Eight Millisecond Pulsars Discovered in the Arecibo PALFA Survey

TL;DR

This paper reports the discovery of eight millisecond pulsars in binary systems from the Arecibo PALFA survey, providing detailed timing solutions and analyzing their distribution and properties in the galaxy.

Contribution

It presents new binary millisecond pulsar discoveries, detailed timing solutions, and insights into their galactic distribution and observational biases, advancing understanding of MSP populations.

Findings

Discovered eight new binary MSPs with detailed timing solutions.

Identified a correlation between Galactic scale height and binary mass function.

Reported possible bimodality in MSP white dwarf mass function.

Abstract

We report on eight millisecond pulsars (MSPs) in binary systems discovered with the Arecibo PALFA survey. Phase-coherent timing solutions derived from 2.5 to 5 years of observations carried out at Arecibo and Jodrell Bank observatories are provided. PSR J1921+1929 is a 2.65-ms pulsar in a 39.6-day orbit for which we detect $\gamma$-ray pulsations in archival Fermi data. PSR J1928+1245 is a very low-mass-function system with an orbital period of 3.3 hours that belongs to the non-eclipsing black widow population. We also present PSR J1932+1756, the longest-orbital-period (41.5 days) intermediate-mass binary pulsar known to date. In light of the numerous discoveries of binary MSPs over the past years, we characterize the Galactic distribution of known MSP binaries in terms of binary class. Our results support and strengthen previous claims that the scatter in the Galactic scale height distribution correlates inversely with the binary mass function. We provide evidence of observational biases against detecting the most recycled pulsars near the Galactic plane, which overestimates the scale height of lighter systems. A possible bimodality in the mass function of MSPs with massive white dwarfs is also reported.