Event Horizon Telescope: Gravitational Sinkhole Hunter
2 and a half years ago a team from Event Horizon Telescope set up on a mission to capture Black Hole. The mystery of the Black Hole started in 1980, when astronomers found that small (stellar-mass) emit X-ray light that flickers in a curious pattern. At first, this flickering occurs every few seconds; however, the time between each flicker shortens over the course of a few months, eventually stopping completely.
On and on the fascination with black holes did not end with Einstein. Astronomers published so many theories about it. And so many agency including NASA have been examining this scientific marvels since then. But till today we’ve never seen a real photograph of it.
In the interstellar Movie we get an up-closed look at a supermassive black hole. Set against a backdrop a bright gases. The black hole’s massive gravitational pulls bends light into a ring. However this isn’t a real photograph but a computer graphic rendering. An artistic interpretation what a black hole might look like.
About a hundred years ago Albert Einstein first published his theory of general relativity. In the years since then scientists have provided a lot of evidence in support of it; but one thing predicted from the theory black holes still have not been directly observed. Although astronomers have some ideas as to what a black hole might look like. But as we know they never actually taken a picture of one before.
But with the Event Horizon Telescope initiative we will soon see the first picture of black hole. Getting this first picture will come down to a international team of scientists, an earth-sized telescope and an algorithm that puts together the final picture.
You might be lucky enough to see a stunning view of the Milky Way galaxy. And we could zoom past millions of stars, 26000 light-years towards the heart of the spiraling Milky Way we eventually reach a cluster of stars tight at the center. Peering past all the galactic dust with infrared telescope astronomers have watched these stars for over 16 years. These stars seem to orbiting an invisible object. By tracking the paths of these stars astronomers have concluded that the only thing small and heavy enough to cause this motion is a supermassive black hole. An object so dense that it sucks up anything that ventures too close, even light. But what happens if astronomers were to zoom in even further.
There is a possibility to see something that by definition is impossible to see. It turns out that if we were to zoom in at radio wavelength, we expect to see a ring of light caused by the gravitational lensing of hot plasma zipping around the black hole. In other words the black hole casts a shadow on this backdrop of bright material carving out of darkness. This bright ring reveals the black hole’s vaporization. Where the gravitational pull becomes so great then not even light can escape.
However this black hole so far away from Earth. So from Earth this ring appears incredibly small. The same size of to us as an orange on the surface of the Moon. That makes taking a picture of it extremely difficult. Due to a phenomenon called the fraction there are fundamental limits the smallest objects that we can possibly see. This governing equation says in order to see smaller and smaller we need to make our telescope bigger and bigger. But even with the most powerful optical telescopes here on Earth we can’t even get close to the resolution necessary to image on the surface of the Moon.
So how big of a telescope do we need in order to see the black hole? Well it turns out we would need a telescope the size of the entire Earth; which is technically impossible. Even if we build this telescope we could just start to make out that distinctive ring of light indicative of block hole’s event horizon.
Although this picture wouldn’t contain all detail we get to see in computer graphic renderings, it would allow us to safely get our first glimpse of the immediate environment around a black hole. Talking about single-dish Earth size of telescope is impossible. But alternatively the connecting telescopes from around the world, an international collaboration called Event Horizon Telescope is creating computational telescope the size of Earth, capable of resolving structure on the scale of black hole’s event horizon. This network of telescopes was scheduled to take its picture in April 2017.
Each telescope in the worldwide network works together. Linked through the precise timing of atomic clocks, teams of researcher at each of sight freeze light by collecting thousands of terabytes of data. And this data is then processed and gives generate a new combined image.
WHAT WE WILL SEE?
When it comes to images from black hole, we’re posed with a real conundrum: since we never seen a black hole before! In that case, what is a likely black hole image, and what should we assume about structure of black holes? What would happen if Einstein’s theories didn’t hold? If they bake Einstein’s equations too much into our algorithms, they will just end up seeing what they expect to see.
By imposing the features of different kinds of images and seeing how the type of image they assume affects reconstructions they get around this. Another way to impose different image features is by using pieces of existing images. So they are taking a large collection of images, and braking it down into their little image patches. Then they can treat each image patch a little bit like pieces of a puzzle, and they can use commonly seen puzzle pieces together an image that also fits telescope measurements.
OPERATION & AFTERMATH
After the 5 days of continuous observation back in April, astronomers captured the first image of the black hole. New Horizon Telescope captured 2 supermassive black hole. Sagittarius A*, which is as massive as 4 million sun lies at the heart of the Milky Way galaxy. And another black hole which is nearby M87 galaxy, about 1500 times heavier.
Astronomers observed these black holes in millimeter radio waves. The wavelength band at which light can penetrate the dense concentration of gas and dust at the center of galaxy. In order to process the data, thousands of servers will perform task of combining time-stamped signals. Comparing and combining radio waves must be done by extraordinary care, so that the all critical information about size and structure of event horizon does not lost.
It will take months to develop the image, but if scientists succeed the results may help peel back mysteries about what the universe is made of and how it came into being.