Discovery, Timing, and Multiwavelength Observations of the Black Widow Millisecond Pulsar PSR J1555-2908

TL;DR

This paper reports the discovery and multiwavelength observations of a new millisecond pulsar, PSR J1555-2908, revealing its binary nature, energetic properties, and companion star heating effects, advancing understanding of black widow pulsar systems.

Contribution

The paper presents the first discovery of PSR J1555-2908 as a radio and gamma-ray pulsar, with detailed timing and multiwavelength observations, including the detection of companion star heating and eclipses.

Findings

Discovered a 1.79 ms pulsar in a 5.6 hr binary system.

Detected gamma-ray pulsations and derived a full timing solution.

Observed eclipses of radio pulses caused by companion star material.

Abstract

We report the discovery of PSR J1555-2908, a 1.79 ms radio and gamma-ray pulsar in a 5.6 hr binary system with a minimum companion mass of 0.052 $M_\odot$. This fast and energetic ($\dot E = 3 \times 10^{35}$ erg/s) millisecond pulsar was first detected as a gamma-ray point source in Fermi LAT sky survey observations. Guided by a steep spectrum radio point source in the Fermi error region, we performed a search at 820 MHz with the Green Bank Telescope that first discovered the pulsations. The initial radio pulse timing observations provided enough information to seed a search for gamma-ray pulsations in the LAT data, from which we derive a timing solution valid for the full Fermi mission. In addition to the radio and gamma-ray pulsation discovery and timing, we searched for X-ray pulsations using NICER but no significant pulsations were detected. We also obtained time-series r-band photometry that indicates strong heating of the companion star by the pulsar wind. Material blown off the heated companion eclipses the 820 MHz radio pulse during inferior conjunction of the companion for ~10% of the orbit, which is twice the angle subtended by its Roche lobe in an edge-on system.