The Unusual Binary Pulsar PSR J1744−3922: Radio Flux Variability, Near‐Infrared Observation, and Evolution

Abstract

PSR J1744À3922 is a binary pulsar exhibiting highly variable pulsed radio emission. We report on a statistical multifrequency study of the pulsed radio flux variability which suggests that this phenomenon is extrinsic to the pulsar and possibly tied to the companion, although not strongly correlated with orbital phase. The pulsar has an unusual combination of characteristics compared to typical recycled pulsars: a long spin period (172 ms); a relatively high magnetic field strength (1:7 ; 10 10 G); a very circular, compact orbit of 4.6 hr; and a low-mass companion (0.08 M ). These spin and orbital properties are likely inconsistent with standard evolutionary models. We find similarities between the properties of the PSR J1744À3922 system and those of several other known binary pulsar systems, motivating the identification of a new class of binary pulsars. We suggest that this new class could result from: a standard accretion scenario of a magnetar or a high magnetic field pulsar; common envelope evolution with a low-mass star and a neutron star, similar to what is expected for ultracompact X-ray binaries; or accretion induced collapse of a white dwarf. We also report the detection of a possible K 0 ¼ 19:30(15) infrared counterpart at the position of the pulsar, which is relatively bright if the companion is a helium white dwarf at the nominal distance, and discuss its implications for the pulsar's companion and evolutionary history.

EINSTEIN@HOMEDISCOVERY OF 24 PULSARS IN THE PARKES MULTI-BEAM PULSAR SURVEY

“…Like our discovery, PSR J1744−3922 also exhibits nulling and is visible for approximately 25 % of the time at 1.4 GHz. PSR J1744−3922, and thus PSR J1726−31, might be the members of a new class of binary pulsars as proposed by Breton et al (2007): these binary pulsars have long spin periods, large magnetic fields (∼ 10 10−11 G), low-mass companions, and low orbital eccentricities. Their evolutionary history is not well understood and known formation channels fail to explain all of their properties.…”

The Slowest Spinning X-Ray Pulsar in an Extragalactic Globular Cluster

“…AIC is anticipated to be responsible for the population of slow isolated pulsars with high magnetic fields in GCs (e.g. Lyne et al 1996;Breton et al 2007) and to be the origin of some slow accreting X-ray pulsars in the field such as 4U 1626−67 (e.g. Yungelson et al 2002), though it has never been observed directly.…”

Formation and evolution of compact binaries in globular clusters – II. Binaries with neutron stars

“…To explain this, it has been suggested that the NS in 4U 1626−67 was recently formed via AIC (Yungelson, Nelemans & van den Heuvel 2002). Several radio pulsars in the Galaxy possess relatively high B fields and long periods, with low‐mass companions in low‐eccentricity orbits (Breton et al 2007). They argue that these systems can be well‐explained through AIC.…”