Magnetic Threads For A Tapestry called the Milky Way (Cosmology)

It’s a spectacular new view of the center of the Milky Way, obtained by combining data from the Chandra space telescope and the MeerKat radio telescope in South Africa. Reveals complex plasma filaments and plumes – evidence of ongoing magnetic reconnection events. The details of the study in Monthly Notices of the Royal Astronomical Society

What you see here is not the canvas of a contemporary artist: it is a new map of the Center of the Milky Way , our galaxy, and shows details that go above and below the galactic plane, the disk in which most of the stars reside. The artist, or rather, the artists in this case are the Nasa Chandra X-ray Space Telescope and the South African MeerKat radio telescope .

The “brushstrokes” of orange, green, blue and purple represent emissions at different energies, but always in the X, detected during 370 pointing by Chandra. Those in lilac and gray are instead the radio emissions picked up by MeerKat, which combined with the first have allowed to create this spectacular vision.

At the origin of the emissions there are complex filiform structures of incandescent plasma immersed in the magnetic fields present. Among these structures, the filament capable of emitting radio and X waves called G0.17-0.41, in the image highlighted with a red rectangle slightly lower left , is particularly interesting . About 20 light years long, according to the study that reports the map analysis – published in the June issue of Monthly Notices of the Royal Astronomical Society –  G0.17-0.41 could be the product of magnetic reconnection events, a process that occurs when two magnetic field lines break and connect with each other, releasing enormous amounts of energy. The same phenomenon underlying events such as solar flares, coronal mass ejections, magnetic storms and polar auroras.

But the new landscape also reveals other wonders of the Galactic Center. In addition to X-rays reflected by dust around X-ray sources (circled in green),  Sagittarius A * (the supermassive black hole at the center of our galaxy), the Arches star cluster , the quintuplet cluster , cold gas clouds and the molecular complex Sagittarius C, the map also shows two large plumes of hot gas extending for about 700 light years respectively above and below the two gas filaments: structures much smaller than Fermi bubbles which, according to the study, could be galactic jets in which the gas is likely heated by supernova explosions and magnetic reconnections near the center of the galaxy.

Magnetic reconnection events – normally not energetic enough to be detected in X-rays, except for the most energetic ones in the center of the galaxy – can play an important role in warming the interstellar medium . These events could also be responsible for the acceleration of the particles that make up cosmic rays and the turbulence in the interstellar medium that triggers the birth of new generations of stars. The analysis of the map conducted by Daniel Wang, of the University of Massachusetts at Amherst (USA), suggests that the basis of the production of these filaments may also be in this case the magnetic reconnection, thanks to the gas plumes we have talked about. The hypothesis is that the gas in these structures leads the magnetic fields to collide, generating the magnetic reconnection events that could lead to the formation of the filaments observed in this cosmic masterpiece, chosen today by NASA as the Astronomy Picture of the Day .

Featured image: Vertical pan of an area around the center of the Milky Way, with the field of view extending for a thousand light years above and below the galaxy. The image was made using a huge set of data collected by NASA’s Chandra X-ray Space Telescope and MeerKat Radio Telescope in South Africa. Credits: X-ray: Nasa / Cxc / UMass / QD Wang; Radio: Nrf / Sarao / MeerKat


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