Multiwavelength Observations of the Redback Millisecond Pulsar J1048+2339

TL;DR

This study presents detailed radio, optical, and gamma-ray observations of the redback millisecond pulsar J1048+2339, revealing its orbital dynamics, companion characteristics, and pulsar wind interactions, enhancing understanding of such binary systems.

Contribution

It provides the first precise astrometric and orbital parameters for J1048+2339, along with insights into its asymmetric heating and intrabinary shock phenomena.

Findings

Precise orbital and astrometric parameters derived from two years of timing.

Identification of a variable optical counterpart with orbital modulation.

Evidence of asymmetric heating likely caused by pulsar wind interactions.

Abstract

We report on radio timing and multiwavelength observations of the 4.66 ms redback pulsar J1048+2339, which was discovered in an Arecibo search targeting the Fermi-LAT source 3FGLJ1048.6+2338. Two years of timing allowed us to derive precise astrometric and orbital parameters for the pulsar. PSR J1048+2339 is in a 6-hour binary, and exhibits radio eclipses over half the orbital period and rapid orbital period variations. The companion has a minimum mass of 0.3 solar masses, and we have identified a $V \sim 20$ variable optical counterpart in data from several surveys. The phasing of its $\sim 1$~mag modulation at the orbital period suggests highly efficient and asymmetric heating by the pulsar wind, which may be due to an intrabinary shock that is distorted near the companion, or to the companion's magnetic field channeling the pulsar wind to specific locations on its surface. We also present gamma-ray spectral analysis of the source and preliminary results from searches for gamma-ray pulsations using the radio ephemeris.