Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by DAMPE show clear hardenings around 100 GeV/n,which provide important implications on the production,propagation,and interaction of Galactic cos...Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by DAMPE show clear hardenings around 100 GeV/n,which provide important implications on the production,propagation,and interaction of Galactic cosmic rays.In this work we investigate a number of models proposed in literature in light of the DAMPE findings.These models can roughly be classified into two classes,driven by propagation effects or by source ones.Among these models discussed,we find that the re-acceleration of cosmic rays,during their propagation,by random magnetohydrodynamic waves may not reproduce sufficient hardenings of B/C and B/O,and an additional spectral break of the diffusion coefficient is required.The other models can properly explain the hardenings of the ratios.However,depending on simplifications assumed,the models differ in their quality in reproducing the data in a wide energy range.The models with significant re-acceleration effect will under-predict low-energy antiprotons but over-predict low-energy positrons,and the models with secondary production at sources over-predict high-energy antiprotons.For all models high-energy positron excess exists.展开更多
Precise measurements of the energy spectra of cosmic rays(CRs)show various kinds of features deviating from single power-laws,which give very interesting and important implications on their origin and propagation.Prev...Precise measurements of the energy spectra of cosmic rays(CRs)show various kinds of features deviating from single power-laws,which give very interesting and important implications on their origin and propagation.Previous measurements from a few balloon and space experiments indicate the existence of spectral softenings around 10 TV for protons(and probably also for Helium nuclei).Very recently,the DArk Matter Particle Explorer(DAMPE)measurement about the proton spectrum clearly reveals such a softening with a high significance.Here we study the implications of these new measurements,as well as the groundbased indirect measurements,on the origin of CRs.We find that a single component of CRs fails to fit the spectral softening and the air shower experiment data simultaneously.In the framework of multiple components,we discuss two possible scenarios,the multiple source population scenario and the background plus nearby source scenario.Both scenarios give reasonable fits to the wide-band data from TeV to 100 PeV energies.Considering the anisotropy observations,the nearby source model is favored.展开更多
The DArk Matter Particle Explorer (DAMPE) is a space high-energy cosmic-ray detector covering a wide energy band with a high energy resolution. One of the key scientific goals of DAMPE is to carry out indirect detecti...The DArk Matter Particle Explorer (DAMPE) is a space high-energy cosmic-ray detector covering a wide energy band with a high energy resolution. One of the key scientific goals of DAMPE is to carry out indirect detection of dark matter by searching for high-energy gamma-ray line structure. To promote the sensitivity of gamma-ray line search with DAMPE, it is crucial to improve the acceptance and energy resolution of gamma-ray photons. In this paper, we quantitatively proved that the photon sample with the largest ratio of acceptance to energy resolution is optimal for line search. We therefore developed a line-search sample specifically optimized for the line-search. Meanwhile, in order to increase the statistics, we also selected the so-called BGO-only photons that convert into e^(+)e^(-) pairs only in the BGO calorimeter. The standard, the line-search, and the BGO-only photon samples are then tested for line-search individually and collectively. The results show that a significantly improved limit could be obtained from an appropriate combination of the date sets, and the increase is about 20% for the highest case compared with using the standard sample only.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFA0718404)the National Natural Science Foundation of China(Nos.12220101003 and 12103094)+1 种基金the Project for Young Scientists in Basic Research of Chinese Academy of Sciences(No.YSBR-061)The calculation was partially done on the Cosmology Simulation Database(CSD)of the National Basic Science Data Center(NBSDC-DB-10).
文摘Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by DAMPE show clear hardenings around 100 GeV/n,which provide important implications on the production,propagation,and interaction of Galactic cosmic rays.In this work we investigate a number of models proposed in literature in light of the DAMPE findings.These models can roughly be classified into two classes,driven by propagation effects or by source ones.Among these models discussed,we find that the re-acceleration of cosmic rays,during their propagation,by random magnetohydrodynamic waves may not reproduce sufficient hardenings of B/C and B/O,and an additional spectral break of the diffusion coefficient is required.The other models can properly explain the hardenings of the ratios.However,depending on simplifications assumed,the models differ in their quality in reproducing the data in a wide energy range.The models with significant re-acceleration effect will under-predict low-energy antiprotons but over-predict low-energy positrons,and the models with secondary production at sources over-predict high-energy antiprotons.For all models high-energy positron excess exists.
基金the Na-tional Key Research and Development Program of China(No.2016YFA0400200)the National Natural Science Foundation of China(Nos.11722328,11525313,U1738205,and 11851305)the 100 Talents Program of Chinese Academy of Sciences.
文摘Precise measurements of the energy spectra of cosmic rays(CRs)show various kinds of features deviating from single power-laws,which give very interesting and important implications on their origin and propagation.Previous measurements from a few balloon and space experiments indicate the existence of spectral softenings around 10 TV for protons(and probably also for Helium nuclei).Very recently,the DArk Matter Particle Explorer(DAMPE)measurement about the proton spectrum clearly reveals such a softening with a high significance.Here we study the implications of these new measurements,as well as the groundbased indirect measurements,on the origin of CRs.We find that a single component of CRs fails to fit the spectral softening and the air shower experiment data simultaneously.In the framework of multiple components,we discuss two possible scenarios,the multiple source population scenario and the background plus nearby source scenario.Both scenarios give reasonable fits to the wide-band data from TeV to 100 PeV energies.Considering the anisotropy observations,the nearby source model is favored.
基金The DAMPE mission was funded by the strategic priority science and technology projects in space science of Chinese Academy of SciencesIn China the data analysis is supported in part by the National Key Research and Development Program of China(No.2016YFA0400200)+2 种基金the National Natural Science Foundation of China(Nos.U1738210,U1738123,U1738205,U1738138,11921003,and 12003074)the Youth Innovation Promotion Association CAS,the Key Research Program of the Chinese Academy of Sciences Grant(No.ZDRW-KT-2019-5)the Entrepreneurship and Innovation Program of Jiangsu Province.
文摘The DArk Matter Particle Explorer (DAMPE) is a space high-energy cosmic-ray detector covering a wide energy band with a high energy resolution. One of the key scientific goals of DAMPE is to carry out indirect detection of dark matter by searching for high-energy gamma-ray line structure. To promote the sensitivity of gamma-ray line search with DAMPE, it is crucial to improve the acceptance and energy resolution of gamma-ray photons. In this paper, we quantitatively proved that the photon sample with the largest ratio of acceptance to energy resolution is optimal for line search. We therefore developed a line-search sample specifically optimized for the line-search. Meanwhile, in order to increase the statistics, we also selected the so-called BGO-only photons that convert into e^(+)e^(-) pairs only in the BGO calorimeter. The standard, the line-search, and the BGO-only photon samples are then tested for line-search individually and collectively. The results show that a significantly improved limit could be obtained from an appropriate combination of the date sets, and the increase is about 20% for the highest case compared with using the standard sample only.
