XMM-Newton confirmation of a new intermediate polar: XMMU J185330.7-012815

TL;DR

This paper confirms XMMU J185330.7-012815 as an intermediate polar through X-ray spectral and timing analysis, identifying its properties and ruling out alternative neutron star scenarios.

Contribution

The study provides the first detailed spectral and timing analysis confirming the intermediate polar nature of XMMU J185330.7-012815 using XMM-Newton data.

Findings

X-ray spectrum fits multi-temperature plasma model with heavy element lines

Detected X-ray periodicity of ~238 seconds

Pulsed fraction increases with energy

Abstract

We report the results from a detailed spectro-imaging and temporal analysis of an archival XMM-Newton observation of a new intermediate polar XMMU J185330.7-012815. Its X-ray spectrum can be well-described by a multi-temperature thermal plasma model with the K-lines of heavy elements clearly detected. Possible counterparts of XMMU J185330.7-012815 have been identified in optical and UV bands. The low value of the inferred X-ray-to-UV and X-ray-to-optical flux ratios help to safely rule out the possibility as an isolated neutron star. We confirm the X-ray periodicity of ~238 s, but different from the previous preliminary result, we do not find any convincing evidence of phase-shift in this observation. We further investigate its properties through an energy-resolved temporal analysis and find the pulsed fraction monotonically increases with energy.