# A NuSTAR Observation of the Gamma-ray Emitting Millisecond Pulsar PSR J1723-2837

## TL;DR

This paper presents the first NuSTAR hard X-ray observation of the gamma-ray millisecond pulsar PSR J1723-2837, revealing X-ray modulations at the binary orbital period and supporting an intrabinary shock origin.

## Contribution

It provides new hard X-ray data and analysis of PSR J1723-2837, constraining the physical parameters of the intrabinary shock model.

## Key findings

- Detection of X-ray radiation up to 79 keV.
- X-ray modulations at the 14.8-hour orbital period.
- Spectrum well described by an absorbed power-law with photon index ~1.3.

## Abstract

We report on the first NuSTAR observation of the gamma-ray emitting millisecond pulsar binary PSR J1723-2837. X-ray radiation up to 79 keV is clearly detected and the simultaneous NuSTAR and Swift spectrum is well described by an absorbed power-law with a photon index of ~1.3. We also find X-ray modulations in the 3-10 keV, 10-20 keV, 20-79 keV, and 3-79 keV bands at the 14.8-hr binary orbital period. All these are entirely consistent with previous X-ray observations below 10 keV. This new hard X-ray observation of PSR J1723-2837 provides strong evidence that the X-rays are from the intrabinary shock via an interaction between the pulsar wind and the outflow from the companion star. We discuss how the NuSTAR observation constrains the physical parameters of the intrabinary shock model.