Tyler O'Neal, Staff Editor GOVERNMENT

CCRG's new study suggests 'Pac-Man-like' mergers could explain massive, spinning black holes

RIT Associate Professor Richard O'Shaughnessy contributes to study in Physical Review Letters

Scientists have reported detecting gravitational waves from 10 black hole mergers to date, but they are still trying to explain the origins of those mergers. The largest merger detected so far seems to have defied previous models because it has a higher spin and mass than the range thought possible. A group of researchers, including Rochester Institute of Technology Assistant Professor Richard O'Shaughnessy, has created simulations that could explain how the merger happened.

In a new paper published in Physical Review Letters, the researchers suggest that such large mergers could happen just outside supermassive black holes at the center of active galactic nuclei. Gas, stars, dust and black holes become caught in a region surrounding supermassive black holes known as the accretion disk. The researchers suggest that as black holes circle around in the accretion disk, they eventually collide and merge to form a bigger black hole, which continues to devour smaller black holes, becoming increasingly large in what O'Shaughnessy calls "Pac-Man-like" behavior. CAPTION This is a simulation of an accretion disk surrounding a supermassive black hole. CREDIT Scott C. Noble{module INSIDE STORY}

"This is a very tantalizing prospect for those of us who work in this field," said O'Shaughnessy, a member of RIT's Center for Computational Relativity and Gravitation (CCRG). "It offers a natural way to explain high mass, high spin binary black hole mergers and to produce binaries in parts of parameter space that the other models cannot populate. There is no way to get certain types of black holes out of these other formation channels."

As the LIGO and Virgo collaboration continue to hunt for gravitational waves, O'Shaughnessy and his fellow researchers hope to find signatures of large, spinning black holes that could help confirm their models. If their assumptions are correct, it could help us better understand how the cosmic web of galaxies assembles.

"This could be a unique way of probing the physics around these supermassive black holes in a way that could not be probed in any other way," said O'Shaughnessy. "It offers unique insight into how the centers of galaxies grow, which is, of course, essential to understanding how galaxies as a whole grow, which explains most of the structure in the universe."

Johns Hopkins' models of the sounds of mosquito mating rituals could lead to quieter drones

Tyler O'Neal, Staff Editor GOVERNMENT

The research could also lead to a nontoxic method using sound to diminish mosquito breeding

Mosquitoes flap their wings not just to stay aloft but for two other critical purposes: to generate sound and to point that buzz in the direction of a potential mate, researchers at Johns Hopkins University have discovered.

Their findings of the aerodynamics of mosquito wings could have implications for building quieter drones and for devising nontoxic methods to trap and exterminate the pests.

In a research paper published in Bioinspiration and Biomimetics, a team from the university's Whiting School of Engineering, Rajat Mittal, a mechanical engineering professor, and Jung-Hee Seo, an associate research professor, explain the aerodynamics and acoustics of the mosquito mating ritual through supercomputer modeling.

"The same wings that are producing sound are also essential for them to fly," said Mittal, an expert in computational fluid dynamics. "They somehow have to do both at the same time. And they're effective at it. That's why we have so much malaria and other mosquito-borne diseases." Complex streamlines generated by the flapping wing of a mosquito in flight. Mosquitoes flap their wings not just to stay aloft but for two other critical purposes: to generate sound and to point that buzz in the direction of a potential mate, researchers at Johns Hopkins University have discovered.{module INSIDE STORY}

His team's research shows that "everything about mosquitoes seems perfectly adapted for accomplishing this sound-based communication."

"Thus," the paper states, "understanding the strategies and adaptations employed by insects such as mosquitoes to control their aeroacoustic noise could eventually provide insights into the development of quiet drones and other bioinspired micro-aerial vehicles."

In addition to devising quieter rotors for drones, Mittal said the findings will likely inform research into how sound can be used to interrupt the mating ritual. That could result in non-toxic methods to disrupt breeding and diminish mosquito populations.

"We continue to pursue that side of the research," he said. "At the right frequency, the mosquitoes have a hard time flying and can't complete their mating ritual."

With a high-frequency buzzing sound, the male mosquito attempts to connect with the low-frequency hum of a female. To do so, the team found the mosquito must flap its long, slender wings at high frequencies while also rotating them rapidly at the end of each stroke.

Yes, that annoying drill-like shrill that precedes a female's bite is also a vibrating serenade to a male mosquito's antennae.

Unlike other flying insects their size, Mittal said mosquitoes have adapted their anatomy and flight physiology to solve the "complex multifactorial problem" of trying to fly and flirt at the same time.

"The wing tones, as well as the aerodynamic forces for flight, are highly directional and mosquitoes need to simultaneously control both for the successful completion of a mate-chase," the paper reports.

The quick rotation of the wings "generate additional lift force" to keep them aloft, according to the research. But this same rotation also aids in directing the "wing tone" in a forward direction, which is important for chasing potential mates.

"If I'm talking to you and I turn my back, you'll have a hard time hearing me," Mittal explained. "They have to be able to direct their sounds properly."

The speedy flapping and truncated range, or amplitude, is far faster and shorter than similarly-sized winged insects such as fruit flies. That's why mosquitoes, unlike fruit flies, possess a "wing tone buzz" that is "particularly annoying to humans," according to the paper.

The "long and slender wing is perfect for making sounds," Mittal said. "Fruit flies, which are similar in size to mosquitoes, have short and stubby wings. Furthermore, mosquitoes are flapping at much higher frequencies than fruit flies. There is a reason for this. Higher frequencies are better at producing sounds."

Russian scientists discover new high-temperature superconductor

Tyler O'Neal, Staff Editor GOVERNMENT

A group of scientists led by Artem Oganov of Skoltech and the Moscow Institute of Physics and Technology and Ivan Troyan of the Institute of Crystallography of RAS has succeeded in synthesizing thorium decahydride (ThH10), a new superconducting material with the very high critical temperature of 161 kelvins. The results of their study, supported by a Russian Science Foundation grant, were published in the journal Materials Today.

A truly remarkable property of quantum materials, superconductivity is the complete loss of electrical resistance under quite specific, and sometimes very harsh, conditions. Despite the tremendous potential for quantum supercomputers and high-sensitivity detectors, the application of superconductors is hindered by the fact that their valuable properties typically manifest themselves at very low temperatures or extremely high pressures.

Until recently, the list of superconductors was topped by a mercury-containing cuprate, which becomes superconducting at 135 kelvins, or −138 degrees Celsius. This year, lanthanum decahydride, LaH10, set a new record of −13 C, which is very close to room temperature. Unfortunately, that superconductor requires pressures approaching 2 million atmospheres, which can hardly be maintained in real-life applications. Scientists, therefore, continue their quest for a superconductor that retains its properties at standard conditions. Figure 1. Crystal structure of thorium decahydride, ThH10. {module INSIDE STORY}

In 2018, Alexander Kvashnin, a researcher at Oganov's lab, predicted a new material -- thorium polyhydride, or ThH10 (fig. 1) -- with a critical temperature of −32 C, stable under 1 million atmospheres. In a recent study, researchers from Skoltech, MIPT, the Institute of Crystallography and Lebedev Institute of Physics of the Russian Academy of Sciences (RAS) have successfully obtained ThH10 and studied its transport properties and superconductivity.

The team's findings corroborated the theoretical predictions, proving that ThH10 exists at pressures above 0.85 million atmospheres and exhibits amazing high-temperature superconductivity. The scientists could only determine the critical temperature at 0.7 million atmospheres and found it to be −112 C, which is consistent with the theoretical prediction for that pressure value. This makes ThH10 one of the record-breaking high-temperature superconductors.

"Modern theory, and in particular, the USPEX method developed by myself and my students, yet again displayed their amazing predictive power," said Skoltech and MIPT Professor Artem Oganov, who co-directed the study. "ThH10 pushes the boundaries of classical chemistry and possesses unique properties that were predicted theoretically and recently confirmed by experiment. Most notably, the experimental results obtained by Ivan Troyan's lab are of very high quality."

"We discovered that superconductivity predicted in theory does exist at −112 C and 0.7 million atmospheres," study co-director Ivan Troyan added. "Given the strong consistency between theory and experiment, it would be interesting to check whether ThH10 will show superconductivity at up to −30 C...−40 C and lower pressures as predicted."

"Thorium hydride is just one of the elements in a large and rapidly growing class of hydride superconductors," said the first author of the study, Skoltech PhD student Dmitry Semenok. "I believe that in the coming years, hydride superconductivity will expand beyond the cryogenic range to find application in the design of electronic devices."