Stig Kristoffersen asked: We have never seen them directly, yet we know they are there.Lurking in dense star clusters, or wandering the dust lanes of the Galaxy were they prey on stars or even swallow plants whole.
Our Milky Way may harbor millions of these – Black Holes, the ultra dense remnants of dead stars.
But now in universe far beyond our galaxy there is evidence of something even more ominous, a breed of Black Holes that have reached incomprehensible size and destructive powers.
It has taken a new era of Astronomy to find these, high technology instruments in space tuned to find high energy forms of life with x-ray and gamma rays that are invisible to our eyes, new precision telescopes on earth with technology enabling them to cancel out the blurring effect from the atmosphere on earth and see to the far reaches of the Universe.
Looking into far distances of our Galaxies, astronomers finding evidence that space and time can be shattered by eruptions so waste they boggle the mind. We are just beginning to understand the impacts these outburst have had on the Universe around us.
That understanding recently took a leap forward when a team working at the Subaru observatory at the top of one of Hawaii’s volcano mountains looked into the deeper parts of the Universe and captured a beam of light that had taken almost 13 billion years to reach the earth. It was a messenger from not long time after the Universe is believed to have been born. They focused their attention towards an object known as a Quasar, short for Quasi radio stellar Source, it offered a stunning surprise.
A tiny region of the object is so bright that the astronomers believe it comes from a single object with at least a billion times the mass of our sun.
In the center of this beacon the space suddenly turns dark as it is literary is swallowed by a black hole.
As strange as it may seem, even Hugh Black holes like these are thought to be products of 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 they die young. The star is a cosmic pressure cooker. In its core the pressure gravity produces such an intense heat that atoms are stripped and re-arranged. Lighter elements like hydrogen and helium fuse together to form heavier ones like calcium, oxygen, silicon and finally iron. When enough iron forms and accumulate it begins to collapse under its own weight. That will send a chock wave that is sent outwards, literary blowing the star apart. A supernova is born – 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 at which point nothing, even not light can escape.
That is how an average size Black Hole is formed.
What about the monster of the Subaru Quasar just recently observed? Recent observations about these giant black holes have led the theorists to re-think their views on history.
Back in 1995, the Hubble Space telescope was enlisted in to begin register details of that history.
Astronomers selected tiny regions in the sky between the stars, looking north, and south and into south again.
For days at a time they focused the Hubble telescope on these tiny patches of sky to examine the deepest regions in the universe. These deep field images offerings clear view of the cosmos in its infancy. What drew astronomer’s attention were the tiniest galaxies covering only a few pixels on Hubble’s lenses. Most of them do not have the spiral or elliptical shapes of the large galaxies we see closer to us today. Instead they are irregular and scrappy collection 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 by simply looking into the sky as many galaxies are gravitating around one another. Some are crashing together; others are ripping each other apart. Gravity calls the tune as these galaxies draw together, exchanging stars and gases, and over time merge to form and form larger composite galaxies. Lately though, this picture of the Universe taking shape from the ground up has gotten a lot more complicated.
The quick appearance of giant black holes and galaxies in early universe is at odds with the gradual way matter builds up in most galaxies. They likely had their beginning in the first generation of stars that literary burst on to the cosmic scene, in a time of incredible turbulence. These stars were born in the knot that developed the fuse gas of the universe. Gravity drew these knots together, in the densest regions the stars were born in waves; they even gave birth to black holes. In a relatively short time by cosmic standards the earliest black holes swallowed more and more matter, growing to monumental proportions and became quasars. These quasars in turn were fed by collapse of matter on a much larger scale. Simulations of this illustrate what happened in the first billion years of cosmic history. Gravity forces driven by gases created an intricate web of strings and knots as if you were looking into a large spider web in three dimensions. In the densest regions are you would find the growth of the largest galaxies and black holes.
As these regions grow stronger and stronger, the galaxies and black holes grow more and larger. In some regions these reach ultra massive proportions, billions of times mass of our sun. In the center of these massive galaxies, you will find developed a black hole driven by the galactic gravity of gases surrounding these galaxies.
The orbiting Chandra X-Ray Space laboratory was dispatched to look into the distant galaxies for black holes on a growths birth, those who swallow gases and summers, glow hot in x-ray light. And Chandra found them; it even spotted some of them in pairs. Black hole companion entwined in a dance of death, as when the music ends, the pair will swallow each other. That moment must be fast approaching for the largest black hole detected in the Universe up to date (or should we say has happened, as light takes some time to arrive here).
It is a quasar called OJ287, flare ups in the surrounding regions of this quasar suggests to the astrophysicists that another black hole is wandering around it. This giant gravitational hole and its companion have led astronomers to estimate it’s mass to be the enormous 18 billion times our sun mass.
A monster this large and ferocious vents its rage on its surrounding area and radically changes it.
Just look at MSO735, 2.5 billion light years away it appears in visible light to be a typical galaxy cluster. But in x-ray light it is in enveloped in a cloud of hot gas held together by immense cavities over a region of 600 000 light years across, in the radio wave light of the cluster, you can see two concentrated streams of matter pushing out from the center. This tells the astronomers that this is formed due to a rupture in the core of the central galaxy. Two jets shooting out of the galaxy have launched a blast away through the gas of the galaxy; it is assumed that it requires energy of billions of super novas. This makes this the single largest eruption seen in our universe since the Big Bang.
The source is a black hole that might weigh around 10 billion solar masses. How is it that a black hole that is famous for hiding in the dark emit this much energy?
Think of the black hole as the eye in the midst of a hurricane storm, kept rotating by the gas, stars and all other matter surrounding its region of influence and other black holes that seem to fall into it. As this matter flows in, it forms a spinning donut feature called an accretion disc. It works like a dynamo, the spinning motion of that disc generates magnetic field that twist around and channel some of the inflowing matter outwards into a pair of high energy beams that projects out from the center of this jet donut.
How much energy, depends on the gravity and size of the black hole and how much matter has already crashed through its event horizon. Is this just another frightening specter of nature, or is it evidence of a more profound process at work?
Black hole jets have been seen all around the Universe, including in our own cosmic neighborhood. Centauries A, also known as the hamburger galaxy exhibits jets seen in x-ray light, jetting out from its center.
Astronomers have come to believe its two galaxies in the act of colliding.
The famous M87 galaxy, at the center of Virgo cluster of galaxies, about 15 million light years away from us has been studied recently by the astronomers.
They have studied the 4 billion solar sun mass black holes that lurk in its hart. They found that in the tiny center of its region that the gas is whipped by its gravity to orbital speeds of millions of kilometers pr hour, which is powered by a jet that is penetrating into its center.
The largest black hole in the universe arose in the edge of quasars around 10-12 billion years ago, by releasing energy in form of jets they heated up the surrounding region. This prevented the 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.
The Chandra made a spectral image Hydra A galaxy cluster illustrates the high energy cavities forming jet streams blasting out from its central galaxy.
Gas on the edge of these jet streams contains higher content of iron and other metals probably from other supernovas from the explosions in the center. By pushing these heavier elements out into regions beyond the black hole seeds the universe with the elements needed to form stars, planets and solar systems like ours.
Then the smaller galaxies begin to seed their own environment.
As two galaxies begin their dance of entanglement and gas streams of each of these galaxies begin to interact, they feed each others black hole gravity field as they close up and at the same time push much of the loose gas beyond its boundaries. The final stage is a merge into one bigger black hole, as gas is sucked into these and creates a massive pull, in the final stages the singular black hole created by this collision emits one final blast of energy.
Our earth, sun and solar system seem to be beneficiaries of the black holes and their activities around in the universe.
The black holes are the evidence of the constant battle between energy and gravity in our universe.
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