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

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_{\mathrm{spin}}\sim$185 ms) and orbital period ($P_{\mathrm{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, $\dot{\ddot{I}}‰=0.00078$(4) deg/yr, which implies a total mass (M${}_{\mathrm{tot}}=2.59$(4) M${}_{\odot }$) consistent with other DNS systems. The $2\ddot{I}ƒ$ constraints on M${}_{\mathrm{tot}}$ place limits on the pulsar and companion masses ($m_{\mathrm{p}}<1.32$ M${}_{\odot }$ and $m_{\mathrm{c}}>1.30$ 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.

8 pages, 6 figures