Today
we're discussing black holes once again, another really exciting discovery from
another really exciting paper and this time it's actually a discovery that
confirms one of the fundamental properties of black holes, the property that
they can actually reflect some of the light back to us or in other words that
the light around a black hole can bend so much that the black hole itself
becomes sort of like a mirror something that was definitely known theoretically
but something that has now been physically shown and physically proven.
But
first what kind of a black hole and where is it located? well this is in a galaxy pretty far away from
us a galaxy that's roughly around 800 million light years away and when
observing this galaxy specifically in the X-rays, the scientists realized
something about the center of the galaxy. It was producing a very intriguing pattern
of different X-ray emissions with very specific light curves being extremely
interesting but it didn't take the scientists long to realize that what they're
looking at is actually something that was predicted by Einstein many years ago.
These were the echoes or the reflections coming from the black hole itself and
not just from any part of the black hole from behind the black hole.
Okay
so here's how you could try to imagine this for example today we know that a
typical black hole will usually start bending the light in such a specific way that
is going to start producing different observable shapes around the black hole
itself, so even though this shows us the front of the accretion disk we know
that this shows us the back of the accretion disk so this is actually a
reflection coming from the other side of the black hole itself but on the
bottom we also get to see what the bottom of the disk looks like as well now on
top of this. There are some other features specifically the feature known as
the photon ring that's theoretically believed to exist here. In a nutshell,
though the photon ring in this case reflects the entire universe around the
black hole and several versions of these photon rings will produce sort of like
the frames individual frames of what I guess you would call the movie of the
universe but because various simulations and various mathematical calculations
always present the black hole as having this funny looking hat and a kind of a beard
sort of important for us to try to figure out if they really look like this so
do they actually truly reflect the backside in the way that you see in this image
and so obviously theoretically the answer is yes but how do you physically
prove this the best picture of the black hole we have so far is M87 but this
image is just not accurate enough to truly show us if there are any reflections
coming from this region.
The
most recent image produced by the same scientists of the Centaurus, a black
hole is just not nearly accurate enough to show us anything either but this is
what it kind of look alike tells us a little bit more about the astrophysical
jets but it tells us nothing about the accretion disk or about the reflections
from the blackhole but there is a way for us to see this even though we cannot
see the details of a black hole it's something to do with another feature of a
black hole that’s actually not visible in this image decades ago the scientists
also predicted that the typical black hole is going to have a region known as
the corona and generally the way that the corona is produced is when the
material from the accretions typical very massive blackhole sort of starts
falling into the blackhole producing a huge amount of energy quite suddenly
this always results in some sort of a massive and very powerful flare and more
often these flares are formed when there is a sudden increase in the mass
that's absorbed by the black hole where the sudden increase in gas sliding into
the black hole suddenly increases the temperature right next to the black hole
by millions of degrees and at these temperatures the electrons start separating
from atoms and this creates a huge amount of plasma right above the black hole
or actually right above and right below the black hole and all of this plasma
gets caught in the magnetic field of the black starts to dramatically get spun
up and gets curled and twirled so much that at some point it completely
disintegrates creating beautiful and extremely powerful effect with an
extremely bright flash
So
this extremely powerful Coronal emission followed by an extremely bright flare
can actually last for a few hours and the pan on the black hole can actually
reach really far up and down from the black hole in this particular case the
black hole that was about 10 million masses of the unproduced a flair that was
about 60million kilometers in size roughly one third of the distance of earth
to the sun but this beautiful flare also produces an extremely bright flash of X-ray
radiation the flash that's so bright that it can be visible from an extremely
far away distance in this case of course from 800 million light years away from
us but at the same time the light from this flash is also reflected from the
accretion disk around the black hole and this reflection can also be visible
from the planet.
As a matter of fact, in some of the previous
studies, some scientists figured out how we can use this reflection to
literally map the region around the black hole. it's not super accurate yet but
it's definitely possible and has been done before and so the scientists in this
paper were doing something similar but while looking at the X-ray emissions
from this particular black hole with this black hole right here being about
twice as massive as the one in the middle of the milky way galaxy making it
about 30 million kilometers in diameter. They realized that they were looking
at some other emissions they didn’t really expect the missions that were
producing some sort of an echo or a reflection and it didn't take them too long
to figure out exactly what's happening here.
So,
essentially as the Coronal flash occurs right here it starts emitting X-rays
going in every direction some of them will got this side some of them will go
to the opposite side but because they're reflected we'll get to see reflections
from the near side and since it's a black hole, some of the light from the
other side will also get bent and sent toward us as well and because these
additional flashes were much smaller and also seem to be slightly red-shifted
or basically had slightly different color. The only reasonable explanation here
was that it was reflected from the back of the black hole and we're literally
looking at something that came from the other side with the time difference
between these flashes naturally also explaining how far away the distance
between these two points is. Although these new X-ray calculations did suggest
that the blackhole could have been much smaller possibly only about 3 million
masses of the sun which of course means that there are still a lot of
unanswered questions. Nevertheless, being able to see all this at such
tremendous distances is still quite an impressive achievement, but hopefully
some of the future telescopes with even more resolution such as for example the
Athena observatory that's going to be operational sometime in the next 10 years
or so, is definitely going to allow the scientists to see all this with so much
detail but we might be able to map an entire region around a black hole. By
using these X-ray echoes coming from a typical X-ray flash and so there are definitely
quite a lot of discoveries that are going to be made in the next decade or so for
now though it's still quite impressive that this galaxy known as eyes wiki 1
also known as Mercarian 1502allowed the scientists to investigate the black
hole in the middle and to confirm something that we sort of expected the black
holes to have their ability to bend light in such a way that we can actually see
what’s behind them now until future discoveries in regards to black holes or
some other observations of the X-ray corona around black holes.
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