Arquivo para November 10th, 2021

But what are black holes ?

10 Nov

Black holes are regions in space-time (neither space nor time are absolute as idealists think) where the gravitational field is so intense that nothing we know, no particle or electromagnetic radiation like light, can escape it, Einstein’s theory of general relativity foresaw this as calculating an extremely compact mass that would deform spacetime to form a black hole.

On April 10, 2019, a gigantic black hole was “photographed” (figure), nestled in the heart of the Messier 87 (M87) galaxy located 55 million light years away was photographed as a dark circle surrounded by a flaming ring.

This photo actually used a computational algorithm, as scientists can’t directly observe with the telescopes they use to detect other bodies using X-ray, light or other forms of electromagnetic radiation, but can infer by detecting interference in bodies next to matter nearby, so if a black hole passes through a cloud of interstellar matter, it will draw the matter inward in a process known as accretion, it first heats up and then is torn apart as it goes towards it, thus having a dramatic interference in the bodies in its vicinity firing powerful bursts of gamma rays.

Black hole formation is so far known as a result of stellar collisions, shortly after launch in December 2004, NASA’s Swift telescope observed powerful flashes of light that were gamma-ray bursts, and shortly after the Chandra event and the Telescope NASA’s Hubble Spacer collected “afterglow” data from this event which led scientists to conclude that powerful explosions occur when a black hole and a neutron star collide, producing another black hole.

Even though the basic process of formation of black holes is known, a mystery remains that they exist on radically different scales, spread across the universe, on the one hand there are many remnants of massive star explosions, they are generally 10 to 24 times larger in “stellar mass” than the Sun, others are small and difficult to detect, but scientists estimate that there are ten million to one billion of these holes in the Milky Way alone.

At the other extreme are “supermassive” black holes that are millions to billions of times more massive than the Sun, astronomers believe they may be at the center of all large galaxies, including our Milky Way, observation is possible from the effects in the stars and in the gases close to it.