Two articles accepted for publication, one in “The Astrophysical Journal” and one in “The Astrophysical Journal Letters”, report different aspects of a study on the Milky Way’s center. A team of researchers used the MeerKAT radio telescope to examine the galactic center with a clarity and depth never obtained before. This made it possible to obtain new information on radio bubbles, supernova remnants, star nurseries, the region around the supermassive black hole at the center of the Milky Way, and many radio filaments.
Increasingly powerful and sensitive instruments are discovering new phenomena and objects at the center of the Milky Way. It’s a difficult region to explore because it’s full of dust that blocks many electromagnetic frequencies. Radio waves are among the ones that pass through dust, so radio telescopes are invaluable in studying that region. MeerKAT is one of the precursors of SKA, the next-generation radio telescope, and uses various technologies being developed for SKA with results that are already excellent.
A survey conducted by SARAO (South African Radio Astronomy Observatory) exploited the MeerKAT radio telescope’s potential to offer the most complete radio map ever obtained of the center of the Milky Way, in this case at 1.28 GHz. MeerKAT observations of the galactic center were already used in conjunction with X-ray observations conducted with NASA’s Chandra X-ray Observatory in a study published in May 2021 in the journal “Monthly Notices of the Royal Astronomical Society”.
The results of this survey based on MeerKAT observations only cover an area 30 times that of the full Moon. The researchers took 20 observations for a total of 200 hours to obtain the data that was subsequently processed by two supercomputers in Cape Town, South Africa. The top image (I. Heywood, SARAO) shows the Milky Way center as seen by MeerKAT with colors indicating bright radio emissions while gray tones indicate weak radio emissions.
Among the discoveries made thanks to this survey, there are many radio filaments, structures up to 100 light-years long whose origin is not yet clear. They were discovered 35 years ago and since then many astronomers tried to uncover their secrets. MeerKAT showed that there are far more of them than were known and now it will be possible to study a lot of them and in detail. It’s no coincidence that one of the two articles linked to this survey is focused on these structures.
Other interesting phenomena and objects observed in this survey are the giant radio bubbles discovered a few years ago, the area around the supermassive black hole Sagittarius A*, star nurseries, and supernova remnants, of which new candidates have been discovered. The various radio sources must be examined to understand which are extragalactic, for example, supermassive black holes in other galaxies.
The bottom image (I. Heywood, SARAO) shows, in particular, an emission that has the appearance of a cirrus of the super bubble in the center of the Milky Way through a radio arc, a complex of many parallel radio filaments. The radio bubble is nested in the region of the supermassive black hole Sagittarius A*.
These extraordinary results obtained thanks to the MeerKAT radio telescope are actually not surprising given that this instrument already demonstrated the progress achieved in the development of radio astronomy technologies. MeerKAT will be upgraded and eventually integrated into the SKA radio telescope over the next few years, so we can expect even more detailed images to discover everything that happens in the center of the Milky Way and beyond.
