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Category: cosmology – Page 5

Escaping cosmic strings: How dark photons could finally work as dark matter

Researchers, in a recent Physical Review Letters paper, introduce a new mechanism that may finally allow ultralight dark photons to be considered serious candidates for dark matter, with promising implications for detection efforts.

Around 85% of all matter is believed to be dark matter, yet this elusive substance continues to puzzle scientists because it cannot be observed directly.

One of the candidates for is dark photons. These hypothetical particles are similar to regular photons but have mass and interact only weakly with normal matter.

Astronomers Discover Rogue Black Hole Devouring Star in the Unlikeliest of Places

UC Berkeley astronomers found a hidden black hole roaming far from the galaxy’s core. It may eventually merge with the central black hole and release gravitational waves. Astronomers have identified nearly 100 cases of massive black holes feasting on stars, almost all located in the dense centers

Elon Musk: Digital Superintelligence, Multiplanetary Life, How to Be Useful

A fireside with Elon Musk at AI Startup School in San Francisco.

Before rockets and robots, Elon Musk was drilling holes through his office floor to borrow internet. In this candid talk, he walks through the early days of Zip2, the Falcon 1 launches that nearly ended SpaceX, and the “miracle” of Tesla surviving 2008.

He shares the thinking that guided him—building from first principles, doing useful things, and the belief that we’re in the middle of an intelligence big bang.

Chapters:

00:00 — Intro.
01:25 — His origin story.
02:00 — Dream to help build the internet.
04:40 — Zip2 and lessons learned.
08:00 — PayPal.
14:30 — Origin of SpaceX
18:30 — Building rockets from first principles.
23:50 — Lessons in leadership.
27:10 — Building up xAI
39:00 — Super intelligence and synthetic data.
39:30 — Multi-planetary future.
43:00 — Nueralink, AI safety and the singularity.

Astronomers are Closing in on the Source of Galactic Cosmic Rays

In 1912, astronomer Victor Hess discovered strange, high-energy particles known as “cosmic rays.” Since then, researchers have hunted for their birthplaces. Today, we know about some of the cosmic ray “launch pads”, ranging from the Sun and supernova explosions to black holes and distant active galactic nuclei. What astronomers are now searching for are sources of cosmic rays within the Milky Way Galaxy.

In a pair of presentations at the recent American Astronomical Society meeting, a team led by Michigan State University’s Zhuo Zhang, proposed an interesting place where cosmic rays originate: a pulsar wind nebula in our own Milky Way Galaxy. A pulsar is a rapidly rotating neutron star, formed as a result of a supernova explosion. High-energy particles and the neutron star’s strong magnetic field combine to interact with the nearby interstellar medium. The result is a pulsar wind nebula that can be detected across nearly the whole electromagnetic spectrum, particularly in X-rays. It makes sense that this object would be a source of cosmic rays. Pulsars are found throughout the Galaxy, which makes them a useful category in the search for cosmic ray engines in the Milky Way.

The Vela Pulsar is a good example of a pulsar wind nebula. The pulsar is at the center, and the surrounding cloudiness is the nebula. Courtesy NASA.
The Vela Pulsar is a good example of a pulsar wind nebula. The pulsar is at the center, and the surrounding cloudiness is the nebula. Courtesy NASA.

Simulation reveals emergence of jet from binary neutron star merger followed by black hole formation

Binary neutron star mergers, cosmic collisions between two very dense stellar remnants made up predominantly of neutrons, have been the topic of numerous astrophysics studies due to their fascinating underlying physics and their possible cosmological outcomes. Most previous studies aimed at simulating and better understanding these events relied on computational methods designed to solve Einstein’s equations of general relativity under extreme conditions, such as those that would be present during neutron star mergers.

Researchers at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Yukawa Institute for Theoretical Physics, Chiba University, and Toho University recently performed the longest simulation of binary neutron star mergers to date, utilizing a framework for modeling the interactions between magnetic fields, high-density matter and neutrinos, known as the neutrino-radiation magnetohydrodynamics (MHD) framework.

Their simulation, outlined in Physical Review Letters, reveals the emergence of a magnetically dominated jet from the , followed by the collapse of the binary neutron star system into a black hole.

AI Uncovers Wild Spin of the Milky Way’s Supermassive Black Hole

Back in 2019, the Event Horizon Telescope (EHT) team revealed the first-ever image of a supermassive black hole in the galaxy M87. In 2022, they followed up with the iconic image of Sagittarius A at the heart of the Milky Way. While these images were groundbreaking, the data behind them held even deeper insights that were hard to decode.

Neural Networks Meet Black Hole Physics

Previous studies by the EHT Collaboration used only a handful of realistic synthetic data files. Funded by the National Science Foundation (NSF) as part of the Partnership to Advance Throughput Computing (PATh) project, the Madison-based CHTC enabled the astronomers to feed millions of such data files into a so-called Bayesian neural network, which can quantify uncertainties. This allowed the researchers to make a much better comparison between the EHT data and the models.

Scientists discover new evidence of intermediate-mass black holes

A series of studies sheds light on the origins and characteristics of intermediate-mass black holes. In the world of black holes, there are generally three size categories: stellar-mass black holes (about five to 50 times the mass of the sun), supermassive black holes (millions to billions of times the mass of the sun), and intermediate-mass black holes with masses somewhere in between.

While we know that intermediate-mass black holes should exist, little is known about their origins or characteristics – they are considered the rare “missing links” in black hole evolution.

However, four new studies have shed new light on the mystery. The research was led by a team in the lab of Assistant Professor of Physics and Astronomy Karan Jani, who also serves as the founding director of the Vanderbilt Lunar Labs Initiative. The work was funded by the National Science Foundation and the Vanderbilt Office of the Vice Provost for Research and Innovation.

Telescopes in Chile Capture Images of the Earliest Galaxies in the Universe

Thanks to observatories like the venerable Hubble Space Telescope (HST) and its next-generation cousin, the James Webb Space Telescope (JWST), astronomers are finally getting the chance to study galaxies that existed just one billion years after the Big Bang. This period is known as “Cosmic Dawn” because it was during this period that the first stars formed and came together to create the first galaxies in the Universe. The study of these galaxies has revealed some surprising and fascinating things that are allowing astronomers to learn how large-scale structures in the Universe came to be and how they’ve evolved since.

For the longest time, it was thought that this cosmological period could only be seen by space telescopes, as they don’t have to deal with interference from Earth’s atmosphere. With advanced technologies ranging from adaptive optics (AO) and coronagraphs to interferometry and spectrometers, ground-based telescopes are pushing the boundaries of what astronomers can see. In recent news, an international team of astronomers using the Cosmology Large Angular Scale Surveyor (CLASS) announced the first-ever detection of radiation from the cosmic microwave background (CMB) interacting with the first stars in the Universe. These findings shed light on one of the least understood periods in cosmological history.

The study that details their findings, which recently appeared in The Astrophysical Journal, was led by Yunyang Li — an observational cosmologist from the Kavli Institute for Cosmological Physics (University of Chicago) and The William H. Miller III Department of Physics and Astronomy at Johns Hopkins University (JHU). He was joined by many JHU colleagues, as well as astrophysicists from the National Institute of Standards and Technology, the Argonne National Laboratory, the Los Alamos National Laboratory, the Harvard-Smithsonian Center for Astrophysics, the Massachusetts Institute of Technology (MIT), the NASA Goddard Space Flight Center, and many prestigious universities.

‘Black hole bomb’ discovery could trigger potential ‘catastrophic’ disaster if it ever detonated

The AI bot explained: If a black hole bomb were somehow constructed and detonated, the energy release could be comparable to that of a supernova, one of the most powerful explosions in the universe. Such an event would release vast amounts of radiation and could have devastating effects on its surroundings.