Nearby source interpretation of differences among light and medium composition spectra in cosmic rays

Abstract

Recently the AMS-02 reported the precise measurements of the energy spectra of medium-mass compositions (Neon, Magnesium, Silicon) of primary cosmic rays, which reveal different properties from those of light compositions (Helium, Carbon, Oxygen). Here we propose a nearby source scenario, together with the background source contribution, to explain the newly measured spectra of cosmic ray Ne, Mg, Si, and particularly their differences from that of He, C, O. Their differences at high energies can be naturally accounted for by the element abundance of the nearby source. Specifically, the abundance ratio of the nearby source to the background of the Ne, Mg, Si elements is lower by a factor of ∼ 1.7 than that of the He, C, O elements. Such a difference could be due to the abundance difference of the stellar evolution of the progenitor star or the acceleration process/environment, of the nearby source. This scenario can simultaneously explain the high-energy spectral softening features of cosmic ray spectra revealed recently by CREAM/NUCLEON/DAMPE, as well as the energy-dependent behaviors of the large-scale anisotropies. It is predicted that the dipole anisotropy amplitudes below PeV energies of the Ne, Mg, Si group are smaller than that of the He, C, O group, which can be tested with future measurements.

Origin of hardening in spectra of cosmic ray nuclei at a few hundred GeV using AMS-02 data *

“…Refs. [32,43,44]). Considering the different kinds of potential CR sources (such as the different populations of supernovae), this assumption is consistent with real astrophysical situations.…”

“…Refs. [28,[31][32][33][34][35][36][37][38][39][40][41][42][43][44]). Based on the galactic CR diffusion model, all these scenarios could provide good fits to specific data sets.…”

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

“…It was first introduced as a Two Halo model (THM) (Tomassetti 2012) to explain the spectral hardening of both proton and helium above 200 GeV (Adriani et al 2011). Afterwards, it is further applied to secondary and heavier components (Tomassetti 2015;Feng et al 2016;Guo et al 2016;Liu et al 2018;Tian et al 2020;Yuan et al 2020), diffuse gamma-ray distribution (Guo & Yuan 2018) and large-scale anisotropy (Liu et al 2019;Qiao et al 2019). For a comprehensive introduction, one can refer to Guo et al (2016) and Liu et al (2018).…”

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

“…It was first introduced as a Two Halo model (THM) (Tomassetti 2012) to explain the spectral hardening of both proton and helium above 200 GeV (Adriani et al 2011). Afterwards, it is further applied to secondary and heavier components (Tomassetti 2015;Feng et al 2016;Guo et al 2016;Liu et al 2018;Tian et al 2020;Yuan et al 2020), diffuse gamma-ray distribution (Guo & Yuan 2018) and large-scale anisotropy (Liu et al 2019;Qiao et al 2019). For a comprehensive introduction, one can refer to Guo et al (2016) and Liu et al (2018).…”