Scientists come up with a mind-bending plan to search for dark matter and new physics near the Sun

The sun. Image: NASA via Getty Images

Physicists have proposed a mind-boggling space mission that could finally reveal the true nature of dark matter, an enigmatic substance considered one of science’s greatest unsolved mysteries, a new study reports.

Dark matter is about five times more abundant in the universe than the familiar matter that makes up stars, planets, and even our bodies, making it stand out as a fundamental component of the universe. But despite its abundance, dark matter has proven completely impenetrable to our instruments, and it has never been directly detected; we only know that it exists through indirect observations of its gravitational influence on luminous bodies, such as galaxy clusters.

Scientists have developed many sophisticated techniques to hook the first direct detection of dark matter, a step that could answer a host of open questions about our universe, but all have so far failed.

Now a team led by Yu-Dai Tsai, a physicist at the University of California at Irvine, has proposed a fascinating space mission that would use the most accurate clocks ever invented to search for dark matter that may be bound to the Sun. That way, the concept mission, which the team calls SpaceQ, could potentially discover “new physics” and “study many topics of fundamental physics,” according to a study published in natural astronomy In Monday.

“Dark matter is one of the most important mysteries in astronomy and cosmology, given its unknown and elusive nature,” Tsai said in an email to Motherboard. “If we could find dark matter and understand its properties, we could understand the evolution of our universe and better understand many astrophysical measurements, including the velocity distribution of these small-scale objects (from small galaxies to clusters of galaxies).”

“It will also be one of the most important breakthroughs in particle physics, as it is also one of the last remaining ingredients to our understanding of particle physics,” he added.

The SpaceQ mission concept is built around the incredible precision of what the team calls “quantum clocks,” a category that includes existing atomic clocks, which are ultra-precise instruments that use oscillations in atoms to telling the time, as well as molecular and nuclear clocks. which are currently in development and should be even more sensitive. In addition to telling the time, these clocks can measure incredibly subtle changes in atomic frequencies.

To that end, Tsai began thinking about the possibility of using these clocks to search for a hypothetical version of dark matter, known as ultralight dark matter (ULDM), which theories theorize could bind to the Sun in a structure called a dark matter halo. . A space mission to the Sun might be able to detect ULDM particles, assuming they exist, by measuring tiny changes in the frequencies of atomic transitions in quantum clocks that expose ULDM’s interactions with other forms of matter.

“We show that the projected sensitivity of space clocks for detecting a sun bound [dark matter] halo exceeds the range of earth clocks by orders of magnitude,” Tsai and colleagues said in the study.

“Currently, to our knowledge, this is the only proposal able to achieve these target sensitivities in our parameter space of interest,” they added.

Since 2020, Tsai has been developing the concept with study co-authors Marianna Safronova, an atomic physics expert at the University of Delaware, and Joshua Eby, a dark matter expert at the Kavli Institute for Physics and Mathematics in the universe.

“The solar probe mission would allow atomic clocks to study enhanced dark matter density near the Sun, and probe very interesting and motivated target models detailed in our paper,” Tsai noted. “Additionally, we can also test the variation of fundamental constants, with the change in gravitational potential, as we get closer to the Sun. This has been one of the main fundamental motivations in physics to develop precise clocks.

The trio were inspired, in part, by two pioneering NASA missions: the Deep Space Atomic Clock, a test of an unprecedented space navigation clock launched in 2019, and the Parker Solar Probe, which was launched in 2018 and has since come closer towards the Sun than any other mission. SpaceQ is a dazzling blend of these two pioneering missions that combines Parker’s solar-shave maneuvers with the sensitive atomic measurements of the Deep Space Clock.

“The Deep Space Atomic Clock (DSAC) is a technology that allows us to achieve space travel, and the Parker Solar Probe is an incredible mission for us to study the Sun,” Tsai said. “Both are existing, state-of-the-art technologies for practical purposes. It’s amazing to use them to study fundamental physics, let alone their combination.”

At this point, the mission is still just an idea, but it offers a new approach to searching for dark matter that could potentially be far more efficient than existing techniques. Moreover, on a purely gut level, how crazy would it be to search for dark matter – one of the largest missing links in the universe – around our Sun using a breaker probe? neck carrying ridiculously accurate clocks?

“A network of clocks in space and on Earth can study many fundamental topics of physics, including transient topological dark matter and multimessenger signatures of exotic particles,” the researchers concluded in the study. “In our consideration, if a signal were to be present, comparing ground and space clocks could help map the density of [dark matter] in the vicinity of the Earth to further constrain the limit [dark matter] script.”