HOW THE FIRST IMAGE OF A BLACK HOLE WAS TAKEN
A black hole is a region of spacetime where gravity is so strong that nothing—no particle or even electromagnetic radiation such as light—can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of no escape is called the event horizon. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe directly.
On Wednesday, April 10th (2019) the world was treated to something unprecedented, the first-ever image of a ‘black hole’. Specifically, the image captured the supermassive black hole or SMBH at the center of M87 or Virgo A a supergiant elliptical galaxy in the Virgo constellation. This accomplishment took more than 10 years of hard work involving astronomers, observatories, and scientific institution from all around the world
They come up with this achievement by using something called Event Horizon Telescope or EHT. They are essentially a planet-size telescope made by linking up observation from around the world. In present EHT consist of eight sites which includes the James Clerk Maxwell Telescope (JCMT) at the
Maunakea observatory in Hawaii, Large Millimetre Telescope “Alfonso Serrano” (LMT)
Sierra Negra in Mexico, Atacama Pathfinder Experiment (APEX) and Atacama Large Millimeter/submillimeter Array (ALMA) Cerro Chajnantor in Chile, IRAM 30-meter Telescope Pico Veleta in Spain, Submillimeter Array (SMA) Maunakea, Hawaii, USA, South Pole Telescope (SPT) South Pole Station, in Antarctica. Three more additional observatories that participated in EHT observations in 2018 (and later): The Greenland Telescope (GLT) Thule Air Base, Greenland in Denmark, Kitt Peak 12-meter Telescope Kitt Peak, Arizona, USA, and NOEMA Observatory
Plateau de Bure in France
The EHT can achieve a level of resolution. That allows scientists to view the intermediate environment around the black hole called the event horizon. Through its eight observatories, the EHT recorded millions of gigabytes of data of black holes. In total each telescope took about one million gigabytes of data and recorded in several mark6 units. Data recorders that were originally developed at the haystack observatory and after the run behind the observatory ended, all the hard drives were packed, which were then flown to MIT HAYSTACK OBSERVATORY IN USA and THE MAX PLANCK institute for radio astronomy Bonn, Germany. Once there the data was cross-correlated and analyzed by 800 computers.
Converting this data into an image requires new methods and procedures and that involves comparing images using three different imagining methods. Whose algorithms were designed and led by Katherine Bauman. She works as a postdoctoral researcher with the Event horizon telescope project where she applied emerging computation methods to push the boundaries of imaging technology. The image produced today is a combination of handwork and multiple methods. On April 10th Katherine and her crew revealed the picture of the black hole.