21 year timing of the black-widow pulsar J2051−0827

Abstract

Timing results for the black-widow pulsar J2051−0827 are presented, using a 21-year dataset from four European Pulsar Timing Array telescopes and the Parkes radio telescope. This dataset, which is the longest published to date for a black-widow system, allows for an improved analysis that addresses previously unknown biases. While secular variations, as identified in previous analyses, are recovered, short-term variations are detected for the first time. Concurrently, a significant decrease of ∼ 2.5 × 10 −3 cm −3 pc in the dispersion measure associated with PSR J2051−0827 is measured for the first time and improvements are also made to estimates of the proper motion. Finally, PSR J2051−0827 is shown to have entered a relatively stable state suggesting the possibility of its eventual inclusion in pulsar timing arrays.

Radio Pulse Search and X-Ray Monitoring of SAX J1808.4−3658: What Causes Its Orbital Evolution?

“…Four of them have anegative orbital period derivative (the orbit is shrinking), whereas only one (PSR J1959+2048) has a positive value (the orbit is expanding). In at least two cases (PSR J2051-0827 and PSR J2339-0533), the sign seems to be changing cyclically over timescales of the order of a few years (Pletsch & Clark 2015;Shaifullah et al 2016).…”

“…Several other low-mass X-ray binaries (LMXBs), comprising both neutron star and black hole accretors, are also observed to show a faster evolution than expected (see Section 6 for an in-depth discussion). There isa similar behavior in many (nonaccreting) binary radio millisecond pulsars with orbital parameters similar to those ofSAX J1808.4−3658, known as BWs,where the rotational power emitted in the form of wind and radiation by the pulsar is impinging and ablating the semi-degenerate 9 donor companion (Nice et al 2000;Doroshenko et al 2001;Lazaridis et al 2011;Shaifullah et al 2016). These systems have a companion star with a typical mass of 0.1 M e , and several (but not all) of them have orbital periods of about 1-3 hr.…”

“…a The orbital period of these pulsars shows a roughly cyclic behavior;see Shaifullah et al (2016) and Pletsch & Clark (2015).…”

Using Long-Term Millisecond Pulsar Timing to Model Pulsar Companions and their Host Star Clusters

“…Even the most recent studies of B1957+20 using twenty-one years of timing data only show marginal evidence for periodicity in its orbital properties (Shaifullah et al 2016). If our sample of stars have solar cycles similar to those seen in RS CVns (Hall 1989) and our own Sun (Hathaway 2010), we would require decades worth of data to accurately identify any periodicity to the data.…”

“…Previous studies of these sources have attempted to characterize the magnetic cycle of the companion star using only a few years of data (with the exception of J2051-0827 which has twenty-one years of observations (Shaifullah et al 2016)). If we consider a red noise process with power spectrum S −2 , the relative likelihood of measuring a periodic signal in only a few years of data can be quite large.…”