A Study On The Contribution Of Cosmic Ray Local Sources

Cosmic rays are high-energy charged particles from space.In recent years,with the operation of a new generation of space experiments and ground experiments,the observation of cosmic rays has entered an era of high precision.These new precise measurements revealed a series of cosmic ray "anomalies",such as the ATIC-2,CREAM and PAMELA experiments observed a hardening of the nucleon spectrum at?200 GV,which was later confirmed by AMS-02 with unprecedented precision;the spectral break-off around ?14 Te V was observed by the CREAM,the NUCLEON and the DAMPE experiments,etc.Three categories of models such as the local sources model,the combined effects from different group sources model and the spatialdependent propagation(SDP)model are proposed to explain these new structures.Coincidentally,in the latest energy spectrum measurement of AMS-02,it was found that the positron dropped sharply at 284 Ge V.Recent studies have shown that if the positron turns at 284 Ge V,the total electron spectrum will have a "bump" at Te V,which means that there are additional primary negative electrons,which may originate from the nearby supernova remnant(SNR).In addition,measurements of cosmic ray anisotropy magnitude and phase from several ground experiments have also challenged the traditional propagation model(CPM).Therefore,we believe that local sources are essential when interpreting these anomalous observations.Taking this opportunity,we conducted a detailed study of the contribution of local sources to the energy spectrum and anisotropy.Some past work has suggested that Geminga SNR could be a suitable local source.Considering that there are many local sources distributed around the solar system,are there other local sources that can make similar contributions? Therefore,we investigate the SNRs of all local sources within 1 kiloparsec(kpc)around the solar system,and analyze their contributions to the energy spectrum and anisotropy one by one.As a result,only the Geminga,Monogem and Vela SNRs have quantitative contribution to the nuclei and electron spectra and the anisotropy.After our detailed analysis of the three SNRs,only Geminga is the only best candidate nearby source,and there is a contradiction between the proton energy spectrum contributed by Monogem and the anisotropy,which cannot be consistent with the observational data at the same time,and can be excluded.In addition,the Vela mainly contributes higher energy electrons due to its relatively young age.Four experiments,DAMPE,CALET,VERITAS,and HESS,observed that the electron energy spectrum shows a hardening trend above the Te V energy.We believe that there may be a new "bulky" structure here,mainly contributed by Vela.In addition,we fit the energy spectrum and anisotropy magnitude with the help of the Bayesian inference toolkit Multi Nest,thereby constraining the parameter space of the adjacent sources.In order to determine the information of the best nearby source,we plan to analyze the(1)proton and helium energy spectra and cosmic ray anisotropy magnitudes in three steps;(2)negative electron energy spectra;(3)combined proton and electron energy spectra.The energy spectrum and anisotropy amplitude are fitted to further limit the range of age and location of adjacent sources.Separate simulations for protons and electrons have now been completed,and the results show that,compared to the current SNR catalog,only Geminga may be the best candidate for a nearby source.In the next step,we will jointly simulate protons and electrons in order to further narrow the parameter space of nearby sources.