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| This shows a still image of the supermassive black hole Sagittarius A*, as seen by the Event Horizon Collaboration (EHT), with an artist’s illustration indicating where the modeling of the ALMA data predicts the superheated blob of gas to be and its orbit around the black hole. Credit: EHT Collaboration, ESO/M. Kornmesser (Acknowledgment: M. Wielgus) |
Astronomers have detected a blob of hot gas whizzing around the supermassive
black hole at the heart of our galaxy at an extraordinary speed. A powerful
magnetic field surrounding the colossal space-time tear has supercharged the
bizarre gaseous globule, speeding it up to 30% the speed of light, a new
study finds.
The supermassive black hole at the center of the Milky Way, known as
Sagittarius A*, is around 4 million times more massive than the sun and
stretches around 40 million miles (60 million kilometers) across. Normally,
anything that gets too close to such a massive black hole gets dragged
beyond its event horizon by an overwhelming gravitational pull. But the
newly discovered gas blob, or hot spot, is moving so quickly that it appears
to have formed a stable orbit around the massive cosmic void.
The gaseous blob's orbit around Sagittarius A* is equivalent in size to the
orbit of Mercury around the sun. But the blazing blob completes a full
rotation around the black hole every 70 minutes, compared with the 88 days
it takes Mercury to travel the same distance, researchers wrote in a new
paper published online
Sept. 22 in the journal Astronomy and Astrophysics.
"This requires a mind-blowing velocity of about 30% of the speed of light,"
study lead author Maciek Wielgus, an astronomer at the Max Planck Institute
for Radio Astronomy in Germany,
said in a statement. That's around 201.2 million mph (323.8 million km/h), or around 3,000
times faster than Earth moves around the sun.
Researchers first spotted the orbiting blob in 2017 using the Atacama Large
Millimeter/submillimeter Array (ALMA) telescope in Chile. The ALMA
telescope, which is made up of 66 antennae, is one of eight telescopes that
make up the Event Horizon Telescope (EHT) network, which produced the first
direct image of Sagittarius A* in May this year.
Researchers were calibrating ALMA to focus on Sagittarius A* for the EHT
project when they detected an unusual X-ray flare coming from the space
surrounding the black hole.
The electromagnetic radiation from the flare, which was also visible in
infrared and radio, was highly polarized, or twisted, and showed signs of
synchrotron acceleration — in which an object is subject to an acceleration
perpendicular to its velocity. This type of acceleration occurs when charged
particles are propelled forward by a strong magnetic field, like how
artificial particle accelerators supercharge electrons,
according to ScienceAlert.
The only explanation for this type of acceleration is that the flare
originated from the black hole's magnetically arrested disk — a ring of
matter surrounding a black hole that is being held in place by a strong
magnetic field, which counterbalances the forces of gravity pulling the
matter into the cosmic void. Researchers, therefore, deduced that the only
possible origin of the flare was a supercharged gas blob trapped within this
disk.
Different research groups have detected similar signals from hot spots
rapidly orbiting other black holes, according to the statement. However,
this is the first time that a flare emitted by a hot spot have been observed
in radio as well as infrared and X-ray, the researchers wrote in the paper.
The researchers think that the radio waves they detected could mean that the
hot spot is slowing down and losing some of its energy, according to the
statement. This could potentially signal that the gas blob will eventually
slow down enough for the black hole's gravity to overcome the magnetic
shielding surrounding it and finally pull the gas into its infinite
maw.
The researchers hope that this new information can be used to help track
additional hot spots around other black holes.
"In the future, we should be able to track hot spots across frequencies
using coordinated multiwavelength observations," study co-author Ivan
Marti-Vidal, a radio astronomer at The University of Valencia in Spain, said
in the statement. "The success of such an endeavor would be a true milestone
for our understanding of the physics of flares in the galactic center."
While the new study improves our understanding of the Milky Way's black hole
heart, researchers said there is still a lot more to learn about Sagittarius
A*.
Until now, telescopes have struggled to focus in on the supermassive
structure because it frequently flares up, shooting out electromagnetic
radiation that interferes with delicate sensors. But the new James Webb
Space Telescope will play a key role in future research into Sagittarius A*
because it will be able to see past this interference.
"Hopefully, one day, we will be comfortable saying that we 'know' what is
going on in Sagittarius A*," Wielgus said. But that day is not today.
Originally published on
Live Science.
Tags:
Space & Astrophysics