NASA’s Swift Sees ‘Wandering’ Mega Black Hole Shredding Star - UNIVERSE

This artist's concept depicts a tidal disruption event, which occurs when a star passes fatally close to a supermassive black hole. Crumbs of the splintering star heat up as they swirl around the black hole, creating a glow astronomers can see from far across the cosmos, and the black hole launches a relativistic jet into space.

NRAO/AUI/NSF/NASA

NASA’s Neil Gehrels Swift Observatory captured an “orphan” black hole lighting up as it devoured a star on the outskirts of a faraway galaxy. These phenomena are rare to begin with, and none had ever before been seen so far outside of a galaxy’s core.

“We were looking for these star-shredding events as a way to find otherwise invisible supermassive black holes wandering away from the galactic cores where they usually reside,” said Robert Stein, a research fellow at The University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “With this discovery, which is one of just a couple that have been confirmed so far, we’ve validated a new technique and can use it to hunt for more.”

A paper describing the results, led by Stein, was published Monday in The Astrophysical Journal Letters.

Researchers saw an ultrabright flare unleashed by a star being torn apart by extreme gravitational forces after drifting too close to a monster black hole — a phenomenon called a tidal disruption event. The black hole behind the blast weighs in at about a million times the Sun’s mass. Its existence was first flagged in November 2025 as an unusual brightening in a galaxy about 750 million light-years away by ZTF (Zwicky Transient Facility), a survey conducted by the Palomar Observatory in Southern California.

“Out of the half million flashes ZTF detects each night, our new artificial intelligence algorithm automatically recognized a flare that looked a lot like a tidal disruption event, despite its unusual location in the outskirts of a galaxy,” Stein said. For a few months, the tidal disruption event outshone its entire host galaxy in ultraviolet wavelengths, temporarily radiating with the light of about 10 billion suns.

This gif shows the galaxy WISEA J014656.04-152214.7, located about 750 million light-years away in the constellation Cetus, before and after a tidal disruption event was spotted on its outer edge in November 2025. The image at left was taken by the DESI (Dark Energy Spectroscopic Instrument) Legacy Survey and the one at right is from the Lowell Discovery Telescope.

Lowell Discovery Telescope/Legacy Survey/Robert Stein

Other telescopes, including the SOAR (Southern Astrophysical Research) telescope in Chile, followed up on the ZTF source to look at the event’s spectrum, which revealed features supporting that it was likely a tidal disruption event. Astronomers then used NASA’s Swift to look at wavelengths they can’t detect with ground-based telescopes to uncover new information. For example, Swift’s UVOT (Ultraviolet/Optical Telescope) took the blip’s temperature and found that it had quite a fever at about 54,000 degrees Fahrenheit (30,000 degrees Celsius).

“The combination of all this data helped us rule out other explanations and confidently say it’s a tidal disruption event, despite its strange location,” said Jonathan Carney, a doctoral student at the University of North Carolina at Chapel Hill, who took the first spectra that supported the flare’s interpretation as a tidal disruption event.

Hidden heavyweights

Nearly every galaxy in the universe is anchored by a supermassive black hole sitting right in the center. About once every 100,000 years, a star will drift too close to this invisible heavyweight and trigger a tidal disruption event.

While they’re rather rare in any given galaxy, scientists scour millions of galaxies for them. Each year, astronomical surveys typically spot about 30 tidal disruption events occurring somewhere in the universe.

Prior to 2024, they’d only been seen in galaxy cores. That’s partly because astronomers mainly looked for them there; after all, it’s where all the known supermassive black holes were, and you can’t get a tidal disruption event without one (the gravitational pull of lighter black holes isn’t strong enough).

Then scientists saw the telltale signs of a star being shredded 2,600 light-years from the center of its host galaxy. That inspired more astronomers to look beyond galaxy cores for similar events, and now a team has identified one more than 30,000 light-years away from a galaxy’s center.

This video visualizes a star approaching a supermassive black hole so closely that it's stretched to a breaking point by the black hole's strong gravity. Intense tidal forces crack the star open and hurl its gaseous guts outward. Stellar debris forms a spinning accretion disk as it continues to spiral into the black hole.

NASA, ESA, STScI, Ralf Crawford (STScI)

Oddball origin story

So how did the newfound black hole become so off-kilter?

“It must have originated in a galaxy’s center, but not the one it’s in the outskirts of now,” Stein said. “We think the host galaxy’s supermassive black hole is still at its core, but the one eating the star could have started off in a small galaxy that merged with the big one we see today.”

The researchers have outlined two possibilities. Three or more galaxies may have merged together, and the gravitational tug-of-war between their central supermassive black holes may have flung the lightest black hole out to the galaxy’s edge.

Or a dwarf galaxy could be midway through a merger. As the dwarf’s stars fell into the larger galaxy, one may have passed too close to the dwarf’s supermassive black hole.

“Further discoveries could reveal the origin of this apparent ‘orphan’ black hole,” Stein said. “The key science question we want to answer is: How common are wandering black holes?”

The answer may soon be within reach. “Pointed science observations with Swift's UVOT and XRT (X-Ray Telescope) instruments are temporarily suspended as the mission awaits an orbit boost, which is planned for this summer,” said co-author S. Bradley Cenko, Swift’s principal investigator at NASA Goddard. The spacecraft, whose primary mission ran from 2004 to 2006, is slowly sinking toward Earth due to atmospheric drag after more than 20 years of observations of the changing universe. Nudging it to a higher orbit could extend its lifetime even longer. “Once it resumes normal operations, Swift could continue searching for more examples of out-of-place black holes.”

In the coming years, scientists will use the new technique to search for disintegrating stars in observations from the newly operational Vera C. Rubin Observatory, jointly funded by the U.S. Department of Energy and National Science Foundation, in Chile and NASA’s upcoming Nancy Grace Roman Space Telescope.

“Rubin’s wide, deep surveys will reveal a much larger sample of tidal disruption events than current observatories are capable of collecting, including ones that are off-center,” Carney said. “And Roman’s space-based surveys will extend the current search zone by seeing ones that are farther away, looking back through 9 billion years of cosmic history.” Adding their observations to Swift’s and those from ground-based observatories will bring astronomers closer than ever before to completing a census of the universe’s behemoth black holes.

To learn more about the Swift mission, visit: https://nasa.gov/swift 

Source: NASA’s Swift Sees ‘Wandering’ Mega Black Hole Shredding Star - NASA Science 

Ultraprecise battery scan maps nanoscale electrode thickness variations to improve EV fire safety - Energy & Green Tech - Automotive

Credit: Pixabay/CC0 Public

A KAIST research team has developed a method capable of detecting minute variations in battery electrode thickness that can contribute to thermal runaway with a precision equivalent to approximately one ten-thousandth of the diameter of a human hair, all without disassembling or damaging the battery. The technology is expected to improve battery safety and quality by identifying invisible defects during the manufacturing process.

A research team led by professor Young-Jin Kim of the Department of Mechanical Engineering has developed a technology that measures the thickness of lithium-ion battery electrodes in a noncontact and nondestructive manner.

The study was led by Dr. Guseon Kang of the KAIST Department of Mechanical Engineering, currently with the Korea Institute of Industrial Technology, as the first author, with Kim serving as the corresponding author. The research findings were published in Nature Communications on June 10.

Why thickness uniformity is critical

The technology combines terahertz waves (electromagnetic waves in the spectral region between light and radio waves) with an optical frequency comb, which divides the frequency of light into evenly spaced intervals like the markings on a ruler and serves as a reference for ultra-precise measurements.

The electrodes in lithium-ion batteries, which are widely used in electric vehicles, are essential components through which electric current flows. Even a slight variation in electrode thickness can cause current to become concentrated in certain areas when charging and discharging, generating heat. If the heat continues to accumulate, it may lead to thermal runaway, a phenomenon in which a battery's internal temperature rises rapidly and can result in a fire or explosion. Maintaining uniform electrode thickness is therefore critically important during battery manufacturing.

Existing inspection technologies, however, have limitations when applied to production environments. X-ray computed tomography can provide detailed images of internal structures, but its relatively long inspection time makes it difficult to use on high-speed production lines. Ultrasonic acoustic microscopy requires direct contact with a liquid medium, while laser displacement sensors can perform rapid measurements but have difficulty precisely analyzing structures inside an electrode.

Combining terahertz with a frequency comb

The research team overcame these limitations by combining optical frequency comb and terahertz technologies. The researchers first directed terahertz waves at a battery electrode and collected signals generated as the waves were repeatedly reflected within the electrode. They then used an optical frequency comb as a reference to analyze the signals with exceptionally high precision and calculate the electrode thickness. This enabled nanometer-scale measurements of the electrode's internal structure without damaging the battery.

At the core of the technology is Fabry–Pérot interference, a regularly spaced interference pattern produced as terahertz waves repeatedly travel back and forth between the front and rear surfaces of an electrode. Much like measuring length by reading the markings on a ruler, the researchers precisely analyzed the interference pattern using the optical frequency comb as a reference to determine the electrode thickness.

As a result, the team successfully measured both the electrode thickness and its complex refractive index (a material's optical property indicating how strongly it transmits and absorbs electromagnetic waves) in a single measurement without requiring a separate calibration process.

Precision at production-line speeds

The researchers validated the technology using battery electrodes measuring between 50 and 150 micrometers in thickness, comparable to the diameter of a human hair. With a measurement time of just 0.2 seconds, the system detected thickness differences as small as 70.1 nanometers in the anode (approximately one fourteen-hundredth of the diameter of a human hair) and 465.5 nanometers in the cathode. This measurement speed is considered sufficient for use on rapidly moving battery production lines.

When the measurement time was increased to 25.6 seconds, the precision improved further. The system distinguished differences as small as 7.8 nanometers in the anode (approximately one ten-thousandth of the diameter of a human hair) and 25.2 nanometers in the cathode. This represents up to a 100-fold improvement in precision compared with conventional time-domain analysis methods, enabling the detection of thickness variations that are completely invisible to the naked eye.

The technology is not limited to measuring thickness at a single point. It can generate a three-dimensional map of thickness across an entire electrode and track gradual thickness variations in real time during production. The researchers also confirmed that the system could accurately measure an electrode tilted at an angle of approximately 45 degrees, demonstrating its potential for application to fast-moving, real-world battery manufacturing lines.

Extending quality control to future batteries

The study is significant because it presents a new inspection technology capable of identifying invisible microscopic defects during production without disassembling or damaging batteries. In addition to lithium-ion batteries, the technology is expected to serve as a key quality-control tool for manufacturing next-generation all-solid-state batteries, which use solid electrolytes instead of liquid electrolytes. By detecting defects at an early stage, the technology could improve battery safety and quality while enabling more stable manufacturing processes.

"This technology is an integrated metrology platform that can simultaneously measure electrode thickness and material properties without requiring a separate calibration process," said Kim. "We expect it to become a key technology for the real-time quality control of production lines for next-generation lithium-ion batteries and all-solid-state batteries." 

Provided by The Korea Advanced Institute of Science and Technology (KAIST) 

by The Korea Advanced Institute of Science and Technology (KAIST)

edited by Swati Mestri, reviewed by Robert Egan 

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