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Category: cosmology – Page 71

The universe is still expanding at an accelerating rate, but it may have slowed down recently compared to a few billion years ago, early results from the most precise measurement of its evolution yet suggested Thursday.

While the preliminary findings are far from confirmed, if they hold up it would further deepen the mystery of dark energy—and likely mean there is something important missing in our understanding of the cosmos.

These signals of our universe’s changing speeds were spotted by the Dark Energy Spectroscopic Instrument (DESI), which is perched atop a telescope at the Kitt Peak National Observatory in the US state of Arizona.

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Using AI and ALMA data, scientists create a groundbreaking 3D video of flares around our galaxy’s central black hole, offering new insights into its dynamic environment.

Scientists believe the environment immediately surrounding a black hole is tumultuous, featuring hot magnetized gas that spirals in a disk at tremendous speeds and temperatures. Astronomical observations show that within such a disk, mysterious flares occur up to several times a day, temporarily brightening and then fading away. Now a team led by Caltech scientists has used telescope data and an artificial intelligence (AI) computer-vision technique to recover the first three-dimensional video showing what such flares could look like around Sagittarius A* (Sgr A*, pronounced sadge-ay-star), the supermassive black hole at the heart of our own Milky Way galaxy.

The 3D flare structure features two bright, compact features located about 75 million kilometers (or half the distance between Earth and the Sun) from the center of the black hole. It is based on data collected by the Atacama Large Millimeter Array (ALMA) in Chile over a period of 100 minutes directly after an eruption seen in X-ray data on April 11, 2017.

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I found this on NewsBreak: New models of Big Bang show that visible universe and invisible dark matter co-evolved.

Physicists have long theorized that our universe may not be limited to what we can see. By observing gravitational forces on other galaxies, they’ve hypothesized the existence of “dark matter,” which would be invisible to conventional forms of observation.

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But not in the Einstein/Newtonian Lambda-cold-dark-matter model

This post is based on the research paper by Mazurenko, Banik, Kroupa & Haslbauer (2023, MNRAS). Sergij Mazurenko is an undergraduate physics student at the University of Bonn, and Indranil Banik was an Alexander-von-Humboldt Fellow with us until recently and is currently at the University of St. Andrews. Moritz Haslbauer is a finishing PhD student at the University of Bonn who has been contributing to The Dark Matter Crisis (DMC). The press release from the University of Bonn on this matter can be read here (and from Charles University in Prague here) and a description can also be found in The Conversation.

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For most stars, neutron stars and black holes are their final resting places. When a supergiant star runs out of fuel, it expands and then rapidly collapses on itself. This act creates a neutron star—an object denser than our sun crammed into a space 13 to 18 miles wide. In such a heavily condensed stellar environment, most electrons combine with protons to make neutrons, resulting in a dense ball of matter consisting mainly of neutrons. Researchers try to understand the forces that control this process by creating dense matter in the laboratory through colliding neutron-rich nuclei and taking detailed measurements.

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Thanks to the dizzying growth of cosmic observations and measurement tools and some new advancements (primarily the “discovery” of what we call dark matter and dark energy) all against the backdrop of General Relativity, the early 2000s were a time when nothing seemed capable of challenging the advancement of our knowledge about the cosmos, its origins, and its future evolution.

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