# Identification of the white dwarf companion to millisecond pulsar J2317+1439

## TL;DR

This study identifies the white dwarf companion to pulsar J2317+1439, estimating its properties and suggesting the pulsar might be more massive than two solar masses, which has implications for neutron star physics.

## Contribution

First identification of the white dwarf companion to pulsar J2317+1439 using optical observations and modeling, providing new constraints on the system's parameters.

## Key findings

- White dwarf companion has a mass of approximately 0.39 solar masses.
- Estimated pulsar mass could exceed two solar masses.
- White dwarf cooling age is about 10.9 billion years.

## Abstract

We report identification of the optical counterpart to the companion of the millisecond pulsar J2317+1439. At the timing position of the pulsar, we find an object with $g=22.96\pm0.05$, $r=22.86\pm0.04$ and $i=22.82\pm0.05$. The magnitudes and colors of the object are consistent with it being a white dwarf. By comparing with white dwarf cooling models, we estimate that it has a mass of $0.39^{+0.13}_{-0.10}$ M$_{\odot}$, an effective temperature of $8077^{+550}_{-470}$ K and a cooling age of $10.9\pm0.3$ Gyr. Combining our results with published constraints on the orbital parameters obtained through pulsar timing, we estimate the pulsar mass to be $3.4^{+1.4}_{-1.1}$ M$_{\odot}$. Although the constraint on the pulsar mass is still weak, there is a significant possibility that the pulsar could be more massive than two solar mass.