Orbital Phase-resolved Analysis of X-ray and Gamma-ray Observations of the High-Mass Gamma-ray Binary 4FGL J1405.1-6119

TL;DR

This study combines multi-wavelength observations to analyze the orbital phase-dependent emission of the high-mass gamma-ray binary 4FGL J1405.1-6119, revealing variability and spectral evolution consistent with an intrabinary shock model.

Contribution

First orbital phase-resolved analysis of 4FGL J1405.1-6119 using 16 years of Fermi-LAT data, refining its orbital period and spectral behavior.

Findings

Refined orbital period to 13.7157 days.

Detected variability in hydrogen column density and photon index.

Spectral evolution consistent with intrabinary shock model.

Abstract

We present the results of multi-wavelength observations of the High-Mass Gamma-Ray Binary 4FGL J1405.1-6119. A pair of joint XMM-Newton and NuSTAR observations taken in 2019 (sampling the gamma-ray maximum and X-ray maximum) characterize the emission of soft and hard X-rays. We find variability of the hydrogen column density along our line of sight, $N_{\rm H}$, and photon index, $\Gamma$, and find no evidence of pulsations in X-rays. We also refine a new best-fit orbital period to $P=13.7157\pm0.0014$ days, the first orbital phase-resolved analysis based on nearly 16 years of Fermi--LAT observations of 4FGL J1405.1-6119 and the evolution of the spectral shape as a function of orbital phase. Finally, the X-ray and $\gamma$-ray spectra for the phases sampled in the new X-ray observations can be interpreted in the framework of the intrabinary shock model, previously applied to High-Mass Gamma-Ray binaries such as LS 5039.