Compelling evidence that the structure of matter surrounding supermassive black holes has changed over cosmic time has been uncovered by an international team of astronomers.
If true, the research led by the National Observatory of Athens and published in the Monthly Notices of the Royal Astronomical Society would challenge a fundamental law which has existed for almost five decades.
The cosmos has served up a gift for a group of scientists who have been searching for one of the most elusive phenomena in the night sky. Their study, presented in Science Advances, reports on the very first observations of a swirling vortex in spacetime caused by a rapidly rotating black hole.
The process, known as Lense-Thirring precession or frame-dragging, describes how black holes twist the spacetime that surrounds them, dragging nearby objects like stars and wobbling their orbits along the way.
Dark matter is an elusive type of matter that does not emit, reflect or absorb light, yet is estimated to account for most of the universe’s mass. Over the past decades, many physicists worldwide have been trying to detect this type of matter or signals associated with its presence, employing various approaches and technologies.
As it has never been directly detected before, the composition and properties of dark matter remain mostly unknown. Initially, dark matter searches focused on the detection of relatively heavy particles. More recently, however, physicists also started looking for lighter particles with masses below one giga-electron-volt (GeV), which would thus be lighter than protons.
Researchers at SLAC National Accelerator Laboratory and The Ohio State University recently showed that signatures of these sub-GeV dark matter particles could also be picked up by neutrino observatories, large underground detectors originally designed to study neutrinos (i.e., light particles that weakly interact with regular matter).
Observations of the formation of light-nuclei from high-energy collisions may help in the hunt for dark matter.
Particle collisions at the Large Hadron Collider (LHC) can reach temperatures over one hundred thousand times hotter than at the center of the sun. Yet, somehow, light atomic nuclei and their antimatter counterparts emerge from this scorching environment unscathed, even though the bonds holding the nuclei together would normally be expected to break at a much lower temperature.
Physicists have puzzled for decades over how this is possible, but now the ALICE collaboration has provided experimental evidence of how it happens, with its results published today in Nature.
An international team of astronomers has investigated a short-lived optical flare designated AT2022zod. As a result, they found evidence indicating that this flare is an unusual tidal disruption event. The findings were presented in a research paper published Dec. 1 on the arXiv pre-print server.
When a star passes close enough to a supermassive black hole and is pulled apart by the black hole’s tidal forces, it triggers the process of disruption, which is known as a tidal disruption event (TDE). Afterward, the tidally disrupted stellar debris starts raining down on the black hole, and radiation emerges from the innermost region of accreting debris, which is an indicator of the presence of a TDE.
“Novae are more than fireworks in our galaxy — they are laboratories for extreme physics,” said Dr. Laura Chomiuk.
What can imaging supernovae (plural for supernova) explosions teach astronomers about their behavior and physical characteristics? This is what a recent study published in Nature Astronomy hopes to address as an international team of researchers investigated the mechanisms behind the thermonuclear eruptions that supernovae cause. This study has the potential to help scientists better understand supernovae, as they are hypothesized to be responsible for spreading the chemical elements and molecules needed for life throughout the universe.
For the study, the researchers used the Georgia State University CHARA Array to observe exploding supernovae from two separate white dwarfs: nova V1674 Her and nova V1405 Cas, which are located approximately 16,200 and 5,500 light-years from Earth, and were observed days 2 & 3 and days 53, 55, & 67 after first light of eruption, also known as t0, respectively. For nova V1674 Her, the researchers observed outflows during days 2 & 3, while they observed this same behavior for nova V1405 Cas during days 53, 55, & 67. The researchers note these contrasting observations challenge longstanding hypotheses regarding supernovae behavior during their eruption periods.
An exploration of ten spooky aspects of the multiverse and our universe within it.
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