14 DAY TRIAL // Detecting and analyzing elementary particles called neutrinos is an extremely complex and difficult task, and physicists need all the help they can get accomplishing it. Recently, they recruited none other than the Moon to aid them in their research.
Regions of distant space are suspected to be generating large amounts of weird, ultra-high-energy neutrinos, that pass right through solid materials such as Earth and the Moon, and then head out further into space.
Neutrinos, as their names imply, are particles without electrical charge, that rarely interact with regular matter. Like dark matter, this makes them incredibly hard to detect, even with specialized detectors.
As part of a new effort aimed at increasing the number of detected neutrinos, researchers decided to enlist the help of Earth's natural satellite for creating an innovative telescope system for the job.
The group used the Very Large Array (VLA) radio telescope – a facility operated by the US National Science Foundation (NSF) – as a base of operations for the research.
Special-purpose electronic equipment brought on-site was used together with the sensitive radio receivers recently installed on the observatory array as part of the Expanded VLA (EVLA) project.
The investigation was led by University of Iowa (UI) and the Naval Research Laboratory (NRL) expert Ted Jaeger, and UI colleagues Robert Mutel and Kenneth Gayley, officials at the National Radio Astronomy Observatory (NRAO) announce.
The first 200 hours of study the team conducted revealed no signs of the subatomic particles the researchers were looking for. This in itself will most likely force a rethinking of some of the theories seeking to explain how many such neutrinos travel through space, and also on how many are produced.
Ultra-high-energy neutrinos of the variety the team is looking for are believed to originate in the active cores of distant galaxies, which are powered by supermassive black holes.
Dark matter annihilation events, massive stellar explosions, tears in the space-time fabric, and interactions between cosmic rays and photons in the Cosmic Microwave Background (CMB) are also theoretical sources for these elementary particles.
While radio telescopes such as the VLA cannot detect neutrinos on their own, they can be used in other manners as well. The research team used the telescope to analyze the edge of the Moon.
The theory is that when neutrinos pass through the natural satellite, they cause brief bursts of radio waves, which can be picked up by the sensitive observations array.
“Our observations have set a new upper limit – the lowest yet – for the amount of the type of neutrinos we sought. This limit eliminates some models that proposed bursts of these neutrinos coming from the halo of the Milky Way Galaxy,” explains Mutel.
“Some of the techniques we developed for these observations can be adapted to the next generation of radio telescopes and assist in more-sensitive searches later,” the expert goes on to say.
“When we develop the ability to detect these particles, we will open a new window for observing the Universe and advancing our understanding of basic astrophysics,” he concludes.
Details of the new investigation and its outcomes are published in the December issue of the esteemed scientific journal Astroparticle Physics.