Archive for the ‘cosmology’ category

Nov 13, 2020

Researchers make most precise measurements of deuterium fusing with a proton to form helium-3

Posted by in categories: cosmology, information science, physics

A large team of researchers affiliated with a host of institutions in Italy, the U.K and Hungary has carried out the most precise measurements yet of deuterium fusing with a proton to form helium-3. In their paper published in the journal Nature, the group describes their effort and how they believe it will contribute to better understanding the events that transpired during the first few minutes after the Big Bang.

Astrophysics theory suggests that the creation of deuterium was one of the first things that happened after the Big Bang. Therefore, it plays an important role in Big Bang nucleosynthesis—the reactions that happened afterward that led to the production of several of the light elements. Theorists have developed equations that show the likely series of events that occurred, but to date, it has been difficult to prove them correct without physical evidence. In this new effort, the researchers working at the Laboratory for Underground Nuclear Astrophysics in Italy have carried out experiments to simulate those first few minutes, hoping to confirm the theories.

The work was conducted deep under the thick rock cover of the Gran Sasso mountain to prevent interference from —it involved firing a beam of protons at a deuterium target—deuterium being a form of hydrogen with just one and one neutron—and then measuring the rate of fusion. But because the rate of fusion is so low, the bombardment had to be carried out many times—the team carried out their work nearly every weekend for three years.

Nov 11, 2020

Black hole or no black hole: On the outcome of neutron star collisions

Posted by in categories: computing, cosmology, physics

A new study lead by GSI scientists and international colleagues investigates black-hole formation in neutron star mergers. Computer simulations show that the properties of dense nuclear matter play a crucial role, which directly links the astrophysical merger event to heavy-ion collision experiments at GSI and FAIR. These properties will be studied more precisely at the future FAIR facility. The results have now been published in Physical Review Letters. With the award of the 2020 Nobel Prize in Physics for the theoretical description of black holes and for the discovery of a supermassive object at the center of our galaxy, the topic currently also receives a lot of attention.

But under which conditions does a black hole actually form? This is the central question of a study lead by the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt within an international collaboration. Using , the scientists focus on a particular process to form namely the merging of two stars.

Neutron stars consists of highly compressed dense matter. The mass of one and a half is squeezed to the size of just a few kilometers. This corresponds to similar or even higher densities than in the inner of atomic nuclei. If two neutron stars merge, the matter is additionally compressed during the collision. This brings the merger remnant on the brink to collapse to a black hole. Black holes are the most compact objects in the universe, even light cannot escape, so these objects cannot be observed directly.

Nov 11, 2020

Physicists say they’ve found a ‘tetraquark’

Posted by in categories: cosmology, particle physics

The finding marks a major breakthrough in a search of almost 20 years, carried out in particle physics labs all over the world.

To understand what a tetraquark is and why the discovery is important, we need to step back in time to 1964, when particle physics was in the midst of a revolution. Beatlemania had just exploded, the Vietnam war was raging and two young radio astronomers in New Jersey had just discovered the strongest evidence ever for the Big Bang theory.

On the other side of the U.S., at the California Institute of Technology, and on the other side of the Atlantic, at CERN in Switzerland, two particle physicists were publishing two independent papers on the same subject. Both were about how to make sense of the enormous number of new particles that had been discovered over the past two decades.

Nov 8, 2020

To Understand Gravity, Toss a Hard Drive into a Black Hole

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

We probably think we know gravity pretty well. After all, we have more conscious experience with this fundamental force than with any of the others (electromagnetism and the weak and strong nuclear forces). But even though physicists have been studying gravity for hundreds of years, it remains a source of mystery.

In our video Why Is Gravity Different? We explore why this force is so perplexing and why it remains difficult to understand how Einstein’s general theory of relativity (which covers gravity) fits together with quantum mechanics.

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Nov 7, 2020

Astrophysicists Solve Mystery of How Dark Matter Is Distributed in Galaxies

Posted by in categories: cosmology, physics

The gravitational force in the Universe under which it has evolved from a state almost uniform at the Big Bang until now, when matter is concentrated in galaxies, stars and planets, is provided by what is termed ‘dark matter.’ But in spite of the essential role that this extra material plays, we know almost nothing about its nature, behavior and composition, which is one of the basic problems of modern physics. In a recent article in Astronomy & Astrophysics Letters, scientists at the Instituto de Astrofísica de Canarias (IAC)/University of La Laguna (ULL) and of the National University of the North-West of the Province of Buenos Aires (Junín, Argentina) have shown that the dark matter in galaxies follows a ‘maximum entropy’ distribution, which sheds light on its nature.

Dark matter makes up 85% of the matter of the Universe, but its existence shows up only on astronomical scales. That is to say, due to its weak interaction, the net effect can only be noticed when it is present in huge quantities. As it cools down only with difficulty, the structures it forms are generally much bigger than planets and stars. As the presence of dark matter shows up only on large scales the discovery of its nature probably has to be made by astrophysical studies.

Nov 7, 2020

The Black Hole Information Paradox Comes to an End

Posted by in categories: cosmology, physics

In a landmark series of calculations, physicists have proved that black holes can shed information, which seems impossible by definition. The work appears to resolve a paradox that Stephen Hawking first described five decades ago.

Nov 4, 2020

Physicists: Fake Black Holes Could Be Pulling the Universe Apart

Posted by in categories: cosmology, physics

O,.o wut?

Cosmic Loners

The problem with the GEODE hypothesis is that the strange objects need to resemble but not act like black holes. The only way that GEODEs could expand the universe without destroying everything around them is if they were isolated in empty pockets of the cosmos. But black holes often sit smack dab in the middle of galaxies.

Continue reading “Physicists: Fake Black Holes Could Be Pulling the Universe Apart” »

Nov 1, 2020

What 50 gravitational-wave events reveal about the Universe

Posted by in categories: cosmology, physics

The catalogue also provides information on how the black holes spin, which holds the key to understanding how the objects came to orbit each other before they merged. It shows that, in some binary systems, the two black holes have misaligned axes of rotation, which would imply that they formed separately. But many other binaries appear to have roughly aligned axes of rotation, which is what astrophysicists expect when the two black holes began their lives as a binary star system. Two schools of thought in astrophysics have each favoured one of the two scenarios, but it now appears that both were correct, Fishbach says.

Astrophysicists now have enough black-hole mergers to map their frequency over the cosmos’s history.

Oct 30, 2020

Bumper crop of black holes in new gravitational wave paper

Posted by in categories: cosmology, physics

Only a few years ago, scientists the world over celebrated as the first-ever gravitational waves were detected—confirming a long-held scientific theory and opening up an entirely new field of research.

Now, the international research team responsible for detecting has announced a further 39 gravitational wave events, bringing the total number of confirmed detections to 50.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Collaborations, which include researchers from the University of Portsmouth, have today published a series of papers that record events including the mergers of binary black holes, binary stars and, possibly, neutron star-black holes.

Oct 27, 2020

The Grantecan finds the farthest black hole that belongs to a rare family of galaxies

Posted by in category: cosmology

An international team of astronomers has identified one of the rarest known classes of gamma-ray emitting galaxies, called BL Lacertae, within the first 2 billion years of the age of the Universe. The team, that has used one of the largest optical telescope in the world, Gran Telescopio Canarias (GTC), located at the Observatorio del Roque de los Muchachos (Garafía, La Palma), consists of researchers from the Universidad Complutense de Madrid (UCM, Spain), DESY (Germany), University of California Riverside and Clemson University (USA). Their finding is published in The Astrophysical Journal Letters.

Only a small fraction of emits gamma rays, which are the most extreme form of light. Astronomers believe that these highly energetic photons originate from the vicinity of a supermassive black hole residing at the centers of these galaxies. When this happens, they are known as active galaxies. The black hole swallows matter from its surroundings and emits jets or, in other words, collimated streams of matter and radiation. Few of these active galaxies (less than 1%) have their jets pointing by chance toward Earth. Scientists call them blazars and are one of the most powerful sources of radiation in the universe.

Blazars come in two flavors: BL Lacertae (BL Lac) and flat-spectrum radio-quasars (FSRQs). Our current understanding about these mysterious astronomical objects is that FSRQs are relatively young active galaxies, rich in dust and gas that surround the central black hole. As time passes, the amount of matter available to feed the black hole is consumed and the FSRQ evolves to become a BL Lac object. “In other words, BL Lacs may represent the elderly and evolved phase of a blazar’s life, while FSRQs resemble an adult,” explains Vaidehi Paliya, a DESY researcher who participated in this program.

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