A new “Black Widow” millisecond pulsar has been discovered

PSRJ1555-2908 multi-band radio pulse profile. Credit: Ray et al. , 2022.

An international team of astronomers is reporting the detection of a new millisecond pulsar (MSP) using the Green Bank Telescope (GBT). The newly discovered pulsar, called PSR J1555-2908, turned out to be one of the so-called “Black Widow” MSPs. The findings are detailed in a paper published on February 10th at

The fastest rotating pulsar, that is, the pulsar with a rotation period of less than 30 milliseconds, is known as MSP. Researchers assume that the heavier components initially turn into neutron stars, and then they are formed in a star system as they spin up due to the accretion of matter from secondary stars.

A class of extreme binary pulsars with semi-degenerate binaries is called a “spider pulsar”. If the companion has a very small mass (less than 0.1), these objects are further classified as “black widow”. Solar mass), When the secondary star is heavy, it is called “redback”.

PSR J1555-2908 was first identified as a gamma-ray point source by NASA’s Fermi spacecraft. Given that many point sources in the sky of GeV gamma rays are known to be powered by pulsars, the PSR J1555-2908 was recognized as a promising target for pulsation. .. Therefore, a team of astronomers, led by Paul S. Ray of the United States Naval Research Laboratory in Washington, DC, used GBT to investigate this source and, as a result, detected radio pulsations.

“This fast and energetic millisecond Pulsar It was first detected as a gamma-ray point source in the sky survey observations of the Fermi Large Area Telescope (LAT). Guided by a radio point source with a steep spectrum in the Fermi error region, we performed a search at 820MHz with the Green Bank Telescope, which first discovered the pulsation, “explained the researchers.

GBT observations confirmed PSRJ1555-2908 radio pulsations with a period of 1.79 ms. Subsequent 5-minute GBT observations in the S band confirmed the discovery and found that the pulse width at 559.4 Hz was very narrow (about 3%). Gamma-ray pulsations from this source were also detected by analyzing Fermi data.

Studies have shown that the PSR J1555-2908 is an interacting binary system with an orbital period of approximately 0.23 days. The mass of a neutron star was estimated to be about 1.4 solar mass, and the minimum mass of a companion star was calculated to be about 0.052 solar mass. These results show the “Black Widow” class of this MSP.

The PSR J1555-2908 has a relatively high spin-down power at the level of 310 decillion erg / s. Other MSPs with comparable spin-down power are known to exhibit bright non-thermal pulsations, so such high values ​​are good candidates for searching for X-ray pulsations. However, the team analyzed the data available from the Neutron Star Interior Composition ExploreR (NICER) and so far found no significant X-ray pulsations from this pulsar. This is subject to change as researchers continue to monitor PSRJ1555-2908 using ground facilities.

Radio pulsation detected from gamma-ray millisecond pulsar PSRJ2039-5617

For more information:
Black Widow Millisecond Pulsar PSRJ1555-2908, arXiv: 2202.04783 discovery, timing, and multi-wavelength observations [astro-ph.HE]

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Quote: Discovered new “Black Widow” millisecond pulsar (February 17, 2022) from https: // February 2022 Obtained on the 17th

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A new “Black Widow” millisecond pulsar has been discovered

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