A possible optical counterpart to the old nearby pulsar J0108-1431

TL;DR

This study suggests a potential optical counterpart to the old pulsar J0108-1431, providing insights into neutron star cooling and magnetosphere evolution through optical/UV observations.

Contribution

The paper identifies a candidate optical counterpart to pulsar J0108-1431 based on re-analyzed VLT data and proper motion measurements, advancing neutron star surface temperature studies.

Findings

Candidate optical counterpart identified near pulsar's radio position.

Optical fluxes are consistent with thermal emission from neutron star surface.

Brightness temperature estimated at 9×10^4 K for the candidate object.

Abstract

The multi-wavelength study of old (>100 Myr) radio pulsars holds the key to understanding the long-term evolution of neutron stars, including the advanced stages of neutron star cooling and the evolution of the magnetosphere. Optical/UV observations are particularly useful for such studies because they allow one to explore both thermal and non-thermal emission processes. In particular, studying the optical/UV emission constrains temperature of the bulk of the neutron star surface, too cold to be measured in X-ray observations.Aim of this work is to identify the optical counterpart of the very old (166 Myr) radio pulsar J0108-1431. We have re-analyzed our original VLT observations (Mignani et al. 2003), where a very faint object was tentatively detected close to the radio position, near the edge of a field galaxy. We found that the backward extrapolation of the PSR J0108-1431 proper motion recently measured by CHANDRA(Pavlov et al. 2008) nicely fits the position of this object. Based on that, we propose it as a viable candidate for the optical counterpart to PSR J0108-1431. The object fluxes (U =26.4+/-0.3; B =27.9; V >27.8) are consistent with a thermal spectrum with a brightness temperature of 9X10^4 K (for R = 13 km at a distance of 130 pc), emitted from the bulk of the neutron star surface. New optical observations are required to confirm the optical identification of PSR J0108-1431 and measure its spectrum.