The High Energy X-ray Probe (HEX-P): locations, spectra, and acceleration mechanisms for the highest-energy electrons in supernova remnants and pulsar wind nebulae

HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<10 arcsec FWHM) and broad spectral coverage (0.1-150 keV) with an effective area far superior to current facilities (including XMM-Newton and NuSTAR) to enable revolutionary new insights into a variety of important astrophysical problems. HEX-P is ideally suited to address important problems in the physics and astrophysics of supernova remnants (SNRs) and pulsar wind nebulae (PWNe). For shell SNRs, HEX-P can greatly improve our understanding in several areas, including detections of, or limits on, ⁴⁴Ti in the youngest supernova remnants and better spectral characterization and localization of nonthermal X-ray emission from both nonthermal-dominated SNRs and those containing both thermal and nonthermal components. For PWNe, HEX-P can fill in a large gap in the spectral-energy distributions (SEDs) of many objects observed in radio, soft X-rays, and gamma rays, constraining the maximum energies to which electrons can be accelerated, with implications for the nature of the Galactic Pevatrons required by the spectrum of Galactic cosmic rays. We shall present simulations of each class of objects, demonstrating the power of both the imaging and spectral capabilities of HEX-P to advance SNR/PWN science. More information on HEX-P, including the full team list, is available at https://hexp.org.