This delayed outflow of material is traveling at 50% of light speed—far faster than typical TDEs.
Category: cosmology – Page 7
Galactic Empire Psychology
We now know that the Galaxy is full of potentially habitable planets. So why do we see no signs that any civilizations have come before us? Matt O’Dowd, astrophysicist and host of PBS Space Time, explains why Fermi’s paradox really is so surprising, and he offers a new piece of evidence that may point towards the solution.
Astrophysicist Matthew O’Dowd spends his time studying the universe, especially really far-away things like Quasars, super-massive black holes and evolving galaxies. He completed his Ph.D. at NASA´s Space Telescope Science Institute, followed by work at the University of Melbourne and Columbia University. Currently he is a professor at the City University of New York´s Lehman College and an Associate at the American Museum of Natural Historys Hayden Planetarium.
Thumbnail © Nadja Niemiec.
This talk was given at a TEDx event using the TED conference format but independently organized by a local community.
New idea explains dark energy AND dark matter (maybe)
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Dark energy and dark matter are two placeholders for mysterious forces and substances that expand our universe and make up the majority of its matter, respectively. In a new theory, one physicist says that defects in spacetime explain both of these mysteries at the same time. Let’s take a look.
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Correction: I mixed up the gems, sorry. I should have said, defects change the colour of sapphires to red and green, not diamonds.
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Astronomers observe the Sausage cluster at very low radio frequencies
Using the Low Frequency Array (LOFAR), European astronomers have investigated a galaxy cluster designated CIZA J2242.8+5301, dubbed the Sausage cluster. The observations conducted at very low radio frequencies provide more insights into the properties of radio relics in this cluster. The new findings are presented in a research paper published May 29 on the arXiv preprint server.
Galaxy clusters consist of up to thousands of galaxies bound together by gravity. They are the largest known gravitationally-bound structures in the universe, and therefore serve as excellent laboratories for studying galaxy evolution and cosmology. Observations show that galaxy clusters generally form as a result of mergers and grow by accreting sub-clusters.
CIZA J2242.8+5301 is a well-studied merging galaxy cluster at a redshift of 0.192. It contains prominent double radio relics (diffuse, elongated radio sources of synchrotron origin) and other diffuse radio sources. CIZA J2242.8+5301 was nicknamed the Sausage cluster due to the distinctive morphology of its northern relic.
Biggest boom since Big Bang: Astronomers uncover most energetic explosions in universe
Astronomers from the University of Hawaiʻi’s Institute for Astronomy (IfA) have discovered the most energetic cosmic explosions yet discovered, naming the new class of events “extreme nuclear transients” (ENTs). These extraordinary phenomena occur when massive stars—at least three times heavier than our sun—are torn apart after wandering too close to a supermassive black hole. Their disruption releases vast amounts of energy visible across enormous distances.
The team’s findings appear in the journal Science Advances.
“We’ve observed stars getting ripped apart as tidal disruption events for over a decade, but these ENTs are different beasts, reaching brightnesses nearly ten times more than what we typically see,” said Jason Hinkle, who led the study as the final piece of his doctoral research at IfA. “Not only are ENTs far brighter than normal tidal disruption events, but they remain luminous for years, far surpassing the energy output of even the brightest known supernova explosions.”
How physicists used antimatter, supercomputers and giant magnets to solve a 20-year-old mystery
Physicists are always searching for new theories to improve our understanding of the universe and resolve big unanswered questions.
But there’s a problem. How do you search for undiscovered forces or particles when you don’t know what they look like?
Take dark matter. We see signs of this mysterious cosmic phenomenon throughout the universe, but what could it possibly be made of? Whatever it is, we’re going to need new physics to understand what’s going on.
Black hole tears neutron star apart in dramatic new simulation
A new simulation by researchers shows how a neutron star violently cracks seconds before vanishing into a black hole.
What if the Big Bang wasn’t the beginning? Research suggests it may have taken place inside a black hole
The Big Bang is often described as the explosive birth of the universe—a singular moment when space, time and matter sprang into existence. But what if this was not the beginning at all? What if our universe emerged from something else—something more familiar and radical at the same time?
In a new paper, published in Physical Review D, my colleagues and I propose a striking alternative. Our calculations suggest the Big Bang was not the start of everything, but rather the outcome of a gravitational crunch or collapse that formed a very massive black hole—followed by a bounce inside it.
This idea, which we call the black hole universe, offers a radically different view of cosmic origins, yet it is grounded entirely in known physics and observations.
New research challenges everything we know about the Big Bang
The Big Bang is often described as the explosive birth of the universe – a singular moment when space, time and matter sprang into existence. But what if this was not the beginning at all? What if our universe emerged from something else – something more familiar and radical at the same time?
In a new paper, published in Physical Review D, my colleagues and I propose a striking alternative. Our calculations suggest the Big Bang was not the start of everything, but rather the outcome of a gravitational crunch or collapse that formed a very massive black hole – followed by a bounce inside it.
This idea, which we call the black hole universe, offers a radically different view of cosmic origins, yet it is grounded entirely in known physics and observations.
Star quakes and monster shock waves: Researchers simulate a black hole consuming a neutron star
Across the cosmos, many stars can be found in pairs, gracefully circling one another. Yet one of the most dramatic pairings occurs between two orbiting black holes, formed after their massive progenitor stars exploded in supernova blasts. If these black holes lie close enough together, they will ultimately collide and form an even more massive black hole.
Sometimes a black hole is orbited by a neutron star—the dense corpse of a star also formed from a supernova explosion but which contains less mass than a black hole. When these two bodies finally merge, the black hole will typically swallow the neutron star whole.
To better understand the extreme physics underlying such a grisly demise, researchers at Caltech are using supercomputers to simulate black hole–neutron star collisions. In one study appearing in The Astrophysical Journal Letters, the team, led by Elias Most, a Caltech assistant professor of theoretical astrophysics, developed the most detailed simulation yet of the violent quakes that rupture a neutron star’s surface roughly a second before the black hole consumes it.