RXTE-PCA Observations of XMMU J054134.7-682550

TL;DR

This study analyzed RXTE-PCA data of the X-ray pulsar XMMU J054134.7-682550, revealing its spin behavior, flux correlation, spectral evolution, and accretion characteristics without evidence of a binary companion or cyclotron line.

Contribution

First detailed RXTE-PCA analysis of XMMU J054134.7-682550, characterizing its timing, spectral properties, and accretion behavior during an outburst.

Findings

Source spins up with higher X-ray flux, indicating accretion disk presence.

No evidence of binary companion or cyclotron line detected.

Variable pulse profiles and spectral features observed over time.

Abstract

We analyzed RXTE-PCA observations of a recent outburst of the X-ray pulsar XMMU J054134.7$-$682550. We calculated the pulse frequency history of the source. We found no sign of a binary companion. The source spins up when the X-ray flux is higher, with a correlation between the spin-up rate and X-ray flux, which may be interpreted as a sign of an accretion disk. On the other hand, the source was found to have an almost constant spin frequency when the X-ray flux is lower without any clear sign of a spin-down episode. The decrease in pulsed fraction with decreasing X-ray flux was intrepreted as a sign of accretion geometry change, but we did not find any evidence of a transition from accretor to propeller regimes. The source was found to have variable pulse profiles. Two peaks in pulse profiles were usually observed. We studied the X-ray spectral evolution of the source throughout the observation. Pulse phase resolved analysis does not provide any further evidence for a cyclotron line, but may suggest a slight variation of intensity and width of the 6.4 keV iron line with phase.