Motion of the hot spot and spin torque in accreting millisecond pulsars

TL;DR

This paper investigates the dynamics of hot spots and spin torque in accreting millisecond pulsars, addressing key questions about observed spin torques, correlations in pulsar signals, and their interrelations.

Contribution

It provides new insights into the behavior of hot spots and spin torque mechanisms in AMXPs, clarifying observational phenomena and their underlying physics.

Findings

The apparent spin torque in AMXPs may not always be real.

Correlations and anti-correlations are linked to hot spot and accretion flow dynamics.

Timing residuals, lightcurve, and QPOs are interconnected through pulsar accretion processes.

Abstract

The primary concern of this contribution is that accreting millisecond pulsars (AMXPs) show a much larger amount of information than is commonly believed. The three questions to be addressed are: 1. Is the apparent spin torque observed in AMXPs real ? 2. Why do we see correlations and anti-correlations between fractional amplitudes and timing residuals in some AMXPs ? 3. Why the timing residuals, the lightcurve and the 1Hz QPO in SAX J1808.4$-$3658 are related ?