PSR J1930-1852: a pulsar in the widest known orbit around another neutron star

TL;DR

The paper reports the discovery and analysis of PSR J1930-1852, a pulsar in the widest known orbit around a neutron star, with unique properties challenging existing models of double neutron star systems.

Contribution

It presents the discovery of a new DNS pulsar with the longest spin and orbital periods, and provides measurements that challenge current population models.

Findings

Longest orbital period among known recycled pulsars in DNS systems

Relativistic periastron advance measurement consistent with other DNS systems

Constraints on pulsar and companion masses based on orbital dynamics

Abstract

In the summer of 2012, during a Pulsar Search Collaboratory workshop, two high-school students discovered J1930$-$1852, a pulsar in a double neutron star (DNS) system. Most DNS systems are characterized by short orbital periods, rapid spin periods and eccentric orbits. However, J1930$-$1852 has the longest spin period ($P_{\rm spin}\sim$185 ms) and orbital period ($P_{\rm b}\sim$45 days) yet measured among known, recycled pulsars in DNS systems, implying a shorter than average and/or inefficient recycling period before its companion went supernova. We measure the relativistic advance of periastron for J1930$-$1852, $\dot{\omega}=0.00078$(4) deg/yr, which implies a total mass (M$_{\rm{tot}}=2.59$(4) M$_{\odot}$) consistent with other DNS systems. The $2\sigma$ constraints on M$_{\rm{tot}}$ place limits on the pulsar and companion masses ($m_{\rm p}<1.32$ M$_{\odot}$ and $m_{\rm c}>1.30$ M$_{\odot}$ respectively). J1930$-$1852's spin and orbital parameters challenge current DNS population models and make J1930$-$1852 an important system for further investigation.