Astrological researchers of Australia's Western Sydney University have discovered a new compact radio source amid continuum observations of the NGC 2082 spiral galaxy. Led by Joel Balzan, the team of astronomers concluded via a paper published within the arXiv preprint repository on May 23 that the bright and compact radio source has no known origin and requires further investigation to understand fully.
Utilizing the Australian Square Kilometer Array Pathfinder (ASKAP) alongside the Parkes radio telescope and the Australian Telescope Compact Array (ATCA), the team could locate the radio source with the designation J054149.24-641813.7 following consistent observations of the NGC 2082 galaxy. The radio source is about 20 arcseconds from the galaxy's center, yet its overall nature remains unresolved.
"We present radio continuum observations of NGC 2082 using ASKAP, ATCA, and Parkes telescopes from 888 MHz to 9,000 MHz," reads the astronomer's findings within the published report. "Some 20 arcsec from the center of this nearby spiral galaxy, we discovered a bright and compact radio source, J054149.29-641813.7, of unknown origin."
Located within the Dorado constellation, which is about 60 million light-years from Earth, NGC 2082 is a G-type spiral galaxy measuring approximately 33,000 light-years in diameter. It's a hotbed of cosmic information for such researchers, allowing astronomers more detailed information on necessary concepts in galaxy formation, magnetic field evolution, and the obvious characteristic denotation of both transient and variable radio sources.
The J054149.29-641813.7 radio source carries a luminosity of about 888 MHz at 129 EW/Hz and, akin to fellow fast radio bursts (FRBs), is positioned on the outskirts of the NGC 2082 galaxy. The astronomers first considered the radio source to be a supernova remnant (SNR), given the fact that a Type II supernova was discovered in the area in 2015 via Robert Evans However, its overall luminosity and flat radio spectral index (about 0.02) suggests it has more of a thermal origin.
Other conditional aspects provided by the team posited it as a pulsar or even a persistent radio source with an embedded FRB progenitor, though, again, its limited brightness proves otherwise. The Australian researchers highlight that it could be an extragalactic background source, which essentially means it can be anything, most prominent among concepts being an active galactic nucleus (AGN), quasi-stellar object (QSO), or full radio galaxy, though the team remains unclear, thus requiring more research.
Within the paper, the team simply posits, "We find that the probability of finding such a source behind NGC 2082 is P = 1.2 percent, and conclude that the most likely origin for J054149.29-641813.7 is a background quasar or radio galaxy."
With little full research into the whole of the NGC-2082 galaxy, like high resolution neutral atomic hydrogen (HI) absorption data, it's difficult to make an adamant hypothesis on the overall nature of J054149.29-641813.7. Its existing weak polarization, which sits at 5,500 and 9,000 MHz, alongside the radio source's flat spectral index lends credence to the team's current positioning of an extragalactic background source.
Astronomical radio sources in space are integral to our understanding of the cosmos. They come in quite a few varied shapes, sizes, and with underlying feature sets that allow researchers like those mentioned in this study to fully map and diagnose various occurrences within space, like defining quasars, pulsars, radio galaxies, and even certain nebulas.
