Inhomogeneity in cosmic ray sources as the origin of the electron spectrum and the PAMELA anomaly.
نویسندگان
چکیده
We show that inhomogeneity of cosmic ray (CR) sources, due to the concentration of supernova remnants (SNRs) towards the galactic spiral arms, can naturally explain the anomalous increase in the positron/electron ratio observed by PAMELA. We consistently recover the observed positron fraction between 1 and 100 GeV using SNRs as the sole source of CRs. The contribution of a few known nearby SNRs dominates the CR electron spectrum above approximately 100 GeV, leading to the relatively flat spectrum observed by Fermi and to the sharp cutoff observed by H.E.S.S.
منابع مشابه
Inhomogeneity in the Supernova Remnant Distribution as the Origin of the PAMELA Anomaly
Recent measurements of the positron/electron ratio in the cosmic ray (CR) flux exhibits an apparent anomaly (Adriani et al. 2009), whereby this ratio increases between 10 and 100 GeV. We show that inhomogeneity of CR sources on a scale of order a kpc, can naturally explain this anomaly. If the nearest major CR source is about a kpc away, then low energy electrons (∼ 1 GeV) can easily reach us. ...
متن کاملInhomogeneity in the Supernova Remnants as a Natural Explanation of the PAMELA/ATIC Observations
Recent measurements of the positron/electron ratio in the cosmic ray (CR) flux exhibits an apparent anomaly1, whereby this ratio increases between 10 and 100 GeV. In contrast, this ratio should decrease according to the standard scenario, in which CR positrons are secondaries formed by hadronic interactions between the primary CR protons and the interstellar medium (ISM)2. The positron excess i...
متن کاملCosmic-ray Electron Excess from Pulsars Is Spiky or Smooth?: Continuous and Multiple Electron/positron Injections
We investigate the observed spectrum of cosmic-ray electrons and positrons from astrophysical sources, especially pulsars, and the physical processes for making the spectrum spiky or smooth via continuous and multiple cosmic-ray injections. We find that (1) the average spectrum with the local birth rate of pulsars (including the off-axis ones) is relatively smooth, consistent with the PAMELA da...
متن کاملTime Delays in Cosmic Ray Propagation
Cosmic Rays (CR) travel at speeds essentially indistinguishable from the speed of light. However whilst travelling through magnetic fields, both regular and turbulent, they are delayed behind the light since they are usually charged particles and their paths are not linear. Those delays can be so long that they are an impediment to correctly identifying sources which may be variable in time. Fu...
متن کاملPossible Interpretations of the High Energy Cosmic Ray Electron Spectrum measured with the Fermi Space Telescope
The Fermi Large Area Telescope has provided the measurement of the high energy (20 GeV to 1 TeV) cosmic ray electrons and positrons spectrum with unprecedented accuracy. This measurement represents a unique probe for studying the origin and diffusive propagation of cosmic rays as well as for looking for possible evidences of Dark Matter. In this contribution we focus mainly on astrophysical sou...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Physical review letters
دوره 103 11 شماره
صفحات -
تاریخ انتشار 2009