Black Holes Archives

October 17, 2022December 7, 2022 by Matt Williams

Shortly Before They Collided, two Black Holes Tangled Spacetime up Into Knots

A binary black hole system, viewed from above. Image Credit: Bohn et al. (see http://arxiv.org/abs/1410.7775)

In February 2016, scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced the first-ever detection of gravitational waves (GWs). Originally predicted by Einstein’s Theory of General Relativity, these waves are ripples in spacetime that occur whenever massive objects (like black holes and neutron stars) merge. Since then, countless GW events have been detected by observatories across the globe – to the point where they have become an almost daily occurrence. This has allowed astronomers to gain insight into some of the most extreme objects in the Universe.

In a recent study, an international team of researchers led by Cardiff University observed a binary black hole system originally detected in 2020 by the Advanced LIGO, Virgo, and Kamioki Gravitational Wave Observatory (KAGRA). In the process, the team noticed a peculiar twisting motion (aka. a precession) in the orbits of the two colliding black holes that was 10 billion times faster than what was noted with other precessing objects. This is the first time a precession has been observed with binary black holes, which confirms yet another phenomenon predicted by General Relativity (GR).

October 13, 2022October 13, 2022 by Matt Williams

A Black Hole Burps out Material, Years After Feasting on a Star

. Credit: DESY/Science Communication Lab

Originally predicted by Einstein’s Theory of General Relativity, black holes are the most extreme object in the known Universe. These objects form when stars reach the end of their life cycle, blow off their outer layers, and are so gravitationally powerful that nothing (not even light) can escape their surfaces. They are also of interest because they allow astronomers to observe the laws of physics under the most extreme conditions. Periodically, these gravitational behemoths will devoir stars and other objects in their vicinity, releasing tremendous amounts of light and radiation.

In October 2018, astronomers witnessed one such event when observing a black hole in a galaxy located 665 million light-years from Earth. While astronomers have witnessed events like this before, another team from the Harvard & Smithsonian Center for Astrophysics noticed something unprecedented when they examined the same black hole three years later. As they explained in a recent study, the black hole was shining very brightly because it was ejecting (or “burping”) leftover material from the star at half the speed of light. Their findings could provide new clues about how black holes feed and grow over time.

October 2, 2022October 2, 2022 by Brian Koberlein

The Milky Way is Surrounded by a Vast Graveyard of Dead Stars

Distribution of stellar remains in the Milky Way. Credit: University of Sydney

Everything dies in the end, even the brightest of stars. In fact, the brightest stars are the ones that live the shortest lives. They consume all the hydrogen they have within a few million years, then explode as brilliant supernovae. Their core remains collapse into a neutron star or black hole. These small, dark objects litter our galaxy, like a cosmic graveyard.

September 23, 2022September 23, 2022 by Carolyn Collins Petersen

There’s a Blob of Gas Orbiting Around the Milky Way’s Supermassive Black Hole

The Atacama Large Millimeter/submillimeter Array (ALMA) looked at Sagittarius A*, (image of Sag A* by the EHT Collaboration) to study something bright in the region around Sag A*. Credit: ESO/José Francisco Salgado.

Sagittarius A* (Sag A) is usually a pretty quiet object, as supermassive black holes go. It’s not wildly active, like the object at the heart of M87, for example. But, every once in a while, there’s a little action in its neighborhood. Right now, there appears to be a hot blob of gas running rapidly in circles around the black hole. Astronomers detected it using the Atacama Large Millimeter Array (ALMA) in Chile. The data from that radio astronomy facility tells them more about the environment around Sag A*.

September 19, 2022September 19, 2022 by Matt Williams

Astronomers Find a Sun-like Star Orbiting a Nearby Black Hole

Gaia BH1 is a Sun-like star co-orbiting with a black hole estimated at 10 times the Sun's mass. Credit: ESO/L. Calcada

In 1916, Karl Schwarzchild theorized the existence of black holes as a resolution to Einstein’s field equations for his Theory of General Relativity. By the mid-20th century, astronomers began detecting black holes for the first time using indirect methods, which consisted of observing their effects on surrounding objects and space. Since the 1980s, scientists have studied supermassive black holes (SMBHs), which reside at the center of most massive galaxies in the Universe. And by April 2019, the Event Horizon Telescope (EHT) collaboration released the first image ever taken of an SMBH.

These observations are an opportunity to test the laws of physics under the most extreme conditions and offer insights into the forces that shaped the Universe. According to a recent study, an international research team relied on data from the ESA’s Gaia Observatory to observe a Sun-like star with strange orbital characteristics. Due to the nature of its orbit, the team concluded that it must be part of a black hole binary system. This makes it the nearest black hole to our Solar System and implies the existence of a sizable population of dormant black holes in our galaxy.

August 24, 2022August 24, 2022 by Brian Koberlein

Colliding Black Holes Provide Another way to Measure Distance in the Universe

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

We know the universe is expanding, and we have a pretty good idea of how fast it’s expanding, but we don’t know the rate exactly. That’s because of the different methods we have to measure the rate of cosmic expansion keep giving us slightly different results. It’s a nagging problem that bugs astronomers, so while they have worked to ensure current methods are accurate, they have also looked to new ways to measure cosmic expansion. One of these new ways involves gravitational waves.

August 19, 2022August 19, 2022 by Brian Koberlein

Astronomers Have Revealed a Black Hole's Photon Ring for the First Time

The calculated photon ring of M87*. Credit: Broderick, et al

In 2019 the Event Horizon Telescope gave us our first direct image of a black hole. It was a powerful image, but not one with much detail. It looks like a blurry orange donut. To be fair, the real meat of the discovery was in the data, not the image. And as a recent study shows, there’s a great deal more in the data than what we’ve seen.

August 13, 2022August 13, 2022 by Brian Koberlein

Primordial Black Holes Could Have Triggered the Formation of Supermassive Black Holes

Artist view of merging black holes in the early universe. Credit: LIGO/Caltech/MIT/R. Hurt (IPAC)

The early moments of the universe were turbulent and filled with hot and dense matter. Fluctuations in the early universe could have been great enough that stellar-mass pockets of matter collapsed under their own weight to create primordial black holes. Although we’ve never detected these small black holes, they could have played a vital role in cosmic evolution, perhaps growing into the supermassive black holes we see today. A new study shows how this could work, but also finds the process is complicated.

July 20, 2022July 20, 2022 by Carolyn Collins Petersen

A Dormant Black Hole has Been Discovered Just Outside the Milky Way

What happens when a massive star dies? Conventional wisdom (and observational evidence) say that it can collapse to form a “stellar-mass” black hole. Astronomers detect black holes by the X-ray emissions they emit.

But, what if the black hole isn’t giving off high levels of X-ray emissions? Then, it could be a very rare object indeed: a dormant black hole. Not many of these have been seen. So, it’s exciting to know that a team of astronomers has found one. It’s called VFTS 243. They detected it in Very Large Telescope observations of stars in the Tarantula Nebula, in the neighboring Large Magellanic Cloud.

July 20, 2022July 20, 2022 by Carolyn Collins Petersen

We Finally Know Where the Highest Energy Cosmic Rays are Coming From: Blazars

Way out there in space is a class of objects called blazars. Think of them as extreme particle accelerators, able to marshall energies a million times stronger than the Large Hadron Collider in Switzerland. It turns out they’re the culprits in one of the great astrophysical mysteries: what creates and propels neutrinos across the universe at blazingly fast speeds? It turns out that the answer’s been there all along: blazars pump out neutrinos and cosmic rays. That’s the conclusion a group of astronomers led by Dr. Sara Buson of Universität Wurzburg in Germany came to as they studied data from a very unique facility here on Earth: the IceCube Neutrino Observatory in Antarctica.