Free Republic

The largest black holes in the universe... sit at the centers of almost every galaxy in the cosmos. Even the Milky Way has one, a monster at 4 million solar masses, designated as Sagittarius A*. ...[A]s far as we know, the only way to form black holes is through the deaths of massive stars. When they die, they leave behind a black hole a few times more massive than the sun. To get to supergiant status, they have to merge with other black holes and/or consume as much gas as possible, bulking up all those millions of solar masses... Either...

The best example is represented by the Sunflower galaxy (Messier 63 / NGC 5055) with the strongest external field among SPARC galaxies, whose well-measured rotation curve shows a mildly declining behavior at large radial distance and can be accurately modeled only with an external field effect. Credit: ESA/Hubble & NASA ================================================================= Team of international collaborators detect ‘external field effect,’ a prediction unique to MOND, rival dark matter hypothesis. An international group of scientists, including Case Western Reserve University Astronomy Chair Stacy McGaugh, has published research contending that a rival idea to the popular dark matter hypothesis more accurately predicts a...

Artist's impression of a galaxy surrounded by gravitational distortions due to dark matter. Galaxies live inside larger concentrations of invisible dark matter (coloured purple in this image), however the dark matter's effects can be seen by looking at the deformations of background galaxies. Credit: Swinburne Astronomy Productions - James Josephides ========================================================================== A small team of astronomers have found a new way to 'see' the elusive dark matter haloes that surround galaxies, with a new technique 10 times more precise than the previous-best method. The work is published in Monthly Notices of the Royal Astronomical Society. Scientists currently estimate that up...

......................................And that led to a remarkable twist in the story. Because the radiation is highly entangled with the black hole it came from, the quantum computer, too, becomes highly entangled with the hole. Within the simulation, the entanglement translates into a geometric link between the simulated black hole and the original. Put simply, the two are connected by a wormhole. “There’s the physical black hole and then there’s the simulated one in the quantum computer, and there can be a replica wormhole connecting those,” said Douglas Stanford, a theoretical physicist at Stanford and a member of the West Coast team....

Explanation: Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and why visible matter is distributed as it is both in the local universe and on the cosmic microwave background. The featured image from the American Museum of Natural History's Hayden Planetarium previous Space Show Dark Universe highlights one example of how pervasive dark matter might haunt our universe. In this frame from a detailed computer...

Roger Penrose’s theoretical work demonstrated the objects could form. Reinhard Genzel and Andrea Ghez independently discovered a supermassive one at the center of the Milky Way. Roger Penrose, Reinhard Genzel, and Andrea Ghez are to be awarded the 2020 Nobel Prize in Physics for their theoretical and observational work on black holes, the Royal Swedish Academy of Sciences announced on Tuesday. Penrose will receive half the 10 million Swedish krona (roughly $1.1 million) prize; Ghez and Genzel will share the other half. Penrose, of the University of Oxford, helped place the previously idealized concept of a black hole on sound...

Image and amplification (in color) of the ultra-diffuse galaxy Dragonfly 44 taken with the Hubble space telescope. Credit: Teymoor Saifollahi and NASA/HST. ============================================================================= At present, the formation of galaxies is difficult to understand without the presence of a ubiquitous, but mysterious component, termed dark matter. Astronomers have measure how much dark matter there is around galaxies, and have found that it varies between 10 and 300 times the quantity of visible matter. However, a few years ago, the discovery of a very diffuse object, named Dragonfly 44, changed this view. It was found that this galaxy has 10,000 times more...

It would be extremely optimistic to suggest that we have a good handle on dark matter. But even the slight grasp we do have may be missing something important. New observations from the Hubble Space Telescope have found much higher concentrations of dark matter than expected in some galaxies, by over an order of magnitude. These concentrations are inconsistent with theoretical models, suggesting that there's a big gap in our understanding - the simulations could be incorrect, or there could be a property of dark matter we don't fully understand, according to the research team. "We have done a lot...

Explanation: How do black holes like this form? The two black holes that spiraled together to produce the gravitational wave event GW190521 were not only the most massive black holes ever seen by LIGO and VIRGO so far, their masses -- 66 and 85 solar masses -- were unprecedented and unexpected. Lower mass black holes, below about 65 solar masses are known to form in supernova explosions. Conversely, higher mass black holes, above about 135 solar masses, are thought to be created by very massive stars imploding after they use up their weight-bearing nuclear-fusion-producing elements. How such intermediate mass black...

The information locked inside black holes could be detected by feeling their 'hair,' new research suggests. As far as we understand them (which, admittedly, is not very much), black holes are suspiciously simple objects. Regardless of what falls in... black holes can be described by three and only three simple numbers: charge, mass and spin. The reason this is suspicious is that something had to happen to all that juicy information that fell into those two black holes. The simplest solution is the theorem, first coined by the American physicist John Wheeler, that "black holes have no hair" — they...

Stephen Hawking won accolades from his peers for having one of the most brilliant minds in science, but he never got a Nobel Prize because no one has yet proven his ideas. The Nobel committee looks for proof, not big ideas. Hawking was a deep thinker — a theorist — and his musings about black holes and cosmology have yet to get the lockdown evidence that accompanies the physics prizes, his fellow scientists said.

An international team of researchers have discovered a dense, cold gas that's been shot out from the center of the Milky Way "like bullets". Exactly how the gas has been ejected is still a mystery, but the research team, including Professor Naomi McClure-Griffiths from The Australian National University (ANU), say their findings could have important implications for the future of our galaxy. The study also raises new questions about what's happening in our galactic center right now. The center of the Milky Way is home to a massive black hole, but it's unclear whether this black hole has expelled the...

Over the past few years, researchers have noticed an odd clustering in the orbits of multiple trans-Neptunian objects (TNOs), which dwell in the dark depths of the far outer solar system. Some scientists have hypothesized that the TNOs' paths have been sculpted by the gravitational pull of a big object way out there, something five to 10 times more massive than Earth (though others think the TNOs may just be tugging on each other). This big "perturber," if it exists, may be a planet — the so-called "Planet Nine," or "Planet X" or "Planet Next" for those who will always...

Artist's conception. Image: Caltech/R. Hurt (IPAC) Astronomers from Caltech have reported that they’ve observed a collision between two black holes. Normally such an event is invisible, but this time a more massive black hole sitting nearby helped illuminate the other two as they collided. If confirmed, the findings, published in Physical Review Letters, would be the first optical observations ever made of a black hole merger. What happened: First detected in May 2019 and dubbed S190521g, the merger happened about 4 billion light-years away, within the vicinity of a supermassive black hole called J1249+3449. This object is 100 million times...

Images from the Hubble Space Telescope have revealed a so-called "ring of dark matter" circling a galaxy cluster. Does dark matter exist? Or is electricity a better explanation for the structure of the universe? {Galaxy Cluster CL0024+17 with an overlay showing a supposed dark matter ring. Credit: NASA, ESA, M. J. Jee and H. Ford et al. (Johns Hopkins University)} In a recent announcement, NASA and the European Space Agency (ESA) reported the discovery of something in deep space that seems to confirm previously inferred observations of "dark matter." Although "dark matter" cannot be seen or detected by instruments, its...

A giant star which was under the observation of astronomers for over ten years has suddenly vanished. The star in question was located in a dwarf galaxy 75 million light-years away, and was one of the largest stars in the known universe. The star, which was 2.5 times brighter than the Sun, left no trace behind The star was located in a very far off galaxy, making its detection and observation very difficult. The astronomers observed it based on its signature, which was picked up and then analysed, instead of a direct observation. A highly unstable blue star, researchers picked...

WE COULD be living inside a black hole. This head-spinning idea is one cosmologist's conclusion based on a modification of Einstein's equations of general relativity that changes our picture of what happens at the core of a black hole. In an analysis of the motion of particles entering a black hole, published in March, Nikodem Poplawski of Indiana University in Bloomington showed that inside each black hole there could exist another universe (Physics Letters B, DOI: 10.1016/j.physletb.2010.03.029). "Maybe the huge black holes at the centre of the Milky Way and other galaxies are bridges to different universes," Poplawski says. If...

On Aug. 14, 2019, a gravitational wave -- a massive ripple through the fabric of space-time -- washed over the Earth. The signal was one of the strongest ever seen by the gravitational wave scientists at the Laser Interferometer Gravitational-wave Observatory and Italy's Virgo observatory. After an alert was sent out moments after detection, teams of astronomers across the world turned their telescopes to the point in space that the wave emanated from. But their searches came up empty. No light, no X-rays, no infrared, no gamma rays. On Tuesday, researchers from the LIGO and Virgo collaborations detail their full...

Scientists working on the Xenon1T experiment have detected more activity within their detector than they would otherwise expect. There are three potential explanations for the new signal from the Xenon1T experiment. Two require new physics to explain, while one of them is consistent with a hypothesised dark matter particle called a solar axion. There are several theories to account for what that particle might be like. The most favoured one has been the WIMP, or Weakly Interacting Massive Particle. Physicists working on the Xenon series of experiments have spent more than a decade hunting for signs of these WIMPs. ......

A Black Hole Relic from the Big Bang –“May Exist in Our Solar System” Posted on May 4, 2020 in Science  A bowling-ball sized primordial black hole, a relic of the Big Bang, may exist in our Solar system that could be detected according to theoretical physicist Edward Witten, at the Institute for Advanced Study, who has been compared to Issac Newton and Einstein.In a paper posted September, 2019 to arXiv, physicists James Unwin, University of Illinois at Chicago and Jakub Scholtz at the University of Durham in the United Kingdom, showed that the likelihood of our Sun capturing a...