Archive for the ‘cosmology’ category: Page 5

Jun 6, 2022

How the universe got its magnetic field?

Posted by in category: cosmology

All cosmic objects are embedded in magnetic fields. However, these fields are weak, but they are dynamically significant because they have profound effects on the dynamics of the universe.

The origin of these cosmic magnetic fields remains one of the most fundamental mysteries in cosmology, despite decades of intensive attention and inquiry.

By studying the dynamics of plasma turbulence, scientists from MIT are helping to solve one of the mysteries of the origins of cosmological magnetic fields.

Jun 6, 2022

Ionizing Black Hole “Atoms”

Posted by in categories: cosmology, particle physics

Distinctive features of gravitational-wave signals from black hole mergers could reveal the existence of long-sought ultralight bosons.

Jun 4, 2022

High contrast imaging revealed an unknown structure in the galaxy

Posted by in category: cosmology

A team of astronomers in Japan, for the first time, discovered a faint radio emission covering a giant galaxy as a result of achieving high imaging dynamic range. Radio emission is emitted by the gas created directly by the central black hole.

Using the same technique to additional quasars, the team hopes to learn more about how a black hole interacts with its host galaxy.

Using the Atacama Large Millimeter/submillimeter Array in Chile (ALMA), astronomers targeted the quasar 3C 273, which lies at 2.4 billion light-years from Earth. It is the first quasar ever discovered, the brightest, and the best studied. However, much less has been known about its host galaxy itself because combining the faint and diffuse galaxy with the 3C273 nucleus required such high dynamic ranges to detect.

Continue reading “High contrast imaging revealed an unknown structure in the galaxy” »

Jun 3, 2022

116,000 New Variable Stars Identified

Posted by in category: cosmology

A new technique locates stellar objects that change brightness.

Jun 3, 2022

A New Signature of a Multiply Connected Universe

Posted by in categories: cosmology, mapping

Scientists have measured an upper-bound to the size of the Universe using the Cosmic Microwave Background (CMB) temperature gradient field [1]. The results show that the universe is most likely multiply connected, which means that it is finite, and the topology is such that it closes back in on itself—such that on the largest scale the universe has the geometry of a torus (and has a global positive curvature). This is contrary to the conventional cosmological models of the universe that model it as spatially infinite and topologically flat—assumed parameters that the researchers of the latest study demonstrate do not match the CMB temperature gradient data.

If the universe were spatially infinite and topologically flat, then the temperature fluctuations seen in the CMB would occur across all size scales—however this is not what is observed in the data. If, instead, the universe has a finite size and a multiply connected topology, like that of a torus, then in the early universe when the CMB was first emitted temperature fluctuations would be restricted in size since they could not be larger than the universe at that time. This would be observable in the extant CMB temperature gradient as a specific wave-length cut-off, which has now been described and demonstrated in a comprehensive analysis of the observed Planck CMB maps.

One of the researchers on the team that performed the study— astrophysicist Thomas Buchert, of the University of Lyon, Astrophysical Research Center in France— told Live Science in an email “We could say: Now we know the size of the universe” [2]. As reported by Live Science, Buchert further explained “In an infinite space, the perturbations in the temperature of the CMB radiation exist on all scales. If, however, space is finite, then there are those wavelengths missing that are larger than the size of the space.”

May 30, 2022

Bizarre neutron star spins every 76 seconds inside a stellar graveyard

Posted by in category: cosmology

Neutron stars are normally extremely fast-spinning stellar corpses left over from the intense violence of a supernova, but researchers have found one in a “stellar graveyard” where one should not be – and it spins at a relatively glacial rate of once every 76 seconds.

Researchers with the University of Sydney found the bizarre radio signal, designated PSR J0901-4046, emitted by the neutron star thanks to the MeerKAT radio telescope in South Africa and weren’t even expecting to see it. The region of the sky they were observing was thought to be free of pulsars, since none had been observed there before.

Now they might know why. Capturing eight-second-long samples of the sky, they caught sight of a single pulse from the star, which had to be confirmed with subsequent observation due to its unexpectedly long rotational period.

Continue reading “Bizarre neutron star spins every 76 seconds inside a stellar graveyard” »

May 26, 2022

New calculations of solar spectrum resolve decade-long controversy about the sun’s chemical composition

Posted by in categories: chemistry, cosmology, mapping, physics

What do you do when a tried-and-true method for determining the sun’s chemical composition appears to be at odds with an innovative, precise technique for mapping the sun’s inner structure? That was the situation facing astronomers studying the sun—until new calculations that have now been published by Ekaterina Magg, Maria Bergemann and colleagues, and that resolve the apparent contradiction.

The decade-long solar abundance crisis is the conflict between the internal structure of the sun as determined from solar oscillations (helioseismology) and the structure derived from the fundamental theory of stellar evolution, which in turn relies on measurements of the present-day sun’s . The new calculations of the physics of the sun’s atmosphere yield updated results for abundances of different chemical elements, which resolve the conflict. Notably, the sun contains more oxygen, silicon and neon than previously thought. The methods employed also promise considerably more accurate estimates of the chemical compositions of stars in general.

May 25, 2022

How the universe got its magnetic field

Posted by in categories: cosmology, engineering

When we look out into space, all of the astrophysical objects that we see are embedded in magnetic fields. This is true not only in the neighborhood of stars and planets, but also in the deep space between galaxies and galactic clusters. These fields are weak—typically much weaker than those of a refrigerator magnet—but they are dynamically significant in the sense that they have profound effects on the dynamics of the universe. Despite decades of intense interest and research, the origin of these cosmic magnetic fields remains one of the most profound mysteries in cosmology.

In previous research, scientists came to understand how turbulence, the churning motion common to fluids of all types, could amplify preexisting magnetic fields through the so-called dynamo process. But this remarkable discovery just pushed the mystery one step deeper. If a turbulent dynamo could only amplify an existing field, where did the “seed” magnetic field come from in the first place?

We wouldn’t have a complete and self-consistent answer to the origin of astrophysical magnetic fields until we understood how the seed fields arose. New work carried out by MIT graduate student Muni Zhou, her advisor Nuno Loureiro, a professor of nuclear science and engineering at MIT, and colleagues at Princeton University and the University of Colorado at Boulder provides an answer that shows the basic processes that generate a field from a completely unmagnetized state to the point where it is strong enough for the dynamo mechanism to take over and amplify the field to the magnitudes that we observe.

May 25, 2022

Blue Origin could land a futuristic telescope on the Moon in one go

Posted by in categories: cosmology, space travel

May 22, 2022

Rapidly descending dark energy and the end of cosmic expansion

Posted by in categories: cosmology, quantum physics

Although the universe is expanding at an accelerating rate today, this paper presents a simple mechanism by which a dynamical form of dark energy (known as quintessence) could cause the acceleration to come to end and smoothly transition from expansion to a phase of slow contraction. That raises questions, How soon could this transition occur? And at what point would it be detectable? The conclusions are that the transition could be surprisingly soon, maybe less than 100 million y from now, and yet, for reasons described in the main text, it is not yet detectable today. The scenario is not far-fetched. In fact, it fits naturally with recent theories of cyclic cosmology and conjectures about quantum gravity.

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