Black Holes Make Complex Gravitational-Wave Chirps as They Merge

Gravitational waves are produced by all moving masses, from the Earth’s wobble around the Sun to your motion as you go about your daily life. But at the moment, those gravitational waves are too small to be observed. Gravitational observatories such as LIGO and VIRGO can only see the strong gravitational waves produced by merging stellar-mass black holes.

The chirp of a gravitational merger is clear. Credit: LIGO/Caltech/MIT/University of Chicago (Ben Farr)
Continue reading “Black Holes Make Complex Gravitational-Wave Chirps as They Merge”

Behold! The Black Hole Collision Calculator!

Black holes have been the subject of intense interest ever since scientists began speculating about their existence. Originally proposed in the early 20th century as a consequence of Einstein’s Theory of General Relativity, black holes became a mainstream subject a few decades later. By 1971, the first physical evidence of black holes was found and by 2016, the existence of gravitational waves was confirmed for the first time.

This discovery touched off a new era in astrophysics, letting people know collision between massive objects (black holes and/or neutron stars) creates ripples in spacetime that can be detected light-years away. To give people a sense of how profound these events are, Álvaro Díez created the Black Hole Collision Calculator (BHCC) – a tool that lets you see what the outcome of a collision between a black hole and any astronomical object would be!

Continue reading “Behold! The Black Hole Collision Calculator!”

Could a tabletop experiment detect gravitational waves and determine the quantum nature of gravity?

Perhaps the most surprising prediction of general relativity is that of gravitational waves. Ripples in space and time that spread through the universe at the speed of light. Gravitational waves are so faint that for decades their detection was thought impossible. Even today, it takes an array of laser interferometers several kilometers long to see their effect. But what if we could detect them with a table-top experiment in a university lab?

In a recent paper published in the New Journal of Physics, a team of physicists proposes just such a device. Rather than using beams of light, they suggest using the quantum superposition of a single electron.

Continue reading “Could a tabletop experiment detect gravitational waves and determine the quantum nature of gravity?”

Why Can Black Hole Binaries Have Dramatically Different Masses? Multiple Generations of Mergers

On the 12th of April, 2019, the LIGO and Virgo gravitational wave observatories detected the merger of two black holes. Named GW190412, one of the black holes was eight solar masses, while the other was 30 solar masses. On the 14th of August that year, an even more extreme merger was observed, when a 2.5 solar mass object merged with a black hole nearly ten times more massive. These mergers raise fundamental questions about the way black hole mergers happen.

Continue reading “Why Can Black Hole Binaries Have Dramatically Different Masses? Multiple Generations of Mergers”

The Moon is an Ideal Spot for a Gravitational Wave Observatory

In the coming years, multiple space agencies will be sending missions (including astronauts) to the Moon’s southern polar region to conduct vital research. In addition to scouting resources in the area (in preparation for the construction of a lunar base) these missions will also investigate the possibility of conducting various scientific investigations on the far side of the Moon.

However, two prominent scientists (Dr. Karan Jani and Prof. Abraham Loeb) recently published a paper where they argue that another kind of astronomy could be conducted on the far side of the Moon – Gravitational Wave astronomy! As part of NASA’s Project Artemis, they explain how a Gravitational-wave Lunar Observatory for Cosmology (GLOC) would be ideal for exploring GW in the richest and most challenging frequencies.

Continue reading “The Moon is an Ideal Spot for a Gravitational Wave Observatory”

A Black Hole Popping Out of a Traversable Wormhole Should Give Off a Very Specific Signal in Gravitational Waves

Gravitational wave astronomy has changed the way we view the cosmos. In only a few years we have observed the collisions of black holes and neutron stars, confirming our theoretical understanding of these strange objects. But as gravitational wave astronomy matures, it will allow us to probe the very nature of space and time itself. While that day is a long way off, it hasn’t stopped the theory folks from dreaming up new discoveries. For example, how it might look if a black hole and a wormhole interact.

Continue reading “A Black Hole Popping Out of a Traversable Wormhole Should Give Off a Very Specific Signal in Gravitational Waves”

Why Pulsars Are So Bright

When pulsars were first discovered in 1967, their rhythmic radio-wave pulsations were a mystery. Some thought their radio beams must be of extraterrestrial origin.

We’ve learned a lot since then. We know that pulsars are magnetized, rotating neutrons stars. We know that they rotate very rapidly, with their magnetic poles sending sweeping beams of radio waves out into space. And if they’re aimed the right way, we can “see” them as pulses of radio waves, even though the radio waves are steady. They’re kind of like lighthouses.

But the exact mechanism that creates all of that electromagnetic radiation has remained a mystery.

Continue reading “Why Pulsars Are So Bright”

New Simulations Show How Black Holes Grow, Through Mergers and Accretion

One of the most pressing questions in astronomy concerns black holes. We know that massive stars that explode as supernovae can leave stellar mass black holes as remnants. And astrophysicists understand that process. But what about the supermassive black holes (SMBHs) like Sagittarius A-star (Sgr A*,) at the heart of the Milky Way?

SMBHs can have a billion solar masses. How do they get so big?

Continue reading “New Simulations Show How Black Holes Grow, Through Mergers and Accretion”

Astronomers Detected a Black Hole Merger With Very Different Mass Objects

In another first, scientists at the LIGO and Virgo gravitational wave detectors announced a signal unlike anything they’ve ever seen before. While many black hole mergers have been detected thanks to LIGO and Virgo’s international network for detectors, this particular signal (GW190412) was the first where the two black holes had distinctly different masses.

Continue reading “Astronomers Detected a Black Hole Merger With Very Different Mass Objects”