Indian astronomers have carried out long-term radio observations of a “black widow” millisecond pulsar often called PSR J1544+4937. Outcomes of the observational marketing campaign, printed November 25 on the arXiv pre-print server, shed extra gentle on the properties of this pulsar.
Probably the most quickly rotating pulsars, these with rotation intervals under 30 milliseconds, are often called millisecond pulsars (MSPs). Researchers assume that they’re fashioned in binary techniques when the initially extra huge part turns right into a neutron star that’s then spun up as a consequence of accretion of matter from the secondary star.
A category of utmost binary pulsars with semi-degenerate companion stars is dubbed “spider pulsars.” These objects are additional categorized as “black widows” if the companion has extraordinarily low mass (lower than 0.1 photo voltaic lots), whereas they’re known as “redbacks” if the secondary star is heavier.
Found by the Large Meterwave Radio Telescope (GMRT) in 1991, PSR J1544+4937 is a black widow MSP with a spin interval of two.16 milliseconds. The pulsar is in a binary system with an orbital interval of two.9 hours orbiting round a low-mass companion star (with a mass of at the least 0.017 photo voltaic lots).
With the goal of unveiling extra insights into the properties of PSR J1544+4937, a crew of astronomers led by Sangita Kumari of the Tata Institute of Elementary Analysis in India has performed a 11-year monitoring marketing campaign of this supply utilizing GMRT and the Inexperienced Financial institution Telescope (GBT).
“The vast majority of the observations reported on this paper had been carried out with the GMRT, which is a radio interferometric array consisting of 30 dishes, every 45 meters in diameter…. In 2012, we used the Inexperienced Financial institution Telescope (GBT) to make a number of observations of PSR J1544+4937, with a view to assist decide the orbit of the system,” the researchers wrote.
To begin with, the crew measured the whole correct movement of PSR J1544+4937, which was discovered to be about 10.14 mas per 12 months. This allowed the astronomers to calculate the two−D transverse velocity of this pulsar utilizing two galactic electron density fashions, particularly NE2001 and YMW16. This velocity turned out to be at a stage of 140 and 58 km/s for NE2001 and YMW16, respectively. The gap to PSR J1544+4937 is estimated to be 3,900 (NE2001) or 9,450 gentle years (YMW16).
The dispersion measure of PSR J1544+4937 was measured to be roughly 23.22 laptop/cm3 and its attribute age was estimated to be some 42 billion years. The research additionally discovered that the pulsar has a floor magnetic discipline at a stage of 42 million Gauss and that the vitality loss fee of this supply is about 12 decillion erg/s. The mass of the companion star was calculated to be 0.0196 photo voltaic lots.
The analysis detected temporal variations of dispersion measure of PSR J1544+4937. Furthermore, the outcomes additionally point out frequency-dependent dispersion measure, variations of which, in response to the authors of the paper, may come up as a consequence of spatial electron density variations within the interstellar medium.
Sangita Kumari et al, Decade Lengthy Timing Research of the Black Widow Millisecond Pulsar J1544+4937, arXiv (2022). DOI: 10.48550/arxiv.2211.14107
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