Spin-Down of the Long-Period Accreting Pulsar 4U 2206+54

TL;DR

This paper reports on the detection and analysis of long-period pulsations in the neutron star 4U 2206+54, revealing a spin-down trend and suggesting it is an accretion-powered magnetar.

Contribution

It provides new observational evidence of spin-down in 4U 2206+54 and proposes the neutron star as an accretion-powered magnetar, combining data from multiple X-ray observatories.

Findings

Detected pulsations at ~5554 s confirming previous results.

Observed a spin-down trend over time.

Suggests the neutron star is an accretion-powered magnetar.

Abstract

4U 2206+54 is a high mass X-ray binary which has been suspected to contain a neutron star accreting from the wind of its companion BD +53 2790. Reig et al. have recently detected 5560 s period pulsations in both RXTE and INTEGRAL observations which they conclude are due to the spin of the neutron star. We present observations made with Suzaku which are contemporaneous with their RXTE observation of this source. We find strong pulsations at a period of 5554 +/- 9 s in agreement with their results. We also present a reanalysis of BeppoSAX observations of 4U 2206+54 made in 1998, in which we find strong pulsations at a period of 5420 +/- 28 seconds, revealing a spin-down trend in this long-period accreting pulsar. Analysis of these data suggests that the neutron star in this system is an accretion-powered magnetar.