XMM-Newton observation of the TeV-discovered supernova remnant HESS J1534-571

¹ Institut für Astronomie und Astrophysik Tübingen (IAAT), Sand 1, 72076 Tübingen, Germany
e-mail: dang-thanh-nhan.nguyen@astro.uni-tuebingen.de
² Dr. Karl Remeis Observatory, Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstraße 7, 96049 Bamberg, Germany
³ Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
⁴ Research Center for the Early Universe, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
⁵ Trans-Scale Quantum Science Institute, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Received: 17 March 2023
Accepted: 17 July 2023

Abstract

We report the results obtained from XMM-Newton observations of the TeV-detected supernova remnant (SNR) HESS J1534-571. We focus on the nature of the cosmic-ray particle content in the SNR, which is revealed by its γ-ray emission. No signatures of X-ray synchrotron emission were detected from the SNR. This is consistent with earlier results obtained with Suzaku from other regions of the object. A joint modeling of the XMM-Newton and Suzaku spectra yields an upper limit for the total X-ray flux from the SNR area of ~5.62 × 10⁻¹³ erg cm⁻² s⁻¹ (95% C.I.) in the energy band of 2.0–10.0 keV for an assumed photon index of 2.0. On the other hand, we do find evidence in the XMM-Newton data for a line-like emission feature at 6.4 keV from localized regions, again confirming earlier Suzaku measurements. We discuss the findings in the context of the origin of the observed γ-ray emission. Although neither hadronic nor leptonic scenarios can be fully ruled out, the observed line emission can be interpreted as the result of interactions between lower-energy (~ MeV) cosmic-ray protons with high gas-density regions in and around HESS J1534-571, and thus potentially be associated with particles accelerated in the SNR.