EROSITA study of the 47~Tucanae globular cluste
2021
We present the results of the analysis of five observations of the globular clutser 47 Tucanae (47 Tuc) with eROSITA (extended Roentgen Survey with an Imaging Telescope Array) on board Spektrum-Roentgen-Gamma (Spektr-RG, SRG). The aim of the work is the study of the X-ray population in the field of one of the most massive globular clusters in our Milky Way. We focused on the classification of point-like sources in the field of 47 Tuc. The unresolved dense core of 47~Tuc (1'.7 radius) and also the sources, which show extended emission are excluded in this study. We applied different methods of X-ray spectral and timing analysis together with multi wavelength studies for the classification of the X-rays sources in the field of 47 Tuc. We detected 888 point-like sources in the energy range of 0.2-5.0 keV. We identified 92 background AGNs and 26 foreground stars. One of the foreground stars is classified as a variable M~dwarf. We also classified 23 X-ray sources as members of 47 Tuc, including 13 symbiotic stars, 3 quiescent low mass X-ray binaries, one millisecond pulsar candidate, and one cataclysmic variable. There are also 4 X-ray sources, which can be either a cataclysmic variable or a contact binary. Moreover, we calculated the X-ray luminosity function of 47 Tuc X-ray sources within a radius of 18'.8. It shows that the main population of X-ray sources in 47 Tuc has a luminosity <10$^{32}$erg s$^{-1}$ in the energy range of 0.5-2.0 keV. These sources can mainly be candidates for quiescent low mass X-ray binaries and different types of accreting white dwarfs, especially symbiotic stars.
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