Pulsars Archives

December 4, 2024December 5, 2024 by Brian Koberlein

MeerKAT Confirms the Gravitational Wave Background of the Universe in Record Time

A MeerKAT antenna disk in front of an illustrated view of black holes and gravitational waves. Credit: Carl Knox, OzGrav, Swinburne University of Technology and South African Radio Astronomy Observatory

The Universe is a turbulent place. Stars are exploding, neutron stars collide, and supermassive black holes are merging. All of these things and many more create gravitational waves. As a result, the cosmos is filled with a rippling sea of gravitational vibrations. While we have been able to directly detect gravitational waves since 2016, gravitational wave astronomy is still in its infancy. We have only been able to observe the gravitational ripples of colliding stellar black holes. Even then, all we can really detect is the final gravitational chirp created in the last moments of merging.

November 19, 2024November 19, 2024 by Evan Gough

The Strange Pulsar at the Center of the Crab Nebula

Hubble image of the Crab Nebula supernova remnant captured with the Wide Field and Planetary Camera 2. Credit: NASA, ESA, J. Hester and A. Loll (ASU)

Thanks to the Hubble Space Telescope, we all have a vivid image of the Crab Nebula emblazoned in our mind’s eyes. It’s the remnant of a supernova explosion Chinese astronomers recorded in 1056. However, the Crab Nebula is more than just a nebula; it’s also a pulsar.

The Crab Pulsar pulsates in an unusual ‘zebra’ pattern, and an astrophysicist at the University of Kansas thinks he’s figured out why.

November 12, 2024November 12, 2024 by Evan Gough

A Spider Stellar Engine Could Move Binary Stars Halfway Across a Galaxy

Illustration of a millisecond pulsar consuming material from a companion star. Pulsars that evaporate their companions rather than consuming them could serve as stellar engines. Credit: NASA / GSFC SVS / Dana Berry

Eventually, every stellar civilization will have to migrate to a different star. The habitable zone around all stars changes as they age. If long-lived technological civilizations are even plausible in our Universe, migration will be necessary, eventually.

Could Extraterrestrial Intelligences (ETIs) use stars themselves as stellar engines in their migrations?

February 22, 2024February 22, 2024 by Brian Koberlein

We Could Snoop on Extraterrestrial Communications Networks

The Atacama Large Millimeter/submillimeter Array (ALMA). Credit: C. Padilla, NRAO/AUI/NSF

The conditions for life throughout the Universe are so plentiful that it seems reasonable to presume there must be extra-terrestrial civilizations in the galaxy. But if that’s true, where are they? The Search for Extra-terrestrial Intelligence (SETI) program and others have long sought to find signals from these civilizations, but so far there has been nothing conclusive. Part of the challenge is that we don’t know what the nature of an alien signal might be. It’s a bit like finding a needle in a haystack when you don’t know what the needle looks like. Fortunately, any alien civilization would still be bound by the same physical laws we are, and we can use that to consider what might be possible. One way to better our odds of finding something would be to focus not on a direct signal from a single world, but the broader echos of an interstellar network of signals.

January 19, 2024January 19, 2024 by Evan Gough

Is this the Lightest Black Hole or Heaviest Neutron Star?

An international team of astronomers have found a new and unknown object in the Milky Way that is heavier than the heaviest neutron stars known and yet simultaneously lighter than the lightest black holes known. Image Credit: University of Manchester/Max Planck Institutue for Radio Astronomy

About 40,000 light-years away, a rapidly spinning object has a companion that’s confounding astronomers. It’s heavier than the heaviest neutron stars, yet at the same time, it’s lighter than the lightest black holes. Measurements place it in the so-called black hole mass gap, an observed gap in the stellar population between two to five solar masses. There appear to be no neutron stars larger than two solar masses and no black holes smaller than five solar masses.

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.

November 30, 2023November 30, 2023 by Evan Gough

Spider Pulsars are Tearing Apart Stars in the Omega Cluster

Omega Centauri is the brightest globular cluster in the night sky. It holds about 10 million stars and is the most massive globular cluster in the Milky Way. It's possible that globulars and nuclear star clusters are related in some way as a galaxy evolves. Image Credit: ESO.

Pulsars are extreme objects. They’re what’s left over when a massive star collapses on itself and explodes as a supernova. This creates a neutron star. Neutron stars spin, and some of them emit radiation. When they emit radiation from their poles that we can see, we call them pulsars.

October 13, 2023October 13, 2023 by Brian Koberlein

Are Pulsars the Key to Finding Dark Matter?

A composite image of the Crab Nebula. Credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech

Ah, dark matter particles, what could you be? The answer still eludes us, and astronomers keep trying new ideas to find them. Such as a new paper in Physical Review Letters that suggests if dark matter is made of axions we might see their remnant glow near pulsars.

September 3, 2023September 3, 2023 by Scott Alan Johnston

A Bizarre Pulsar Switches Between Two Brightness Modes. Astronomers Finally Figured Out Why.

Pulsars are the lighthouses of the universe. These rotating dead stars shoot twin jets of radiation from their poles, usually with a predictable rhythm. But sometimes pulsars behave strangely, and one pulsar in particular has had astronomers scratching their heads for years. It’s called PSR J1023+0038, and a decade ago, it shut off its jets and began oscillating between two brightness levels in an unpredictable pattern. Now, scientists think they understand why: it is busy eating a neighboring star.

September 2, 2023September 2, 2023 by Brian Koberlein

Astronomers are Hoping the Event Horizon Telescope saw Pulsars Near the Milky Way's Supermassive Black Hole

Visualization of a fast-rotating pulsar. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab

Millisecond pulsars are amazing astronomical tools. They are fast-rotating neutron stars that sweep beams of radio energy from their magnetic poles, and when they are aligned just right we see them as rapidly flashing radio beacons. They flash with such regularity that we can treat them as cosmic clocks. Any change in their motion can be measured with extreme precision. Astronomers have used millisecond pulsars to measure their orbital decay due to gravitational waves and to observe the background gravitational rumblings of the universe. They have even been proposed as a method of celestial navigation. They may soon also be able to test the most fundamental nature of gravity.