Event Horizon Telescope captures the very first image of the Supermassive Black Hole in Milky Way
The very first image of the Black hole present in our Milky way galaxy known as Sagittarius A* has been released by The Event Horizon Telescope Team.
The first ever image of the Supermassive Black hole was also released by the same team of EHT back in 2019, M87 much larger than the one present in our Galaxy. Sagittarius A* is the location of a supermassive black hole, similar to massive objects at the centers of most, if not all, spiral and elliptical galaxies. Imaging Sagittarius A* is the end result of decades of observations that began with our first tantalizing hints of its presence in 1918, when the astronomer Harlow Shapley first noticed stars congregating toward the center of the Milky Way. Later observations detected powerful radio emissions coming from that spot, pointing to the presence of a massive yet compact object, most likely a black hole — a phenomenon predicted by Einstein’s general theory of relativity.
The two black holes have roughly the same apparent size in the sky, because M87* is nearly 2,000 times farther away but also roughly 1,600 times larger. This also means that any blobs of matter that spiral around M87* are covering much larger distances — larger than the orbit of Pluto around the Sun — and the radiation they emit is essentially constant over short time scales. But Sagittarius A* can change quickly even over the few hours the EHT observes it every day.
Getting accurate pictures of these supermassive black holes are next to impossible. Black Holes are so ‘massive’ that nothing can escape its gravitational pull — even Light. This makes it more difficult to exactly locate them in cosmos. If a supermassive black hole is surrounded by a swirling disc of gas and dust, that material will glow bright since the gas and dust is sped up and heated by the powerful gravitational pull of the nearby hole. What EHT is actually capturing is the black hole’s shadow against the backdrop of that glowing gas and dust.
According to EHT Group, a single telescope of the size of Earth would be needed to get clear snaps, as these becomes unrealistic, Scientists came up with a different plan. The EHT sets up array of radio dishes spread out across five different continents. The radio telescopes all work together to observe the same object, behaving as if they are one giant planet-sized telescope. The Scientists then adds the pieces of data collected from the telescope to create a single image.
Though it’s closer to Earth than M87’s black hole, Sgr A* is smaller and less active, and the material surrounding the object is much dimmer, making it harder to observe. On top of that, the material that does surround Sgr A* exhibits weird flaring when the particles surrounding the black hole are accelerated to much higher energies. While it makes for an interesting light show, it changes the composition of the black hole every few hours, making it tricky to observe over time.
When the EHT scientists observed Sgr A*, they collected roughly 3.5 petabytes of data. The data was then transferred to different centers. The supercomputers compiled the signals together. After that, the data underwent an intense calibration process, as the scientists attempted to construct the best image they could make of the black hole. The resultant image was that what we observed today.
Future observations will now focus on getting sharper images to better understand the physics of turbulence in the ring around the black hole, as well as how the black hole affects the environment of the galaxy around it. Now, with two black hole images on its resume, the EHT collaboration has big plans for the future. EHT is adding even more telescopes with the goal of creating the next-generation Event Horizon Telescope (ngEHT).
Einstein spent the decade between the two publications determining that particularly massive objects warp the fabric of space-time, a distortion that manifests as gravity. The scope of the latest images obtained with the advancement of science and technology proved the existence of such heavenly bodies around us.
