- 4490 - BLACKHOLE DISCOVERIES? - Latest astronomy reveals magnetic fields around Our Galaxy’s giant Black Hole. The “Event Horizon Telescope” traces the lines of powerful magnetic fields spiraling out from the edge of the supermassive black hole at the center of our Milky Way galaxy, and suggests that strong magnetism may be common to all supermassive black holes.
---------------------------------------- 4490 - BLACKHOLE DISCOVERIES?
- The black hole known as Sagittarius A*,
which is about 27,000 light-years from Earth, observed using radio-wave
observations from the Event Horizon Telescope’s network of observatories around
the world.
-
- Sagittarius A* wasn’t the first black hole
whose shadow was imaged by the EHT. In
2019, astronomers showed off a similar picture of the supermassive black hole
at the center of the galaxy M87, which is more than a thousand times bigger and
farther away than the Milky Way’s black hole.
-
- In 2021, the EHT team charted the magnetic
field lines around M87’s black hole by taking a close look at the black hole in
polarized light, which reflects the patterns of particles whirling around magnetic field lines. Researchers used the
same technique to determine the magnetic signature of Sagittarius A*, or Sgr
A*.
-
- The resulting picture is that there are
strong, twisted and organized magnetic fields near the black hole at the center
of the Milky Way galaxy. Along with Sgr
A* having a strikingly similar polarization structure to that seen in the much
larger and more powerful M87* black hole, we’ve learned that strong and ordered
magnetic fields are critical to how black holes interact with the gas and
matter around them.
-
- The structure of the magnetic fields around
Sgr A* suggests that the black hole is launching a jet of material into the
surrounding environment. Previous research has shown that to be the case for
M87’s black hole.
-
- A computer simulation of the disk of plasma
around M87’s supermassive black hole shows how magnetic fields help launch jets
of matter at near the speed of light.
The Milky Way’s black hole appears to be doing something similar.
-
- The fact that the magnetic field structure
of M87* is so similar to that of Sgr A* is significant because it suggests that
the physical processes that govern how a black hole feeds and launches a jet
might be universal among supermassive black holes, despite differences in mass,
size and surrounding environment.
-
- In the seven years since the EHT began
gathering observations, the collaboration has been adding to its array of radio
telescopes, which is resulting in the production of higher-quality imagery.
-
- Gravity is the oldest known, but the least
understood force in nature. For students
of gravity, black holes are amongst the most interesting objects to study
because gravity is the dominant force there, it is infinitely strong! Black holes is that they are very ‘simple’
especially when compared to stars and other astrophysical objects. This is a
consequence of the so-called ‘no hair’ theorem that states that black holes can
be fully characterized by only 3 attributes — their mass, charge and spin.
-
- Black holes are known for exhibiting
gravity so strong that light can’t even escape, and while Albert Einstein’s
theory of general relativity in 1915 is often credited with first proposing the
concept of black holes, the concept of an object whose size and gravity would
not allow light to escape was first proposed in a November 1784 letter by
English philosopher and clergyman, John Mitchell.
-
- In this letter, Mitchell referred to these
objects as “dark stars” since he postulated that stars whose diameters exceeded
500 times that of our Sun’s diameter would trigger the formation of these
objects. Additionally, he suggested that gravitational waves influencing nearby
celestial bodies would enable these objects to be detected.
-
- Einstein’s theory of general relativity,
which also predicted both the existence of black holes and gravitational waves,
both of which continued to be scrutinized throughout the 20th century, which
includes what’s called the “golden age of general relativity” during the 1960s
and 1970s. -
- This includes the first object accepted by
the scientific community as a black hole, called Cygnus X-1, which was
discovered in 1964. However, it took another 52 years for the existence of
gravitational waves to be confirmed through a black hole merger, which was
accomplished by the LIGO Scientific Collaboration.
-
- To develop a complete understanding of the
quantum nature of gravity, black holes are the key to unlocking that
mystery. Black holes can only be
observed indirectly. Unlike stars, since they don’t emit radiation themselves,
it is difficult for astronomers to collect data on them. At best, we can
observe their influence on their environment (like gas, stars, etc.) and infer
their properties and behavior.
-
- While it took over 100 years between
Einstein introducing his theory of general relativity in 1915 and the
confirmation of gravitational waves in 2016, it only took another three years
for astronomers to publish the first direct image of a black hole at the center
of the Messier 87 galaxy.
-
- While Messier 87 is located approximately
53 million light-years from Earth, the closest hypothesized black hole, Gaia
BH1, is located approximately 1,560 light-years from Earth. In 2022,
astronomers published a direct image of Sagittarius A*, which is the
supermassive black hole at the center of our Milky Way Galaxy.
-
- Scientists have hypothesize the number of
black holes in our Milky Way Galaxy is in the hundreds of millions, despite
only a few dozen known black holes having been confirmed, thus far.
-
- Black holes are studied by astronomers,
who use a combination of theory and observations to construct what black holes
might look like, and in rare cases, obtain direct images of them. It is important to note that these direct
images capture the gases that are
encircling the black hole’s “event horizon”.
-
- In recent years, computer simulations have
advanced rapidly, and one can now make major discoveries about deep questions
using computational tools. In the long run, computer programming would be a
very promising tool for advancing research in this field.
-
- Sagittarius A* wasn’t the first black hole
whose shadow was imaged by the EHT. Back in 2019, astronomers showed off a
similar picture of the supermassive black hole at the center of the galaxy M87,
which is more than a thousand times bigger and farther away than the Milky
Way’s black
-
- The structure of the magnetic fields around
Sgr A* suggests that the black hole is launching a jet of material into the
surrounding environment. Previous research has shown that to be the case for
M87’s black hole.
-
-
May 22, 2024 BLACKHOLE
DISCOVERIES? 4490
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