A light redback companion of PSR J1622-0315 and irradiation power in spider systems

TL;DR

This study presents optical observations of the redback pulsar PSR J1622-0315, revealing a low irradiation power in its companion star, and compares its properties with other spider systems to understand irradiation effects.

Contribution

First detailed optical analysis of PSR J1622-0315's companion, establishing its classification as a spider system and assessing its irradiation properties.

Findings

Companion mass estimated at 0.122 solar masses.

Pulsar irradiation in PSR J1622-0315 is negligible.

Higher irradiation luminosities observed in transitional millisecond pulsars.

Abstract

We report optical observations of the millisecond pulsar binary system PSR J1622-0315 with the Lulin 1m telescope in Taiwan and the Lijiang 2.4m telescope in China between 2019 and 2021. The companion of the pulsar, which is of V~19 mag, showed ellipsoidal-distorted orbital variations in its light curves. The best-fit model to the light curves, with the binary code PHOEBE, gives a companion mass of 0.122+/-0.006 M_sun. This places PSR J1622-0315 in the spider-system subclass. We compared the properties of PSR J1622-0315 with other spider pulsar binaries for the scalings between the spin-down luminosity derived for the pulsar, irradiation luminosity of the companion, and X-ray luminosity of the binary. We find that pulsar irradiation in PSR J1622-0315 is insignificant and the irradiation luminosity of the transitional millisecond pulsars PSR J1023+0038 and PSR J1227-4853 are the highest among the redback systems.