Breakthrough: FIRST IMAGE OF A
BLACK HOLE AND ITS EVENT HORIZON (in Messier87, April 10 2019)
As scientists know, most
“active” galaxies house “supermassive black holes” right in their centers, and thought
to be their gravitational engines; but up to now black
holes had only been detected indirectly, sometimes by the curving of the light of
a galaxy (reaching us) when a black hole passes in front of it -- and creating
an apparent ring or gravitational lensing --, or by the jets they emit, mostly
gamma rays. 
On April 10, 2019, was published the first
image of a supermassive black hole surrounded by its event
horizon, the one set at the center of Messier 87, a large elliptical galaxy in the
constellation of Virgo (part
of our neighboring Virgo Galaxy Cluster). The ring shape
on this image is “the bright emissions from the hot gasses immediately
surrounding the colossal maw of a supermassive black hole’s event horizon”
explains the Perimeter article.*
This supermassive black hole has a mass of 6.5 billion Suns, is ½ light-day
across, and is 55-million light-years away. To give an idea of its gigantism,
our own supermassive black hole in the
center of our galaxy the Milky Way -- called
Sagittarius A*, or Sgr A* for short – is 2.6 million solar
masses, thus about 2500 times less
massive.
(see image: Sagittarius A*, image taken with NASA's
Chandra X-Ray Observatory. Ellipses indicate light echoes. Full-field is 12.5
arcmin across.)
It took almost
two decades to create the EHT - the Event Horizon Telescope - a network of radio telescopes around the world
that creates an Earth-sized virtual telescope; EHT uses Interferometry to combine images taken from widely distant
observatories distributed all over earth, to gain a higher resolution picture.
Avery
Broderick (professor at the University of Waterloo, associate faculty member at
Perimeter Institute for Theoretical Physics, Cambridge, UK), is one of the key
scientists and theorists of the project. The University of Waterloo’s News release, said about these black
holes, referring to him, “This first image is undeniable proof
of their existence and is a robust test of general relativity in the most
extreme gravitational environment known, added Broderick. ‘A black hole is a
gravitational feature that comes right out of Einstein’s theory of general
relativity, first described over a century ago and implicated – but never
proven – to exist. Until now.’” (https://uwaterloo.ca/news/news/first-image-black-hole-captured)
Broderick disclosed that their next target was to be our own
supermassive black hole, Sgr A*, as well as tracking
the dynamics of these two.
“We now have exceptionally strong evidence for the link between supermassive black holes and the centres of active galaxies – this is how black holes shape our universe on galactic scales,” said EHT project director Sheperd S. Doeleman.
* See https://insidetheperimeter.ca/black-hole-breakthrough-astronomers-release-landmark-image/
xxxxxxxxxxxxx xxxxxxxxxxxxx
xxxxxxxxxxxxx xxxxxxxxxxxxx xxxxxxxxxxxxx
xxxxxxxxxxxxx
xxxxxxxxxxxxx xxxxxxxxxxxxx