A lot of the time, when someone mentions the University of Nevada Las Vegas, they’re speaking of its renowned School of Hospitality, its fast-growing medical school or its Jerry Tarkanian-era men’s basketball teams. But UNLV is also one of the nation’s top research universities, awarded an R1 classification (“very high research activity”) from the Carnegie Classification of Institutions of Higher Education. Join the Weekly as we peek into the laboratories where world-changing scientific research is ongoing.

Understanding black holes

An astrophysicist of 30 years, Bing Zhang sees his job a bit differently than most.

“Our job is like a detective’s job,” says Zhang, a distinguished professor at UNLV, who also leads the Nevada Center for Astrophysics. “What we get are some fingerprints, footprints, occasionally some smoking guns, and then you try to figure out the crime scene. It’s a lot of fun.”

Recently, Zhang and a team of international scientists observed the jet activity of a black hole, one of the universe’s most magnetically powerful entities. With a solar mass three to more than 10 times that of the sun, a stellar black hole has the gravitational strength to swirl around the fabric of time and space, and eat material from nearby stars. As star material gets sucked into the orbit of the black hole, an extremely hot accretion disc forms, and the black hole unleashes a jet of plasma, purging itself of its stellar leftovers at nearly the speed of light.

“The jet is very powerful,” Zhang says. “If there is a star along the jet axis and it’s close enough, it would be destroyed or pushed away.”

Using China’s Five-hundred-meter Aperture Spherical Telescope (FAST)—a highly sensitive machine located in a natural depression in that country’s southwest region—scientists detected a quasi-periodic oscillation (fluctuation in radio signal) never observed before in the jet. Every 0.2 seconds, the signal would modulate, suggesting to Zhang that changes within the jet were produced by a misalignment between the jet direction and the black hole’s rapidly spinning axis. This observation, published in Nature this summer, highlights a compelling new feature for black holes.

Fast radio bursts (FRBs) have been another area of study and discovery for Zhang. First detected in 2007, these deep-space explosions last only milliseconds and were thought to exist outside of our galaxy exclusively. In 2020, the first FRB in our Milky Way was detected.

“It was super, super bright,” Zhang says. “That one was a million times brighter than the others because it was nearby, and so because that happened in our Milky Way galaxy, we were able to figure out where it came from.”

In one of Science’s 2020 Top 10 Breakthroughs of the Year, it was determined that magnetars—exceptionally strong and compact neutron stars that are the size of a city— had produced the Milky Way’s FRB.

Zhang and a team of astronomers wasted little time using FAST again to monitor the same magnetar from 2020 after a larger burst. Together, they discovered that magnetars were responsible for two emission modes seen in space: They could create intensely bright bursts at random or faint pulses during narrow “phase window” periods, and that happened within different regions of the magnetar’s magnetosphere, Zhang says.

Those findings, published in Science Advances in 2023, have advanced our knowledge of magnetars and the signals they’re capable of sending. -Amber Sampson

Discovering a new way planets can form

The secret to giant planet formations like Jupiter is quite literally written in the stars.

“By studying these young stars, we will be able to understand how our solar system formed billions of years ago,” says Zhaohuan Zhu, an associate professor in the department of physics and astronomy at UNLV.

In the galaxy, there are molecular clouds full of interstellar dust and hydrogen. As a cloud grows more dense, it collapses under its own gravity. The material at the cloud’s core then heats up, eventually becoming a star.

“Our universe is continuously doing this,” Zhu says. “Young stars form from a cloud, the stars will evolve, stars will explode and then disperse all the gas back into the interstellar medium and have a new generation of stars born from these clouds. Stars have their own life cycle.”

So do planets. Not all cloud matter lands in the star at collapse, Zhu says. Dust grains and gas might gather around it to form a spinning protoplanetary disc. The leftover matter continues to coagulate, eventually snowballing into planet size. That process, known as core accretion, is the most common form of planet creation.

But in 2012, Zhu predicted that if researchers utilized Chile’s Atacama Large Millimeter/submillimeter Array (ALMA) telescope, they could eventually detect a previously unseen stage of a protoplanetary disc growing so massive, it becomes unstable against gravity.

“The disc now becomes subject to something called gravitational instability,” Zhu says. “It starts to form these spirals in the discs, and sometimes these spirals fragment and clump. These clumps could eventually form giant planets.”

At the time of his prediction, Zhu says the ALMA didn’t have a high enough resolution to see these clumps. But Chilean astronomers later reached out to him after discovering the clumps around a young star roughly 5,000 light years away while deploying ALMA and the European Southern Observatory’s Very Large Telescope (VLT).

This is the first observation of clump formation from gravitational instability of this scale. And Zhu says new radio telescopes in development, such as the Next Generation Very Large Array, will offer even greater resolution to capture such remarkable proof of planet origins. –AS

Studying the Red Planet’s future potential

Was there life on Mars? UNLV geoscientists Elisabeth “Libby” Hausrath and Arya Udry are working with NASA to find out.

The professors were selected to join NASA’s Mars 2020 Mission, a project that has given them a rare look at the Red Planet—both its geology and its potentially habitable past. NASA’s Perseverance rover has been on Mars since 2021, examining native rocks and soil samples in preparation for an eventual human landing.

“In order to really make a definitive statement, we would need to have samples in hand to examine potential evidence of past life, but life leaves organic molecules,” says Hausrath, an aqueous geochemist and astrobiologist. “It leaves changes in the isotopes, in trace metals, in the morphology. All of those can be potential bio signatures of past life.”

The evidence of water on Mars is especially exciting to her. “I’m really looking forward to when we arrive outside the crater, because this is a completely different environment, one that has a lot of aqueously altered minerals,” Hausrath says. “They look, from orbit, like potential soils on Earth. So this is a really exciting change that we’re approaching in terms of the rover.”

Udry, who studies planetary magmatic rocks and martian meteorites, was amazed to find lava flows in the exploration’s first year via rover images, and magma that had crystallized into the planet’s crust.

“What I love is seeing some of the images I was able to process, being one of the first humans to ever see this part of this planet,” she says. “That’s so cool, especially when the rocks are very interesting to me. Us geologists have our favorite rocks.”

Currently, Perseverance is packaging rock samples to be shipped back, and a helicopter will be launched to Mars to retrieve them. Samples are expected to return to Earth around 2033. Until then, the scientists are studying the mineral chemistry of found rocks and determining how “minerals and micro organisms can interact to preserve potential bio signatures,” Hausrath says.

As the only university besides MIT with two Participating Scientists selected for this project, UNLV is leading by example. “It’s a real privilege to be on the mission,” Hausrath says. –AS

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