Astronomers spotted a mysterious radio source coming from a spiral galaxy

(J. C. F Balzan et al. / aXiv, 2022)

Australian astronomers discovered a mysterious new source of radio emission coming from the spiral galaxy NGC 2082.

The scientists believe that the source could be a quasar or a background radio galaxy.

Radio emissions of a spiral galaxy without an active galactic nucleus are mainly due to nonthermal synchrotron radiation from supernova remnants.

The other option could be a thermal bremsstrahlung from ionized hydrogen regions where new stars are forming.

So, scientists conduct deep surveys of galaxies in the radio range to obtain important data on the effect of star formation on the interstellar medium inside galaxies.

Now a team of astronomers from the University of Western Sydney report the discovery of a new radio source J054149.24–641813.7, whose nature is still unclear.

They made the discovery during a radio survey of the spiral galaxy NGC 2082, located 60 million light-years from us.

The researchers, led by Joel C. F. Balzan, used the ASKAP, ATCA and Parkes telescopes in the frequency range from 888 to 9000 megahertz.

Balzan’s team also used observations of the galaxy from the Hubble Space Telescope.

The astronomers spotted J054149.24–641813.7 located about 20 arc seconds from the center of the galaxy.

The compact radio source of unknown origin has a flat spectral index of radio emission, which does not look like a supernova remnant or a radio pulsar.

However, the researchers have not completely ruled out a pulsar wind nebula.

The radiation from the source can be of a thermal nature and is characterized by a low linear polarization.

At the same time, J054149.24–641813.7 is two orders of magnitude less bright than radio sources associated with repetitive fast radio bursts.

Right now, the most plausible hypothesis explaining the nature of J054149.24–641813.7 is a background source of radio emission.

It could be a quasar, a radio galaxy, or an active galactic nucleus. However, new observational data are needed to confirm either idea.

Sources:

• arXiv.org: https://arxiv.org/abs/2205.11144
• Phys.org: https://phys.org/news/2022-05-astronomers-radio-source-unknown.html
• Wikipedia: https://en.wikipedia.org/wiki/Bremsstrahlung

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