Lifeboat Foundation

Astronomers analyzing 13 years of data from NASA’s Fermi Gamma-ray Space Telescope have found an unexpected and as yet unexplained feature outside of our galaxy.

“It is a completely serendipitous discovery,” said Alexander Kashlinsky, a cosmologist at the University of Maryland and NASA’s Goddard Space Flight Center in Greenbelt, who presented the research at the 243rd meeting of the American Astronomical Society in New Orleans. “We found a much stronger signal, and in a different part of the sky, than the one we were looking for.”

Intriguingly, the gamma-ray signal is found in a similar direction and with a nearly identical magnitude as another unexplained feature, one produced by some of the most energetic cosmic particles ever detected.

Light can behave in strange ways when it interacts with materials. For example, in a photonic material that consists of periodic arrangements of nanoscale optical cavities, light can slow to a crawl or even stop altogether. Theorists have explained this phenomenon for some of these photonic “metacrystals” using the simplifying assumption that the light in each cavity interacts only with the light in its nearest neighbor cavities. But recent observations of photonic metacrystals with larger unit cells suggest that longer-range interactions should also be considered. Now Thanh Xuan Hoang at the Agency for Science, Technology and Research in Singapore and collaborators have theoretically confirmed the importance of long-range interactions for slowing or stopping light in a one-dimensional photonic metacrystal [1]. The team says that the finding could be used to help researchers design nanoparticle arrays for analog image processing and optical computing.

For their study, Hoang and his collaborators modeled the light–matter interactions within a row of identical dielectric nanoparticles whose diameters were similar to the wavelength of the light. Such a system is relatively tractable with precise solutions, making it a useful tool for investigating the long-range effects hinted at by recent experiments.

When the researchers extended their one-dimensional system to hundreds of nanoparticles, they found that they could collectively excite the particles by oscillating a nearby electric dipole. The resulting system displayed a resonant state that slowed a specific wavelength of light. This outcome occurred only when long-range interactions between particles were permitted. Hoang likens the dipolar emitter to the conductor of an orchestra and the particles to musicians. The nanoparticles harmonize under the conductor’s direction to create a cohesive piece, he says.

The universe is governed by four known fundamental forces: gravity, electromagnetism, the weak force, and the strong force. The strong force is responsible for dynamics on an extremely small scale, within and between the individual nucleons of atomic nuclei and between the constituents – quarks and gluons – that make up those nucleons. The strong force is described by a theory called Quantum Chromodynamics (QCD). One of the key details of this theory, known as “asymptotic freedom”, is responsible for both the subatomic scale of the strong force and the significant theoretical difficulties that the strong force has presented to physicists over the past 50 years.

Given the complexity of the strong force, experimental physicists have often led the research frontier and made discoveries that theorists are still trying to describe. This pattern is distinct from many other areas of physics, where experimentalists mostly search for and confirm, or exclude, theoretical predictions. One of the QCD areas where experimentalists have led progress is in the description of the collective behavior of systems with many bodies interacting via the strong force. An example of such a system is the quark-gluon plasma (QGP). A few microseconds after the Big Bang, the universe is supposed to have existed in such a state. The way the universe evolved in these brief moments and the structure that subsequently developed over billions of years is studied, in part, through experimental research on collective QCD effects. This briefing describes a recent exciting development in that research. To better understand the results, we begin with a series of analogies.

Imagine you are on a large university campus. You observe student movements in the middle of a busy exam period and find that the number of students entering the library in the morning is related to the number of students leaving in the evening. Perhaps this indicates some conserved quantity, like the number of students at the school. Each student in the library wants enough room to lay out their supplies and textbooks and get comfortable while studying. The library is nearly full and the students are evenly distributed across all the floors and halls of the library to ensure they have ample space. Recognizing and quantifying correlations like these can be useful for studying collective systems. By counting students “here” you can predict how many students are “there”, or by counting students “now” you can predict how many students you will get “later”. In this example, you may have insight into basic temporal and spatial correlations.

Insights from NASA ’s IXPE mission have transformed our understanding of particle acceleration in black holes, using the microquasar SS 433 as a case study to reveal aligned magnetic fields within its jets.

The powerful gravity fields of black holes can devour whole planets’ worth of matter – often so violently that they expel streams of particles traveling near the speed of light in formations known as jets. Scientists understand that these high-speed jets can accelerate these particles, called cosmic rays, but little is definitively known about that process.

Recent findings by researchers using data from NASA’s IXPE (Imaging X-ray Polarimetry Explorer) spacecraft give scientists new clues as to how particle acceleration happens in this extreme environment. The observations came from a “microquasar,” a system comprised of a black hole siphoning off material from a companion star.

The ‘ten electron’ rule provides guidance for the design of single-atom alloy catalysts for targeted chemical reactions.

A collaborative team across four universities have discovered a very simple rule to design single-atom alloy catalysts for chemical reactions. The ‘ten electron rule’ helps scientists identify promising catalysts for their experiments very rapidly. Instead of extensive trial and error experiments of computationally demanding computer simulations, catalysts’ composition can be proposed simply by looking at the periodic table.

Single-atom alloys are a class of catalysts made of two metals: a few atoms of reactive metal, called the dopant, are diluted in an inert metal (copper, silver, or gold). This recent technology is extremely efficient at speeding up chemical reactions but traditional models don’t explain how they work.

Emerging research suggests it may be easier to use fusion as a power source if liquid lithium is applied to the internal walls of the device housing the fusion plasma.

Plasma, the fourth state of matter, is a hot gas made of electrically charged particles. Scientists at the Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) are working on solutions to efficiently harness the power of fusion to offer a cleaner alternative to fossil fuels, often using devices called tokamaks, which confine plasma using magnetic fields.

“The purpose of these devices is to confine the energy,” said Dennis Boyle, a staff research physicist at PPPL. “If you had much better energy confinement, you could make the machines smaller and less expensive. That would make the whole thing a lot more practical, and cost-effective so that governments and industry want to invest more in it.”

A research team from Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences (CAS), discovered a new superconducting material called (InSe2)xNbSe2, which possesses a unique lattice structure. The superconducting transition temperature of this material reaches 11.6 K, making it the transition metal sulfide superconductor with the highest transition temperature under ambient pressure.

TMD materials have received lots of attention due to the numerous applications in the fields of catalysis, energy storage, and integrated circuit. However, the relatively low superconducting transition temperatures of TMD superconductors have limited their potential use.

In this study, scientists successfully fabricated a new superconducting material with the chemical formula (InSe2)xNbSe2. Unlike the conventional conditions where isolated atoms are inserted into the van de Waals gaps of low dimensional materials, in (InSe2)xNbSe2 the intercalated indium atoms were found to form InSe2-bonded chains.

A trio of chemists at the Chinese Academy of Sciences’ Dalian Institute of Chemical Physics, working with a colleague from the University of Western Ontario, has tied the smallest knot ever, using just 54 atoms. In their study, published in the journal Nature Communications, Zhiwen Li, Jingjing Zhang, Gao Li and Richard Puddephatt accidentally tied the knot while trying to create metal acetylides in their lab.

The researchers were attempting to create types of alkynes called metal acetylides as a means to conduct other types of organic reactions. More specifically, they were attempting to connect carbon structures to gold acetylides—typically, such work results in the creation of simple chains of gold known as caternames.

But, unexpectedly, the result of one reaction created a chain that knotted itself into a trefoil knot with no loose ends. Trefoil knots are used in making pretzels and play a major role in knot theory. The researchers noted that the knot had a backbone crossing ratio (BCR) of 23. Knot BCRs are a measure of the strength of the knot. Most organic knots, the team notes, have a BCR somewhere between 27 and 33.

Researchers at HZB have created an innovative technique to precisely measure minuscule temperature variations as small as 100 microkelvin in the thermal Hall effect, overcoming previous limitations caused by thermal noise. By applying this technique to terbium titanate, the team showcased its effectiveness in producing consistent and dependable outcomes. This advancement in measuring the thermal Hall effect sheds light on the behavior of coherent multi-particle states in quantum materials, particularly their interactions with lattice vibrations, known as phonons.

The laws of quantum physics apply to all materials. However, in so-called quantum materials, these laws give rise to particularly unusual properties. For example, magnetic fields or changes in temperature can cause excitations, collective states, or quasiparticles that are accompanied by phase transitions to exotic states. This can be utilised in a variety of ways, provided it can be understood, managed, and controlled: For example, in future information technologies that can store or process data with minimal energy requirements.

The thermal Hall effect (THE) plays a key role in identifying exotic states in condensed matter. The effect is based on tiny transverse temperature differences that occur when a thermal current is passed through a sample and a perpendicular magnetic field is applied (see Figure 2). In particular, the quantitative measurement of the thermal Hall effect allows us to separate the exotic excitations from conventional behavior.