Probing the Propeller Regime with Symbiotic X-ray Binaries

TL;DR

This paper investigates the potential for observing a neutron star in the propeller stage within symbiotic X-ray binaries, emphasizing the importance of system parameters and propeller models in understanding this phase.

Contribution

It applies various propeller spin-down models to assess the likelihood of detecting neutron stars in the propeller stage in symbiotic X-ray binaries.

Findings

The duration of the propeller stage is highly sensitive to the rotational loss regime.

Only the slow propeller model by Davies and Pringle (1981) predicts a long enough phase for observation.

Future measurements of system parameters can constrain propeller behavior.

Abstract

At the moment, there are two neutron star X-ray binaries with massive red supergiants as donors. De et al. (2023) proposed that the system SWIFT J0850.8-4219 contains a neutron star at the propeller stage. We study this possibility by applying various models of propeller spin-down. We demonstrate that the duration of the propeller stage is very sensitive to the regime of rotational losses. Only in the case of a relatively slow propeller model proposed by Davies and Pringle (1981), the duration of the propeller is long enough to provide a significant probability to observe the system at this stage. Future determination of the system parameters (orbital and spin periods, magnetic field of the compact object, etc.) will allow putting strong constraints on the propeller behavior.