Scientists have discovered the first evidence for a rare type of stellar explosion, or supernova in the Milky Way. This intriguing object lies near the center of our galaxy in a supernova remnant called Sagittarius A East (Sgr A East). Chandra data revealed that Sgr A East may belong to a spec.
Category: cosmology – Page 327
Astronomers Can Predict When a Galaxy’s Star Formation Ends Based on the Shape and Size of its Disk
Eventually, galaxies stop making new stars. But why did some stop so much sooner than others? Hint: black holes play a role.
A galaxy’s main business is star formation. And when they’re young, like youth everywhere, they keep themselves busy with it. But galaxies age, evolve, and experience a slow-down in their rate of star formation. Eventually, galaxies cease forming new stars altogether, and astronomers call that quenching. They’ve been studying quenching for decades, yet much about it remains a mystery.
A new study based on the IllustrisTNG simulations has found a link between a galaxy’s quenching and its stellar size.
BASE Antimatter Experiment opens up new possibilities in the search for cold dark matter
BASE opens up new possibilities in the search for cold dark matter.
The Baryon Antibaryon Symmetry Experiment (BASE) at CERN’s Antimatter Factory has set new limits on how easily axion-like particles in a narrow mass range around 2.97 neV can turn into photons, the particles of light. BASE’s new result, published by Physical Review Letters, describes this pioneering method and opens up new experimental possibilities in the search for cold dark matter.
Axions, or axion-like particles, are candidates for cold dark matter. From astrophysical observations, we believe that around 27% of the matter-energy content of the universe is made up of dark matter. These unknown particles feel the force of gravity, but they barely respond to the other fundamental forces, if they experience them at all. The best accepted theory of fundamental forces and particles, called the Standard Model of particle physics, does not contain any particles that have the right properties to be cold dark matter.
Since the Standard Model leaves many questions unanswered, physicists have proposed theories that go beyond it, some of which explain the nature of dark matter. Among such theories are those that suggest the existence of axions or axion-like particles. These theories need to be tested, and many experiments have been set up around the world to look for these particles, including at CERN. For the first time, BASE has turned the tools developed to detect single antiprotons, the antimatter equivalent of a proton, to the search for dark matter. This is especially significant as BASE was not designed for such studies.
“BASE has extremely sensitive detection systems to study the properties of single trapped antiprotons. These detectors can also be used to search for signals of particles other than those produced by antiprotons in traps. In this work, we used one of our detectors as an antenna to search for a new type of axion-like particles,” says Jack Devlin, a CERN research fellow working on the experiment.
Compared to the large detectors installed in the Large Hadron Collider (LHC), BASE is a small experiment. It is connected to CERN’s Antiproton Decelerator, which supplies it with antiprotons. BASE captures and suspends these particles in a Penning trap, a device that combines electric and strong magnetic fields. To avoid collisions with ordinary matter, the trap is operated at 5 kelvins (around-268 degrees Celsius), a temperature at which exceedingly low pressures, similar to those in deep space, are reached. In this extremely well-isolated environment, clouds of trapped antiprotons can exist for years at a time. By carefully adjusting the electric fields, the physicists at BASE can isolate individual antiprotons and move them to a separate part of the experiment. In this region, very sensitive superconducting resonant detectors can pick up the tiny electrical currents generated by single antiprotons as they move around the trap.
Astronomers Have Discovered a Star That Survived Being Swallowed by a Black Hole
I don’t think that star is the same after that one night stand.
When black holes swallow down massive amounts of matter from the space around them, they’re not exactly subtle about it. They belch out tremendous flares of X-rays, generated by the material heating to intense temperatures as it’s sucked towards the black hole, so bright we can detect them from Earth.
This is normal black hole behaviour. What isn’t normal is for those X-ray flares to spew forth with clockwork regularity, a puzzling behaviour reported in 2019 from a supermassive black hole at the centre of a galaxy 250 million light-years away. Every nine hours, boom — X-ray flare.
After careful study, astronomer Andrew King of the University of Leicester in the UK identified a potential cause — a dead star that’s endured its brush with a black hole, trapped on a nine-hour, elliptical orbit around it. Every close pass, or periastron, the black hole slurps up more of the star’s material.
Wormholes may be lurking in the universe — and new studies are proposing ways of finding them
Very interesting.
Albert Einstein’s theory of general relativity profoundly changed our thinking about fundamental concepts in physics, such as space and time. But it also left us with some deep mysteries. One was black holes, which were only unequivocally detected over the past few years. Another was “wormholes” – bridges connecting different points in spacetime, in theory providing shortcuts for space travellers.
Wormholes are still in the realm of the imagination. But some scientists think we will soon be able to find them, too. Over the past few months, several new studies have suggested intriguing ways forward.
Black holes and wormholes are special types of solutions to Einstein’s equations, arising when the structure of spacetime is strongly bent by gravity. For example, when matter is extremely dense, the fabric of spacetime can become so curved that not even light can escape. This is a black hole.
