Archive for the ‘cosmology’ category: Page 160

Jun 2, 2020

A plague of magnetic spots among the hot stars of globular clusters

Posted by in categories: chemistry, cosmology, evolution

For more than six decades, the quest to understand the formation of hot (about 20,000−30,000 K) extreme horizontal branch (EHB) stars in Galactic globular clusters has remained one of the most elusive in stellar evolutionary theory. Here we report on two discoveries that challenge the idea of the stable luminosity of EHB stars. The first mode of EHB variability is periodic and cannot be ascribed to either binary evolution or pulsation. Instead, we attribute it here to the presence of magnetic spots: superficial chemical inhomogeneities whose projected rotation induces the variability. The second mode of EHB variability is aperiodic and manifests itself on timescales of years. In two cases, six-year-long light curves display superflare events that are several million times more energetic than solar analogues. We advocate a scenario in which the two EHB variability phenomena are different manifestations of diffuse, dynamo-generated, weak magnetic fields. Magnetism is therefore a key player driving the formation and evolution of EHB clusters stars and, likewise, operating in the Galactic field counterparts. Our conclusions bridge similar variability/magnetism phenomena in all radiative-enveloped hot-stars: young main-sequence stars, old EHBs and defunct white dwarfs.

Jun 2, 2020

A census of baryons in the Universe from localized fast radio bursts

Posted by in category: cosmology

More than three-quarters of the baryonic content of the Universe resides in a highly diffuse state that is difficult to detect, with only a small fraction directly observed in galaxies and galaxy clusters1,2. Censuses of the nearby Universe have used absorption line spectroscopy3,4 to observe the ‘invisible’ baryons, but these measurements rely on large and uncertain corrections and are insensitive to most of the Universe’s volume and probably most of its mass. In particular, quasar spectroscopy is sensitive either to the very small amounts of hydrogen that exist in the atomic state, or to highly ionized and enriched gas4,5,6 in denser regions near galaxies7. Other techniques to observe these invisible baryons also have limitations; Sunyaev–Zel’dovich analyses8,9 can provide evidence from gas within filamentary structures, and studies of X-ray emission are most sensitive to gas near galaxy clusters9,10. Here we report a measurement of the baryon content of the Universe using the dispersion of a sample of localized fast radio bursts; this technique determines the electron column density along each line of sight and accounts for every ionized baryon11,12,13. We augment the sample of reported arcsecond-localized14,15,16,17,18 fast radio bursts with four new localizations in host galaxies that have measured redshifts of 0.291, 0.118, 0.378 and 0.522. This completes a sample sufficiently large to account for dispersion variations along the lines of sight and in the host-galaxy environments11, and we derive a cosmic baryon density of \({\varOmega }_{{\rm{b}}}={0.051}_{-0.025}^{+0.021}{h}_{70}^{-1}\) (95 per cent confidence; h70 = H0/(70 km s−1 Mpc−1) and H0 is Hubble’s constant). This independent measurement is consistent with values derived from the cosmic microwave background and from Big Bang nucleosynthesis19,20.

Jun 1, 2020

How close can you get to a black hole?

Posted by in categories: cosmology, physics

Physicists are figuring out how close you can get to a black hole before you are unlikely to escape. That threshold is called the innermost stable circular orbit (ISCO).

Jun 1, 2020

A new theorem predicts that stationary black holes must have at least one light ring

Posted by in categories: cosmology, physics

Black holes, regions in space with such an intense gravitational field that no matter or radiation can escape from them, are among the most mysterious and fascinating cosmological phenomena. Over the past five years or so, astrophysicists collected the first observations of the strong gravitational forces around black holes.

The LIGO-Virgo collaboration was able to detect gravitational waves around these using some of the most advanced gravitational-wave detectors in the world. Meanwhile, the Event Horizon Telescope research group captured the very first image of a black hole shadow.

While both these observations are highly promising and captivating, neither of them is likely to unveil the event horizon, the boundary defining the specific region in space around a black hole from which nothing can escape. Nonetheless, they should contain a signature pointing to a neighboring region just outside of the event horizon, wherein is bent so strongly that its path closes over itself and forms circular orbits known as light rings.

Jun 1, 2020

Evidence of New X17 Particle Reported, but Scientists Are Wary

Posted by in categories: cosmology, particle physics

Could the mysterious particle be our window into studying dark matter?

Jun 1, 2020

Dark matter engine

Posted by in categories: cosmology, space travel

The Dark matter engine is the key to the extreme acceleration capabilities of the modern space ship. Invented by Professor Hubert J. Farnsworth, the engines on the Planet Express ship harness the power created by burning dark matter in large furnaces, channels it through an afterburner that gives 200% fuel efficiency and propelles the ship through space fast enough to cover the whole universe in a matter of days.

How it works Edit

Let’s look at the real universe example of Rigel, a star in Orion’s Belt approximately 900 light-years away from Earth. This means that even traveling at the speed of light (300,000 km/s) it would take 900 years to get there. Traveling at 9 times the speed of light (2,700,000 km/s) it would take 100 years to get there and at 100 times the speed of light (30,000,000 km/s) it would take nine years. Albert Einstein’s famous statements that it would be mathematically impossible to travel faster than light seem to have held up through out the 3rd millennia and although in 2208 the scientific community allegedly raised the speed of light so that they could go faster, the problem that one cannot go faster than the speed of light remains.

May 31, 2020

Black Holes Help Prove That a Special Kind of Space-Time Is Unstable

Posted by in categories: cosmology, information science, quantum physics

Einstein’s equations describe three canonical configurations of space-time. Now one of these three — important in the study of quantum gravity — has been shown to be inherently unstable.

May 31, 2020

Discovery of Massive Galaxy Just 1.5 Billion Years After the Big Bang Has Astronomers Questioning Formation Models

Posted by in category: cosmology

Published recently in Nature, an international team of researchers has observed a massive, rotating disk galaxy just 1.5 billion years after the Big Bang —1.5 billion years earlier in cosmic history than astronomers had expected to find such a galaxy based on previous studies. The research has fueled debate about how galaxies in the early Universe assembled.

The observations were made using one of the most powerful radio telescopes in the world, the Atacama Large Millimeter/submillimeter Array (ALMA), in the Atacama Desert in northern Chile.

“This is an exciting discovery for astronomers because it provides clues as to how large-scale structure began to form in the Universe,” said Dr. Alfred Tiley from the UWA node of the International Centre for Radio Astronomy Research (ICRAR).

May 30, 2020

The universe had a ‘missing matter’ problem. Now it’s been solved

Posted by in category: cosmology

Half of the normal matter in the universe has been hiding since the Big Bang. Astronomers have just detected it for the first time.

May 30, 2020

A Parallel Universe Where Time Runs Backwards Has Been Detected By NASA Scientists

Posted by in categories: cosmology, particle physics, quantum physics

NASA has conducted an experiment in Antarctica, which has revealed new evidence that a parallel universe exists, except the rules of physics, are the opposite of ours.

Physicists have been debating among one another since 1952 of the possibility of a multiverse, whereby many universes exist parallel to ours. These universes could have different laws of physics, or even be similar to ours — just with different timelines.

The original theory was proposed by Quantum science pioneer Erwin Schrodinger, and even he admitted that he might have seemed a little crazy when he hosted that lecture. But now a new discovery has pushed scientists to reconsider if his theory is really as far-fetched as they thought it was. A cosmic ray detection experiment in Antarctica found a particle that very well may be from another universe.