Yiqing Guo

Implications of the AMS-02 positron fraction in cosmic rays

The AMS-02 collaboration has just released its first result of the cosmic positron fraction e(+)/(e(-) + e(+)) with high precision up to similar to 350 GeV. The AMS-02 result shows the same trend with the previous PAMELA result, which requires extra electron/positron sources on top of the conventional cosmic ray background, either from astrophysical sources or from dark matter annihilation/decay. In this paper we try to figure out the nature of the extra sources by fitting to the AMS-02 e(+)/(e(-) + e(+)) data, as well as the electron and proton spectra by PAMELA and the (e(-) + e(+)) spectrum by Fermi and HESS. We adopt the GALPROP package to calculate the propagation of the Galactic cosmic rays and the Markov Chain Monte Carlo sampler to do the fit. We find that under the conventional assumptions about the background and the extra source of the e(-) + e(+), we cannot fit the AMS-02 and Fermi/HESS data well simultaneously. The AMS-02 data require less electrons/positrons from the extra sources than that required by Fermi/HESS. It may indicate that the model needs to be refined or the data between these experiments have systematic uncertainties. The pulsar scenario generally fits the data better than the DM scenario. Furthermore, the constraints from gamma-rays also disfavor the DM scenario to explain the cosmic ray lepton data

On the Galactic Center being the main source of galactic cosmic rays as evidenced by recent cosmic ray and gamma ray observations

We revisit the idea that the Galactic Center (GC) is the dominant source of galactic cosmic rays (GCRs), based on a series of new observational evidence. A unified model is proposed to explain the new phenomena of GCRs and gamma-rays simultaneously. The GCRs are thought to be accelerated during past activities of the GC. The pair production process of GCRs in the strong radiation field due to the GC activity is responsible for the knee structure of the CR spectra. A fraction of e(+)e(-) produced by pair production interactions can be reaccelerated in the induced bipolar jets and be transported into the halo, leaving the Fermi gamma-ray bubbles and WMAP microwave haze as the remnant signal. Finally, the CRs diffuse in the bulge could further interact with the interstellar medium to produce low energy e(+)e(-). After cooling down, these positrons may annihilate to produce the 511 keV line emission as discovered by INTEGRAL.

On the contribution of a hard galactic plane component to the excesses of secondary particles

The standard model of cosmic ray propagation has been very successful in explaining all kinds of the Galactic cosmic ray spectra. However, high precision measurement recently revealed the appreciable discrepancy between data and model expectation, from spectrum observations of

Study on a wide field-of-view Cherenkov telescope with large dimensional refractive lens for high energy Cosmic Rays detection

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Study on the Sensitivity of high-energy GRB detection using the single-particle technique at an altitude 5200 m a.s.l

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Interpretations of the DAMPE electron data

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Performance of a scintillation detector array operated with LHAASO-KM2A electronics

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Study of the γ /p discrimination at ∼100 TeV energy range with LHAASO experiment

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Using the single particle technique search for GRBs in Tibet at altitude Higher than 5000m

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A search for 5000-6000m sites in Tibet Autonomous Region to observe the high energy cosmologicalgamma rays

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