A white dwarf companion to the relativistic pulsar PSR J1141-6545

TL;DR

This paper reports optical observations of the white dwarf companion to the pulsar PSR J1141-6545, confirming its nature and highlighting its significance for gravitational physics and binary evolution studies.

Contribution

First optical detection and characterization of the white dwarf companion to PSR J1141-6545, supporting its role in gravitational tests and binary evolution.

Findings

Optical counterpart detected with specific magnitudes.

Companion confirmed as a white dwarf.

Color discrepancy with theoretical cooling models.

Abstract

Pulsars with compact companions in close eccentric orbits are unique laboratories for testing general relativity and alternative theories of gravity. Moreover, they are excellent targets for future gravitational wave experiments like LISA and they are also highly important for understanding the equation of state of super-dense matter and the evolution of massive binaries. Here we report on optical observations of the 1.02 M_sun companion to the pulsar PSR J1141-6545. We detect an optical counterpart with apparent magnitudes V=25.08(11) and R=24.38(14), consistent with the timing position of the pulsar. We demonstrate that our results are in agreement with a white dwarf companion. However the latter is redder than expected and the inferred values are not consistent with the theoretical cooling tracks, preventing us from deriving the exact age. Our results confirm the importance of the PSR J1141-6545 system for gravitational experiments.