Discovery of the Galactic High-Mass Gamma-ray Binary 4FGL J1405.1-6119
Abstract
We report the identification from multi-wavelength observations of the Fermi Large Area Telescope (LAT) source 4FGL J1405.1-6119 (= 3FGL J1405.4-6119) as a high-mass gamma-ray binary. Observations with the LAT show that gamma-ray emission from the system is modulated at a period of 13.7135 +/- 0.0019 days, with the presence of two maxima per orbit with different spectral properties. X-ray observations using the Neil Gehrels Swift Observatory X-ray Telescope (XRT) show that X-ray emission is also modulated at this period, but with a single maximum that is closer to the secondary lower-energy gamma-ray maximum. A radio source, coincident with the X-ray source, is also found from Australia Telescope Compact Array (ATCA) observations, and the radio emission is modulated on the gamma-ray period with similar phasing to the X-ray emission. A large degree of interstellar obscuration severely hampers optical observations, but a near-infrared counterpart is found. Near-infrared spectroscopy indicates an O6 III spectral classification. This is the third gamma-ray binary to be discovered with the Fermi LAT from periodic modulation of the gamma-ray emission, the other two sources also have early O star, rather than Be star, counterparts. We consider at what distances we can detect such modulated gamma-ray emission with the LAT, and examine constraints on the gamma-ray binary population of the Milky Way.
Keywords
Cite
@article{arxiv.1908.10764,
title = {Discovery of the Galactic High-Mass Gamma-ray Binary 4FGL J1405.1-6119},
author = {R. H. D. Corbet and L. Chomiuk and M. J. Coe and J. B. Coley and G. Dubus and P. G. Edwards and P. Martin and V. A. McBride and J. Stevens and J. Strader and L. J. Townsend},
journal= {arXiv preprint arXiv:1908.10764},
year = {2019}
}
Comments
Accepted for publication in the Astrophysical Journal