Composite image of the Milky Way flat area and Potoroo, where the red layer shows the ASKAP total intensity image at 1368 MHz, and the green and blue layers represent the WISE infrared images at 12 m and 22 m respectively. Known Galactic SNRs are represented by red circles (green, 2019, 2022), while known Galactic HII regions are marked by green circles (Anderson et al., 2014). This box highlights the parts that people are deeply interested in. The inset is a magnified ASKAP image showing Potoroo, where the red cross marks the location of the X-ray source and the red dashed line is Potoroo’s axis of symmetry, corresponding to the tail length studied in this paper. Credit: arXiv (2023). DOI: 10.48550/arxiv.2312.06961
Astronomers at the University of Western Sydney in Australia and elsewhere report the discovery of a new pulsar wind nebula and the pulsar that powers it.The findings were published in a paper posted on a preprint server on December 12 arXivproduced using the Australian Square Kilometer Array Pathfinder (ASKAP) and the MeerKAT and Parkes radio telescopes.
Pulsar wind nebulae (PWNe) are nebulae driven by pulsar winds. The pulsar wind is composed of charged particles; a pulsar core is created when it collides with the pulsar’s surroundings, specifically the slowly expanding supernova ejecta.
Particles in PWNe lose energy due to radiation and decrease as they move away from the central pulsar. Multi-wavelength studies of these objects, including X-ray observations, especially using spatially integrated spectroscopy in the X-ray band, have the potential to reveal important information about the particle flows in these nebulae. This can reveal important insights into the general properties of PWNe.
Now, a team of astronomers led by Sanja Lazarevi of Western Sydney University has discovered a new pulsar wind nebula in radio continuum surveys acquired by ASKAP and MeerKAT. They called the new PWN “Potoroo,” after a small marsupial native to Australia.
Next, they used the Parkes Ultra-Wideband Low Frequency (UWL) receiving system to detect the candidate pulsar, numbered PSR J16384713. Further observations of PSR J16384713 confirmed that it powers Potoroo.
Observations show that Potoroo exhibits a unique cometary morphology in both radio and X-ray bands. This means that the pulsar guides the PWN and travels through the ambient medium at supersonic speeds.
“For pulsars traveling at supersonic speeds through the ambient medium, the resulting ram pressure converts the PWN into a bow shock. This process confines the pulsar wind in the opposite direction to the direction of the pulsar’s motion, forming a comet-like flow. Shaped tail ,” explained the paper’s authors.
According to the study, Potoroo is at least 32,500 light-years away and has a radio size of about 68.5 light-years, while its X-ray size appears to be 10 times smaller. As a result, Potoroo has by far the longest PWN radio path.
The results show that Potoroo’s overall radio spectrum is unusually steep, with a level of -1.27. This is lower than typical values for known PWNe. Astronomers speculate that such a steep total spectral index may be due to the interaction of the parent supernova reverse shock wave with the PWN.
PSR J16384713 has a rotation period of 65.74 milliseconds and a dispersion of 1,553 pc/cm3It ranks second among all known radio pulsars. Observations found that PSR J16384713 is a young pulsar (characteristic age 24,000 years) with high spin luminosity and a large predicted velocity, exceeding 1,000 kilometers/second.
More information:
Sanja Lazarevi et al., Fast as Potoroo: Radio Continuous Sounding of the Bow Shock Pulsar Wind Nebula Powered by Pulsar J1638-4713, arXiv (2023). DOI: 10.48550/arxiv.2312.06961
Journal information:
arXiv
2023 Science X Network
citation: Astronomers detect new pulsar wind nebula and its associated pulsars (2023, December 26) Retrieved December 26, 2023 https://phys.org/news/2023-12-astronomomers- pulsar-nebula.html
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