Nobel Physics Winner Backed Operations of Mendoza Observatory
The Royal Swedish Academy of Sciences distinguished on Tuesday with the Nobel Prize in Physics Belgian researcher Francis Halzen, professor at the University of Wisconsin-Madison and director of the IceCube Neutrino Observatory, aged 82. The news had a direct impact in Mendoza: Halzen was part in 2023 of the international committee of experts that evaluated the operations of the Pierre Auger Observatory, located in Malargüe, and endorsed its operational continuity for an additional decade starting 2025.
The link between both scientific projects is not coincidental. According to researcher Nicolás Leal, member of the team at the Pierre Auger Observatory, in the program Opinión on LV10, the two ventures are “cousins” within the field of ultra-high-energy particle astrophysics. Both detectors, despite being located at opposite ends of the planet—one in Antarctic ice and another in the Patagonian steppe—share scientific objectives and physical detection principles.
Francis Halzen, Nobel Prize in Physics 2026.
A key audit for the observatory's continuity
The link between Halzen and the Mendoza project dates back to a visit made in 2023, when the Belgian physicist arrived in Malargüe as part of an external evaluation committee tasked with reviewing the technical and scientific status of the Pierre Auger Observatory. The instance proved crucial: the renewal of funding and the research center's work plan for a new ten-year period depended on that evaluation.
“He was conducting a kind of audit alongside other specialists from external projects”, Leal recounted about Halzen's time in the province. During that week, described by the researcher himself as “very intense”, the committee toured the observatory facilities, met with the local technical team, and analyzed in detail the project's future development plans.
"He gave a lecture at the Malargüe Convention Center and was in the field visiting the detectors. Together with other specialists, they said the observatory had potential to continue taking data for 10 more years"
Leal added details about that working visit: “They toured all the facilities, we explained their operation and future plans to them. They conducted an evaluation and it was very positive”. The result of that audit allowed the Pierre Auger Observatory to continue operations from 2025 onward with a guaranteed work horizon through the middle of the next decade.
Two “cousin” observatories in the search for extragalactic particles
Both the Pierre Auger Observatory and IceCube, which Halzen directs from Antarctica, share the same scientific mission: to detect ultra-high-energy particles from extragalactic sources to understand violent astrophysical phenomena, such as supernovae explosions or active galactic nuclei activity.
“Both aim to detect ultra-high-energy phenomena from extragalactic sources. Both use similar detection systems to understand the origin of the particles because of their extreme energy and ultimately to understand what we can do with this knowledge”, Leal explained about the scientific relationship between both projects.
Team from the Malargüe Observatory that worked with Nobel Prize winner in Physics, Francis Halzen.
The substantial difference between them lies in the type of particle they seek and the physical medium used to detect them. IceCube, installed beneath Antarctic ice, is designed for neutrino detection, subatomic particles that barely interact with matter and which, as Leal explained, have “a very straight trajectory toward the source”, allowing precise identification of the cosmic origin of each detected event, although their capture proves technically complex.
The Pierre Auger Observatory, meanwhile, uses water instead of ice as the detection medium. “IceCube uses an ice cube so that the neutrino can impact the ice, causing particles (photons) to be emitted and detected by light sensors. In our observatory we use water”, the researcher clarified. In both cases, the physical principle that enables detection is the same: the so-called Cherenkov Radiation, an effect that converts the kinetic energy of a high-speed particle into light energy. “We see a flash of light”, Leal summarized.
A complementary window for observing the universe
According to the Pierre Auger researcher, this type of detection constitutes a fundamental complement to other traditional forms of astronomical observation. “It complements other forms of outer space research. It is an astrophysics that allows us to ‘visualize’ sources of particle emission without the need to see them optically with a telescope”, he noted.
The mechanism allows identification, from the trace particles leave upon reaching Earth, of regions of the universe with greater activity in generating these high-energy phenomena. “We are seeing sources generating high-energy particles through the trace they leave when arriving at Earth. This way you can see hot zones where there is more particle production than others. You can distinguish zones that produce these particles, generally when there are violent astronomical events such as supernova generation”, Leal concluded.
The institutional impact of the distinction in Malargüe
For the team of researchers working at the Pierre Auger Observatory, the international recognition of Halzen transcended the strictly scientific realm. Leal noted that the news of the Nobel Prize generated among the Mendoza team a feeling of “joy”, partly because it reaffirms the prestige and seriousness of the evaluation process that in 2023 endorsed the continuation of the project based in the southern province.
The Pierre Auger Observatory, which for more than two decades has made Malargüe an international reference hub for the study of cosmic rays, will thus continue with its data-gathering program in the coming years, as part of an international network of observatories dedicated to uncovering the origin of some of the most energetic particles known in the universe.