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Category: cosmology – Page 311

(8 April 2020 — ESA) Astronomers have assumed for decades that the Universe is expanding at the same rate in all directions. A new study based on data from ESA’s XMM-Newton, NASA’s Chandra and the German-led ROSAT X-ray observatories suggests this key premise of cosmology might be wrong.

Konstantinos Migkas, a PhD researcher in astronomy and astrophysics at the University of Bonn, Germany, and his supervisor Thomas Reiprich originally set out to verify a new method that would enable astronomers to test the so-called isotropy hypothesis. According to this assumption, the Universe has, despite some local differences, the same properties in each direction on the large scale.

Widely accepted as a consequence of well-established fundamental physics, the hypothesis has been supported by observations of the cosmic microwave background (CMB). A direct remnant of the Big Bang, the CMB reflects the state of the Universe as it was in its infancy, at only 380 000 years of age. The CMB’s uniform distribution in the sky suggests that in those early days the Universe must have been expanding rapidly and at the same rate in all directions.

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Shoot a rifle, and the recoil might knock you backward. Merge two black holes in a binary system, and the loss of momentum gives a similar recoil—a “kick”—to the merged black hole.

“For some binaries, the kick can reach up to 5000 kilometers a second, which is larger than the escape velocity of most galaxies,” said Vijay Varma, an astrophysicist at the California Institute of Technology and an incoming inaugural Klarman Fellow at Cornell University’s College of Arts & Sciences.

Varma and his fellow researchers have developed a new method using gravitational wave measurements to predict when a final black hole will remain in its host galaxy and when it will be ejected. Such measurements could provide a crucial missing piece of the puzzle behind the origin of heavy black holes, said Varma, as well as offer insights into galaxy evolution and tests of general relativity. He is lead author of “Extracting the Gravitational Recoil from Black Hole Merger Signals,” published March 13 in Physical Review Letters and co-authored with Maximiliano Isi and Sylvia Biscoveanu of the Massachusetts Institute of Technology.

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A long-held mystery in the field of nuclear physics is why the universe is composed of the specific materials we see around us. In other words, why is it made of “this” stuff and not other stuff?

Specifically of interest are the responsible for producing heavy elements—like gold, platinum and uranium—that are thought to happen during neutron star mergers and explosive stellar events.

Scientists from the U.S. Department of Energy’s (DOE) Argonne National Laboratory led an international nuclear physics experiment conducted at CERN, the European Organization for Nuclear Research, that utilizes novel techniques developed at Argonne to study the nature and origin of heavy elements in the universe. The study may provide critical insights into the processes that work together to create the exotic , and it will inform models of stellar events and the early universe.

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O,.,o.

In the far reaches of the Universe, astronomers have managed to capture a rare interaction. As a supermassive black hole ravenously slurps down matter around it, it’s sending out jets of plasma — pushing into and heating the gas in the galaxy around it.

This is difficult to capture at the best of times, but this case was a particularly impressive feat. The galaxy in question is a whopping 11 billion light-years away — when the Universe was less than 3 billion years old.

It’s called MG J0414+0534, and astronomers managed to capture it in detail because of gravitational lensing. In between us and the galaxy is a different, rather massive galaxy whose gravity distorts the path of the light travelling from behind it, creating four images of MG J0414+0534 around it (see image below).

Continue reading “Astronomers Observe Blasting Supermassive Black Hole Jets From The Early Universe” | >

Circa 2006

By Maggie Mckee

Nearly all of the information that falls into a black hole escapes back out, a controversial new study argues. The work suggests that black holes could one day be used as incredibly accurate quantum computers – if enormous theoretical and practical hurdles can first be overcome.

Black holes are thought to destroy anything that crosses a point of no return around them called an “event horizon”. But in the 1970s, Stephen Hawking used quantum mechanics to show black holes do emit radiation, which eventually evaporates them away completely.

Continue reading “Black holes: The ultimate quantum computers?” | >

Researchers at the Center for Axion and Precision Physics Research (CAPP), within the Institute for Basic Science (IBS, South Korea), have reported the first results of their search of axions, elusive, ultra-lightweight particles that are considered dark matter candidates. IBS-CAPP is located at Korea Advanced Institute of Science and Technology (KAIST). Published in Physical Review Letters, the analysis combines data taken over three months with a new axion-hunting apparatus developed over the last two years.

Proving the existence of axions could solve two of the biggest mysteries in modern physics at once: why galaxies orbiting within galaxy clusters are moving far faster than expected, and why two fundamental forces of nature follow different symmetry rules. The first conundrum was raised back in the 1930s, and was confirmed in the 1970s when astronomers noticed that the observed mass of the Milky Way galaxy could not explain the strong gravitational pull experienced by the stars in the galaxies. The second enigma, known as the strong CP problem, was dubbed by Forbes magazine as “the most underrated puzzle in all of physics” in 2019.

Symmetry is an important element of particle physics and CP refers to the Charge+Parity symmetry, where the laws of physics are the same if particles are interchanged with their corresponding antiparticles © in their mirror images ℗. In the case of the strong force, which is responsible for keeping nuclei together, CP violation is allowed theoretically, but has never been detected, even in the most sensitive experiments. On the other hand, CP symmetry is violated both theoretically and experimentally in the weak force, which underlies some types of radioactive decays. In 1977, theoretical physicists Roberto Peccei and Helen Quinn proposed the Peccei-Quinn symmetry as a theoretical solution to this problem, and two Nobel laureates in Physics, Frank Wilczek and Steven Weinberg, showed that the Peccei-Quinn symmetry results in a new particle: the . The particle was named after an American detergent, because it should clean the strong interactions mess.

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