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  • We've never seen them directly,

  • yet we know they are there,

  • Lurking within dense star clusters,

  • Or wandering the dust lanes of the galaxy,

  • Where they prey on stars,

  • Or swallow planets whole.

  • Our Milky Way may harbor millions of these black holes,

  • the ultra dense remnants of dead stars.

  • But now, in the universe far beyond our galaxy, there's evidence of something even more ominous,

  • A breed of black holes that have reached incomprehensible size and destructive power.

  • It has taken a new era in astronomy to find them.

  • High-tech instruments in space tuned to sense high-energy forms of light - x-rays and gamma

  • rays - that are invisible to our eyes.

  • New precision telescopes equipped with technologies that allow them to cancel out the blurring

  • effects of the atmosphere,

  • and see to the far reaches of the universe.

  • Peering into distant galaxies, astronomers are now finding evidence that space and time

  • can be shattered by eruptions so vast they boggle the mind.

  • We are just beginning to understand the impact these outbursts have had on the universe around

  • us.

  • That understanding recently took a leap forward.

  • A team operating at the Subaru Observatory atop Hawaii's Mauna Kea volcano looked out

  • to one of the deepest reaches of the universe,

  • And captured a beam of light that had taken nearly 13 billion years to reach us.

  • It was a messenger from a time not long after the universe was born.

  • They focused on an object known as a quasar, short for "quasi-stellar radio source."

  • It offered a stunning surprise,

  • A tiny region in its center is so bright that astronomers believe it's light is coming from

  • a single object at least a billion times the mass of our sun.

  • Inside this brilliant beacon, space suddenly turns dark,

  • as it's literally swallowed by a giant black hole.

  • As strange as they may seem, even huge black holes like these are thought to be products

  • of the familiar universe of stars and gravity.

  • They get their start in rare types of large stars, at least ten times the mass of our

  • sun.

  • These giants burn hot and fast, and die young.

  • The star is a cosmic pressure-cooker. In its core, the crush of gravity produces such intense

  • heat that atoms are stripped and rearranged.

  • Lighter elements like hydrogen and helium fuse together to form heavier ones like calcium,

  • oxygen, silicon, and finally iron.

  • When enough iron accumulates in the core of the star, it begins to collapse under its

  • own weight.

  • That can send a shock wave racing outward,

  • Literally blowing the star apart:

  • a supernova.

  • At the moment the star dies, if enough matter falls into its core, it collapses to a point,

  • forming a black hole.

  • Intense gravitational forces surround that point with a dark sphere, the event horizon,

  • beyond which nothing, not even light, can escape.

  • That's how an average-size black hole forms.

  • What about a monster the size of the Subaru quasar?

  • Recent discoveries about the rapid rise of these giant black holes have led theorists

  • to rethink their view of cosmic history.

  • Back in 1995, the Hubble Space Telescope was enlisted to begin filling in the details of

  • that history.

  • Astronomers selected tiny regions in the sky, between the stars,

  • Looking North, South, And south again.

  • For days at a time, they focused Hubble's gaze on tiny patches of sky to examine the

  • deepest regions of the universe.

  • These Deep Field images offer incredibly clear views of the cosmos in its infancy.

  • What drew astronomers' attention were the tiniest galaxies, covering only a few pixels

  • on Hubble's detector.

  • Most of them do not have the grand spiral or elliptical shapes of the large galaxies

  • we see closer to us today.

  • Instead, they are irregular, scrappy collections of stars.

  • The Hubble Deep Field confirmed the idea that the universe must have evolved in a series

  • of building blocks,

  • with small galaxies gradually merging and assembling into larger ones.

  • You can see evidence of this pattern simply by looking out into the universe.

  • Many galaxies are gyrating around one another.

  • Some are crashing together,

  • others ripping each other apart.

  • Gravity calls the tune as these galaxies draw together, exchange stars and gas,

  • and, over time, merge to form larger composite galaxies.

  • Lately, though, this picture of a universe taking shape from the ground up has gotten

  • a lot more complicated.

  • The

  • quick appearance of giant black holes and galaxies in the early universe is at odds

  • with the gradual way matter builds up of matter in most galaxies.

  • They likely had their beginnings in the first generations of stars that literally burst

  • onto the cosmic scene, in a time of incredible turbulence.

  • These stars were born in knots that developed in the diffuse gas of the early universe.

  • Gravity drew these knots together. In the densest regions, stars were born in waves.

  • Many of them gave birth to black holes.

  • Within a relatively short time by cosmic standards, the earliest black holes swallowed more and

  • more matter, growing to monumental proportions,

  • becoming quasars.

  • These quasars, in turn, were fed by the collapse of matter on a much larger scale.

  • This computer simulation recreates a region in the early universe that measured over a

  • hundred million light years on a side.

  • It shows what took place in the first one billion years of cosmic history.

  • This virtual universe is set in motion by equations describing the properties of gas,

  • the energy released in star birth, and the outward motion of space and time.

  • The result: an intricate cosmic web, with gravity drawing matter into filaments and

  • knots,

  • as if you're looking down through a vast tangle of interconnected spider webs.

  • Inside the most dense regions is where the largest galaxies, and black holes, grew.

  • Here, circles indicate the appearance of black holes deep in the data.

  • As they bulk up, by eating up their surroundings, the circles grow larger.

  • A few, in the largest galaxies, reach ultra massive proportions, billions of times the

  • mass of our sun.

  • This is the scene in one of those dense intersections. Thousands of galaxies, and gigantic clouds

  • of gas, spiral inward.

  • A large galaxy emerges in the center, and at its center, a giant black hole forcefed

  • by gravity.

  • The orbiting Chandra X-Ray Observatory was dispatched to look into distant galaxies for

  • black holes on a growth spurt.

  • Those that swallow gas and stars glow hotly in X-ray light.

  • Chandra found them. It even spotted some in pairs, black hole companions entwined in a

  • dance of death.

  • When the music ends, the pair swallows each other!

  • That moment must be fast approaching for the largest black hole detected in the universe

  • to date. It's a quasar called OJ-287.

  • Flareups in the surrounding region suggest to astrophysicists that another black hole

  • is flying around it.

  • This giant's gravitational hold on its companion has led astronomers to estimate it's mass

  • at a whopping 18 billion solar masses.

  • A monster this large and ferocious vents its rage on the surrounding universe, and radically

  • changes it.

  • Just look at MS0735. Two and a half billion light years away, it appears in visible light

  • to be a typical galaxy cluster.

  • But in X-ray light, it's enveloped in a cloud of hot gas.

  • Hollowed out of this cloud are two immense cavities up to 600,000 light years across.

  • Now, add in a radio image of the cluster, and you can see two concentrated streams of

  • matter pushing out from the center.

  • That's a give-away that the cavities were formed by an eruption in the core of the giant

  • central galaxy.

  • Two jets, shooting out of the galaxy, have launched blast waves that have plowed through

  • the gas between the galaxies.

  • How much energy must that take? That of several billion supernovas, according to one calculation.

  • That makes this the largest single eruption recorded since the big bang.

  • Its source: a black hole that may weigh around 10 billion solar masses.

  • But how does a black hole, a creature famous for hiding in the dark, emit this much energy?

  • Think of a black hole as the eye of a cosmic hurricane, kept rotating by all the stars,

  • gas, and other black holes that happen to fall into it.

  • As this matter flows in,

  • It forms a spinning donut-like feature called an accretion disk, which works like a dynamo.

  • The spinning motion of that disk generates magnetic fields that twist around and channel

  • some of the inflowing matter outwards into a pair of high-energy beams, or jets.

  • How much energy depends upon the black hole's gravity and how much matter has already crashed

  • through its event horizon.

  • Is this just another frightening spectacle of Nature? Or is it part of a more profound

  • process at work?

  • Black hole jets have been seen all around the universe, including in our own cosmic

  • neighborhood.

  • This is Centaurus A, also known as the "hamburger galaxy."

  • In X-rays, you can see a jet erupting from the center.

  • Peering through the dense dust lanes that dominate our line of sight, astronomers have

  • come to believe that it's actually two galaxies in the act of colliding.

  • Then there's the famous M87 galaxy, at the center of the Virgo cluster of galaxies, around

  • 50 million light years away.

  • Astronomers have been intensely studying the four billion solar mass black hole that lurks

  • in its heart.

  • They found that in the tiny central region, the gas is whipped by gravity to orbital speeds

  • of millions of kilometers per hour.

  • That's powering a pair of high-powered jets that are plowing into the larger galaxy cluster.

  • The largest black holes in the universe probably rose in the age of quasars, between 10 and

  • 12 billion years ago.

  • By releasing energy in the form of jets, they heated up the surrounding region.

  • This prevented gas from collapsing into the center from the surrounding region, and allowed

  • smaller galaxies on the periphery to form and grow.

  • But the monsters' impact did not stop there.

  • This Chandra image of the Hydra A galaxy cluster shows the same immense hot cavities, glowing

  • in X-ray light,,

  • And a jet blasting out of its central galaxy.

  • Gas along the edge of the jet contains high levels of iron and other metals probably from

  • supernova explosions in the center.

  • By pushing these metals into regions beyond, a black hole seeds the universe with the elements

  • needed to form stars, planets, and solar systems like ours.

  • Those smaller galaxies then begin to seed their own environments.

  • This computer simulation shows the fate of gas in the merger of two galaxies with black

  • holes embedded in their cores.

  • As the two pass by each other by, the pull of gravity disrupts their spiral shapes, forcing

  • huge volumes of gas into their cores.

  • As these black holes continue to feed, they emit a series of powerful shock waves that

  • push much of the loose gas beyond their boundaries.

  • In the final steps of this ballet, the two black holes merge, emitting one final blast.

  • Our Earth, our star, the Sun,

  • our Solar System, and ourselves,

  • we all seem to be the beneficiaries of these far-away monsters.

  • But equally amazing is the role these largest black holes play in the great cosmic struggle

  • between gravity and energy.

We've never seen them directly,

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宇宙中最大的黑洞(第一版) (The Largest Black Holes in the Universe (VERSION ONE))

  • 1171 86
    Ronnie Chiang 發佈於 2021 年 01 月 14 日
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