Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of electrons and positrons

Abstract

High-energy cosmic-ray electrons and positrons (CREs), which lose energy quickly during their propagation, provide a probe of Galactic high-energy processes and may enable the observation of phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been measured directly up to approximately 2 teraelectronvolts in previous balloon- or space-borne experiments, and indirectly up to approximately 5 teraelectronvolts using ground-based Cherenkov γ-ray telescope arrays. Evidence for a spectral break in the teraelectronvolt energy range has been provided by indirect measurements, although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the Dark Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The largest part of the spectrum can be well fitted by a 'smoothly broken power-law' model rather than a single power-law model. The direct detection of a spectral break at about 0.9 teraelectronvolts confirms the evidence found by previous indirect measurements, clarifies the behaviour of the CRE spectrum at energies above 1 teraelectronvolt and sheds light on the physical origin of the sub-teraelectronvolt CREs.

Explaining the DAMPE data with scalar dark matter and gauged $$U(1)_{L_e-L_\mu }$$ U ( 1 ) L e

“…Obviously, this function depends on a series of parameters such as m χ , m Z , σ v 0 , M halo , the distance of the subhalo way from the earth d as well as the parameters appearing in the background. Since DAMPE experiment has collected more than thirty electron/positron events in each energy bin around 1.4 TeV [1], we can determine the favored ranges of these parameters by the binned likelihood fit adopted in this work. For the flux in the ith bin, we get its theoretical value by averaging the flux over the width of the energy bin, i.…”

“…More details of the procedure were introduced in [4,10,13,15]. Finally, we construct a likelihood function by comparing the predicted spectrum with the AMS-02 data and the DAMPE data, which are distributed from 0.5 to 24 GeV in 36 energy bins for the former [35] and from 24 GeV to 4.57 TeV in 40 energy bins for the latter [1]. Obviously, this function depends on a series of parameters such as m χ , m Z , σ v 0 , M halo , the distance of the subhalo way from the earth d as well as the parameters appearing in the background.…”

“…Recently, the DArk Matter Particle Explorer (DAMPE) experiment released the new measurement of the total cosmic e + +e − flux between 25 GeV and 4.6 TeV and reported a hint of an excess in the e + e − spectrum at around 1.4 TeV [1,2]. Although such an excess may originate from certain new unobserved astrophysical sources, it may also be explained by DM annihilation [3].…”

Simplified TeV leptophilic dark matter in light of DAMPE data

“…The DArk Matter Particle Explorer (DAMPE) is a new cosmic ray detector [1,2], which has great energy resolution (better than 1.5%@TeV for electrons and gamma rays) and good hadron rejection power (higher than 10 5 ). Very recently, DAMPE released their first results about cosmic-ray e + + e − flux up to 5 TeV [3]. A sharp peak at ∼ 1.…”

DAMPE electron-positron excess in leptophilic Z′ model

“…The search for such an excess in the electron and positron spectra have been already in progress by different particle detectors in the space; the PAMELA satellite experiment observed an abundance of the positron in the cosmic radiation energy range of 15 − 100 GeV [1], also a positron fraction in primary cosmic rays of 0.5 − 350 GeV [2] and 0.5 − 500 GeV [3] and the measurement of electron plus positron flux in the primary cosmic rays from 0.5 GeV to 1 TeV [4] reported by the Alpha Magnetic Spectrometer (AMS02). The motivation of the current paper is however the recent report of the first results of the DArk Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background in the measurement of the cosmic ray electrons and positrons (CREs) in 25 GeV to 4.6 TeV energy range [5]. At energy about 1.4 TeV a peak associated to a monoenergetic electron source is observed.…”