# Understanding the nature of the intriguing source X Persei: A deep look with a Suzaku observation

## TL;DR

This study provides a detailed broadband timing and spectral analysis of X Persei, revealing variable accretion states and evidence of a cyclotron resonance scattering feature at high intensity levels, which informs about its magnetic field.

## Contribution

It offers the most comprehensive broadband spectral model of X Persei to date and clarifies the presence of a CRSF at high intensity levels, advancing understanding of its magnetic properties.

## Key findings

- CRSF detected at ~40 keV during high intensity states
- Spectral models constrained for the first time for X Persei
- Evidence of changing accretion geometry with intensity variations

## Abstract

We present detailed broadband timing and spectral analysis of the persistent, low luminosity and slowly spinning pulsar X Persei using a deep Suzaku observation of the source. The spectrum is unusually hard with a cyclotron resonance scattering feature (CRSF), the presence of which has been debated. By comparing the spectral models relevant for accretion powered pulsars, we have obtained the best constraint on the broadband spectral model of X Persei obtained so far. The CRSF is not confirmed in the average spectrum. We have also identified, the presence of different intensity levels in the source with distinct changes in the pulse profile and energy spectrum indicating changes in the accretion geometry. We further find evidence of a CRSF in the highest intensity levels at $\sim$ 40 keV, indicating a magnetic field strength of 3.4$\times10^{12}$ G.