New observations help explain the universe’s most energetic objects

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admin February 23, 2022
Updated 2022/02/28 at 3:33 PM
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Observations of a doughnut-shaped cloud of cosmic dust and gas shrouding a massive black hole at the centre of a galaxy equal in size to our Milky Way have given scientists fresh insight into the universe’s most powerful objects.

On Wednesday, scientists claimed their observations of the supermassive black hole at the centre of galaxy Messier 77 and its surrounding cloud backed up predictions made three decades ago regarding “active galactic nuclei.”

These are regions in the centres of many massive galaxies that exhibit tremendous luminosity – sometimes outshining all of a galaxy’s billions of stars combined – and cause the universe’s most explosive outbursts since the Big Bang 13.8 billion years ago. The energy comes from gas falling forcefully towards a supermassive black hole, which is surrounded by a cloud of microscopic rock and soot particles, as well as mainly hydrogen gas.

Black holes are very dense objects with gravitational forces that are so strong that light can not escape them. The biggest of these are supermassive black holes, which may be found at the centre of many galaxies, including our own.

In the constellation Cetus, Messier 77, commonly known as NGC 1068 or the Squid Galaxy, is situated 47 million light-years away—the distance light travels in a year, 9.5 trillion km from Earth. Its supermassive black hole has a mass ten million times that of the sun.

The observations, made with the Very Large Telescope of the European Southern Observatory in Chile’s Atacama Desert, offered significant support for what is known as the “unified model” of active galactic nuclei. According to this hypothesis, all active galactic nuclei are essentially the same, yet some seem to have distinct features from Earth’s perspective.

Because the orientation of their ring-like clouds does not conceal the gas hurtling into the black hole from our viewing point, some seem very brilliant. Others seem gloomy because the cloud obscures our vision of the true situation.

The active galactic nucleus of Messier 77 is one of the dark ones, but fresh studies show that it has the same properties as the bright ones.

Violeta Gamez Rosas, an astronomy doctoral student at Leiden University in the Netherlands and lead author of the research published in the journal Nature, said the dust and gas in these clouds are probably blown out of the atmospheres of stars at a greater distance from the black hole – hundreds of light years away – and are falling towards the centre under the influence of the black hole’s gravity.

Some clouds spiral inwards towards the black hole, while others are propelled upwards into a ‘fountain’ that spills out into the cosmos. Due to the dust, it’s tough to detect what’s going on in this area with telescopes, but it’s easier at infrared wavelengths than at visible wavelengths since the dust absorbs less infrared light. ” One of the study’s co-authors is Walter Jaffe, a professor of astronomy at Leiden University.

The Milky Way’s supermassive black hole, with a mass of 4 million times that of the Sun, is now “pretty quiet,” according to Gamez Rosas, but it may have been more active in the past, similar to Messier 77’s.

Gamez Rosas was pleased with his research on active galactic nuclei.

“A lot of it is simply curiosity about such massive explosions and the difficulty of attempting to explain them with what we believe we know about physics,” Gamez Rosas said.

“Building and operating telescopes to produce these photos of objects so far away is also a difficulty,” Gamez Rosas noted. And then there’s the peace of mind that comes from knowing that there’s a big, complicated, diverse world out there that doesn’t care what we do on Earth.

Source: The Hindu

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