Astronomers have detected a new pulsar wind nebula and its companion pulsar

Composite image of the Galactic plane region and Potoroo, with the red layer showing the ASKAP total intensity image at 1368 MHz, and the green and blue layers representing the WISE infrared images at 12 m and 22 m respectively. Known Galactic SNRs are shown in red circles (Green, 2019, 2022), while known Galactic HII regions are marked in green circles (Anderson et al., 2014). The box highlights the section of deep interest. The inset is an ASKAP zoomed-in image showing Potoroo where a red cross marks the position of the X-ray source, while a red dashed line is Potoroo’s axis of symmetry, which corresponds to the length of the tail studied in this paper. Credit: arXiv (2023). DOI: 10.48550/arxiv.2312.06961

Astronomers from Western Sydney University in Australia and elsewhere have reported the discovery of a new pulsar wind nebula and a pulsar that drives it. The discovery, presented in a paper published on December 12 in the pre-print server arXivperformed using the Australian Square Kilometer Array Pathfinder (ASKAP), as well as the MeerKAT and Parkes radio telescopes.

Pulsar wind nebulae (PWNe) are nebulae powered by the wind of a pulsar. The pulsar wind is composed of charged particles; when it collides with the pulsar’s surroundings, especially with the slowly expanding supernova ejecta, it develops a PWN.

PWNe particles lose their radiation energy and become less energetic with distance from the central pulsar. Multiwavelength studies of these objects, including X-ray observations, especially using spatially-integrated spectra in the X-ray band, have the potential to uncover important information about the particle flow in this nebulae. This may reveal important insights into the nature of PWNe in general.

Now, a team of astronomers led by Sanja Lazarevi of Western Sydney University has found a new pulsar wind nebula in radio-continuum surveys obtained from ASKAP and MeerKAT. They named the new PWN “Potoroo,” after a small marsupial native to Australia.

Next, using the Parkes Ultra-Wideband Low (UWL) frequency receiver system, they found the pulsar candidate, which received the designation PSR J16384713. Further observations of PSR J16384713 confirm that it powers the Potoroo.

Observations show that Potoroo exhibits a distinct cometary morphology in the radio and X-ray bands. This suggests that the pulsar leads the PWN and travels supersonically through the ambient medium.

“For pulsars driven through the ambient medium at supersonic velocities, the resulting ram pressure transforms the PWN into a bow-shock. This process keeps the pulsar wind in the opposite direction of the pulsar motion, which forms a cometary-like. shaped tail,” the authors of the paper explained.

According to the study, Potoroo is located at a distance of at least 32,500 light years, has a radio magnitude of about 68.5 light years, while its X-ray magnitude appears to be 10 times smaller. Thus, Potoroo has the longest PWN radio paths known to date.

The results show that Potoroo has an unusually steep total radio spectrum at a level of -1.27. This is below the typical values ​​for known PWNe. Astronomers believe that such a steep total spectral index may be due to the interaction of the parent supernova reverse shock with the PWN.

As for PSR J16384713, it has a spin period of 65.74 milliseconds and a dispersion scale of 1,553 pc/cm3the second longest of all known radio pulsars. The observations found that PSR J16384713 is a young pulsar (with a characteristic age of 24,000 years), has a high spin-down luminosity, and a large projected velocity, exceeding 1,000 km / s.

More information:
Sanja Lazarevi et al, Fast as Potoroo: Radio Continuum Detection of a Bow-Shock Pulsar Wind Nebula Powered by Pulsar J1638-4713, arXiv (2023). DOI: 10.48550/arxiv.2312.06961

Journal information:

2023 Science X Network

Citation: Astronomers spot new pulsar wind nebula and its companion pulsar (2023, December 26) Retrieved December 26, 2023 from nebula.html

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