Cosmic Journeys - Supermassive Black Hole at the Center of the Galaxy

on clear summer nights we have long watched in awe as a broad band of light rose up across the sky now we know that behind this luminous veil of gas and stars a restless universe is being shamed by shattering collisions explosions and shockwaves two groups of astronomers of tracking a star that has accelerated to mind-boggling speeds they believe it holds clues to the origin of nature of a mysterious object that's lurking deep within the galaxy what are they learning about the supermassive black hole at the center of the Milky Way to observers in distant space our Milky Way galaxy would look something like this a flat spiral with vast arcs of gas dust and about 200 billion stars swirling around it the center bulging up and out of the Galactic disk is tightly packed with stars thick dust and blinding starlight have long obscured our view of the mysterious inner regions of the Bulge and yet the clues have been piling up that something important something strange is lurking there the first to take notice was the physicist Karl Jansky back in the 1930s he had been asked by his employer Bell Telephone labs to investigate sources of static that might interfere with what it saw as the killer app of its time radio voice transmissions using this ungainly radio receiver Jansky methodically scanned the airwaves he traced most of the static to thunderstorms nearby and far away there was one signal he could not explain it was a hiss of radio noise that sounded like steam Jansky narrowed it to a region in the sky the constellation of Sagittarius in the direction of the center of the galaxy located within a larger pattern of radio emissions Jansky source would become known as Sagittarius a word of Jan skis finding got out he assured the public that it was not aliens seeking contact whether it was or wasn't no one could really save for the next three decades then a young astronomer named Erich Becklund got interested in probing deeper into the galactic center Sagittarius rises right about there first comes Scorpio around midnight and then Sagittarius and the very big Milky Way and the very core is one of those rare researchers whose curiosity and determination push our understanding to a whole new level it was the 1960s and astronomy like Society was in a period of ferment astronomers were peering into ever more distant corners of the universe looking for answers to a whole new set of questions when Eric began his career a class of extremely powerful radio beacons called quasars had just been discovered in distant space what powerful objects were generating them did they come from the bright Centers of galaxies as some astronomers suspected to look into the center of another galaxy you have to pinpoint its precise location young Beckley first took aim at our luminous neighbor Andromeda in this recent ultraviolet image you can see a dense glow in the middle Beckman found the point where the light reaches peak intensity and marked it as the center from our orientation in space the Andromeda galaxy is in full view but our galaxy is a different story we live inside it to pinpoint its center back then had to find a way to see through all the dust and gas that obscure our line of sight he went to a military contractor and obtained a device that reads infrared light its wavelengths are similar to the distances between particles in a dust cloud which allow it to move right through the dust looking toward the galactic center Beckman began measuring the brightness of infrared light as it rose to a peak marking its exact location thus began Becklund long quest to see what lies deep in the milky way's heart well this is the center of the cluster bechler wasn't the old astronomer interested in the galactic center that a star can be a black hole now we know of course Reinhard genzel and a team based at the Max Planck Institute for extraterrestrial physics in Germany began a similar campaign in 1990 more than a fighting chance they came to the mountains of Chile in South America to use the recently christened new technology telescope of the European Southern Observatory a few years later in 1993 I atop Hawaii's Mauna Kea volcano Eric bechler and colleague including Andrea gates began using the giant new 10 meter Keck telescope the American and German groups shared the same goal to identify the source of radiation first observed by Karl Jansky they found that most of the energy is coming from a region they called Sagittarius a star this is a roadmap and that center of our galaxy that is too small and dim to actually see that was not true of stars that are orbiting around it tracking the precise locations of these stars would take the sensitivity of qex wide aperture you can ask how well can we position stars in our field of view and it's we can position things to 2 centimeters in LA if as viewed from New York so you can basically tell somebody's waving like this with their finger in Los Angeles excuse New York it's powerful enough to detect an object with the luminosity of a candle on the moon meanwhile astronomers had focused the new Hubble Space Telescope on a different galaxy a giant elliptical cloud made up of nearly a trillion stars 50 million light-years away called m87 they tracked gas whipping around its center at speeds of almost 2 million km/h that led them to calculate the mass of the gravitational source at m87 Center at four billion times that of our Sun this measurement the first-of-its-kind pointed to the presence of a black hole of truly supermassive proportions but that did not conclusively prove its identity if a supermassive black hole lay at the center of our galaxy the German and American teams each hope that Earth's proximity would allow them to assemble conclusive evidence their search was part of a larger effort to map the layout of our galaxy and find clues to its history astronomers were eager to train a new generation of space telescopes the Great observatories on the galactic center using Hubble astronomers documented vast arcs of gas heated up by ferocious winds from large stars capturing infrared light the Spitzer Space Telescope picked up the swirling heat signatures of dense star concentrations the Chandra x-ray Observatory recorded multiple sources of high-energy radiation most likely given off by ultra dense neutron stars and small black holes based on Chandra data scientists estimated that a swarm of 20,000 black holes likely inhabits the inner three light-years of the galactic center if he would stand the center of the Gaia the galactic center right now first of all it would be stars all around us you know there unlike the situation you're used to where we have one Sun in that direction that's it it will be stars all around us and very massive stars lots of radiation it would be very we couldn't exist it has lots of ultraviolet radiation x-rays are floating around gas clouds bash into each other and then of course the black hole itself from time to time it creates material and then releases radiation so it's a very hostile environment to show there's a supermassive black hole in the center the teams would have to prove that it's confined to a very small region and that it has enough gravity to whip the stars orbiting it to high speeds the light of these stars travels 26,000 light years to reach us only to be blurred in the last few kilometers as it hits the Earth's atmosphere so both teams turned to view methods desired to sharpen the light the idea was to snap thousands of pictures in a short time because the atmosphere is in motion a star's apparent position may shift from image to image to pinpoint the Stars true location a computer averages the positions and looks for correlations in the wavelength of the star's light the first few years data allowed the teams to calculate the speeds of these Stern's and their ruff trajectories around the center these stars are going as fast as ten thousand kilometres per second when they go through closest approach that's going about three percent the speed of light keep our fingers crossed that allowed them to narrow the position of their target and to calculate the strength of its gravitational pull that gave them it's max roughly three million times that of our Sun because no other single object is known to weigh that much it was strong evidence of a black hole but it was still not ironclad proof their data for example didn't rule out a dense concentration of stars packed into the center held there by their mutual gravity the proof the team sought would come in the wake of an extraordinary event in the early years of the new century large telescopes around the world began to install upgrades most large new telescope mirrors these days are thin designed to be mounted on metal scaffolding behind the mirrors engineer's installed pistols and motors to subtly correct the shape of the glass as changing temperatures deform it or as atmospheric turbulence blurs the incoming light to these adaptive optics systems they added lasers designed to project an artificial star onto the upper atmosphere as turbulence distorts its light a computer subtracts the same degree of distortion from the light of the real stars bringing them back into focus this is a Keck telescope image of the galactic center without adaptive optics applied and with it this increase in sharpness allowed the teams to see what happened in 2002 the German team had begun making observations from the new very large telescope array at the Paranal Observatory in northern Chile in the spring of that year one of the stars they had been following known as s2 made a dramatic move s2 suddenly swooped around the centre accelerating to an astonishing 18 million km/h the American teams are too it had come incredibly close to the suspected black hole about three times the distance between the Sun and Pluto if there had been a cluster of stars in there s twos path and its light would have wobbled it did not this was the evidence the teams had sought it showed that Sagittarius a star is a single object without doubt it could now be called a black hole this observation came at a time when astronomers had begun to believe that supermassive black holes play an active role in the evolution of galaxies they had found that they occupy the centres of nearly every large galaxy in fact the larger the galaxy the larger the black hole that suggests that the two must have evolved hand in hand each shaping the life story of the other as matter flows into a black hole it heats up to millions of degrees despite the black holes intense gravity much of the inflowing matter blows off in fierce winds and shoots out in powerful Jets that roar out of its poles the more matter that rushes him the more the black hole pushes back out the force and heat from an active black hole can have the effect of limiting a galaxy's growth by slowing star birth and by pushing gas out of its central region as a result a strict relationship has developed between the size of the black hole and the size of the Galactic bulge that surrounds it the astronomers wanted to know is the Milky Way's own supermassive black hole still active and growing or has it gone dormant just as the black hole that Sagittarius a star revealed its existence it would show its true colors the year 2001 scientists were beginning to work with the recently launched Chandra x-ray Space Telescope they pointed it at Sagittarius a star and by chance at that moment the black hole erupted the teams on the ground began focusing on it for longer periods hoping to see it happen again and so they did they saw what are now thought to be flares outbursts that take place when matter builds up near the event horizon when it falls in around once an earth day the black hole lights up okay here we can clearly see a region between those two sources where there is no other object and here we have the same region the same two sources and now in between we see an additional source so this is the flaring state of Sagittarius a star as gas gas clouds if you like come in there sort of spiral into this innermost regions and get ever hotter before they disappear and in the very innermost we just before it disappears from our side that's where there would be the hottest and so an accretion event think of it sort of a clump falls into the thousand percent it could also look like a group of astronomers is now making plans to get a closer look at these flares and perhaps to directly glimpse the black hole from Earth it is but the size of a grapefruit on the moon no single telescope on earth has enough resolution to see something so small so far away astronomers think that they will be able to see it by linking observatories around the world to create what amounts to an earth-sized radio telescope known as the event horizon telescope this simulation shows what they expect to see a supermassive black hole in silhouette framed by eruptions on its surface that travel around the monster as it spins the reason that this periodicity the fact that things change repetitively the same in the same way over a certain time scale is that the materials orbiting the black hole and so this timescale corresponds the time it takes to go completely around the black hole so that also tells you how close it is to the black hole and the key here is that if the black holes not rotating there's no rotating the shortest period that you should be able to detect is about 24 minutes so if it is rotating and you think it is coming from the secretion disk then that's telling you that the black hole spinning because material can get closer if it's spinning faster meanwhile astronomers have mounted a major effort to map the turbulent environment of Sagittarius a star to shed light on the monsters current state and how it might change the great space observatories Hubble Spitzer and Chandra combined to produce the most detailed image yet of the galactic center in this image the central zone 160 light-years across stretches out like a vast claw Sagittarius a star is the x-ray hot region on the lower wrist out on the hand is a dense grouping of about a thousand stars called the arches cluster it formed just a few million years ago only its tight formation saves it from being torn apart by the intense tidal forces of the center below is the quintuplet cluster with the largest star documented in the Milky Way the pistol star weighs in at 150 times the mass of the Sun large stars like these generate fierce winds of plasma that filled the galactic center they should provide a steady diet for the black hole and cause it to glow brightly monitoring x-ray emissions with the Chandra telescope astronomers found that these and other large stars are just a little too far away to feed the monster as gas whirls if a portion heats up and pushes outward this outward wing is enough to block much of what's flowing here so what would cause it to flare up a separate study suggested that what's falling in is not gas but comets and asteroids that have been stripped away from stars whose orbits have brought them in close this is the center of the cluster and sadly a star was over there the black hole remains in a state of semi-retirement this is a bit of a puzzle that there's so many other booster will it become active again working in the cold clear air of the Antarctic one group of radio astronomers surveyed the broader region surrounding the galactic center data from their South Pole telescope contains signs that a spectacular flare-up is slowly materializing a huge ring of gas looms beyond the galactic center when it accumulates some 300 million solar masses worth of matter it will reach a tipping point the cloud will begin to funnel into a second ring that orbits close to the center this inner ring will condense then erupt with star formation before spiraling down toward the ravenous black hole as the cloud falls into the black hole will erupt in a blaze of glory visible across patch of the universe don't wait around for such outbursts half of every four hundred million years or so there is another much smaller fire that is now on a black hole rendezvous the cloud weighing several times the mass of Earth approached Ground Zero this simulation shows the cloud passing within less than a fifth of a Lightyear it stretched out as the black hole began ripping it apart it's momentum will carry most of its swirling past the black hole in time it will settle into an orbit and slowly but surely collapse into the center meanwhile on a rocky outpost 25,000 light-years from the turmoil of the galactic center astronomers continue to watch for surprises they have found ways to track patterns of change shaping our universe over billions of years time and yet it's often the small and sudden events that feed their sense of wonder since they started their world these groups became the first to witness an object making a complete orbit around the center of the galaxy the star s2 does it every 16 earth years it's dimmer cousin as 102 goes around every 11.5 years no doubt over the course of their next orbits will answer many of the questions that swirl around their companion the supermassive black hole how did it form and shape the galaxies that surrounds it will it one day from the dim heart of the Milky Way become bright and powerful enough to light up the universe you you

Channel: SpaceRip

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Keywords: higgs, Space, deep space, universe, observatory, keck, hole, event horizon, NASA, supernova, milky way, gravity, spacerip, nasa, jupiter, telescop, astronomy, Astronomy Picture Of The Day (Website), Black Hole (Celestial Object Category), jansky, einstein, singularity, esa, hubble, speed of light, star, string, Supermassive Black Hole, cosmos, Stephen Hawking (Academic), Astronomy (Field Of Study), Galaxy (Celestial Object Category), chandra, Galactic Center (Orbital Relationship), cosmic journeys, black

Id: XwkMCHf516s

Length: 31min 24sec (1884 seconds)

Published: Thu Aug 27 2015