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https://www.space.com/38937-china-monkey-king-satellite-dark-matter.html
China's Cosmic 'Monkey King' Satellite Looks for Dark Matter
By Charles Q. Choi, Space.com Contributor | November 29, 2017 05:33pm ET
An artist's illustration of China's Dark Matter Particle Explorer satellite — called "Wukong" after the fabled Sun Wukong, the Monkey King —is studying cosmic rays to help scientists understand the origins of dark matter.
Credit: China Academy of Sciences
By analyzing cosmic rays in space, China's "Monkey King" satellite is now helping pin down the identity of dark matter, a new study finds.
The Dark Matter Particle Explorer (DAMPE) satellite, launched in 2015, is China's first space observatory. DAMPE's aim is to help find the origins of dark matter — the mysterious, invisible substance that researchers suspect makes up about five-sixths of all matter in the universe.
DAMPE is nicknamed "Wukong" after Sun Wukong, the Monkey King, the mischievous, shape-shifting hero of the epic Chinese tale "Journey to the West." "Wu" means "understanding" and "kong" means "void," so Wukong can also mean "understanding the void" — hence, the name underscores DAMPE's mission to help scientists understand dark matter. [The Search for Dark Matter in Images]
DAMPE is specifically designed to detect the highest-energy beams of light, known as gamma rays, as well as cosmic rays. The latter are particles that zip through outer space with extraordinarily high amounts of energy. Many cosmic rays are composed of the nuclei of atoms, but some are electrons, while others are the positively charged antimatter counterparts of electrons known as positrons.
Some models of dark matter suggest that it can break down into cosmic rays — specifically, pairs of electrons and positrons. When these positrons hit electrons, they annihilate each other, releasing gamma rays. However, there are many other potential sources of cosmic rays and gamma rays, such as pulsars — which are rapidly whirling collapsed stars — or supernova remnants, which are debris from stars that died in catastrophic explosions. DAMPE measures the amount of energy in gamma rays and cosmic rays to help shed light on what their sources are.
Previous balloon- or space-borne experiments analyzing cosmic rays only directly measured energies up to 2 trillion electron volts, while ground-based telescope arrays could indirectly measure energies up to about 5 trillion electron volts. (One trillion electron volts is about the amount of kinetic energy packed by a flying mosquito.)
In comparison, DAMPE can detect cosmic-ray electrons and positrons with energies of about 10 trillion electron volts. "It extends the direct measurement of cosmic-ray electrons and positrons to the highest energies so far," Jordan Goodman, a particle astrophysicist at the University of Maryland, who did not take part in the DAMPE research, told Space.com. [100 Years of Cosmic Rays: The Discovery Explained]
So far, DAMPE has detected more than 3.5 billion cosmic rays, the most energetic of which exceed 100 trillion electron volts. DAMPE is expected to detect more than 10 billion cosmic rays over its projected lifetime of more than five years.
Notably, DAMPE found a "spectral break" — a dip in the number of cosmic-ray electrons and positrons — at about 900 billion electron volts. "No one is sure why there is a break," Goodman said.
Previously, the five-telescope H.E.S.S. array in Namibia and the CALorimetric Electron Telescope on the International Space Station had seen signs of this spectral break, but the Fermi Gamma-ray Space Telescope had not.
"Our measurements have clarified the behavior of the electron and positron spectrum at trillion-electron-volt energies," study co-author Yi-Zhong Fan, a particle astrophysicist at the Chinese Academy of Sciences in Nanjing, told Space.com. "The first results of DAMPE demonstrate its ability to explore new astrophysics."
Dark matter particles could explain this spectral break if the masses of those particles lie right below 900 billion electron volts, Goodman said. (Energy is equivalent to mass, as Einstein's famous equation E = mc^2 proved.) As such, these findings challenge models that suggest dark matter particles might have different masses.
On the other hand, this spectral break might be due to cosmic rays from pulsars or supernova remnants somehow cooling on their way through space, Fan said. "Either way, we are now getting solid data against which any model must be tested," Goodman said.
The scientists detailed their findings in the Nov. 30 issue of the journal Nature.
Follow Charles Q. Choi on Twitter @cqchoi. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.
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Author Bio
Charles Q. Choi, Space.com Contributor
Charles Q. Choi is a contributing writer for Space.com and Live Science. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica.
Charles Q. Choi, Space.com Contributo
http://usa.chinadaily.com.cn/china/2017-11/30/content_35129575.htm
New space telescope may help crack the secrets of dark matter
By Zhang Zhihao | China Daily | Updated: 2017-11-30 06:34
Illustration of the Wukong space telescope.[Photo provided to China Daily]
A Chinese space telescope has found a strange peak in high-energy cosmic ray electrons and positrons, which are highly energetic particles blazing across the universe at close to the speed of light. Scientists say they think such an anomaly can help crack the secrets of dark matter, the strangest ingredient in the universe.
The strange peak was picked up by the Dark Matter Particle Explorer, nicknamed Wukong, at around 1.4 trillion electronvolts, when the flux of cosmic ray electrons and positrons suddenly rose before collapsing.
"This phenomena is unexpected because no other stellar events behave like this at such high energy," said Fan Yizhong, deputy chief designer of Wukong's scientific application system.
"Our best guess is it could be due to a special astrophysical event, or some weird new particles," Fan said. "We will collect more data in this energy range to make sure this is not a fluke, so it is still too early say we found something groundbreaking."
The discovery was part of the first published scientific results of Wukong, which was named after the Monkey King in the classic novelJourney to the West. The results were published in the science journal Nature on Thursday.
Launched in December 2015, Wukong is China's first astronomical satellite and is tasked with finding dark matter, an invisible ingredient that makes up around 25 percent of the universe yet cannot interact with any known matter other than through gravity, said Chang Jin, the Wukong project's chief scientist.
"Many countries have spent billions of dollars over decades to find dark matter, yet we still know very little about it because we cannot observe it directly," he said. "However, we can observe the particles and energy released when dark matter particles interact and destroy each other."
Previously, there were three space detectors dedicated to finding dark matter - the AMS-02 spectrometer, and the Fermi and CALET space telescopes. Wukong is the newest and most advanced member of the family, and has superior precision in the trillion electronvolt energy range, Chang said.
Since its launch, Wukong has recorded over 3.5 billion cosmic ray events, with the highest energy levels exceeding 100 trillion electronvolts, more than 10 times the highest recorded energy level created by the Large Hadron Collider, the world's most powerful particle accelerator.
Wukong is expected to record more than 10 billion cosmic ray events during its lifetime, and it is likely to be operating well beyond its designed life span of three years, Chang said.
"In the Chinese novel, Wukong has a pair of magical eyes that can see through the devil's disguise," he said. "Similarly, we hope the Wukong satellite can open a new window in science discovery, and grant us the ability to see through the disguise of dark matter."
Bai Chunli, president of the Chinese Academy of Sciences, said the discovery of dark matter is the most cutting-edge of science projects and will fundamentally change how we view the universe, such as understanding how galaxies evolve.
A galaxy is a gravitationally bound system of billions of stars rotating around its center. But the strength of gravity becomes weaker as the distance between objects grows, hence stars at the edge of the galaxy should be flying off, like raindrops flinging off a spinning umbrella.
"But this is not the case, and galaxies continue to spin like a spiral disk without disintegrating," Bai said. "So there has to be something we cannot see that is holding the galaxy together. Dark matter is the prime suspect."
Ed Gerstner, Nature's scientific director for Chinese research, said the discovery is exciting despite all the uncertainties, and he will be looking forward to more results and collaboration with Chinese scientists.
"The most exciting phrase to hear in scientific discovery is not 'Eureka, I have found it', but rather 'Hmm that's weird'," Gerstner said. This is especially true for cutting-edge physics, such as the case of the discovery of the Higgs-boson elementary particle in 2013, he added.
"Chinese scientists have a long and proud history of groundbreaking contributions to high energy particle physics … and changing the way we see the universe," he said.
[email protected]
https://www.space.com/38937-china-monkey-king-satellite-dark-matter.html
China's Cosmic 'Monkey King' Satellite Looks for Dark Matter
By Charles Q. Choi, Space.com Contributor | November 29, 2017 05:33pm ET
- MORE
An artist's illustration of China's Dark Matter Particle Explorer satellite — called "Wukong" after the fabled Sun Wukong, the Monkey King —is studying cosmic rays to help scientists understand the origins of dark matter.
Credit: China Academy of Sciences
By analyzing cosmic rays in space, China's "Monkey King" satellite is now helping pin down the identity of dark matter, a new study finds.
The Dark Matter Particle Explorer (DAMPE) satellite, launched in 2015, is China's first space observatory. DAMPE's aim is to help find the origins of dark matter — the mysterious, invisible substance that researchers suspect makes up about five-sixths of all matter in the universe.
DAMPE is nicknamed "Wukong" after Sun Wukong, the Monkey King, the mischievous, shape-shifting hero of the epic Chinese tale "Journey to the West." "Wu" means "understanding" and "kong" means "void," so Wukong can also mean "understanding the void" — hence, the name underscores DAMPE's mission to help scientists understand dark matter. [The Search for Dark Matter in Images]
DAMPE is specifically designed to detect the highest-energy beams of light, known as gamma rays, as well as cosmic rays. The latter are particles that zip through outer space with extraordinarily high amounts of energy. Many cosmic rays are composed of the nuclei of atoms, but some are electrons, while others are the positively charged antimatter counterparts of electrons known as positrons.
Some models of dark matter suggest that it can break down into cosmic rays — specifically, pairs of electrons and positrons. When these positrons hit electrons, they annihilate each other, releasing gamma rays. However, there are many other potential sources of cosmic rays and gamma rays, such as pulsars — which are rapidly whirling collapsed stars — or supernova remnants, which are debris from stars that died in catastrophic explosions. DAMPE measures the amount of energy in gamma rays and cosmic rays to help shed light on what their sources are.
Previous balloon- or space-borne experiments analyzing cosmic rays only directly measured energies up to 2 trillion electron volts, while ground-based telescope arrays could indirectly measure energies up to about 5 trillion electron volts. (One trillion electron volts is about the amount of kinetic energy packed by a flying mosquito.)
In comparison, DAMPE can detect cosmic-ray electrons and positrons with energies of about 10 trillion electron volts. "It extends the direct measurement of cosmic-ray electrons and positrons to the highest energies so far," Jordan Goodman, a particle astrophysicist at the University of Maryland, who did not take part in the DAMPE research, told Space.com. [100 Years of Cosmic Rays: The Discovery Explained]
So far, DAMPE has detected more than 3.5 billion cosmic rays, the most energetic of which exceed 100 trillion electron volts. DAMPE is expected to detect more than 10 billion cosmic rays over its projected lifetime of more than five years.
Notably, DAMPE found a "spectral break" — a dip in the number of cosmic-ray electrons and positrons — at about 900 billion electron volts. "No one is sure why there is a break," Goodman said.
Previously, the five-telescope H.E.S.S. array in Namibia and the CALorimetric Electron Telescope on the International Space Station had seen signs of this spectral break, but the Fermi Gamma-ray Space Telescope had not.
"Our measurements have clarified the behavior of the electron and positron spectrum at trillion-electron-volt energies," study co-author Yi-Zhong Fan, a particle astrophysicist at the Chinese Academy of Sciences in Nanjing, told Space.com. "The first results of DAMPE demonstrate its ability to explore new astrophysics."
Dark matter particles could explain this spectral break if the masses of those particles lie right below 900 billion electron volts, Goodman said. (Energy is equivalent to mass, as Einstein's famous equation E = mc^2 proved.) As such, these findings challenge models that suggest dark matter particles might have different masses.
On the other hand, this spectral break might be due to cosmic rays from pulsars or supernova remnants somehow cooling on their way through space, Fan said. "Either way, we are now getting solid data against which any model must be tested," Goodman said.
The scientists detailed their findings in the Nov. 30 issue of the journal Nature.
Follow Charles Q. Choi on Twitter @cqchoi. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.
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Author Bio
Charles Q. Choi, Space.com Contributor
Charles Q. Choi is a contributing writer for Space.com and Live Science. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica.
Charles Q. Choi, Space.com Contributo
http://usa.chinadaily.com.cn/china/2017-11/30/content_35129575.htm
New space telescope may help crack the secrets of dark matter
By Zhang Zhihao | China Daily | Updated: 2017-11-30 06:34
Illustration of the Wukong space telescope.[Photo provided to China Daily]
A Chinese space telescope has found a strange peak in high-energy cosmic ray electrons and positrons, which are highly energetic particles blazing across the universe at close to the speed of light. Scientists say they think such an anomaly can help crack the secrets of dark matter, the strangest ingredient in the universe.
The strange peak was picked up by the Dark Matter Particle Explorer, nicknamed Wukong, at around 1.4 trillion electronvolts, when the flux of cosmic ray electrons and positrons suddenly rose before collapsing.
"This phenomena is unexpected because no other stellar events behave like this at such high energy," said Fan Yizhong, deputy chief designer of Wukong's scientific application system.
"Our best guess is it could be due to a special astrophysical event, or some weird new particles," Fan said. "We will collect more data in this energy range to make sure this is not a fluke, so it is still too early say we found something groundbreaking."
The discovery was part of the first published scientific results of Wukong, which was named after the Monkey King in the classic novelJourney to the West. The results were published in the science journal Nature on Thursday.
Launched in December 2015, Wukong is China's first astronomical satellite and is tasked with finding dark matter, an invisible ingredient that makes up around 25 percent of the universe yet cannot interact with any known matter other than through gravity, said Chang Jin, the Wukong project's chief scientist.
"Many countries have spent billions of dollars over decades to find dark matter, yet we still know very little about it because we cannot observe it directly," he said. "However, we can observe the particles and energy released when dark matter particles interact and destroy each other."
Previously, there were three space detectors dedicated to finding dark matter - the AMS-02 spectrometer, and the Fermi and CALET space telescopes. Wukong is the newest and most advanced member of the family, and has superior precision in the trillion electronvolt energy range, Chang said.
Since its launch, Wukong has recorded over 3.5 billion cosmic ray events, with the highest energy levels exceeding 100 trillion electronvolts, more than 10 times the highest recorded energy level created by the Large Hadron Collider, the world's most powerful particle accelerator.
Wukong is expected to record more than 10 billion cosmic ray events during its lifetime, and it is likely to be operating well beyond its designed life span of three years, Chang said.
"In the Chinese novel, Wukong has a pair of magical eyes that can see through the devil's disguise," he said. "Similarly, we hope the Wukong satellite can open a new window in science discovery, and grant us the ability to see through the disguise of dark matter."
Bai Chunli, president of the Chinese Academy of Sciences, said the discovery of dark matter is the most cutting-edge of science projects and will fundamentally change how we view the universe, such as understanding how galaxies evolve.
A galaxy is a gravitationally bound system of billions of stars rotating around its center. But the strength of gravity becomes weaker as the distance between objects grows, hence stars at the edge of the galaxy should be flying off, like raindrops flinging off a spinning umbrella.
"But this is not the case, and galaxies continue to spin like a spiral disk without disintegrating," Bai said. "So there has to be something we cannot see that is holding the galaxy together. Dark matter is the prime suspect."
Ed Gerstner, Nature's scientific director for Chinese research, said the discovery is exciting despite all the uncertainties, and he will be looking forward to more results and collaboration with Chinese scientists.
"The most exciting phrase to hear in scientific discovery is not 'Eureka, I have found it', but rather 'Hmm that's weird'," Gerstner said. This is especially true for cutting-edge physics, such as the case of the discovery of the Higgs-boson elementary particle in 2013, he added.
"Chinese scientists have a long and proud history of groundbreaking contributions to high energy particle physics … and changing the way we see the universe," he said.
[email protected]
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