arXiv subjects

Bing-qiang Qiao

Publications and source records attributed to Bing-qiang Qiao.

5 recordsLinked to original sources

arXiv2025

The Compton-Getting origin of the large-scale anisotropy of Galactic cosmic rays

Recent studies suggest that the anisotropy in cosmic-ray arrival directions can provide insight into local acceleration sites and propagation conditions. We developed a unified framework to interpret both the observed energy spectra and the large-scale anisotropy. In this work, we explore the influence of the Sun's motion relative to the local plasma frame - the Compton-Getting (CG) effect - on the anisotropy. We find that incorporating the CG effect could slightly reduce the dipole amplitude and shift the phase away from the direction of the local regular magnetic field at tens of TeV. At lower energies, where the anisotropy from the cosmic-ray density gradient is weak, the Sun's relative motion becomes more prominent. Below $\sim 200$ GeV, the dipole amplitude increases again, approaching the value expected from the CG effect. Additionally, a phase flip is observed at a few hundred GeV, aligning with the CG direction. Future anisotropy measurements from $100$ GeV to TeV energies could serve as a critical test of this effect.

astro-ph.HE↗

arXiv2022

Constraining the position of the knee in the galactic cosmic ray spectrum with ultra-high-energy diffuse $γ$-rays

The diffuse $γ$-ray emission was measured up to $957$ TeV by the Tibet-AS$γ$ experiment recently. Assuming that it is produced by the hadronic interaction between cosmic ray nuclei and the interstellar medium, it requires that the cosmic ray nuclei should be accelerated well beyond PeV energies. Measurements of the cosmic ray spectra for different species show diverse results at present. The Tibet experiments showed that the spectrum of proton plus helium has an early knee below PeV. If this is correct, the diffuse $γ$-ray emission would suggest an additional component of Galactic cosmic rays above PeV energies. This second component may originate from a source population of so-called PeVatrons revealed by recent ultra-high energy $γ$-ray observations, and could contribute to the cosmic ray fluxes up to the energy of the second knee. On the other hand, the KASCADE measurement showed that the knee of protons is higher than PeV. In this case, the diffuse $γ$-rays observed by Tibet-AS$γ$ can be well accounted for by only one cosmic ray component. These two scenarious (ie. the Tibet and KASCADE knees) could be distinguished by the spectral structures of diffuse $γ$-rays and cosmic ray nuclei. Future measurements of spectra of individual nuclei by HERD and LHAASO experiments and diffuse $γ$-rays by LHAASO can jointly constrain these two scenarios.

astro-ph.HE↗

arXiv2022

Statistically study the optimal local sources for cosmic ray nuclei and electron

The local sources, such as Geminga SNR, may play important role for the anomaly of proton, electron and anisotropy in the past works. In fact, there exists twelve SNRs around solar system within $1$ kpc. One question is that can other SNRs also possibly contribute the spectra of nuclei and electron and explain the special structure of anisotropy? In this work, under the spatial-dependent propagation, we systematically study the contribution of all local SNRs within 1 kpc around solar to the spectra of nuclei and electron, as well as the energy dependence of anisotropy. As a result, only Geminga, Monogem, and Vela SNRs have quantitive contribution to the nuclei and electron spectra and anisotropy. Here, Geminga SNR is the sole optimal candidate and Monogem SNR is controversial due to the tension of anisotropy between model calculation and observations. The Vela SNR contributes a new spectral structure beyond TeV energy, hinted by HESS, VERITAS, DAMPE and CALET measurements. More interesting is that the electron anisotropy satisfies the Fermi-LAT limit below TeV energy, but rises greatly and reaches $10\%$ at several TeV. This new structure will shed new light to check our model. We hope that the new structure of electron spectrum and anisotropy can be observed by space-borne DAMPE and HERD and ground-based HAWC and LHAASO experiments in the near future.

astro-ph.HE↗

arXiv2022

Ultrahigh-energy diffuse gamma-ray emission from cosmic-ray interactions with medium surrounding acceleration sources

The diffuse $γ$-ray spectrum at sub-PeV energy region has been measured for the first time by the Tibet-AS$γ$ experiment. It will shed new light on the understanding of origin and propagation of Galactic cosmic rays at very high energies. It has been pointed out that the traditional cosmic ray propagation model based on low energy measurements undershoot the new data, and modifications of the model with new ingredients or alternative propagation framework is required. In this work, we propose that the hadronic interactions between freshly accelerated cosmic rays and the medium surrounding the sources, which was neglected in the traditional model, can naturally account for the Tibet-AS$γ$ diffuse emission. We show that this scenario gives a consistent description of other secondary species such as the positron spectrum, the boron-to-carbon ratio, and the antiproton-to-proton ratio. As a result, the electron spectrum above 10 TeV will have a hardening due to this secondary component, which may be tested by future measurements.

astro-ph.HE↗

arXiv2021

Possible bump structure of cosmic ray electrons unveiled by AMS-02 data and its common origin along with the nuclei and positron

The local pulsar and its progenitor, SNR, can together accelerate the positron, electron and nuclei to very high energy. The famous excesses of positron(nuclei) above $20$($200$) GeV possibly come from such kind of local source. This hints that the primary electron should also hold "excess" above $200$ GeV, synchronously accelerated along with the nuclei. The recent precise measurement of sharp dropoff at 284 GeV of positron by AMS-02 experiment takes chance to study this expected electron excess. In this work, the spatially-dependent propagation with a local source is used to reproduce the spectrum of positron, electron and proton. When considering the dropoff at 284 GeV of positron, a sharp bump structure for primary electron above 284 GeV is required to fit the total spectrum of positron and electron. Then we systematically study the common origin of the excesses of positron, electron and nuclei from Geminga pulsar and SNR. Those excesses can be reproduced under this unified single-source model. Lastly, we hope that the fine bump structure can be observed to support our model by AMS-02 experiment in future.

astro-ph.HE↗