The long-awaited dawn of neutrino astronomy arrives
They weigh next to nothing, they move at more than 99 percent the speed of light and they have no electric charge. They can go straight through planets, usually without leaving a trace.
Detecting these subatomic particles, known as neutrinos, is difficult. But scientists are chasing them for their promise of revealing the distant universe in ways that light and other electromagnetic radiation cannot. A sensor, a single component from one of the few devices that can capture an occasional neutrino—the IceCube array buried in the ice of Antarctica—has traveled all the way to Columbus, Ohio.
There it helped show science reporters about how the new field of neutrino astronomy was recently born. It was on display Oct. 19-20 at the New Horizons in Science briefing Oct. 19-20, organized by the Council for the Advancement of Science Writing and hosted by Ohio State University as part of the ScienceWriters2014 conference.
New windows on the universe
“We now know that we actually have opened new windows on the universe,” said Francis Halzen, IceCube’s principal investigator, who won the Smithsonian American Ingenuity Award and gained recognition for neutrino astronomy. The IceCube Collaboration hopes that through improved statistics from the detector they will be able to test in the coming five years a wider variety of hypotheses about how high-energy neutrinos are spewed into the universe. “And of course, that’s what’s exciting about doing this.”
In a presentation at the meeting, John Beacom, professor of physics and astronomy at Ohio State University and one of the field’s pioneers, described the device he helped design to detect the elusive particle. While neutrinos from nearby objects such as the sun and nuclear reactors have been routinely detected for decades, recently the vast Ice Cube array under the South Pole convincingly measured the first ones from violent processes—such as collapsing stars—in distant galaxies.
The IceCube neutrino telescope has hundreds of such spherical optical sensor modules. Each detects light produced when neutrinos collide with atoms in the ice. The sensors are on cables strung up to two and a half kilometers down into the ice. They must be deep enough that the only light detected is from neutrino interactions, not from more ordinary phenomena such as cosmic rays.
The IceCube Research Center is chasing neutrinos that originated millions to billions of years ago.
A way to peer inside stars
Unlike photons of radio or light rays, and unlike subatomic particles, neutrinos are nearly oblivious to gravity or magnetic fields. So they can reach Earth directly from parts of the universe otherwise shielded from view. These include the core of the sun or of a supernova. For this reason, neutrinos may hold the answers to many scientific questions about the origins and nature of the Milky Way, gamma ray bursts, cosmic rays and the invisible “dark matter” that suffuses much of the universe and is gathered largely around and in galaxies.
Through Nov. 2013, 28 such high-energy “cosmological” neutrinos had been detected.
“In every second of your life, approximately one hundred trillion neutrinos pass through your eyes,” Beacom told the science writers. Among them, scientists now can say for sure, are many of these so-called cosmological neutrinos that are key to the new field of neutrino astronomy.
The neutrino astronomy project is still in its formative years, Beacom says, and more research needs to be done before any scientific questions can be answered. With IceCube’s detection of its first neutrinos from deep space, the project seems to be off to a good start.