gravitational wave astronomy Archives

January 7, 2025January 7, 2025 by Andy Tomaswick

A CubeSat Mission Will Detect X-rays from GRBs and Black-Hole Mergers

The long-awaited detection of gravitational waves has opened up a whole new world of astronomy. One of the key efforts is now to tie signals across multiple domains – for example, a gravitational wave and the associated electromagnetic radiation created by that same event, such as a black hole merger or a gamma-ray burst. We’ll need new equipment to detect such “multimodal” signals, especially electromagnetic ones. One such project is the Black Hole Coded Aperture Telescope (BlackCAT), which will be launched early this year by a team led by researchers at Penn State.

December 26, 2024December 26, 2024 by Brian Koberlein

Neutron Stars With Less Mass Than A White Dwarf Might Exist, and LIGO and Virgo Could Find Them

Illustration of a neutron star. Credit: NASA’s Goddard Space Flight Center/Chris Smith (USRA/GESTAR)

Most of the neutron stars we know of have a mass between 1.4 and 2.0 Suns. The upper limit makes sense, since, beyond about two solar masses, a neutron star would collapse to become a black hole. The lower limit also makes sense given the mass of white dwarfs. While neutron stars defy gravitational collapse thanks to the pressure between neutrons, white dwarfs defy gravity thanks to electron pressure. As first discovered by Subrahmanyan Chandrasekhar in 1930, white dwarfs can only support themselves up to what is now known as the Chandrasekhar Limit, or 1.4 solar masses. So it’s easy to assume that a neutron star must have at least that much mass. Otherwise, collapse would stop at a white dwarf. But that isn’t necessarily true.

December 19, 2024December 19, 2024 by Brian Koberlein

Building the Black Hole Family Tree

Illustration of how black hole mergers might reveal their ancestors. Credit: Instituto Galego de Física de Altas Enerxías, IGFAE

In 2019, astronomers observed an unusual gravitational chirp. Known as GW190521, it was the last scream of gravitational waves as a black hole of 66 solar masses merged with a black hole of 85 solar masses to become a 142 solar mass black hole. The data were consistent with all the other black hole mergers we’ve observed. There was just one problem: an 85 solar mass black hole shouldn’t exist.

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.

June 5, 2024June 5, 2024 by Evan Gough

Primordial Black Holes Can Only Explain a Fraction of Dark Matter

This artist's illustration shows what primordial black holes might look like. In reality, the black holes would struggle to form accretion disks, as shown. Image Credit: NASA’s Goddard Space Flight Center

What is Dark Matter? That question is prominent in discussions about the nature of the Universe. There are many proposed explanations for dark matter, both within the Standard Model and outside of it.

One proposed component of dark matter is primordial black holes, created in the early Universe without a collapsing star as a progenitor.

January 5, 2024January 5, 2024 by Brian Koberlein

Do Neutron Stars Have Mountains? Gravitational Wave Observatories Could Detect Them

Light bursts from the collision of two neutron stars. Credit: NASA's Goddard Space Flight Center/CI Lab

The surface gravity of a neutron star is so incredibly intense that it can cause atoms to collapse into a dense cluster of neutrons. The interiors of neutron stars may be dense enough to allow quarks to escape the bounds of nuclei. So it’s hard to imagine neutron stars as active bodies, with tectonic crusts and perhaps even mountains. But we have evidence to support this idea, and we could learn even more through gravitational waves.

January 23, 2022April 13, 2022 by Matt Williams

Astronomers Might Have Detected the Background Gravitational Waves of the Universe

Artistic impression of the Double Pulsar system, where two active pulsars orbit each other in just 147 min. The orbital motion of these extremely dense neutrons star causes a number of relativistic effects, including the creation of ripples in spacetime known as gravitational waves. The gravitational waves carry away energy from the systems which shrinks by about 7mm per days as a result. The corresponding measurement agrees with the prediction of general relativity within 0.013%. The picture at high resolution and two alternative versions (1b, 1c) are accessible in the left column. [less] © Michael Kramer/MPIfR

In February 2016, Gravitational Waves (GWs) were detected for the first time in history. This discovery confirmed a prediction made by Albert Einstein over a century ago and triggered a revolution in astronomy. Since then, dozens of GW events have been detected from various sources, ranging from black hole mergers, neutron star mergers, or a combination thereof. As the instruments used for GW astronomy become more sophisticated, the ability to detect more events (and learn more from them) will only increase.

For instance, an international team of astronomers recently detected a series of low-frequency gravitational waves using the International Pulsar Timing Array (IPTA). These waves, they determined, could be the early signs of a background gravitational wave signal (BGWS) caused by pairs of supermassive black holes. The existence of this background is something that astrophysicists have theorized since GWs were first detected, making this a potentially ground-breaking discovery!