On November 20th, astronomers released an image of the Milky Way’s violent center similar in importance to the Event Horizon Telescope (EHT) image of Galaxy M87’s gargantuan black hole. The image, above, which shows what our galaxy would look like if human eyes could see radio waves, is a new view of our galactic center from the Murchison Widefield Array with the lowest frequencies in red, middle frequencies in green, and the highest frequencies in blue.
Huge golden filaments indicate enormous magnetic fields, supernova remnants are visible as little spherical bubbles, and regions of massive star formation show up in blue. The supermassive black hole at the center of our galaxy is hidden in the bright white region in the center.
Using the images, award-winning radio astronomer, Natasha Hurley-Walker, and her colleagues at the International Center for Radio Astronomy Research discovered the remnants of 27 massive stars that exploded in supernovae at the end of their lives. These stars would have been eight or more times more massive than our Sun before their dramatic destruction thousands of years ago.
“This new view captures low-frequency radio emission from our galaxy, looking both in fine detail and at larger structures,” she said. “Our images are looking directly at the middle of the Milky Way, towards a region astronomers call the Galactic Center.”
This week, astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array radio telescope, captured for the first time an image of large-scale, coherent, magnetic fields in the halo of the faraway spiral galaxy, The Whale, confirmed theoretical modeling of how galaxies generate magnetic fields and potentially increasing knowledge of how galaxies form and evolve.
The international consortium, led by scientists from the Max Planck Institute for Radio Astronomy in Bonn, Germany, and including astronomers from the NSF-funded National Radio Astronomy Observatory in Charlottesville, Virginia, reported the results in the journal Astronomy & Astrophysics.
“To understand how stars like the sun and planets like Earth came to be, we must understand how galaxies, such as our Milky Way, form and evolve,” said Matthew Benacquista, a project director in NSF’s division of Astronomical Sciences. “This project is an attempt to measure galactic magnetic fields and learn how they influence the way that interstellar gases are ejected from galaxy disks and contribute to galaxy formation and evolution.”
The spiral galaxy, identified as NGC 4631 or the “Whale Galaxy,” is seen edge-on in the image, with its disk of stars shown in pink. The field lines are shown in green and blue, extending beyond the disk into the galaxy’s extended halo. Green indicates filaments with their magnetic field pointing roughly toward the viewer, and blue indicates filaments with their magnetic fields pointing away. This phenomenon, with the field alternating in direction, has never been seen before in the halo of a galaxy.
Sources: Silvia Carolina Mora-Partiarroyo et al. CHANG-ES, Astronomy & Astrophysics (2019). DOI: 10.1051/0004-6361/201935961 and ‘New candidate radio supernova remnants detected in the GLEAM survey over 345° < l < 60°, 180° < l < 240°’, published in Publications of the Astronomical Society of Australia (PASA) on November 20th, 2019.
Image credit Whale Galaxy: Dr Natasha Hurley-Walker (ICRAR/Curtin) and the GLEAM Team
Image Credit Milky Way Galaxy: Jayanne English of the University of Manitoba, with NRAO VLA radio data from Silvia Carolina Mora-Partiarroyo and Marita Krause of the Max-Planck Institute for Radio Astronomy