ray Sources in NGC 6553
See also: VII/195 : Globular Clusters in the Milky Way (Harris, 1996) V/106 : Catalogue of X-ray binaries (Liu+ 2001) IX/50 : XMM-Newton Serendipitous Source Catalogue 3XMM-DR6 (XMM-SSC, 2016) J/A+A/331/70 : JKVI photometry of NGC 6553 stars (Guarnieri+ 1998) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Name Object name (XMMU JHHMMSS+DDMMSS) 21- 29 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000) 31- 33 F3.1 arcsec e_RAdeg Uncertainty in RAdeg 35- 43 F9.5 deg DEdeg Declination in decimal degrees (J2000) 45- 47 F3.1 arcsec e_DEdeg Uncertainty in DEdeg 49- 53 F5.1 --- S/N Detection significance provided by wavdetect 55- 56 I2 --- ID [01/43] Source identifier
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 I2 --- ID [01/43] Source identifier 4- 8 F5.1 ct/ks pnRate Background subtracted count rates in the 0.3-10 keV range 10- 12 F3.1 ct/ks e_pnRate Uncertainty in pnRate 13 A1 --- n_pnRate [a] Note on pnRate (1) 15- 18 F4.1 --- Gamma ? Best-fit photon index when a power law (PL) model was used 19 A1 --- n_Gamma [)] Note on Gamma (2) 22- 24 F3.1 --- E_Gamma ? Upper limit uncertainty in Gamma 26- 28 F3.1 --- e_Gamma ? Lower limit uncertainty in Gamma 31- 35 F5.3 keV kTeff ? Best-fit effective temperature when a thermal model was used 37- 41 F5.3 keV E_kTeff ? Upper limit uncertainty in kTeff 43- 47 F5.3 keV e_kTeff ? Lower limit uncertainty in kTeff 49- 52 F4.2 keV kTeff1 ? Best-fit effective temperature when a thermal model was used 54- 57 F4.2 keV E_kTeff1 ? Upper limit uncertainty in kTeff1 59- 62 F4.2 keV e_kTeff1 ? Lower limit uncertainty in kTeff1 64- 68 F5.2 10-16W/m2 FX Unabsorbed X-ray flux in the band 0.5-10 keV (10-13 erg/cm2/s) (3) 70- 73 F4.2 --- chi2 χ2 statistic of the fit 75- 77 I3 --- dof [3/115] Number of degrees of freedom 79- 82 F4.2 --- Prob [0/1] Null hypothesis probability 84- 93 A10 --- Model Model used (4)
Note (1): Note as follows: a = The MOS1/2 count rates are, respectively, 8.5±0.8 and 6.6±0.7 counts/ks in the 0.3-10 keV range. Note (2): Note as follows: ) = Values were held fixed. Note (3): Note that the flux is not corrected for the finite aperture in this table. This energy range is different from that used for the spectrum extraction (0.3-10 keV), for comparison purposes with previously published work. Note (4): Model as follows: PL = Power law; RS = Raymond-Smith plasma; nsatmos = (McClintock et al. 2004ApJ...615..402M; Heinke et al. 2006ApJ...644.1090H); nsatmos as been computed for the range g=(0.63-6.3)x1014 cm/s2.
History: From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 17-Aug-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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