New research by University of Massachusetts Amherst astronomer Daniel Wang
reveals, with unprecedented clarity, details of violent phenomena in the
center of our galaxy. The images, published recently in Monthly Notices of
the Royal Astronomical Society, document an X-ray thread, G0.17-0.41, which
hints at a previously unknown interstellar mechanism that may govern the
energy flow and potentially the evolution of the Milky Way.
"The galaxy is like an ecosystem," says Wang, a professor in UMass Amherst's
astronomy department, whose findings are a result of more than two decades
of research. "We know the centers of galaxies are where the action is and
play an enormous role in their evolution." And yet, whatever has happened in
the center of our own galaxy is hard to study, despite its relative
proximity to Earth, because, as Wang explains, it is obscured by a dense fog
of gas and dust. Researchers simply can't see the center, even with an
instrument as powerful as the famous Hubble Space Telescope. Wang, however,
has used a different telescope, NASA's Chandra X-Ray Observatory, which
'sees' X-rays, rather than the rays of visible light that we perceive with
our own eyes. These X-rays are capable of penetrating the obscuring fog—and
the results are stunning.
Wang's findings, which were supported by NASA, give the clearest picture yet
of a pair of X-ray-emitting plumes that are emerging from the region near
the massive black hole lying at the center of our galaxy. Even more
intriguing is the discovery of an X-ray thread called G0.17-0.41, located
near the southern plume. "This thread reveals a new phenomenon," says Wang.
"This is evidence of an ongoing magnetic field reconnection event." The
thread, writes Wang, probably represents "only the tip of the reconnection
iceberg."
A magnetic field reconnection event is what happens when two opposing
magnetic fields are forced together and combine with one another, releasing
an enormous amount of energy. "It's a violent process," says Wang, and is
known to be responsible for such well-known phenomena as solar flares, which
produce space weather powerful enough to disrupt power grids and
communications systems here on Earth. They also produce the spectacular
Northern Lights. Scientists now think that magnetic reconnection also occurs
in interstellar space and tends to take place at the outer boundaries of the
expanding plumes driven out of our galaxy's center.
"What is the total amount of energy outflow at the center of the galaxy? How
is it produced and transported? And how does it regulate the galactic
ecosystem?" These, says Wang, are the fundamental questions whose answers
will help to unlock the history of our galaxy. Though much work remains to
be done, Wang's new map points the way. For more information, including
additional images and video, visit the Chandra X-Ray Observatory's Galactic
Center website.
Reference:
Q Daniel Wang, Chandra large-scale mapping of the Galactic Centre: probing
high-energy structures around the central molecular zone, Monthly Notices of
the Royal Astronomical Society (2021). DOI:
10.1093/mnras/stab801
Tags:
Space & Astrophysics