Dual-wavelength image of SNR CTB 87: NVSS 1.4 GHz radio continuum image in red and Chandra X-ray image (0.5–7 keV) in blue. The white cross indicates the location of the X-ray point source. Credit: Liu et al., 2024.
Using the Five Hundred Meter Aperture Spherical Radio Telescope (FAST), astronomers from Nanjing University in China and elsewhere have detected a radio pulsar in a supernova remnant known as CTB 87. The discovery is reported in an article published on February 1 on the arXiv pre-print server.
Pulsars are highly magnetized rotating neutron stars that emit a beam of electromagnetic radiation. They are usually detected as short bursts of radio emission; however, some of them are also observed via optical, x-ray and gamma-ray telescopes.
CTB 87 is a plerion supernova remnant (SNR) with an X-ray luminosity nearly 100 times lower than that of the Crab Nebula in the 0.15 to 3 keV band. It hosts a pulsar wind nebula (PWN) with an X-ray trailing morphology. However, although PWNe are nebulae powered by the wind of a pulsar, no such object in this SNR has been found at this day.
Recently, a team of astronomers led by Qian-Cheng Liu of Nanjing University studied a point X-ray source in CTB 87, designated CXOU J201609.2+371110. They report that FAST radio pulses were discovered from this source.
“We report our discovery of the radio pulsar, PSR J2016+3711, in the supernova remnant CTB 87, with a pulse significance ∼10.8 ????, which confirms the compact nature of the point source of X-rays in CTB 87,” the researchers wrote.
According to the paper, PSR J2016+3711, located at a distance of about 43,400 light years, has a rotation period of 50.8 milliseconds and a dispersion measurement of about 428 pc/cm.3. The pulsar’s descending luminosity was measured at 22 undecillion erg/s, while its characteristic age is estimated at 11,100 years. PSR J2016+3711 is therefore the first SNR pulsar detected with FAST.
The strength of the dipolar magnetic field of the equatorial surface of PSR J2016+3711 was found to be at a level of 1.9 TG. The study also found that the radio pulse profile of this pulsar is narrow, without broad wings, suggesting that the radio beam starting near the magnetic polar cap is inherently narrow, or that the line of sight passes just a small segment of a broad beam. .
Since many pulsars also emit gamma rays, Liu’s team also analyzed data from NASA’s Fermi spacecraft to look for a possible gamma-ray pulse from PSR J2016+3711. However, they found no gamma ray pulses coming from this source. The researchers added that more observations are needed to definitively rule out PSR J2016+3711 as a gamma ray emitter.
“More follow-up radio observations spanning years would be helpful in obtaining a more precise timing solution, which could then be used to fold gamma-ray data and search for pulsation,” the authors concluded. study.
More information:
Qian-Cheng Liu et al, Discovery and timing of pulsar J2016+3711 in the CTB 87 supernova remnant with FAST, arXiv (2024). DOI: 10.48550/arxiv.2402.00578
Journal information:
arXiv
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Quote: Chinese astronomers find a radio pulsar in a supernova remnant (February 9, 2024) retrieved February 9, 2024 from
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