The high energy X-ray probe (HEX-P): a new window into neutron star accretion

Ludlam RM, Malacaria C, Sokolova-Lapa E, Fuerst F, Pradhan P, Shaw AW, Pottschmidt K, Pike S, Vasilopoulos G, Wilms J, Garciá JA, Madsen KK, Stern D, Maitra C, Del Santo M, Walton DJ, Brumback MC, van den Eijnden J (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Book Volume: 10

DOI: 10.3389/fspas.2023.1292500

Abstract

Accreting neutron stars (NSs) represent a unique laboratory for probing the physics of accretion in the presence of strong magnetic fields (B ≳ 108 G). Additionally, the matter inside the NS itself exists in an ultra-dense, cold state that cannot be reproduced in Earth-based laboratories. Hence, observational studies of these objects are a way to probe the most extreme physical regimes. Here we present an overview of the field and discuss the most important outstanding problems related to NS accretion. We show how these open questions regarding accreting NSs in both low-mass and high-mass X-ray binary systems can be addressed with the High-Energy X-ray Probe (HEX-P) via simulated data. In particular, with the broad X-ray passband and improved sensitivity afforded by a low X-ray background, HEX-P will be able to 1) distinguish between competing continuum emission models; 2) provide tighter upper limits on NS radii via reflection modeling techniques that are independent and complementary to other existing methods; 3) constrain magnetic field geometry, plasma parameters, and accretion column emission patterns by characterizing fundamental and harmonic cyclotron lines and exploring their behavior with pulse phase; 4) directly measure the surface magnetic field strength of highly magnetized NSs at the lowest accretion luminosities; as well as 5) detect cyclotron line features in extragalactic sources and probe their dependence on luminosity in the super-Eddington regime in order to distinguish between geometrical evolution and accretion-induced decay of the magnetic field. In these ways HEX-P will provide an essential new tool for exploring the physics of NSs, their magnetic fields, and the physics of extreme accretion.

Authors with CRIS profile

Involved external institutions

California Institute of Technology (Caltech) United States (USA) (US) Embry-Riddle Aeronautical University (ERAU) United States (USA) (US) Wayne State University (WSU) United States (USA) (US) University of Hertfordshire United Kingdom (GB) International Space Science Institute (ISSI) Switzerland (CH) National Aeronautics and Space Administration (NASA) United States (USA) (US) European Space Astronomy Centre (ESAC) Spain (ES) Middlebury College United States (USA) (US) Butler University United States (USA) (US) University of Maryland, Baltimore County United States (USA) (US) Max-Planck-Institut für extraterrestrische Physik (MPE) / Max Planck Institute for Extraterrestrial Physics Germany (DE) University of California, San Diego United States (USA) (US) University of Warwick United Kingdom (GB) National and Kapodistrian University of Athens Greece (GR) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT)

How to cite

APA:

Ludlam, R.M., Malacaria, C., Sokolova-Lapa, E., Fuerst, F., Pradhan, P., Shaw, A.W.,... van den Eijnden, J. (2023). The high energy X-ray probe (HEX-P): a new window into neutron star accretion. Frontiers in Astronomy and Space Sciences, 10. https://dx.doi.org/10.3389/fspas.2023.1292500

MLA:

Ludlam, R. M., et al. "The high energy X-ray probe (HEX-P): a new window into neutron star accretion." Frontiers in Astronomy and Space Sciences 10 (2023).

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