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Astronomy

A New Theory on Dark Matter: From High-Energy Particles to Heavy Lumps

Researchers propose a new theory for the origin of dark matter, the invisible substance thought to give the universe its shape and structure. Their mathematical models show that dark matter could have formed in the early universe from the collision of massless particles that lost their energy and condensed — like steam turning into water — into cold, heavy particles. They report that their theory can be tested using existing data — these dark matter particles would have a unique signature on the radiation that fills all of the universe known as the Cosmic Microwave Background.

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A team of researchers from Dartmouth University has proposed a groundbreaking new theory on the origin of dark matter, the mysterious substance thought to comprise 85% of the universe’s total mass. The study, published in Physical Review Letters, suggests that dark matter formed when fast-moving particles slowed down and took on an incredible amount of mass immediately after pairing up.

Dark matter is believed to exist based on observed gravitational effects that cannot be explained by visible matter. However, the researchers’ theory is distinct because it can be tested using existing observational data from the Cosmic Microwave Background (CMB), the leftover radiation from the Big Bang.

According to Robert Caldwell, a professor of physics and astronomy at Dartmouth, dark matter started its life as near-massless relativistic particles, almost like light. However, as these particles cooled down, an imbalance in their spins caused their energy to plummet, leading to the formation of cold, heavy particles that scientists think constitute dark matter.

The researchers theorize that extremely large numbers of massless particles bonded together due to the opposing directions of their spin, much like the attraction between the north and south poles of magnets. As these particles cooled down, they underwent a phase transition, where their energy plummeted, resulting in the formation of heavy, dark matter lumps.

The study introduces a theoretical particle that would have initiated this transition, but scientists already know that electrons can undergo a similar transition to form Cooper pairs at low temperatures. This existence of Cooper pairs provides evidence that the massless particles in the researchers’ theory could condense into dark matter.

The metamorphosis of these particles from high-energy to heavy lumps explains the vast deficit in energy density between the early universe and its current state, as well as the increase in mass density due to the formation of cold dark matter. The mathematical model behind this theory is surprisingly simple, relying on concepts and timelines that scientists already know exist.

The researchers believe that their theory can be tested using existing data from large-scale observational projects, such as the CMB Stage 4 experiment or the Simons Observatory in Chile. If proven correct, this new approach to thinking about dark matter could revolutionize our understanding of the universe’s composition and behavior.

Astronomy

A Rare Rhythm: Discovery of 2020 VN40, an Object Dancing with Neptune

Astronomers have discovered a bizarre object in the outer solar system, 2020 VN40, that dances to Neptune’s gravitational beat in a never-before-seen rhythm. It’s the first of its kind, orbiting the Sun once for every ten orbits of Neptune, and could reshape how we understand the movement and evolution of distant cosmic bodies.

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A team of astronomers has made a groundbreaking discovery, shedding new light on the mysteries of our solar system. Led by the Center for Astrophysics | Harvard & Smithsonian, researchers have identified a rare object, 2020 VN40, that is “dancing” with Neptune in the outer reaches of the solar system.

Located far beyond Neptune’s orbit, this enigmatic body belongs to a class known as trans-Neptunian objects (TNOs). What makes 2020 VN40 remarkable is its unique motion, which is synchronized with Neptune’s orbital period. In other words, this object completes one orbit around the sun for every ten orbits that Neptune makes.

This extraordinary discovery has significant implications for our understanding of the outer solar system and how it evolved. It supports the idea that many distant objects are temporarily “caught” in Neptune’s gravity as they drift through space. This phenomenon could be a key to unraveling the secrets of the solar system’s early days, when the planets were still forming.

“This is a big step in understanding the outer solar system,” said Rosemary Pike, lead researcher from the Center for Astrophysics | Harvard & Smithsonian. “It shows that even very distant regions influenced by Neptune can contain objects, and it gives us new clues about how the solar system evolved.”

The discovery was made possible through the Large inclination Distant Objects (LiDO) survey, which used advanced telescopes to search for unusual objects in the outer solar system. The LiDO team’s findings were published this month in The Planetary Science Journal.

The LiDO survey has already discovered over 140 distant objects, and more discoveries are expected from future surveys. With new telescopes like the Vera C. Rubin Observatory, scientists hope to find many more objects like 2020 VN40, revealing even more secrets about our solar system’s past.

As Dr. Samantha Lawler (University of Regina), a core member of the LiDO team, noted, “It has been fascinating to learn how many small bodies in the solar system exist on these very large, very tilted orbits.” The discovery of 2020 VN40 is indeed a thrilling moment for astronomy, as it opens a new window into the solar system’s past and promises to reveal fresh insights about the workings of our cosmic neighborhood.

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Astronomy

The Cosmic Conundrum: A Billion-Light-Year Hole Around Earth Unmasks Faster Space Expansion

Our galaxy may reside in a billion-light-year-wide cosmic bubble that accelerates local expansion, potentially settling the long-running Hubble tension. Galaxy counts reveal a sparsely populated neighborhood, and “fossil” sound waves from the Big Bang bolster the void scenario, hinting that gravity has hollowed out this region. Confirming the bubble could refine the universe’s age and reshape our grasp of cosmic growth.

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The Cosmic Conundrum: A Billion-Light-Year Hole Around Earth Unmasks Faster Space Expansion

Astronomers have long been puzzled by the discrepancy in the measured expansion rate of the universe, which they refer to as the Hubble tension. This conundrum has left scientists searching for a solution, and recent research suggests that our galaxy might be situated within a massive, billion-light-year hole that makes the cosmos expand faster here than in neighboring regions.

The idea is not new, but it gained momentum with the latest study presented at the Royal Astronomical Society’s National Astronomy Meeting (NAM) in Durham. The researchers’ theory proposes that our galaxy sits near the center of a large, local void, which would cause matter to be pulled by gravity towards the higher-density exterior of the void.

As the void empties out over time, the velocity of objects away from us would increase, giving the appearance of a faster local expansion rate. This potential solution to the Hubble tension is largely a local phenomenon, with little evidence that the expansion rate disagrees with expectations in the standard cosmology further back in time.

The researchers also used baryon acoustic oscillations (BAOs) – essentially the sound waves from the early universe – to support their theory. These sound waves travelled for only a short while before becoming frozen in place once the universe cooled enough for neutral atoms to form. They act as a standard ruler, whose angular size can be used to chart the cosmic expansion history.

By considering all available BAO measurements over the last 20 years, the researchers showed that a void model is about one hundred million times more likely than a void-free model with parameters designed to fit the CMB observations taken by the Planck satellite, the so-called homogeneous Planck cosmology.

The next step for researchers is to compare their local void model with other methods to estimate the history of the universe’s expansion. This involves looking at galaxies that are no longer forming stars and observing their spectra or light to find what kinds of stars they have and in what proportion.

Astronomers can then combine this age with the galaxy’s redshift – how much the wavelength of its light has been stretched – which tells us how much the universe has expanded while light from the galaxy was traveling towards us. This sheds light on the universe’s expansion history.

The Hubble constant was first proposed by Edwin Hubble in 1929 to express the rate of the universe’s expansion. It can be measured by observing the distance of celestial objects and how fast they are moving away from us. The Hubble tension refers to the discrepancy in the measured expansion rate of the universe, specifically between the value based on observations of the early universe and the value related to observations of the local universe.

Baryon acoustic oscillations provide an independent way to measure the expansion rate of the universe and how that rate has changed throughout cosmic history. The discovery of a billion-light-year hole around Earth might be just the solution scientists need to unravel the mysteries of the cosmos.

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Astronomy

Record-Breaking Black Hole Collision Detected by LIGO

Gravitational-wave detectors have captured their biggest spectacle yet: two gargantuan, rapidly spinning black holes likely forged by earlier smash-ups fused into a 225-solar-mass titan, GW231123. The record-setting blast strains both the sensitivity of LIGO-Virgo-KAGRA and the boundaries of stellar-evolution theory, forcing scientists to rethink how such cosmic heavyweights arise.

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The Laser Interferometer Gravitational-wave Observatory (LIGO) has made history once again with its groundbreaking detection of gravitational waves from a record-breaking black hole collision. This monumental event, designated GW231123, produced a final black hole with an unprecedented mass of approximately 225 times that of our Sun. The observation was made during the fourth observing run of the LIGO-Virgo-KAGRA (LVK) Collaboration network on November 23, 2023.

LIGO’s twin detectors in Livingston, Louisiana, and Hanford, Washington, jointly detected the signal, which emanated from a black hole merger that resulted in an extremely massive final product. This is the most massive black hole ever observed with gravitational waves, shattering the previous record held by GW190521, which had a total mass of 140 times that of the Sun.

The black holes involved in this event were each approximately 100 and 140 times the mass of our Sun, and their rapid spinning pushed the limits of both gravitational-wave detection technology and current theoretical models. Extracting accurate information from the signal required the use of intricate dynamics models that account for highly spinning black holes.

Mark Hannam, a member of the LVK Collaboration at Cardiff University, comments on the significance of this event: “This is the most massive black hole binary we’ve observed through gravitational waves, and it presents a real challenge to our understanding of black hole formation.” One possibility is that the two black holes in this binary formed through earlier mergers of smaller black holes.

Dave Reitze, the executive director of LIGO at Caltech, emphasizes the importance of this observation: “This observation once again demonstrates how gravitational waves are uniquely revealing the fundamental and exotic nature of black holes throughout the universe.”

The detection of GW231123 pushes the limits of both gravitational-wave detection technology and current theoretical models. Researchers continue to refine their analysis and improve the models used to interpret such extreme events. As Gregorio Carullo, a member of the LVK Collaboration at the University of Birmingham, notes: “It will take years for the community to fully unravel this intricate signal pattern and all its implications.”

This groundbreaking event serves as a testament to the power of gravitational-wave astronomy in probing the universe’s most extreme phenomena. The detection of GW231123 is a significant milestone in the field, pushing the boundaries of our understanding of black holes and their role in shaping the cosmos.

Gravitational-wave detectors like LIGO, Virgo, and KAGRA will continue to observe the universe with unprecedented precision, revealing the secrets of the most violent and exotic events that shape the fabric of space-time. As Sophie Bini, a postdoctoral researcher at Caltech and member of the LVK Collaboration, remarks: “This event pushes our instrumentation and data-analysis capabilities to the edge of what’s currently possible.”

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