Funnel-flow accretion onto highly magnetized neutron stars and shock generation

TL;DR

This paper explores steady funnel-flow accretion onto highly magnetized neutron stars, focusing on shock formation and flow characteristics within a simplified Newtonian framework, with implications for observed X-ray pulsars.

Contribution

It introduces a simplified model for shock generation in funnel-flow accretion onto magnetized neutron stars, including shock location and flow features.

Findings

Identification of shock location in funnel flow

Flow becomes subsonic after shock

Application to observed X-ray pulsars

Abstract

In this paper, we initiate a new study of steady funnel-flow accretion onto strongly magnetized neutron stars, including a full treatment of shock generation. As a first step, we adopt a simplified model considering the flow within Newtonian theory and neglecting radiative pressure and cooling. The flow is taken to start from an accretion disc and then to follow magnetic field lines, forming a transonic funnel flow onto the magnetic poles. A standing shock occurs at a certain point in the flow and beyond this material accretes subsonically onto the star with high pressure and density. We calculate the location of the standing shock and all other features of the flow within the assumptions of our model. Applications to observed X-ray pulsars are discussed.