Enlarge / Scientists have found a large black hole that “hiccups,” giving off plumes of gas. (credit: Jose-Luis Olivares, MIT)

In December 2020, astronomers spotted an unusual burst of light in a galaxy roughly 848 million light-years away—a region with a supermassive black hole at the center that had been largely quiet until then. The energy of the burst mysteriously dipped about every 8.5 days before the black hole settled back down, akin to having a case of celestial hiccups.

Now scientists think they've figured out the reason for this unusual behavior. The supermassive black hole is orbited by a smaller black hole that periodically punches through the larger object's accretion disk during its travels, releasing a plume of gas. This suggests that black hole accretion disks might not be as uniform as astronomers thought, according to a new paper published in the journal Science Advances.

Co-author Dheeraj "DJ" Pasham of MIT's Kavli Institute for Astrophysics and Space research noticed the community alert that went out after the All Sky Automated Survey for SuperNovae (ASAS-SN) detected the flare, dubbed ASASSN-20qc. He was intrigued and still had some allotted time on the X-ray telescope, called NICER (the Neutron star Interior Composition Explorer) on board the International Space Station. He directed the telescope to the galaxy of interest and gathered about four months of data, after which the flare faded.

Enlarge / A new image from the Event Horizon Telescope has revealed powerful magnetic fields spiraling from the edge of a supermassive black hole at the center of the Milky Way, Sagittarius A*. (credit: EHT Collaboration)

Physicists have been confident since the1980s that there is a supermassive black hole at the center of the Milky Way galaxy, similar to those thought to be at the center of most spiral and elliptical galaxies. It's since been dubbed Sagittarius A* (pronounced A-star), or SgrA* for short. The Event Horizon Telescope (EHT) captured the first image of SgrA* two years ago. Now the collaboration has revealed a new polarized image (above) showcasing the black hole's swirling magnetic fields. The technical details appear in two new papers published in The Astrophysical Journal Letters. The new image is strikingly similar to another EHT image of a larger supermassive black hole, M87*, so this might be something that all such black holes share.

The only way to "see" a black hole is to image the shadow created by light as it bends in response to the object's powerful gravitational field. As Ars Science Editor John Timmer reported in 2019, the EHT isn't a telescope in the traditional sense. Instead, it's a collection of telescopes scattered around the globe. The EHT is created by interferometry, which uses light in the microwave regime of the electromagnetic spectrum captured at different locations. These recorded images are combined and processed to build an image with a resolution similar to that of a telescope the size of the most distant locations. Interferometry has been used at facilities like ALMA (the Atacama Large Millimeter/submillimeter Array) in northern Chile, where telescopes can be spread across 16 km of desert.

In theory, there's no upper limit on the size of the array, but to determine which photons originated simultaneously at the source, you need very precise location and timing information on each of the sites. And you still have to gather sufficient photons to see anything at all. So atomic clocks were installed at many of the locations, and exact GPS measurements were built up over time. For the EHT, the large collecting area of ALMA—combined with choosing a wavelength in which supermassive black holes are very bright—ensured sufficient photons.

Enlarge (credit: NASA/JPL-Caltech )

You win some, you lose some. Earlier this week , observations made by the Webb Space Telescope provided new data that supports what we thought we understood about planet formation. On Thursday, word came that astronomers spotted a large planet orbiting close to a tiny star—a star that's too small to have had enough material around it to form a planet that large.

This doesn't mean that the planet is "impossible." But it does mean that we may not fully understand some aspects of planet formation.

A big mismatch

LHS 3154 is, by any reasonable measure, a small, dim star. Imaging by the team behind the new work indicates that the red dwarf has just 11 percent of the Sun's mass. Temperature estimates place it at about 2,850 K, far lower than the Sun's 5,800 K temperature and barely warm enough to keep it out of ultracool dwarf category. (Yes, ultracool dwarfs are enough of a thing to merit their own Wikipedia entry .)

Enlarge / Image of a planet-forming disk, with gaps in between higher-density areas. (credit: ALMA(ESO/NAOJ/NRAO); C. Brogan, B. Saxton )

Where do planets come from? The entire process can get complicated. Planetary embryos sometimes run into obstacles to growth that leave them as asteroids or naked planetary cores. But at least one question about planetary formation has finally been answered—how they get their water.

For decades, planetary formation theories kept suggesting that planets receive water from ice-covered fragments of rock that form in the frigid outer reaches of protoplanetary disks, where light and heat from the emerging system’s star lacks the intensity to melt the ice. As friction from the gas and dust of the disk moves these pebbles inward toward the star, they bring water and other ices to planets after crossing the snow line, where things warm up enough that the ice sublimates and releases huge amounts of water vapor. This was all hypothesized until now.

NASA’s James Webb Telescope has now observed groundbreaking evidence of these ideas as it imaged four young protoplanetary disks.The telescope used its Medium-Resolution Spectrometer (MRS) of Webb’s Mid-Infrared Instrument (MIRI) to gather this data, because it is especially sensitive to water vapor. Webb found that in two of these disks, massive amounts of cold water vapor appeared past the snow line, confirming that ice sublimating from frozen pebbles can indeed deliver water to planets like ours.

Enlarge (credit: NOIRLab/NSF/AURA/M. Garlick/M. Zamani )

What is hundreds of billions of times more powerful than the Sun, flashes on repeat with intense bursts of light, and verges on defying the laws of physics? No, it’s not your neighbors’ holiday lights glitching again. It’s an LFBOT in the depths of space.

LFBOTs (Luminous Fast Blue Optical Transients) are already quite bizarre. They erupt with blue light, radio, X-ray, and optical emissions, making them some of the brightest explosions ever seen in space, as luminous as supernovae. It is no exaggeration that they give off more energy than hundreds of billions of stars like our own. They also tend to live fast, blazing for only minutes before they burn themselves out and fade into darkness.

LFBOTs are quite rare, and in many cases their sources are unidentified. But we’ve never seen anything with the intensity of an LFBOT named AT2022tsd—aka the “Tasmanian Devil.” Its strange behavior was caught by 15 telescopes and observatories, including the W.M. Keck Observatory and NASA’s Chandra Space Telescope. Like other phenomena of its kind, it initially emitted incredible amounts of energy and then dimmed. Unlike any other LFBOT observed before, however, this one seemed to come back from the dead. It flared again—and again and again.

Astronomers involved with the Telescope Array experiment in Utah's West Desert have detected an ultra-high-energy cosmic ray (UHECR) with a whpping energy level of 244 EeV, according to a new paper published in the journal Science. It's the most energetic cosmic ray detected since 1991, when astronomers detected the so-called "Oh-My-God' particle , with energies of an even more impressive 320 EeV. Astronomers have dubbed this latest event the "Amaterasu" particle, after the Shinto sun goddess said to have created Japan. One might even call it the "Oh-My-Goddess" particle.

Cosmic rays are highly energetic subatomic particles traveling through space near the speed of light. Technically, a cosmic ray is just an atomic nucleus made up of a proton or a cluster of protons and neutrons. Most originate from the Sun, but others come from objects outside our solar system. When these rays strike the Earth’s atmosphere, they break apart into showers of other particles (both positively and negatively charged).

They were first discovered in 1912 by Austrian physicist Victor Hess via a series of ascents in a hydrogen balloon to take measurements of radiation in the atmosphere with an electroscope. He found that the rate of ionization was a good three times the rate at sea level, thereby disproving a competing theory that this radiation came from the rocks of  Earth. If you've ever seen a cloud chamber in a science museum, cosmic ray tracks look like wispy little white lines, similar to tiny jet contrails.

Enlarge / Artist's conception of a gamma-ray burst. (credit: NASA )

Supernovae are some of the most energetic events in the Universe. And a subset of those involves gamma-ray bursts, where a lot of the energy released comes from extremely high-energy photons. We think we know why that happens in general terms—the black hole left behind the explosion expels jets of material at nearly the speed of light. But the details of how and where these jets produce photons are not at all close to being fully worked out.

Unfortunately, these events happen very quickly and very far away, so it's not easy to get detailed observations of them. However, a recent gamma-ray burst that's been called the BOAT (brightest of all time) may be providing us with new information on the events within a few days of a supernova's explosion. A new paper describes data from a telescope that happened to be both pointing in the right direction and sensitive to the extremely high-energy radiation produced by the event.

I need a shower

The "telescope" mentioned is the Large High Altitude Air Shower Observatory (LHAASO). Based nearly three miles (4,400 meters) above sea level, the observatory is a complex of instruments that aren't a telescope in the traditional sense. Instead, they're meant to capture air showers—the complex cascade of debris and photons that are produced when high-energy particles from outer space slam into the atmosphere.

On the morning of October 9, 2022, multiple space-based detectors picked up a powerful gamma-ray burst (GRB) passing through our Solar System, sending astronomers around the world scrambling to train their telescopes on that part of the sky to collect vital data on the event and its aftermath. Dubbed GRB 221009A and deemed likely to be the "birth cry" of a new black hole, the gamma-ray burst is the most powerful yet recorded. That's why astronomers nicknamed it the BOAT , or Brightest Of All Time.

The event was promptly published in the Astronomer's Telegram, and we now have new data from follow-up observations in several new papers published in a special focus issue of the Astrophysical Journal Letters. The findings confirmed that GRB 221009A was indeed the BOAT, appearing especially bright because its narrow jet was pointing directly at Earth. “It’s probably the brightest event to hit Earth since human civilization began,” Eric Burns, an astronomer at Louisiana State University, told New Scientist . “The energy of this thing is so extreme that if you took the entire sun and you converted all of it into pure energy, it still wouldn’t match this event. There’s just nothing comparable.”

But the various analyses also yielded several surprising results that puzzle astronomers and may lead to a significant overhaul of our current models of gamma ray bursts. For instance, a supernova should have occurred a few weeks after the initial burst, but astronomers have yet to detect one. Radio data from observations of the afterglow didn't match predictions of existing models, and astronomers detected rare extended rings of X-ray light echoes from the initial blast in distant dust clouds.

Enlarge / The CHIME telescope has proven adept at picking up fast radio bursts. (credit: Andre Renard / CHIME Collaboration )

By combing through a collection of data, researchers may have discovered evidence that we've already observed the first "blitzar," a bizarre astronomical event caused by the sudden collapse of an overly massive neutron star. The event is driven by an earlier merger of two neutron stars; this creates an unstable intermediate neutron star, which is kept from collapsing immediately by its rapid spin. In a blitzar, the strong magnetic fields of the neutron star slow down its spin, causing it to collapse into a black hole several hours after the merger.

That collapse suddenly deletes the dynamo powering the magnetic fields, releasing their energy in the form of a fast radio burst. The researchers who performed the analysis suggest that this phenomenon could explain the non-repeating forms of these events.

Too big to live

How big can a neutron star get before it collapses into a black hole? We don't have a good answer, in part because we're not sure what happens to the bizarre forms of matter inside one of these massive objects. We don't even know if the neutrons that give the star its name survive or fall apart into their component quarks. It's one of those annoying questions where the answer includes the phrase "it depends."