AsianScientist (Dec. 8, 2017) – In a study published in Nature, a team of researchers in China have made a precise measurement of cosmic ray electron flux using the Dark Matter Particle Explorer (DAMPE), a Chinese satellite-borne detector.
The DAMPE, also known as Wukong, is China’s first astronomical satellite, which was launched from China’s Jiuquan Satellite Launch Center into sun-synchronous orbit on December 17, 2015. The mission is a collaboration among more than a hundred scientists, technicians and students at nine institutes in China, Switzerland and Italy, under the leadership of the Purple Mountain Observatory (PMO) of the Chinese Academy of Sciences (CAS). At an altitude of about 500 km, DAMPE has been collecting data since a week after its launch.
In its first 530 days of science operation through June 8 of this year, DAMPE has detected 1.5 million cosmic ray electrons and positrons above 25 giga-electronvolts (GeV). The electron and positron data are characterized by unprecedentedly high energy resolution and low particle background contamination.
Additionally, DAMPE has directly detected a spectral break at approximately 0.9 tera-electronvolts (TeV), with the spectral index changing from 3.1 to 3.9. This finding considerably narrows the parameter space of models for particle dark matter, such as nearby pulsars and supernova remnants, that were proposed to account for the ‘positron anomaly’ revealed previously by other satellite-borne detectors, the PAMELA and the AMS-02.
“Together with data from the cosmic microwave background experiments, high energy gamma-ray measurements, and other astronomical telescopes, the DAMPE data may help to ultimately clarify the connection between the positron anomaly and the annihilation or decay of particle dark matter,” said Professor Fan Yizhong, deputy chief designer of DAMPE’s scientific application system.
The researchers hope to make more precise measurements of the cosmic ray electron and positron spectrum, up to energies as high as 10 TeV. They also intend to explore spectral features potentially generated by dark matter particle annihilation or nearby astrophysical sources, such as pulsars.
The article can be found at: DAMPE Collaboration (2017) Direct Detection of a Break in the Teraelectronvolt Cosmic-ray Spectrum of Electrons and Positrons.
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Source: Chinese Academy of Sciences.
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