EROSITA study of the 47~Tucanae globular cluster

Sara Saeedi; Teng Liu; Jonathan Knies; Manami Sasaki; Werner Becker; Esra Bulbul; Konrad Dennerl; Michael Freyberg; Andrea Merloni

arXiv · 2106.14535

EROSITA study of the 47~Tucanae globular cluster

Sara Saeedi·Teng Liu·Jonathan Knies·Manami Sasaki·Werner Becker·Esra Bulbul·Konrad Dennerl·Michael Freyberg·Andrea Merloni

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Abstract

Aims. We present the results of the analysis of five observations of the globular cluster 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. Methods. 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. Results. We detected 888 point-like sources in the energy range of 0.2-5.0 keV. We identified 126 background AGNs and 25 foreground stars. One of the foreground stars is classified as a variable M dwarf. We also classified 14 X-ray sources as members of 47 Tuc, including 1 symbiotic stars, 2 quiescent low mass X-ray binaries, and 4 cataclysmic variable. There are also 5 X-ray sources, which can either be a cataclysmic variable or a contact binary, and also 1 X-ray sources which can be an active binary (Type RS CVn). We identified one X-ray binary, which belongs to the Small Magellanic Cloud. Moreover, we calculated the X-ray luminosity function of 47 Tuc. No significant population that seems to belong to the globular cluster has been observed in the energy range of 0.5-2.0 keV using eROSITA observations.

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Sara Saeedi, Teng Liu, Jonathan Knies, Manami Sasaki, Werner Becker, Esra Bulbul, Konrad Dennerl, Michael Freyberg, Andrea Merloni. 2021-06-28. EROSITA study of the 47~Tucanae globular cluster. https://arxiv.org/abs/2106.14535

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