Stars are born in clouds of gas and dust, making it difficult to observe their early development. But researchers at Chalmers have now succeeded in simulating how a star with the mass of the sun absorbs material from the surrounding disk of material—a process called accretion.
The size and spin of black holes can reveal important information about how and where they formed, according to new research.
The study, led by scientists at Cardiff University, tests the idea that many of the black holes observed by astronomers have merged multiple times within densely populated environments containing millions of stars.
The work is published in the journal Physical Review Letters.
Focused on the Antlia Cluster — a dense assembly of galaxies within the Hydra–Centaurus Supercluster located around 130 million light-years from Earth — the image captures only a small portion of the 230 galaxies that make up the cluster, revealing a diverse array of galaxy types within as well as thousands of background galaxies beyond.
The Dark Energy Camera (DECam) was originally built for the Dark Energy Survey (DES), an international collaboration that began in 2013 and concluded its observations in 2019. Over the course of the survey, scientists mapped hundreds of millions of galaxies in an effort to understand the nature of dark energy — a mysterious force thought to drive the accelerated expansion of our universe. The universe’s acceleration challenges predictions made by Albert Einstein’s theory of general relativity, making dark energy one of the most perplexing mysteries in modern cosmology. Dark matter, meanwhile, refers to the mysterious and invisible substance that seems to hold galaxies together. This is another major conundrum scientists are still trying to fully penetrate.
Observations made of galaxy clusters have already helped scientists unravel some of the processes driving galaxy evolution as they search for clues about the history of our universe. In this sense, galaxy clusters act as “cosmic laboratories” where gravitational influence driven by dark matter and cosmic expansion driven by dark energy can be studied on incredibly large scales.
Dipole toroidal modes are a unique set of excitations that are predicted to occur in various physical systems, ranging from atomic nuclei to metamaterials. What characterizes these excitations, or modes, is a toroidal distribution of currents, which results in the formation of vortex-like structures.
A classic example is smoke rings, the characteristic “rings” of smoke produced when puffs of smoke are released into the air through a narrow opening. Physics theories have also predicted the existence of toroidal dipole excitations in atomic nuclei, yet observing these modes has so far proved challenging.
Researchers at Technische Universitat Darmstadt, the Joint Institute for Nuclear Research, and other institutes recently identified candidates for toroidal dipole excitations in the nucleus 58 Ni for the very first time. Their paper, published in Physical Review Letters, opens new possibilities for the experimental observations of these elusive modes in heavy nuclei.
Physicists have proposed a solution to a long-standing puzzle surrounding the GD-1 stellar stream, one of the most well-studied streams within the galactic halo of the Milky Way, known for its long, thin structure, and unusual spur and gap features.
The team of researchers, led by Hai-Bo Yu at the University of California, Riverside, proposed that a core-collapsing self-interacting dark matter (SIDM) “subhalo” — a smaller, satellite halo within the galactic halo — is responsible for the peculiar spur and gap features observed in the GD-1 stellar stream.
Study results appear in The Astrophysical Journal Letters in a paper titled “The GD-1 Stellar Stream Perturber as a Core-collapsed Self-interacting Dark Matter Halo.” The research could have significant implications for understanding the properties of dark matter in the universe.
Jacob Bernoulli returned to Switzerland and taught mechanics at the University in Basel from 1,683, giving a series of important lectures on the mechanics of solids and liquids. Since his degree was in theology it would have been natural for him to turn to the Church, but although he was offered an appointment in the Church he turned it down. Bernoulli’s real love was for mathematics and theoretical physics and it was in these topics that he taught and researched. During this period he studied the leading mathematical works of his time including Descartes’ Géométrie and van Schooten’s additional material in the Latin edition. Jacob Bernoulli also studied the work of Wallis and Barrow and through these he became interested in infinitesimal geometry. Jacob began publishing in the journal Acta Eruditorum which was established in Leipzig in 1682.
In 1,684 Jacob Bernoulli married Judith Stupanus. They were to have two children, a son who was given his grandfather’s name of Nicolaus and a daughter. These children, unlike many members of the Bernoulli family, did not go on to become mathematicians or physicists.
You can see the Bernoulli family tree at THIS LINK.
Shooting a laser pulse at a porous silver target generates more intense x rays than previous targets, which will help studies of matter in extreme conditions.
Physicists rely on intense bursts of high-energy x rays to observe the progress of fusion experiments and to probe the dynamics of matter under conditions of extreme temperature and pressure. Current techniques for generating such bursts involve firing a laser pulse at a material target but typically turn only a small fraction of the laser energy into usable x rays, thereby limiting the burst energy and intensity. Now researchers have demonstrated a doubling of the efficiency by using a target made of a low-density metallic foam [1]. They expect that the new targets will lead to much brighter x-ray bursts capable of illuminating extreme physical processes under conditions that were previously inaccessible to x-ray observations.
When a powerful laser pulse strikes a foil of material such as silver, the laser strips away the electrons, leaving exposed the highly charged nuclei. Surrounding electrons then fall back into the lowest energy levels, creating high-energy x rays. However, most of the laser energy can be lost in the process, and the overall efficiency is very sensitive to the nature of the material target. Researchers have found, for example, that solid targets generally yield low efficiencies, as x rays emerge from only a small volume near the surface, while laser energy is otherwise consumed by stirring up plasma waves in the material. This low efficiency limits the x-ray intensity.
Scientists are diving deep into the origins of supermassive black holes, using recent gravitational wave detections as a key tool.
By leveraging signals from smaller black holes, researchers hope to detect the harder-to-catch waves from supermassive pairs, potentially unlocking the secrets of their formation and growth.
Unveiling the mystery of supermassive black holes.
The Firefly Sparkle was previously imaged by Hubble Space Telescope and Keck Observatory, but was followed-up using the power of both gravitational lensing and multi-wavelength data from JWST’s CAnadian NIRISS Unbiased Cluster Survey (CANUCS). The role of the lens was played by the massive galaxy cluster called MACS J1423.8 + 2,404, which lies between us and the Firefly Sparkle.
“Without the benefit of this gravitational lens, we would not be able to resolve this galaxy,” said Kartheik Iyer, a co-lead author of the paper, in a press release. “We knew to expect it based on current physics, but it’s surprising that we actually saw it.”
In the team’s paper, published in Nature on Dec. 11, they created a model to “undo” the visual distortions of the lensing. It turns out that the Firefly Sparkle’s original form appears like a stretched raindrop; its stars have not yet settled into either the central bulge or a thin disk. In other words, the galaxy is still very much in the process of forming.
