Pulsar J1411+2551: A Low Mass New Double Neutron Star System

Abstract

In this work, we report the discovery and characterization of PSR J1411+2551, a new binary pulsar discovered in the Arecibo 327 MHz Drift Pulsar Survey. Our timing observations of the radio pulsar in the system span a period of about 2.5 years. This timing campaign allowed a precise measurement of its spin period (62.4 ms) and its derivative (9.6 $\pm$ 0.7) $\times 10^{-20}\mathrm{s}{\mathrm{s}}^{-1}$; from these, we derive a characteristic age of $\sim 10$Gyr and a surface magnetic field strength of 2.5 $\times 10^9$ G. These numbers indicate that this pulsar was mildly recycled by accretion of matter from the progenitor of the companion star. The system has an eccentric ($e=0.17$) 2.61 day orbit. This eccentricity allows a highly significant measurement of the rate of advance of periastron, $\dot{\ddot{I}}‰=0.07686\pm 0.00046^{\circ }{\mathrm{yr}}^{-1}$. Assuming general relativity accurately models the orbital motion, this implies a total system mass M = $2.538\pm 0.022M_{\odot }$. The minimum companion mass is $0.92M_{\odot }$ and the maximum pulsar mass is $1.62M_{\odot }$. The large companion mass and the orbital eccentricity suggest that PSR J1411+2551 is a double neutron star system; the lightest known to date including the DNS merger GW 170817. Furthermore, the relatively low orbital eccentricity and small proper motion limits suggest that the second supernova had a relatively small associated kick; this and the low system mass suggest that it was an ultra-stripped supernova.

Accepted for publication in APJ letters