The High Energy X-ray Probe (HEX-P): Magnetars and Other Isolated Neutron Stars

TL;DR

HEX-P is a proposed high-energy X-ray mission designed to significantly advance the study of magnetars and isolated neutron stars through improved sensitivity, resolution, and spectral coverage, enabling new insights into their physics and transient behaviors.

Contribution

This paper introduces HEX-P, a mission concept that combines high spatial resolution and broad spectral coverage to enhance the study of neutron stars and magnetars beyond current capabilities.

Findings

HEX-P will provide high-resolution imaging of neutron stars.

It will enable detailed spectral and timing studies of magnetars.

The mission will improve understanding of transient X-ray emissions.

Abstract

The hard X-ray emission from magnetars and other isolated neutron stars remains under-explored. An instrument with higher sensitivity to hard X-rays is critical to understanding the physics of neutron star magnetospheres and also the relationship between magnetars and Fast Radio Bursts (FRBs). High sensitivity to hard X-rays is required to determine the number of magnetars with hard X-ray tails, and to track transient non-thermal emission from these sources for years post-outburst. This sensitivity would also enable previously impossible studies of the faint non-thermal emission from middle-aged rotation-powered pulsars (RPPs), and detailed phase-resolved spectroscopic studies of younger, bright RPPs. The High Energy X-ray Probe (HEX-P) is a probe-class mission concept that will combine high spatial resolution X-ray imaging ($<5$ arcsec half-power diameter (HPD) at 0.2--25 keV) and broad spectral coverage (0.2--80 keV) with a sensitivity superior to current facilities (including XMM-Newton and NuSTAR). HEX-P has the required timing resolution to perform follow-up observations of sources identified by other facilities and positively identify candidate pulsating neutron stars. Here we discuss how HEX-P is ideally suited to address important questions about the physics of magnetars and other isolated neutron stars.