Frontiers in Astronomy and Space Sciences (Jan 2024)

The high energy X-ray probe (HEX-P): Resolving the nature of Sgr A* flares, compact object binaries and diffuse X-ray emission in the Galactic center and beyond

  • Kaya Mori,
  • Gabriele Ponti,
  • Gabriele Ponti,
  • Matteo Bachetti,
  • Arash Bodaghee,
  • Jonathan Grindlay,
  • Jaesub Hong,
  • Roman Krivonos,
  • Ekaterina Kuznetsova,
  • Shifra Mandel,
  • Antonio Rodriguez,
  • Giovanni Stel,
  • Shuo Zhang,
  • Tong Bao,
  • Franz Bauer,
  • Maïca Clavel,
  • Benjamin Coughenour,
  • Javier A. García,
  • Julian Gerber,
  • Brian Grefenstette,
  • Amruta Jaodand,
  • Bret Lehmer,
  • Kristin Madsen,
  • Melania Nynka,
  • Peter Predehl,
  • Ciro Salcedo,
  • Daniel Stern,
  • John Tomsick

DOI
https://doi.org/10.3389/fspas.2023.1292130
Journal volume & issue
Vol. 10

Abstract

Read online

HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<10″ FWHM) and broad spectral coverage (0.2–80 keV) with an effective area far superior to current facilities’ (including XMM-Newton and NuSTAR). These capabilities will enable revolutionary new insights into a variety of important astrophysical problems. We present scientific objectives and simulations of HEX-P observations of the Galactic Center (GC) and Bulge. We demonstrate the unique and powerful capabilities of the HEX-P observatory for studying both X-ray point sources and diffuse X-ray emission. HEX-P will be uniquely equipped to explore a variety of major topics in Galactic astrophysics, allowing us to 1) investigate broad-band properties of X-ray flares emitted from the supermassive black hole (BH) at Sgr A* and probe the associated particle acceleration and emission mechanisms; 2) identify hard X-ray sources detected by NuSTAR and determine X-ray point source populations in different regions and luminosity ranges; 3) determine the distribution of compact object binaries in the nuclear star cluster and the composition of the Galactic Ridge X-ray emission; 4) identify X-ray transients and measure fundamental parameters such as black hole spin; 5) find hidden pulsars in the Galactic Center; 6) search for BH–OB binaries and hard X-ray flares from young stellar objects in young massive clusters; 7) measure white dwarf (WD) masses of magnetic CVs to deepen our understanding of CV evolution and the origin of white dwarf magnetic fields; 8) explore primary particle accelerators in the GC in synergy with future TeV and neutrino observatories; 9) map out cosmic-ray distributions by observing non-thermal X-ray filaments; 10) explore past X-ray outbursts from Sgr A* through X-ray reflection components from giant molecular clouds.

Keywords