A Cosmic Breakthrough Like Never Before…


The first ever photograph of a black hole might not be crispy and clear as compared to the immensely popular movie rendition (above) featured in Christopher Nolan’s Interstellar, but it is in every regard the most realistic and marks the achievement of something that was widely considered to be impossible. Not only scientists but people in general have always been obsessed with black hole, and the fact still remains that black holes are one of the most fascinating and remarkable marvel of nature, which are yet to be fully understood. 

So, to begin with, what exactly is a black hole? Albert Einstein first predicted black holes in 1916 with his general theory of relativity. The term “black hole” was coined in 1967 by American astronomer John Wheeler, and the first one was discovered in 1971. Albert Einstein, in his theory of general relativity, predicted the existence of black holes, in the form of infinitely dense, compact regions in space, where gravity is so extreme that nothing, not even light, can escape from within. By definition, black holes are invisible. But if a black hole is surrounded by light-emitting material such as plasma, Einstein’s equations predict that some of this material should create a “shadow,” or an outline of the black hole and its boundary, also known as its event horizon. If you want to know more about black holes watch the video below.





But black holes are so small, dark and distant that observing them directly requires a telescope with a resolution equivalent to being able to see a doughnut on the moon. As previously mentioned, this was once thought to be an insurmountable challenge.
The Event Horizon Telescope (EHT) achieved the necessary firepower by combining data from eight of the world’s leading radio observatories, including the Atacama Large Millimetre Array (Alma) in Chile and the South Pole Telescope, creating an effective telescope the size of the Earth.This method of observation is referred to as Very-Long-Baseline Interferometry (VLBI), a  type of astronomical interferometry used in radio astronomy.


When observations were launched in 2017, the EHT had two primary targets. First was Sagittarius A*, the black hole at the centre of the Milky Way, which has a mass of about 4m suns. The second target, which yielded the image, was a supermassive black hole in the galaxy M87, into which the equivalent of 6.5 billion suns of light and matter has disappeared.
The success of the project hinged on clear skies on several continents simultaneously and exquisite coordination between the eight far-flung teams. This method of observation is referred to as Very-Long-Baseline Interferometry (VLBI), a  type of astronomical interferometry used in radio astronomy.Observations at the different sites were coordinated using atomic clocks, called hydrogen masers, accurate to within one second every 100 million years. And, on one night in April 4th 2017, everything came together. “We got super lucky, the weather was perfect,” said Ziri Younsi, a member of the EHT collaboration who is based at University College London.

The sheer volume of data generated was also unprecedented – in one night the EHT generated enough data to fill half a tonne of hard drives. This meant waiting for half a year for the South Pole data, which could only be shipped out at the end of Antarctic winter. After the observing run ended, researchers at each station packed up the stack of hard drives and flew them via FedEx to Haystack Observatory, in Massachusetts, and Max Planck Institute for Radio Astronomy, in Germany. (Air transport was much faster than transmitting the data electronically.) At both locations, the data were played back into a highly specialized supercomputer called a correlator, which processed the data two streams at a time.


And all of that work culminated into the magnificent image that was released on April 10, 2019 in coordinated press conferences across the globe.

 The image reveals the black hole at the center of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5-billion times that of the Sun.


Also watch this video which sums up all that was needed to make this possible.



The links to all the 6 papers detailing the research that were published in “The Astrophysical Journal Letters” are linked below.
PAPERS:

Source:
https://science.nasa.gov/astrophysics/focus-areas/black-holes/
https://www.nsf.gov/news/special_reports/blackholes/formedia.jsp
http://news.mit.edu/2019/mit-haystack-first-image-black-hole-0410?fbclid=IwAR2Dk3cH3O2wKmUFk9SqZPj3halrDJgQv0KJvIl63EEq3retX0bCWqjoqko
https://www.space.com/15421-black-holes-facts-formation-discovery-sdcmp.html
https://www.theguardian.com/science/2019/apr/10/black-hole-picture-captured-for-first-time-in-space-breakthrough
https://www.bbc.com/news/science-environment-47873592
https://blackholecam.org/research/bhshadow/vlbi/

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