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The standard model of fundamental particles and interactions has now been in place for about a half-century. It has successfully passed experimental test after experimental test at particle accelerators. However, many of the model’s features are poorly understood, and it is now clear that standard-model particles only compose about 5% of the observed energy density of the Universe. This situation naturally encourages researchers to look for new particles and interactions that fall outside this model. One way to perform this search is to prepare a gas of polarized atoms and to look for changes in this polarization that might come from new physics. Haowen Su from the University of Science and Technology of China and colleagues have used two separated samples of polarized xenon gas to probe spin-dependent interactions [1] (Fig. 1). The results place constraints on axions—a candidate for dark matter—in a theoretically favored mass range called the axion window.

Searches for new spin-dependent interactions have exploded over the past decade. Special relativity and quantum mechanics tightly constrain the mathematical form for such interactions, with the main adjustable parameters being the coupling strength and the spatial range. Since the form of these interactions is generic across many models, it is possible to conduct experimental searches for new interaction signatures, even in the absence of a specific theory for beyond-standard-model physics.

Fine tuning an experimental setup improved a detector’s sensitivity to neutrinos and perhaps eventually dark matter—two difficult-to-measure forms of matter which hold great importance for understanding particle physics and experimental cosmology. The University-of-Michigan-led study is published in Physical Review D.

A newly discovered crescent of galaxies spanning 3.3 billion light-years is one of the world’s largest known structures, challenging some of astronomers’ most fundamental assumptions about the universe.

The epic arrangement known as the Giant Arc is made up of galaxies, galaxy clusters, and a lot of gas and dust. It is located 9.2 billion light-years away and stretches across roughly a 15th of the observable universe.

Its discovery was “serendipitous,” according to Alexia Lopez, a doctoral candidate in cosmology at the University of Central Lancashire (UCLan) in the United Kingdom. Lopez was creating maps of things in the night sky using light from approximately 120,000 quasars, which are distant brilliant cores of galaxies where supermassive black holes consume material and produce energy.

Using data from NASA’s JWST and Chandra X-ray Observatory, a team of U.S. National Science Foundation NOIRLab astronomers have discovered a supermassive black hole at the center of a galaxy just 1.5 billion years after the Big Bang that is consuming matter at a phenomenal rate — over 40 times the theoretical limit. While short lived, this black hole’s ‘feast’ could help astronomers explain how supermassive black holes grew so quickly in the early Universe.

Supermassive black holes exist at the center of most galaxies, and modern telescopes continue to observe them at surprisingly early times in the Universe’s evolution. It’s difficult to understand how these black holes were able to grow so big so rapidly. But with the discovery of a low-mass supermassive black hole feasting on material at an extreme rate, seen just 1.5 billion years after the Big Bang, astronomers now have valuable new insights into the mechanisms of rapidly growing black holes in the early Universe.

LID-568 was discovered by a cross-institutional team of astronomers led by International Gemini Observatory/NSF NOIRLab astronomer Hyewon Suh. They used the James Webb Space Telescope (JWST) to observe a sample of galaxies from the Chandra X-ray Observatory’s COSMOS legacy survey. This population of galaxies is very bright in the X-ray part of the spectrum, but are invisible in the optical and near-infrared. JWST’s unique infrared sensitivity allows it to detect these faint counterpart emissions.

Hot spots and tunnels to neighboring “superbubbles” seem to have been created by supernovas and infant star outbursts.

First indications of the neutrino fog—an important background for dark matter searches—from the PandaX & XENON collaborations Letters: https://go.aps.org/3AwVxQG & https://go.aps.org/3YSjX0l

Hypothetical particles called axions could form dense clouds around neutron stars – and if they do, they will give off signals that radio telescopes can detect, say researchers in the Netherlands, the UK and the US. Since axions are a possible candidate for the mysterious substance known as dark matter, this finding could bring us closer to understanding it.

Around 85% of the universe’s mass consists of matter that appears “dark” to us. We can observe its gravitational effect on structures such as galaxies, but we cannot observe it directly. This is because dark matter hardly interacts with anything as far as we know, making it very difficult to detect. So far, searches for dark matter on Earth and in space have found no evidence for any of the various dark matter candidates.

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Detecting exploding primordial black holes from the universe’s first second may unveil new physics.

In that moment, pockets of hot material may have been dense enough to form black holes, potentially with masses ranging from 100,000 times less than a paperclip to 100,000 times more than the sun’s, according to scientists.

Continue reading “Hawking radiation may unveil hidden physics in black hole explosions” »

A black hole formula worked out in the 1970s remains the most concrete clue physicists have about the threads of the space-time fabric.