A microquasar’s jets are creating shockwaves that could be creating the strange cosmic rays we see bombarding Earth.
What is the universe made of? This question has driven astronomers for hundreds of years.
For the past quarter of a century, scientists have believed “normal” stuff like atoms and molecules that make up you, me, Earth, and nearly everything we can see only accounts for 5% of the universe. Another 25% is “dark matter”, an unknown substance we can’t see but which we can detect through how it affects normal matter via gravity.
The remaining 70% of the cosmos is made of “dark energy”. Discovered in 1998, this is an unknown form of energy believed to be making the universe expand at an ever-increasing rate.
Intermediate-Mass Black Holes (IMBHs) represent a cosmic puzzle, with their existence and formation mechanisms shrouded in mystery.
A recent study led by Gran Sasso Science Institute researcher Manuel Arca Sedda and published in Monthly Notices of the Royal Astronomical Society journal (MNRAS), sheds light on the mechanisms that lead to the formation of mysterious Intermediate-Mass Black Holes (IMBHs). These are objects with masses between a few hundred and tens of thousands of solar masses, which could represent the link between their smaller relatives, stellar black holes, and the supermassive giants that populate the centers of galaxies.
Continue reading “Cracking the Code: How Intermediate-Mass Black Holes Form” »
A recent discovery of a Gamma-ray burst (GRB) named GRB 220627A has left astronomers puzzled. GRBs are the most powerful explosions in the universe since the Big Bang, and typically last only seconds to a few minutes. However, GRB 220627A lasted for more than a thousand seconds, or just shy of 17 minutes, and arrived in two powerful bursts from an unknown event 2 billion years into the universe’s existence.
While the source of the burst appears to be ordinary, its length and double-burst nature have left astronomers puzzled. The likeliest explanation is that the GRB is the product of gravitational lensing, which is the warping of distant light sources by extremely massive objects such as galaxies and black holes. This would stretch, distort, and create echoes of the GRB’s signal before it arrived at Earth.
When a massive star runs out of fuel, it collapses before exploding outward in a gigantic supernova, leaving behind an ultra-dense neutron star or a black hole. It is these stellar explosions —and occasionally even collisions between two neutron stars — that produce powerful bursts of gamma rays that can be picked up by space observatories such as NASA’s Fermi Gamma-ray Space Telescope, which detected the new GRB.
Chinese scientists have opened the deepest and largest underground lab in the world.
The newly expanded facility, located around 7,800 feet below the Jinping Mountains, will allow scientists to study dark matter, the mysterious substance that’s believed to account for more than 80 percent of the mass in the universe.
While scientists believe it’s the “glue” that holds the structures of the universe together, we have yet to directly observe it, since it’s thought to be unable to interact with other matter or reflect or absorb light.
Astronomers have discovered a mysterious radio signal at the heart of an ancient, tightly packed ball of stars, and it may be coming from a long-hidden black hole.
The radio signal was picked up by the Australia Telescope Compact Array (ATCA) radio telescope as it created the most sensitive image of a globular cluster — a clump of ancient stars like these — ever taken. The ball of stars in question, named 47 Tucanae, is the second-brightest globular cluster in the sky over Earth and is located around 13,000 light-years from our planet.
Using various ground-based telescopes, astronomers have performed photometric and spectroscopic observations of a nearby Type Ia supernova known as SN 2020nlb. Results of the observations campaign, presented January 16 on the pre-print server arXiv, deliver important insights regarding the evolution of this stellar explosion.
Type Ia supernovae (SN Ia) are found in binary systems in which one of the stars is a white dwarf. Stellar explosions of this type are important for the scientific community, as they offer essential clues into the evolution of stars and galaxies.
SN 2020nlb was detected on June 25, 2020 with the Asteroid Terrestrial-impact Last Alert System (ATLAS), shortly after its explosion in the lenticular galaxy Messier 85 (or M85 for short), located some 60 million light years away. Spectroscopic observations of SN 2020nlb, commenced shortly after its detection, confirmed that it is a Type Ia supernova.
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 expansion of the universe at some stage of evolution is well described by the Friedmann model. It was derived from general relativity a hundred years ago, but it is still considered one of the most important and relevant cosmological models.
RUDN University astrophysicists have now proven the theoretical possibility of the existence of traversable wormholes in the Friedmann universe. The research is published in the journal Universe.
“A wormhole is a type of highly curved geometry. It resembles a tunnel either between distant regions of the same universe or between different universes. Such structures were first discussed in the framework of solutions to the gravitational field equations a hundred years ago. But the wormholes considered then turned out to be non-traversable even for photons—they could not move from one ‘end of the tunnel’ to the other, not to mention going back,” said Kirill Bronnikov, doctor of physical and mathematical sciences, professor of RUDN University.
