Gravitational Waves Archives

October 14, 2024October 14, 2024 by Andy Tomaswick

How Gravitational Waves Could Let Us See the First Moments After the Big Bang

Cosmology has had several ground-breaking discoveries over the last 100+ years since Einstein developed his theory of relativity. Two of the most prominent were the discovery of the Cosmic Microwave Background (CMB) in 1968 and the confirmation of gravitational waves in 2015. Each utilized different tools, but both lent credence to the Big Bang Theory, which relates to the universe’s formation. However, we still don’t understand a vital part of that formation, and a new review paper by Rishav Roshan and Graham White at the University of Southampton suggests that we might be able to make some headway on our one-second “gap” in knowledge by using our newfound understanding of gravitational waves.

September 17, 2024September 20, 2024 by Matt Williams

Future Gravitational Wave Observatories Could See the Earliest Black Hole Mergers in the Universe

A simulation of two merging black holes. Credit: Simulating eXtreme Spacetimes (SXS) Project

In February 2016, scientists at the Laser Interferometer Gravitational-wave Observatory (LIGO) confirmed they made the first-ever detection of gravitational waves (GWs). These events occur when massive objects like neutron stars and black holes merge, sending ripples through spacetime that can be detected millions (and even billions) of light-years away. Since the first event, more than 100 GW events have been confirmed by LIGO, the Advanced VIRGO collaboration, and the Kamioka Gravitational Wave Detector (KAGRA).

Moreover, scientists have found numerous applications for GW astronomy, from probing the interiors of supernovae and neutron stars to measuring the expansion rate of the Universe and learning what it looked like one minute after the Big Bang. In a recent study, an international team of astronomers proposed another application for binary black hole (BBH) mergers: using the earliest mergers in the Universe to probe the first generation of stars (Population III) in the Universe. By modeling how the events evolved, they determined what kind of GW signals the proposed Einstein Telescope (ET) could observe in the coming years.

September 10, 2024September 10, 2024 by Carolyn Collins Petersen

Two Supermassive Black Holes on a Collision Course With Each Other

An artist's concept of what two merging supermassive black holes might look like. Each one is surrounded by an accretion disk of hot gas and material streaming away via jets. CourtesyNASA, ESA, Joseph Olmsted (STScI)

Galaxy collisions are foundational events in the Universe. They happen when two systems mingle stars in a cosmic dance. They also cause spectacular mergers of supermassive black holes. The result is one very changed galaxy and a singular, ultra-massive black hole.

September 10, 2024September 10, 2024 by Evan Gough

The Milky Way’s Supermassive Black Hole Might Have Formed 9 Billion Years Ago

This is the first image of Sgr A*, the supermassive black hole at the centre of our galaxy. Scientists are working hard to figure out how old it is and how it grew so massive. Image Credit: EHT

Large galaxies like ours are hosts to Supermassive Black Holes (SMBHs.) They can be so massive that they resist comprehension, with some of them having billions of times more mass than the Sun. Ours, named Sagittarius A* (Sgr A*), is a little more modest at about four million solar masses.

Astrophysicists have studied Sgr A* to learn more about it, including its age. They say it formed about nine billion years ago.

August 30, 2024August 30, 2024 by Mark Thompson

If Gravitons Exist, this Experiment Might Find Them

It’s thought that gravity consists of minute quantum building blocks called gravitons, but so far they have been too elusive to observe. A new result from Pikovski’s Research Group now shows that next-generation quantum sensors can catch a single one.

There are four fundamental forces in the Universe; strong, weak, electromagnetic and gravity. Quantum theory explains three of the four through the interaction of particles but science has yet to discover a corresponding particle for gravity. Known as the ‘graviton’, the hypothetical gravity particle is thought to constitute gravitational waves but it hasn’t been detected in gravity wave detector. A new experiment hopes to change that using an acoustic resonator to identify individual gravitons and confirm their existence.

August 29, 2024August 29, 2024 by Mark Thompson

For Their Next Trick, Gravitational Wave Observatories Could Detect Collapsing Stars

After the death of a massive, spinning star, a disk of material forms around the central black hole. As the material cools and falls into the black hole, new research suggests that detectable gravitational waves are created. Ore Gottlieb

The merging of black holes and neutron stars are among the most energetic events in the universe. Not only do they emit colossal amounts of energy, they can also be detected through gravitational waves. Observatories like LIGO/Virgo (Laser Interferometer Gravitational Wave Observatory) and KAGRA (The Kamioka Gravitational Wave Detector) have detected their gravitational waves but new gravitational wave observatories are now thought to be able to detect the collapse of a massive rapidly spinning star before it becomes a black hole. According to new research, collapsing stars within 50 million light years should be detectable.

August 10, 2024August 10, 2024 by Matt Williams

Scientists Develop a Novel Method for Detecting Supermassive Black Holes: Use Smaller Black Holes!

In 1974, astronomers Bruce Balick and Robert L. Brown discovered a powerful radio source at the center of the Milky Way galaxy. The source, Sagittarius A*, was subsequently revealed to be a supermassive black hole (SMBH) with a mass of over 4 million Suns. Since then, astronomers have determined that SMBHs reside at the center of all galaxies with highly active central regions known as active galactic nuclei (AGNs) or “quasars.” Despite all we’ve learned, the origin of these massive black holes remains one of the biggest mysteries in astronomy.

The most popular theories are that they may have formed when the Universe was still very young or have grown over time by consuming the matter around them (accretion) and through mergers with other black holes. In recent years, research has shown that when mergers between such massive objects occur, Gravitational Waves (GWs) are released. In a recent study, an international team of astrophysicists proposed a novel method for detecting pairs of SMBHs: analyzing gravitational waves generated by binaries of nearby small stellar black holes.

July 25, 2024July 25, 2024 by Evan Gough

A Solution to the “Final Parsec Problem?”

Simulation of merging supermassive black holes. Credit: NASA's Goddard Space Flight Center/Scott Noble — Simulation of merging supermassive black holes. New research shows how dark matter overcomes the Final Parsec Problem. Credit: NASA's Goddard Space Flight Center/Scott Noble

Supermassive Black Holes are Nature’s confounding behemoths. It’s difficult for Earth-bound minds to comprehend their magnitude and power. Astrophysicists have spent decades studying them, and they’ve made progress. But one problem still baffles even them: the Final Parsec Problem.

New research might have solved the problem, and dark matter plays a role in the solution.

June 24, 2024June 24, 2024 by Matt Williams

Simulating the Last Moments Before Neutron Stars Merge

Volume rendering of density in a simulation of a binary neutron star merger. New research shows that neutrinos created in the hot interface between the merging stars can be briefly trapped and remain out of equilibrium with the cold cores of the merging stars for 2 to 3 milliseconds. Credit: David Radice/Penn State

When stars reach the end of their life cycle, they shed their outer layers in a supernova. What is left behind is a neutron star, a stellar remnant that is incredibly dense despite being relatively small and cold. When this happens in binary systems, the resulting neutron stars will eventually spiral inward and collide. When they finally merge, the process triggers the release of gravitational waves and can lead to the formation of a black hole. But what happens as the neutron stars begin merging, right down to the quantum level, is something scientists are eager to learn more about.

When the stars begin to merge, very high temperatures are generated, creating “hot neutrinos” that remain out of equilibrium with the cold cores of the merging stars. Ordinarily, these tiny, massless particles only interact with normal matter via weak nuclear forces and possibly gravity. However, according to new simulations led by Penn State University (PSU) physicists, these neutrinos can weakly interact with normal matter during this time. These findings could lead to new insights into these powerful events.

May 18, 2024May 18, 2024 by Mark Thompson

More Evidence for the Gravitational Wave Background of the Universe

Pulsar timing array. Credit: David Champion/Max Planck

The gravitational wave background was first detected in 2016. It was announced following the release of the first data set from the European Pulsar Timing Array. A second set of data has just been released and, joined by the Indian Pulsar Timing Array, both studies confirm the existence of the background. The latest theory seems to suggest that we’re seeing the combined signal of supermassive black hole mergers.