VERITAS observations of the Be/X-ray binary system LS V +44 17 during a major outburst

TL;DR

This paper reports VERITAS observations of the Be/X-ray binary LS V +44 17 during a major outburst, focusing on detecting very high energy gamma-ray emission associated with the system's activity.

Contribution

It presents the first VHE gamma-ray observational campaign of LS V +44 17 during an outburst, providing insights into its high-energy emission properties.

Findings

No significant VHE gamma-ray emission detected.

Constraints set on gamma-ray flux during outburst.

Enhanced understanding of high-energy processes in Be/X-ray binaries.

Abstract

The Be/X-ray binary system LS V +44 17 (RX J0440.9+4431) is a potential member of the rare class of gamma-ray binaries. The system is comprised of a Be star and a neutron star companion with an orbital period of 150 days. In December of 2022, MAXI detected an X-ray outburst from the source, which peaked in early January before declining and then re-brightening. During the second peak, the flux exceeded 1 Crab in the 15-50 keV range, and exhibited a pulsed emission component with a pulse period of 208 seconds. VERITAS observations were conducted close to the peak of the second outburst, from January 24 to January 27, 2023. We report here on the search for very high energy (VHE) gamma-ray emission in these data.