|
Description
Galactic globular clusters harbor binary systems that are detected as faint X-ray sources. These close binaries are thought to play an important role in the stability of the clusters by liberating energy and delaying the inevitable core collapse of globular clusters. The inventory of close binaries and their identification is therefore essential. This table contains some of the results, namely an X-ray source catalog, from XMM-Newton observations of the Galactic globular cluster NGC 2808. The authors use X-ray spectral and variability analysis combined with ultraviolet observations made with the XMM-Newton optical monitor and published data from the Hubble Space Telescope to identify sources associated with the clusters. They compare the results of their observations with estimates from population synthesis models. Five sources out of 96 X-ray sources detected above 4-sigma significance are likely to be related to NGC 2808. The authors find one quiescent neutron star low-mass X-ray binary candidate in the core of NGC 2808, and propose that the majority of the central sources in NGC 2808 are cataclysmic variables. An estimation leads to 20 +/- 10 cataclysmic variables with luminosity above 4.25 x 10<sup>31</sup> erg s<sup>-1</sup>. Millisecond pulsars could also be present in the core of NGC 2808, and some sources outside the half-mass radius could possibly be linked to the cluster. NGC 2808 was observed on February 1st 2005, for 41.8 kiloseconds (ks) with the three European Photon Imaging Cameras (EPIC MOS1, MOS2 and pn) on board the XMM-Newton observatory, in imaging mode, using a full frame window and a medium filter. This table was created by the HEASARC in February 2009 based on the electronic version of Table 2 from the paper which was obtained from the CDS (their catalog J/A+A/480/397 file table2.dat). This is a service provided by NASA HEASARC .
|
