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J/A+A/445/155       XMM count-rates in M 55 and NGC 3201     (Webb+, 2006)

XMM-Newton X-ray and optical observations of the globular clusters M 55 and NGC 3201. Webb N.A., Wheatley P.J., Barret D. <Astron. Astrophys. 445, 155 (2006)> =2006A&A...445..155W
ADC_Keywords: Clusters, globular ; X-ray sources Keywords: globular clusters: individual: M 55, NGC 3201 - X-rays: general - binaries: general - stars: variables: general Abstract: We have observed two low concentration Galactic globular clusters with the X-ray observatory XMM-Newton. We detect 47 faint X-ray sources in the direction of M 55 and 62 in the field of view of NGC 3201. Using the statistical LogN-LogS relationship of extragalactic sources derived from XMM-Newton Lockman Hole observations, to estimate the background source population, we estimate that very few of the sources (1.5±1.0) in the field of view of M 55 actually belong to the cluster. These sources are located in the centre of the cluster as we expect if the cluster has undergone mass segregation. NGC 3201 has approximately 15 related sources, which are centrally located but are not constrained to lie within the half mass radius. The sources belonging to this cluster can lie up to 5 core radii from the centre of the cluster which could imply that this cluster has been perturbed. Using X-ray (and optical, in the case of M 55 ) colours, spectral and timing analysis (where possible) and comparing these observations to previous X-ray observations, we find evidence for sources in each cluster that could be cataclysmic variables, active binaries, millisecond pulsars and possible evidence for a quiescent low mass X-ray binary with a neutron star primary, even though we do not expect any such objects in either of the clusters, due to their low central concentrations. The majority of the other sources are background sources, such as AGN. Description: We obtained XMM-Newton observations of the two globular clusters M 55 and NGC 3201, during the Routine Observing Phase. Approximately 3 and 4ks of the pn data of the two clusters respectively were affected by high background activity (a soft proton flare). All of the data were reduced with version 6.0 of the XMM-Newton SAS (Science Analysios Software). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 48 47 *X-ray sources in the direction of M 55 table3.dat 48 62 *X-ray sources in the direction of NGC 3201
Note on table2.dat and table3.dat: as determined from the EPIC observations, 0.5-10.0keV band.
See also: J/A+A/309/116 : 10 globular cluster ROSAT observations (Johnston+, 1996) Byte-by-byte Description of file: table2.dat table3.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Seq Identification number given in this paper 3 A1 --- n_Seq [ch] Note as to whether it is in the core (1) 5- 6 A2 --- [JVH96] Johnson et al. (1996, Cat. J/A+A/309/116 number (2) 8- 9 I2 h RAh Right ascension (J2000) 11- 12 I2 min RAm Right ascension (J2000) 14- 18 F5.2 s RAs Right ascension (J2000) 20 A1 --- DE- Declination sign (J2000) 21- 22 I2 deg DEd Declination (J2000) 24- 25 I2 arcmin DEm Declination (J2000) 27- 31 F5.2 arcsec DEs Declination (J2000) 33- 37 F5.2 arcsec e_Pos Error in the position 39- 43 F5.2 10-3ct/s CR Count rate in the 0.5-10.0keV band 45- 48 F4.2 10-3ct/s e_CR Count rate error
Note (1): c = sources within the core h = sources within the half mass radius Note (2): Nomenclature: [JVH96] 6809 NN for table2.dat [JVH96] 3201 NN for table3.dat
Acknowledgements: Natalie Webb, Natalie.Webb(at)
(End) Natalie Webb [CESR, France], Patricia Vannier [CDS] 06-Sep-2005
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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