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Category: cosmology – Page 83

Astronomers at MIT, NASA, and elsewhere have a new way to measure how fast a black hole spins, by using the wobbly aftermath from its stellar feasting.

The method takes advantage of a black hole tidal disruption event—a blazingly bright moment when a black hole exerts tides on a passing star and rips it to shreds. As the star is disrupted by the black hole’s immense tidal forces, half of the star is blown away, while the other half is flung around the black hole, generating an intensely hot accretion disk of rotating stellar material.

The MIT-led team has shown that the wobble of the newly created accretion disk is key to working out the central black hole’s inherent spin.

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Related: If the Big Bang created miniature black holes, where are they?

The research team thinks that super-color-charged black holes may have impacted the balance of fusing nuclei in the infant universe. Though the exotic objects ceased to exist in the first moments of the cosmos, future astronomers could potentially still detect this influence.

“Even though these short-lived, exotic creatures are not around today, they could have affected cosmic history in ways that could show up in subtle signals today,” study co-author David Kaiser, a professor of physics at the Massachusetts Institute of Technology (MIT), said in a statement.

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Now, however, astronomers Fan Zou and W. Niel Brandt, both of Penn State University, have led a team that connected the two mechanisms of black-hole growth from observations and simulations. The results may provide some answers at last.

Related: NASA telescope spots ‘cosmic fireworks’ and faint echos from the Milky Way’s supermassive black hole

“A very big question is how do these supermassive black holes grow so massive?” said Zou while presenting their work at the 244th meeting of the American Astronomical Society in Wisconsin… “To address that, we need to track the overall growth history of these supermassive black holes.”

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Observational astronomy shows that newly discovered young stellar objects (YSOs) in the immediate vicinity of the supermassive black hole Sagittarius A located in the center of our galaxy behave differently than expected. They describe similar orbits to already known young evolved stars and are arranged in a particular pattern around the supermassive black hole.

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The study is based on several intriguing coincidences. First, observations show that there is about the same amount of ordinary and dark matter, which exceeds baryonic by about five times. And secondly, neutrons and protons have almost the same mass, which allows them to form stable atoms — this is a random but stable property of the quantum world, because otherwise our universe would not be home to any of the atoms that make up stars, planets and ourselves.

In fact, the theory suggests that there may be a parallel universe like ours in which neutrons and protons do not have such convenient symmetry in mass. In this world, there is a “soup” of subatomic particles that interact little, which explains why dark matter does not seem to clump together.

It is important to note that this is just one more of many hypotheses that try to explain the mystery of dark matter – an annoying and lingering unknown in our understanding of the universe.

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Scientists may be one step closer to unraveling one of the universe’s greatest mysteries. Their recent calculations suggest that neutron stars could play a crucial role in shedding light on the mysterious dark matter.

In a paper published in The Journal of Cosmology and Astroparticle Physics, physicists from the ARC Centre of Excellence for Dark Matter Particle Physics, led by the University of Melbourne, calculated that energy transferred when dark matter particles collide and annihilate inside cold dead neutron stars can heat the stars up very quickly.

It was previously thought that this energy transfer could take a very long time, in some cases, longer than the age of the universe itself, rendering this heating irrelevant.

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