Friday, December 12, 2025

Mysterious X-ray variability of the strongly magnetized neutron star NGC 7793 P13

Over 10 years of monitoring

Ehime University

The galaxy NGC 7793 and NGC 7793 P13 — image:
The image that combines data from X-ray, optical, and Hα line observations. NGC 7793 P13 is located away from the galactic center of NGC 7793.
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Credit: X-ray（NASA/CXC/Univ of Strasbourg/M.Pakull et al）； Optical（ESO/VLT/Univ of Strasbourg/M.Pakull et al）；H-alpha（NOAO/AURA/NSF/CTIO 1.5m）

When gas falls onto a compact object, such as a neutron star or black hole, due to its strong gravity (a process called accretion), it emits electromagnetic waves. High-sensitivity observations have discovered objects with extremely high X-ray luminosities. One possible explanation for the ultraluminosity is that an extraordinary amount of gas falls onto a compact object through a process called supercritical accretion. However, the mechanism of supercritical accretion remains unclear.

The research team focused on NGC 7793 P13 (hereafter, P13), which is a neutron star in supercritical accretion, located in the galaxy NGC 7793 (about 10 million light-years from the Earth; Figure 1). As gas falls onto a neutron star, it forms a column structure (called an accretion column) on magnetic poles, from which intense X-ray is thought to be emitted. Then, coherent X-ray pulsation accompanied by the rotation of a neutron star can be detected. According to previous studies, P13 rotates with a period of 0.4 s with a constant acceleration rate. Moreover, the luminosity changed by more than two orders of magnitude in about 10 years. Both rotation velocity and luminosity are effective parameters to estimate the amount of gas accreted. However, the relation between them was not found for P13.

The research team investigated the long-term evolution of the X-ray luminosity and rotation period of P13 from 2011 to 2024, using the archival data of XMM-Newton, Chandra, NuSTAR, and NICER. It was found that P13 was in a faint phase in 2021 and started to be bright again in 2022. By 2024, it reached a high luminosity, more than two orders of magnitude higher than in 2021 (Figure 2). Moreover, in the rebrightening phase in 2022, the acceleration rate of the rotation velocity was increased by a factor of 2, and it was maintained until 2024. This result suggests a relationship between X-ray luminosity and rotation velocity, and that the accretion system changed during the faint phase. The research team then focused on the pulsation and performed detailed analyses. It was suggested that the height of the accretion column was changed with the 10-year flux modulation (Figure 3). Those results are expected to be clues to reveal the mechanism of supercritical accretion.

The luminosity and rotation speed changed significantly. There is an inverse relationship between rotational speed and period; a shorter period indicates faster rotation. The acceleration rate of rotational speed is represented by the slope.

During the bright phase, the accretion column is tall, while during the faint phase, it becomes shorter.

Credit

Marina Yoshimoto（Ehime University）

Journal

The Astrophysical Journal Letters

DOI

10.3847/2041-8213/ae018f

Sweeping study shows similar genetic factors underlie multiple psychiatric disorders

Global analysis of over 6 million people groups disorders into five categories

University of Colorado at Boulder

Distinct psychiatric disorders have more in common biologically than previously believed, according to the largest and most detailed analysis to date of how genes influence mental illness.

The study, led by University of Colorado Boulder and Mass General Brigham researchers, could inform efforts to improve the way psychological disorders are diagnosed and provide insight for developing novel treatments that address multiple disorders at once.

The findings were published Dec. 10 in the journal Nature.

“Right now, we diagnose psychiatric disorders based on what we see in the room, and many people will be diagnosed with multiple disorders. That can be hard to treat and disheartening for patients,” said corresponding author, Andrew Grotzinger, PhD, assistant professor of psychology and neuroscience at CU Boulder. “This work provides the best evidence yet that there may be things that we are currently giving different names to that are actually driven by the same biological processes.”

Co-corresponding author Jordan Smoller, MD, director of the Center for Precision Psychiatry at Mass General Brigham in Boston, said the findings also provide key insight into the biological pathways and gene expression in brain cell types that may underly certain conditions.

“These findings provide valuable clues for advancing our understanding and treatment of mental illness with greater precision,” said Smoller.

Five categories

The researchers, in collaboration with the international Psychiatric Genomics Consortium Cross-Disorder Working Group, examined DNA data from more than 1 million individuals diagnosed with at least one of 14 psychiatric disorders and 5 million individuals with no diagnoses.

They found that five underlying “genomic factors” involving 238 genetic variants made up the majority of the genetic differences between those with a particular disorder and those without it. The paper groups disorders into five categories, each with a shared genetic architecture, including: disorders with compulsive features such as anorexia nervosa, Tourette disorder and obsessive-compulsive disorder (OCD); “internalizing conditions” including depression, anxiety and post-traumatic stress disorder; substance use disorders; and neurodevelopmental conditions, including autism and attention-deficit/hyperactivity disorder (ADHD).

Notably, the paper groups bipolar disorder and schizophrenia in a fifth category, reporting that 70% of the genetic signal associated with schizophrenia is also associated with bipolar disorder. The field of psychology has historically viewed bipolar disorder and schizophrenia as very different, and clinicians typically will not diagnose an individual with both.

“Genetically, we saw that they are more similar than they are unique,” said Grotzinger.

Pinpointing biological pathways

The paper also points to specific biological pathways that may underlie the individual groupings.

For instance, genes that influence excitatory neurons, which are involved in transmitting signals across other neurons, tend to be over-expressed in both bipolar disorder and schizophrenia, the research suggests.

In internalizing disorders like depression and anxiety, variants in genes that control non-neuronal cells called oligodendrocytes, were common. These specialized cells help maintain and protect the brain’s wiring infrastructure.

The findings suggest that some shared genetic factors play a role very early in brain development during the fetal stages of life, while others could have a greater influence later in adult life. This insight could help to create a more biological way of understanding psychiatric conditions and lead to new treatment strategies, the authors said.

According to one 2018 review, more than half of people diagnosed with one psychiatric disorder will be diagnosed with a second or third in their lifetime. About 41% will meet the criteria for four or more.

Grotzinger said it is too early to begin combining diagnoses based on the findings. But as researchers work to update the Diagnostic and Statistical Manual of Mental Disorders (DSM), the guiding handbook for the field of psychology, he hopes the new study will be considered.

“By identifying what is shared across these disorders, we can hopefully come up with strategies to target them in a different way that doesn’t require four separate pills or four separate psychotherapy interventions.”

Journal

Nature

DOI

10.1038/s41586-025-09820-3

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Mapping the genetic landscape across 14 psychiatric disorders

Article Publication Date

10-Dec-2025

New window insulation blocks heat, but not your view

University of Colorado at Boulder

Seeing clearly — image:
Abram Fluckiger holds up a sample panel square that has five sandwiched layers of a new material nearly transparent insulation material called MOCHI, which was designed buy CU Boulder researchers in physics professor Ivan Smalyukh’s lab.
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Credit: Photo by Glenn J. Asakawa/CU Boulder

Physicists at the University of Colorado Boulder have designed a new material for insulating windows that could improve the energy efficiency of buildings worldwide—and it works a bit like a high-tech version of Bubble Wrap.

The team’s material, called Mesoporous Optically Clear Heat Insulator, or MOCHI, comes in large slabs or thin sheets that can be applied to the inside of any window. So far, the team only makes the material in the lab, and it’s not available for consumers. But the researchers say MOCHI is long-lasting and is almost completely transparent.

That means it won’t disrupt your view, unlike many insulating materials on the market today.

“To block heat exchange, you can put a lot of insulation in your walls, but windows need to be transparent,” said Ivan Smalyukh, senior author of the study and a professor of physics at CU Boulder. “Finding insulators that are transparent is really challenging.”

He and his colleagues will publish their results Dec. 11 in the journal Science.

Buildings, from single-family homes to office skyscrapers, consume about 40% of all energy generated worldwide. They also leak, losing heat to the outdoors on cold days and absorbing heat when the temperature rises.

Smalyukh and his colleagues aim to slow down that exchange.

The group’s MOCHI material is a silicone gel with a twist: The gel traps air through a network of tiny pores that are many times thinner than the width of a human hair. Those tiny air bubbles are so good at blocking heat that you can use a MOCHI sheet just 5 millimeters thick to hold a flame in the palm of your hand.

“No matter what the temperatures are outside, we want people to be able to have comfortable temperatures inside without having to waste energy,” said Smalyukh, a fellow at the Renewable And Sustainable Energy Institute (RASEI) at CU Boulder.

Bubble magic

Smalyukh said the secret to MOCHI comes down to precisely controlling those pockets of air.

The team’s new invention is similar to aerogels, a class of insulating material that is in widespread use today. (NASA uses aerogels inside its Mars rovers to keep electronics warm).

Like MOCHI, aerogels trap countless pockets of air. But those bubbles tend to be distributed randomly throughout aerogels and often reflect light rather than let it pass through. As a result, these materials often look cloudy, which is why they’re sometimes called “frozen smoke.”

In the new research, Smalyukh and his colleagues wanted to take a different approach to insulation.

To make MOCHI, the group mixes a special type of molecule known as surfactants into a liquid solution. These molecules natural clump together to form thin threads in a process not unlike how oil and vinegar separate in salad dressing. Next, molecules of silicone in the same solution begin to stick to the outside of those threads.

Through a series of steps, the researchers then replace the clumps of detergent molecules with air. That leaves silicone surrounding a network of incredibly small pipes filled with air, which Smalyukh compares to a “plumber’s nightmare.”

In all, air makes up more than 90% of the volume of the MOCHI material.

Trapping heat

Smalyukh said that heat passes through a gas in a process something like a game of pool: Heat energizes molecules and atoms in the gas, which then bang into other molecules and atoms, transferring the energy.

The bubbles in MOCHI material are so small, however, that the gases inside can’t bang into each other, effectively keeping heat from flowing through.

“The molecules don’t have a chance to collide freely with each other and exchange energy,” Smalyukh said. “Instead, they bump into the walls of the pores.”

At the same time, the MOCHI material only reflects about .2% of incoming light.

The researchers see a lot of uses for this clear-but-insulating material. Engineers could design a device that uses MOCHI to trap the heat from sunlight, converting it into cheap and sustainable energy.

“Even when it’s a somewhat cloudy day, you could still harness a lot of energy and then use it to heat your water and your building interior,” Smalyukh said.

You probably won’t see these products on the market soon. Currently, the team relies on a time-intensive process to produce MOCHI in the lab. But Smalyukh believes the manufacturing process can be streamlined. The ingredients his team uses to make MOCHI are also relatively inexpensive, which the physicist said bodes well for turning this material into a commercial product.

For now, the future for MOCHI, like the view through a window coated in this insulating material, looks bright.

Co-authors of the new study include Amit Bhardwaj, Blaise Fleury, Eldo Abraham and Taewoo Lee, postdoctoral research associates in the Department of Physics at CU Boulder. Bohdan Senyuk, Jan Bart ten Hove and Vladyslav Cherpak, former postdoctoral researchers at CU Boulder, also served as co-authors.

Shakshi Bhardwaj holds up blocks in different sizes of a new material nearly transparent insulation material called MOCHI, which was designed buy CU Boulder researchers in physics professor Ivan Smalyukh’s lab.