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arXiv · 2306.09960

X-ray emission from Westerlund 2 detected by SRG/ART-XC and Chandra: search for radiation of TeV leptons

A. M. Bykov·Yu. A. Uvarov·M. E. Kalyashova·D. V. Badmaev·I. Yu. Lapshov·A. A. Lutovinov·I. A. Mereminskiy·A. N. Semena
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Abstract

We present the results of current observations of the young compact cluster of massive stars Westerlund 2 with the Mikhail Pavlinsky ART-XC telescope aboard the Spectrum-Roentgen-Gamma (SRG) observatory which we analysed together with the archival Chandra data. In general, Westerlund 2 was detected over the whole electromagnetic spectrum including high-energy gamma rays, which revealed a cosmic ray acceleration in this object to the energies up to tens of TeV. The detection of Westerlund 2 with ART-XC allowed us to perform a joint spectral analysis together with the high resolution Chandra observations of the diffuse emission from a few selected regions in the vicinity of the Westerlund 2 core in the 0.4 - 20 keV range. To fit the Westerlund 2 X-ray spectrum above a few keV one needs either a non-thermal power-law emission component, or a hot plasma with temperatures $\sim$ 5 keV. Our magnetohydrodynamic modeling of the plasma flows in Westerlund 2 shows substantially lower electron temperatures in the system and thus the presence of the non-thermal component is certainly preferable. A kinetic model of the particle acceleration demonstrated that the non-thermal component may originate from the synchrotron radiation of multi-TeV electrons and positrons produced in Westerlund 2 in accordance with the TeV photons detection from the source.

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A. M. Bykov, Yu. A. Uvarov, M. E. Kalyashova, D. V. Badmaev, I. Yu. Lapshov, A. A. Lutovinov, I. A. Mereminskiy, A. N. Semena. 2023-06-16. X-ray emission from Westerlund 2 detected by SRG/ART-XC and Chandra: search for radiation of TeV leptons. https://doi.org/10.1093/mnras%2Fstad2356

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