Astronomers detect new radio source of unknown origin

Astronomers detect new radio source of unknown origin

Astronomers detect new radio source of unknown origin

Tricolor HST image of NGC 2082 superimposed on ASKAP and ATCA contours. The inset image at lower left provides a zoom in from J054149.24–641813.7, showing the absence of any optical counterpart. Credit: Balzan et al., 2022.

During observations of the radio continuum of a spiral galaxy known as NGC 2082, Australian astronomers discovered a mysterious bright and compact radio source, which was given the designation J054149.24–641813.7. The origin and nature of this source is unknown and requires further investigation. The discovery is reported in an article published May 23 on the arXiv preprint repository.

In general, radio sources are various objects in the universe that emit relatively large amounts of radio waves. Among the most powerful sources of such emissions are pulsars, certain nebulae, quasars and radio galaxies.

Now, a team of astronomers led by Joel Balzan of the University of Western Sydney in Australia, reports the discovery of a new radio source, the true nature of which is still uncertain. While observing NGC 2082 using the Australian Square Kilometer Array Pathfinder (ASKAP), Australia Telescope Compact Array (ATCA) and Parkes Radio Telescope, they identified a strong point radio source positioned 20 arc seconds away from the center of the galaxy. NGC 2082 is a G-type spiral galaxy in the constellation Dorado, located about 60 million light-years from Earth, with a diameter of about 33,000 light-years.

“We present observations of the radio continuum of NGC 2082 using the ASKAP, ATCA, and Parkes telescopes from 888 MHz to 9000 MHz. Some 20 arcseconds from the center of this nearby spiral galaxy, we discovered a source bright compact radio, J054149.24–641813.7, origin unknown,” the researchers wrote in the paper.

The study found that the radio luminosity of J054149.24–641813.7 at 888 MHz is at a level of 129 EW/Hz and has a flat radio spectral index (about 0.02). This, the astronomers say, disfavors the scenario in which J054149.24–641813.7 could be a supernova remnant (SNR) or a pulsar, suggesting that the source could be thermal in origin.

The researchers noted that the compact nature of J054149.24–641813.7 and its location on the outskirts of NGC 2082 are reminiscent of those of some fast radio bursts (FRBs). However, the results suggest that J054149.24–641813.7 is probably not bright enough to be a persistent radio source with an embedded FRB progenitor.

Astronomers have concluded that the most likely remaining possibility is that J054149.24–641813.7 is an extragalactic background source, such as a near-stellar object (QSO, quasar), radio galaxy, or active galactic nucleus (AGN) . They added that the flat spectral index as well as a somewhat weak bias at 5500 and 9000 MHz support this hypothesis. However, there are currently no high-resolution neutral atomic hydrogen (HI) absorption data for NGC 2082, which could confirm this hypothesis.

“We find that the probability of finding such a source behind NGC 2082 is P=1.2%, and conclude that the most likely origin for J054149.24–641813.7 is a background quasar or radio galaxy,” the authors explained. authors of the article.


Astronomers discover new extragalactic circular radio source


More information:
Joel CF Balzan et al, A study of the radio continuum of NGC 2082. arXiv:2205.11144v1 [astro-ph.GA]arxiv.org/abs/2205.11144

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Quote: Astronomers detect new radio source of unknown origin (2022, May 31) Retrieved May 31, 2022 from https://phys.org/news/2022-05-astronomers-radio-source-unknown.html

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