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Category: cosmology – Page 17

JWST uncovers hidden black holes devouring stars in dusty galaxies

Astronomers at MIT, Columbia University, and elsewhere have used NASA’s James Webb Space Telescope (JWST) to peer through the dust of nearby galaxies and into the aftermath of a black hole’s stellar feast.

In a study appearing today in Astrophysical Journal Letters, the researchers report that for the first time, JWST has observed several tidal disruption events—instances when a galaxy’s central black hole draws in a nearby star and whips up tidal forces that tear the star to shreds, giving off an enormous burst of energy in the process.

Scientists have observed about 100 tidal disruption events (TDEs) since the 1990s, mostly as X-ray or optical light that flashes across relatively dust-free galaxies. But as MIT researchers recently reported, there may be many more star-shredding events in the universe that are “hiding” in dustier, gas-veiled galaxies.

Solving a 13-Billion-Year-Old Mystery: Scientists Recreate the Universe’s First Chemical Reaction

Researchers have uncovered new insights into the reaction pathways of the universe’s first molecule. Shortly after the Big Bang, which took place around 13.8 billion years ago, the universe was a seething, dense expanse of extreme heat. In just a matter of seconds, it began to cool enough for the f

Sweeping survey maps hundreds of satellite systems orbiting dwarf galaxies

We usually think of satellites as small objects orbiting planets or stars. But in the broader universe, galaxies themselves can have satellites—smaller galaxies bound by gravity that orbit a larger host, carrying with them stars, gas, dust, and dark matter.

Most of what we know about satellite galaxies comes from studying the Milky Way and other similarly large galaxies. But a new study led by Dartmouth astronomers broadens that understanding by exploring the satellites of dwarf galaxies—systems less than a tenth the size of the Milky Way.

The multi-institutional survey triples the number of dwarf galaxies surveyed for satellites, the researchers report in The Astrophysical Journal. The study identifies 355 candidate satellite galaxies, including 264 that were previously undocumented. The researchers suggest that 134 of these candidates are highly likely to be satellite galaxies.

Theories on dark matter’s origins point to ‘mirror world’ and universe’s edge

Two recent studies by Professor Stefano Profumo at the University of California, Santa Cruz, propose theories that attempt to answer one of the most fundamental open questions in modern physics: What is the particle nature of dark matter?

Science has produced overwhelming evidence that the mysterious substance, which accounts for 80% of all matter in the universe, exists. Dark matter’s presence explains what binds galaxies together and makes them rotate. Findings such as the large-scale structure of the universe and measurements of the cosmic microwave background also prove that something as-yet undetermined permeates all that darkness.

What remains unknown are the origins of dark matter, and hence, what are its particle properties? Those weighty questions primarily fall to theoretical physicists like Profumo. And in two recent papers, he approaches those questions from different directions, but both centered on the idea that dark matter might have emerged naturally from conditions in the very early universe—rather than dark matter being an exotic new particle that interacts with ordinary matter in some detectable way.

NASA’s Roman telescope will catch 100,000 explosions — and rewrite the Universe’s story

NASA’s Roman Space Telescope is set to embark on a deep-sky survey that could capture nearly 100,000 cosmic explosions, shedding light on everything from dark energy to black hole physics. Its High-Latitude Time-Domain Survey will revisit the same region of the sky every five days for two years, catching transient phenomena like supernovae — particularly type Ia, which are cosmic mileposts for tracking the universe’s expansion. Roman’s simulations suggest it could push the boundary of what we know about the early universe, observing ancient supernovae over 11.5 billion years old.

Scientists predict one of the major surveys by NASA’s upcoming Nancy Grace Roman Space Telescope may reveal around 100,000 celestial blasts, ranging from exploding stars to feeding black holes. Roman may even find evidence of some of the universe’s first stars, which are thought to completely self-destruct without leaving any remnant behind.

Cosmic explosions offer clues to some of the biggest mysteries of the universe. One is the nature of dark energy, the mysterious pressure thought to be accelerating the universe’s expansion.

Neutrino masses are not likely to originate from interactions with dark matter, study finds

Neutrinos are fundamental particles characterized by no electric charge and very small masses, which are known to interact with other matter via the weak force or gravity. While these particles have been the focus of numerous research studies, the processes through which they acquire their masses have not yet been elucidated.

One hypothesis is that neutrino masses originate from interactions with ultralight dark matter, a type of dark matter theorized to be made up of particles or fields with extremely small masses below 10 electron volts (eV). Researchers at Shanghai Jiao Tong University and University of Salerno recently set out to test this hypothesis by comparing data collected by the Kamioka Liquid Scintillator Antineutrino Detector (KamLAND) experiment to theoretical predictions.

Their findings, published in a paper in Physical Review Letters, suggest that neutrino masses are not likely to have a dark origin.

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