Arecibo PALFA survey and Einstein@Home: binary pulsar discovery by volunteer computing

We report the discovery of the 20.7 ms binary pulsar J1952+2630, made using the distributed computing project Einstein@Home in Pulsar ALFA survey observations with the Arecibo telescope. Follow-up observations with the Arecibo telescope confirm the binary nature of the system. We obtain a circular orbital solution with an orbital period of 9.4 hr, a projected orbital radius of 2.8 lt-s, and a mass function of f = 0.15 M ☉ by analysis of spin period measurements. No evidence of orbital eccentricity is apparent; we set a 2σ upper limit e 1.7 × 10-3. The orbital parameters suggest a massive white dwarf companion with a minimum mass of 0.95 M ☉, assuming a pulsar mass of 1.4 M ☉. Most likely, this pulsar belongs to the rare class of intermediate-mass binary pulsars. Future timing observations will aim to determine the parameters of this system further, measure relativistic effects, and elucidate the nature of the companion star.