Our milky way is a single unremarkable mid-range spiral galaxy a little collection of stars and
other objects in a universe that most current estimates say contains at least 2 trillion
galaxies the tiniest galaxy known to astronomers is seguae 2 a dwarf galaxy with only roughly 1
000 stars its tenants are among the oldest in the universe and no new stars are being formed there
and then there's the opposite of the spectrum the largest currently known galaxy has a generic
designation of ic1101 some 1.045 billion light years from earth the nondescript name gives no
indication of its incredible size and remarkable features not to mention what it is hiding in its
core hiding is very likely a slab or stupendously large black hole of gargantuan proportions that
may prove to be the largest in the known universe welcome the fact nominal in today's video we look
at the largest galaxy ever found and explore its truly incredible features including its completely
out of proportion dark matter content and the supermassive black hole hiding in its center
IC1101 was discovered on June 19 1790 by British astronomer William Herschel at the extreme
edge of the constellation virgo the virgin on the border with the serpent
it was early 20th century before it was determined to be a galaxy beforehand galaxies were thought to
be nebulae in our own milky way this monstrosity is a super giant elliptical to lenticular galaxy
meaning it has the rounded shape of an ellipse without the large scale spiral arms
of galaxies such as the milky way astronomy demands awareness of size mass and distance
all can become incomprehensible quickly when imagining the scale of even our own cosmic
neighborhood which is only a remote outpost in a solar system that's part of an average galaxy
our average galaxy has roughly 250 billion stars while IC1101 is home to about 100 trillion
some estimate IC1101's diameter to be 6 million light years or even greater though astronomers
debate what constitutes the edge of an elliptical galaxy thus varying figures for the cosmic giant
no doubt it's extremely large for perspective our milky way has a visible diameter of 150,000
to 200,000 light years and more recent estimates have increased that number dramatically
either way ic1101 is up to 60 times larger than our home for even more perspective if ic1101
replaced the milky way in our little cosmic neighborhood it would encompass andromeda
triangulum the Large and Small Magellanic Clouds and all the space in between believe this
behemoth is the result of galaxies like our own colliding and forming a newer and much larger one
its halo is so immense it's difficult to get exact measurements on the boundaries
but what lies inside those boundaries is a much larger question
IC1101 part of the Abell 2029 galaxy cluster has the brilliance of at least one trillion suns so an
observer on a planet within the system would see a night sky still illuminated virtually everywhere
Abell 2029 contains thousands of galaxies hundreds of which are giant galaxies and
IC1101 is so bright it produces over one quarter of the total light from the galaxy cluster
so bright that it qualifies for the designation of bcg which is brightest galaxy in a cluster even
with its remarkable light IC1101 is birthing very few new stars due to galactic collisions
stripping away star forming gas and dust this aging gives the giant a telltale yellowish hue
so unless it cannibalizes other galaxies in the astronomical sense it will die but far more
interesting is the extreme imbalance between light and mass in IC1101 in favor of its mass in a very
old elliptical galaxy such as this astronomers expect the presence of mainly m-type main sequence
stars which are red dwarfs and white dwarfs for comparison a typical red dwarf has 20 percent
of the sun's mass but emits only 0.55 percent of its luminosity so suffice it to say it's very dim
with a population of these stars having the balance favoring mass is expected due to the
lack of recent star formation activity as well as with dust but nowhere near as much as ic1101
the ratio is so skewed that no known stellar objects populating ic1101 can explain it
this leaves astronomers with one suspect dark matter until recently all galaxies were thought
to be largely filled with dark matter though some now appear strangely devoid of the substance
astronomers use data from hubble to determine that one of them ngc 1052-df4
was stripped of its dark matter by a neighboring galaxy that is tearing it apart
that still leaves others that have little or no dark matter with no explanation yet
still the overwhelming vast majority of observed galaxies have dark matter and great abundance
and some are thought to form inside massive halos of dark matter
but that alone doesn't come close to explaining the extreme amount that appears to dominate ic1101
so what is this dark matter astronomers have known for decades that galaxies rotate at a
speed that the gravity of its observable mass could not possibly hold it together
stars and other objects would have flown off into the intergalactic void long ago
and while objects we can see such as planets asteroids stars and galaxies constitute under five
percent of the universe's total matter dark matter is estimated to be 27 percent of what fills space
without direct detection due to its particles not interacting with electromagnetic force
meaning it does not absorb reflect or emit light theories abound as to what it actually is we know
of its existence of something's existence only by what it does and what it does is spectacular like
a gigantic spider web extending across and even around galaxies dark matter exerts gravitational
force to hold entire systems of billions and in the case of ic1101 and a few others
trillions of stars together even more importantly astronomers believe dark matter will determine
if the universe continues to expand expense to a point and then collapses in on itself
or ultimately stop expanding and stay put when it reaches equilibrium as for its massive presence in
ic1101 there are only theories thus far as we are limited to seeing its results perhaps the james
webb space telescope will shed light infrared or otherwise on this cosmic mystery and if you're
ever in the neighborhood it's a good idea to avoid traveling to the middle of this monstrous galaxy
at the center of ic1101 is a radio source named pks1508 plus zero five nine we really need to
get better at naming celestial objects that emits two jets in opposite directions the jets initially
collimated end up dispersing this suggests a stupendously large black hole at the galaxy center
astronomers determined that ic1101's core is an incredible 13 700 light years across
but it emits much less light than it should given its size so what does this mean in a study
published in october 2017 in the monthly notices of the royal astronomical society astronomers who
researched the core of ic1101 photometrically found the core to be larger than that of any
known galaxy they also found the light deficiency and determined a high likelihood of a long series
of galactic mergers with black holes that sank towards the center of the new and larger galaxy
the black holes merged propelling billions of stars away from the galactic center
this would account for the study's finding of a total mass equivalent to 490 billion solar masses
that should be there but is not the size of the stupendously large black hole at the core
of ic1101 between 40 and 100 billion solar masses research from the university of new
amsterdam suggests that these stupendously large black holes or slabs are primordial
birthed in the early days of the universe well before galaxies and since these earliest black
holes were not formed from collapsing stars their sizes could range from tiny to extremely large
the authors of this study even suggest that some of these slabs may exist in intergalactic space
away from galaxies which opens up a whole other realm of incredible possibilities
what all of this means is that ic1101 is not only the largest known galaxy in the
visible universe with an extraordinary amount of dark matter that up to now defies explanation
but it has a gigantic black hole at its center that dwarfs just about all others
but its distance and halo complicate determining specific answers to its multitude of questions
what is ic1101 hiding a lot that we hope to unravel in years to come so what do you
think about this amazing galaxy and its secrets does it have more to reveal as we get better at
deciphering its mysteries tell us in the comments and as always thank you for watching fact nominal