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Category: cosmology – Page 135

Particle Accelerators in the Sky: NASA’s IXPE Explores “Microquasar” Mechanics

Insights from NASA ’s IXPE mission have transformed our understanding of particle acceleration in black holes, using the microquasar SS 433 as a case study to reveal aligned magnetic fields within its jets.

The powerful gravity fields of black holes can devour whole planets’ worth of matter – often so violently that they expel streams of particles traveling near the speed of light in formations known as jets. Scientists understand that these high-speed jets can accelerate these particles, called cosmic rays, but little is definitively known about that process.

Recent findings by researchers using data from NASA’s IXPE (Imaging X-ray Polarimetry Explorer) spacecraft give scientists new clues as to how particle acceleration happens in this extreme environment. The observations came from a “microquasar,” a system comprised of a black hole siphoning off material from a companion star.

Astrophysicists offer theoretical proof of traversable wormholes in the expanding universe

The expansion of the universe at some stage of evolution is well described by the Friedmann model. It was derived from general relativity a hundred years ago, but it is still considered one of the most important and relevant cosmological models.

RUDN University astrophysicists have now proven the theoretical possibility of the existence of traversable wormholes in the Friedmann universe. The research is published in the journal Universe.

“A wormhole is a type of highly curved geometry. It resembles a tunnel either between distant regions of the same universe or between different universes. Such structures were first discussed in the framework of solutions to the gravitational field equations a hundred years ago. But the wormholes considered then turned out to be non-traversable even for photons—they could not move from one ‘end of the tunnel’ to the other, not to mention going back,” said Kirill Bronnikov, doctor of physical and , professor of RUDN University.

Scientists want your help to search for black holes

Even though black holes swallow anything that comes near them — even light — they are still possible to locate by looking for signs of their effects. Black holes are extremely dense, so they have a lot of mass and a strong gravitational effect that can be observed from light-years away. But the universe is a big place, and researchers are hoping that the public can help them to identify more black holes in the name of scientific exploration.

A project called Black Hole Hunter invites members of the public to search through data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS) to look for signs of a black hole. Using a technique called gravitational microlensing, citizen scientists will look at how the brightness of light from various stars changes over time, looking for indications that a black hole could have passed in front of a star and bent the light coming from it. This should enable the project to identify black holes that would otherwise be invisible.

One of the researchers on the project, Matt Middleton of the University of Southampton, explained in a statement: Black holes are invisible. Their gravitational pull is so strong that not even light can escape, making them incredibly hard to see, even with specialist equipment. But that gravitational pull is also how we can detect them because it’s so strong that it can bend and focus light, acting like a lens that magnifies light from stars. We can detect this magnification and that’s how we know a black hole exists.

Dark energy is one of the biggest puzzles in science and we’re now a step closer to understanding it

Over ten years ago, the Dark Energy Survey (DES) began mapping the universe to find evidence that could help us understand the nature of the mysterious phenomenon known as dark energy. I’m one of more than 100 contributing scientists that have helped produce the final DES measurement, which has just been released at the 243rd American Astronomical Society meeting in New Orleans.

Dark energy is estimated to make up nearly 70% of the , yet we still don’t understand what it is. While its nature remains mysterious, the impact of dark energy is felt on grand scales. Its primary effect is to drive the accelerating expansion of the universe.

The announcement in New Orleans may take us closer to a better understanding of this form of energy. Among other things, it gives us the opportunity to test our observations against an idea called the cosmological constant that was introduced by Albert Einstein in 1917 as a way of counteracting the effects of gravity in his equations to achieve a universe that was neither expanding nor contracting. Einstein later removed it from his calculations.

Hubble captures an exceptionally luminous supernova site

This week’s image from the Hubble Space Telescope shows the aftermath of an epic explosion in space caused by the death of a massive star.

Some of the most dramatic events in the cosmos are supernovas, when a massive star runs out of fuel to fuse — first running out of hydrogen, then helium, then burning through heavier elements — and eventually can no longer sustain the outward pressure from heat caused by this fusion. When that happens, the star collapses suddenly into a dense core, and its outer layers are thrown off in a tremendous explosion called a Type II supernova.