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

TITLE=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

JOURNAL=Frontiers in Astronomy and Space Sciences

VOLUME=10

YEAR=2024

URL=https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2023.1292130

DOI=10.3389/fspas.2023.1292130

ISSN=2296-987X

ABSTRACT=<p><italic>HEX-P</italic> is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<inline-formula id="inf1"><mml:math id="m1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>&lt;</mml:mo><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>″</mml:mo></mml:mrow></mml:msup></mml:math></inline-formula> FWHM) and broad spectral coverage (0.2–80 keV) with an effective area far superior to current facilities’ (including <italic>XMM-Newton</italic> and <italic>NuSTAR</italic>). These capabilities will enable revolutionary new insights into a variety of important astrophysical problems. We present scientific objectives and simulations of <italic>HEX-P</italic> observations of the Galactic Center (GC) and Bulge. We demonstrate the unique and powerful capabilities of the <italic>HEX-P</italic> observatory for studying both X-ray point sources and diffuse X-ray emission. <italic>HEX-P</italic> 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 <italic>NuSTAR</italic> 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.</p>