Rare cosmic neutrino traced to star-shredding black hole

doi:10.1126/science.371.6532.872

GSTDTAP > 气候变化

DOI	10.1126/science.371.6532.872
	Rare cosmic neutrino traced to star-shredding black hole
	Daniel Clery
	2021-02-26
发表期刊	Science
出版年	2021
英文摘要	Neutrinos are everywhere, streaming through your body by the trillions every second. But the chargeless, nearly massless particles are notoriously hard to pin down, especially the rare high-energy ones from deep space. Only about a dozen cosmic neutrinos are detected annually, and only one had been linked to a source in the sky. Now, IceCube, the kilometer-wide neutrino detector nestled deep beneath the South Pole, has traced another one to its birthplace: a supermassive black hole tearing a star to pieces in a galaxy 750 million light-years away. “It's a very exciting story if this is correct,” says Tsvi Piran, a theorist at the Hebrew University of Jerusalem. The discovery suggests these rare tidal disruption events (TDEs) could be a major source of high-energy neutrinos and cosmic rays—other deep-space visitors whose origins have also been a mystery. The only way to detect neutrinos is to wait for one to hit an atomic nucleus. The result is a shower of debris particles and a flash of light. The collisions are rare, however, so researchers need a huge volume of matter to detect them. IceCube uses 1 cubic kilometer of Antarctic ice, threaded with photon detectors. From the arrival time and brightness of the flash at each detector, researchers can calculate a neutrino's direction and whether its source is nearby or in deep space. In 2017, IceCube connected the first deep-space neutrino to a known source: a superbright galaxy known as a blazar. Blazars contain voracious supermassive black holes, which suck in matter and are thought to spurt out a jet of particles. On 1 October 2019, a flash in the detector revealed another likely deep-space candidate. IceCube researchers sent out an alert so astronomers could scan the sky in the direction of the arriving neutrino. A California telescope, the Zwicky Transient Facility, swung into action and found that the apparent source was a known TDE, the team reported this week in Nature Astronomy . “When we saw it could be a TDE, we immediately went ‘Wow!’” says lead author Robert Stein of the DESY particle physics laboratory in Germany. Based on less than 100 observed TDEs, researchers believe they occur when the gravity of a supermassive black hole rips up a star that has strayed too close. Half the mass is pulled into a disk around the black hole and the rest arcs outward in a long streamer. The new result suggests TDEs also produce a short-lived particle jet, like a blazar burp. With two cosmic neutrinos now traced to them, jets are emerging as a primary explanation for deep-space neutrinos, edging ahead of neutron stars and stellar explosions. Jets could produce neutrinos much as particle physicists do on Earth: with a high-energy beam of protons that slams into surrounding material, says co-author Suvi Gezari of the Space Telescope Science Institute. “For TDEs to emerge as a likely site for neutrino production is very exciting,” she says. They might also help explain the source of ultra–high-energy cosmic rays, particles like protons that zip across the cosmos and bombard Earth's atmosphere daily. Making neutrinos requires accelerating protons to high energy, Piran says, so TDEs could be producing the cosmic rays at the same time. IceCube's pointing ability is poor, so Stein concedes the apparent match between the neutrino and the TDE could be a coincidence. “We will have to wait and see if there are additional events,” he says.
领域	气候变化 ; 资源环境
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文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/315908
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Daniel Clery. Rare cosmic neutrino traced to star-shredding black hole[J]. Science,2021.
APA	Daniel Clery.(2021).Rare cosmic neutrino traced to star-shredding black hole.Science.
MLA	Daniel Clery."Rare cosmic neutrino traced to star-shredding black hole".Science (2021).