At the center of nearly every galaxy resides a gargantuan black hole. For the Milky Way, the supermassive black hole — dubbed Sagittarius A* — is so massive that its gravity flings stars around at speeds of up to 18.5 million miles (30 million kilometers) per hour. In order to accelerate stars to these breakneck speeds, astronomers estimate that
Sagittarius A* must be about 4 million times more massive than the Sun.
With such a monstrous and intriguing object located in the center of our galaxy, you would think that astronomers know a great deal about it. However, thanks to the fact that the Milky Way is full of light-blocking gas and dust, many questions still remain about the structure and behavior of Sagittarius A*.
In a
paper published last month in the
Monthly Notices of the Royal Astronomical Society, astronomers shed a bit of light on this black hole by producing a new high-resolution map that traces the magnetic field lines present within gas and dust swirling around Sagittarius A*. The team created the map, which is the first of its kind, by observing polarized infrared light that is emitted by warm, magnetically aligned dust grains.
“This collaborative work is an exciting step forward in our collective efforts to gain a greater understanding of our own galaxy and the supermassive black hole at the center of it,” said Chris Packham, a professor of physics and astronomy at the University of Texas at San Antonio, in a
press release. “It also demonstrates the importance of access to the largest telescopes using advanced cameras [and] techniques."
To create the detailed map, which spans about one light-year on each side of Sagittarius A*, the researchers used the CanariCam infrared camera on the Gran Telescopio Canarias (GTC), located on the island of La Palma, Spain. Because infrared light passes straight through the visual-light-blocking dust located between Earth and the Milky Way’s core, astronomers were able to view the area around Sagittarius A* much more clearly than would have been possible with other types of telescopes. Furthermore, since CanariCam combines infrared imaging with a device that preferentially filters polarized light associated with magnetic fields, the team was able to trace the magnetic field lines around Sagittarius A* in unprecedented detail.
“Big telescopes like GTC, and instruments like CanariCam deliver real results,” said Pat Roche, a professor of astrophysics at The University of Oxford, in a
press release. “We’re now able to watch material race around a black hole 25,000 light-years away, and for the first time see magnetic fields there in detail.”