High-Energy Variability of PSR J1311-3430

TL;DR

This study investigates the multi-wavelength variability of the black-widow pulsar PSR J1311-3430, revealing orbital modulation in gamma-ray emission and correlated X-ray and optical flares, suggesting complex intrabinary interactions.

Contribution

It provides the first detailed analysis of the pulsar's orbital modulation and multi-wavelength flaring activity, linking gamma-ray, X-ray, and optical variability to intrabinary shock dynamics.

Findings

Orbital modulation observed in gamma-ray emission peaking near inferior conjunction.

X-ray and optical flares are correlated and occur at various orbital phases.

Flaring activity exhibits a power-law intensity distribution with a duty cycle of 7-19%.

Abstract

We have studied the variability of the black-widow type binary millisecond pulsar PSR J1311$-$3430 from optical to gamma-ray energies. We confirm evidence for orbital modulation in the weak off-pulse $\ge$200-MeV emission, with a peak at $\phi_B\approx 0.8$, following pulsar inferior conjunction. The peak has a relatively hard spectrum, extending above $\sim 1$\,GeV. XMM-Newton and Swift UV observations also show that this source's strong X-ray flaring activity is associated with optical/UV flares. With a duty cycle $\sim 7-19$%, this flaring is quite prominent with an apparent power-law intensity distribution. Flares are present at all orbital phases, with a slight preference for $\phi_B=0.5-0.7$. We explore possible connections of these variabilities with the intrabinary shock and magnetic activity on the low mass secondary.