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Category: cosmology – Page 20

Matter in intergalactic space is distributed in a vast network of interconnected filamentary structures, collectively referred to as the cosmic web. With hundreds of hours of observations, an international team of researchers has now obtained an unprecedented high-definition image of a cosmic filament inside this web, connecting two active forming galaxies—dating back to when the universe was about 2 billion years old.

A pillar of modern cosmology is the existence of dark matter, which constitutes about 85% of all matter in the universe. Under the influence of gravity, dark matter forms an intricate cosmic web composed of filaments, at whose intersections the brightest galaxies emerge. This cosmic web acts as the scaffolding on which all visible structures in the universe are built: within the filaments, gas flows to fuel star formation in galaxies. Direct observations of the fuel supply of such galaxies would advance our understanding of galaxy formation and evolution.

However, studying the gas within this cosmic web is incredibly challenging. Intergalactic gas has been detected mainly indirectly through its absorption of light from bright background sources. But the observed results do not elucidate the distribution of this gas. Even the most abundant element, hydrogen, emits only a faint glow, making it basically impossible for instruments of the previous generation to directly observe such gas.

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An international team of scientists has modeled the formation and evolution of the strongest magnetic fields in the universe.

Led by scientists from Newcastle University, University of Leeds and France, the paper was published in the journal Nature Astronomy. The researchers identified the Tayler-Spruit dynamo caused by the fall back of supernova material as a mechanism leading to the formation of low-field magnetars. This new work solves the mystery of low-field formation, which has puzzled scientists since low-field magnetar discovery in 2010.

The team used advanced numerical simulations to model the magneto-thermal evolution of these stars, finding that a specific dynamo process within the proto-neutron star can generate these weaker magnetic fields.

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Using the MIRI instrument onboard the James Webb Space Telescope, an international team of scientists made the first-ever detection of a mid-IR flare from Sagittarius A*, the supermassive blackhole at the heart of the Milky Way. In simultaneous radio observations, the team found a radio counterpart of the flare lagging behind in time. The paper is published on the arXiv preprint server.

Scientists have been actively observing Sagittarius A* (Sgr A)—a supermassive black hole roughly 4 million times the mass of the sun— since the early 1990s. Sgr A regularly exhibits flares that can be observed in multiple wavelengths, allowing scientists to see different views of the same flare and better understand how it emits light and how the emission is generated. Despite a long history of successful observations, and even imaging of the cosmic beast by the Event Horizon Telescope in 2022, one crucial piece of the puzzle— mid-infrared observations (Mid-IR)—was missing until now.

Infrared (IR) light is a type of electromagnetic radiation that has longer wavelengths than visible light, but shorter wavelengths than radio light. Mid-IR sits in the middle of the infrared spectrum, and allows astronomers to observe objects, like flares, that are often difficult to observe in other wavelengths due to impenetrable dust. Until the recent study, no team had yet successfully detected Sgr A*’s variability in the mid-IR, leaving a gap in scientists’ understanding of what causes flares, and questions about whether theoretical models are complete.

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NASA, the National Aeronautics and Space Administration, is the United States government agency responsible for the nation’s civilian space program and for aeronautics and aerospace research. Established in 1958 by the National Aeronautics and Space Act, NASA has led the U.S. in space exploration efforts, including the Apollo moon-landing missions, the Skylab space station, and the Space Shuttle program.

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The Theory of Relativity, published in 1905 by Albert Einstein, postulated the existence of gravitational waves—oscillations of the space-time fabric—and more than a century later, we have irrefutable evidence of it. Now, a new study has managed to find clear indications of relativistic procession in the orbits of two colliding black holes.

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Some scientists think that dark energy could be a sort of defect in the fabric of the universe itself; defects like cosmic strings, which are hypothetical one-dimensional “wrinkles” thought to have formed in the early universe.

Some scientists think that dark energy isn’t something physical that we can discover. Rather, they think there could be an issue with general relativity and Einstein’s theory of gravity and how it works on the scale of the observable universe. Within this explanation, scientists think that it’s possible to modify our understanding of gravity in a way that explains observations of the universe made without the need for dark energy. Einstein actually proposed such an idea in 1919 called unimodular gravity, a modified version of general relativity that scientists today think wouldn’t require dark energy to make sense of the universe.

Dark energy is one of the great mysteries of the universe. For decades, scientists have theorized about our expanding universe. Now, for the first time ever, we have tools powerful enough to put these theories to the test and really investigate the big question: “what is dark energy?”

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