TIGERISS space station’s new experiment will probe the origins of the elements

UNIVERSITY PARK, Pennsylvania — A team of physicists including Penn State researchers is developing a new experiment envisioned for the International Space Station (ISS) as part of NASA’s Astrophysics Pioneers program. The Pioneers program, which began in 2020, supports small-scale astrophysics missions that enable innovative investigations of cosmic phenomena and has a total cost cap of $20 million.

The new experiment, the Trans-Iron Galactic Element Recorder for the International Space Station (TIGERISS), will be designed to measure the abundance of ultra-heavy galactic cosmic rays – high-energy particles that have been rapidly accelerated by the violent collapse of a star, called a supernova, or other cosmic events. By measuring the amount of each atomic element in cosmic rays, scientists gain information about their origin.

TIGERISS is an evolution of the balloon-mounted instruments TIGER and SuperTIGER, developed by scientists from the University of Washington, NASA Goddard, Caltech and others over the past three decades, with the Penn State contingent invited to participate in the next phase of the scientific program.

“We are thrilled to join old friends in the cosmic-ray balloon community to investigate rare but fascinating ultra-heavy cosmic rays,” said Stéphane Coutu, Professor of Physics, Astronomy and Astrophysics and Principal Investigator. from Penn State for the TIGERISS program. . “The origin of heavy elements in the periodic table, such as gold that you might wear around your neck or finger, ultimately points to intriguing, violent, and exotic astrophysical phenomena.”

Other members of the Penn State team include physics research professors Samuel Isaac Mognet and Tyler Anderson. Together, the Penn State team has decades of experience successfully developing sensing elements for space instruments flown on high-altitude balloons or to the ISS where TIGERISS will be deployed in a few years.

Origins of heavy elements

All stars exist in a delicate balance; they must produce enough energy to counteract their own gravity. This energy comes from the fusion of elements into heavier ones, including carbon, nitrogen and oxygen, which are important for life as we know it. But once a giant star tries to fuse iron atoms together, the reaction doesn’t generate enough power to fight the pressure, and the star collapses. During a violent stellar collapse known as a supernova, shock waves ejected heavy elements that had been manufactured in the star’s core. Swept up and mixed with interstellar matter, these heavy elements are accelerated almost to the speed of light in the form of “cosmic rays”.

“We can find signatures from different sources in our cosmic-ray elemental abundance measurements,” said Brian Rauch, associate research professor of physics at Washington University in St. Louis and principal investigator of the TIGERISS program. “We do this using our instrument, TIGERISS, and nucleosynthetic production models. With these tools and the benefit of other multi-messenger astronomical observations, we can construct a much more convincing picture of the origins of heavy elements.

But the collapse of a supernova is not the only way heavy atoms can form. When a super dense remnant of a supernova called a neutron star collides with another neutron star, this cataclysmic event can also create heavy elements.

To what extent do supernova and neutron star mergers each contribute to the manufacture of heavy elements? “That’s the most interesting question we can hope to address,” Rauch said.

TIGERISS won’t be able to report particular collisions of supernovae or neutron stars, but it will add context about the behavior of fast-moving heavy elements.

Other observatories directly observe supernovae and neutron star collisions through other cosmic messengers, such as gamma rays, neutrinos, and gravitational waves, which result from such violent cosmic events and contain additional information. on their sources. Coutu and others at Penn State developed the Astrophysical Multimessenger Observatory Network (AMON) to enable new astrophysical discoveries by combining observations of multiple types of messengers from operating telescopes and astrophysical particle observatories. of the whole world.

“TIGERISS will add to the new multimessenger paradigm in astrophysics,” Coutu said.

TIGERISS will also be able to provide information on the general abundance of cosmic rays, which pose a hazard to astronauts.

Leave a Reply