Kavli Affiliate: Igor Moskalenko
| First 5 Authors: Mikhail Malkov, Igor Moskalenko, Patrick Diamond, Mingyun Cao,
| Summary:
Recent measurements of primary and secondary CR spectra, their arrival
directions, and our improved knowledge of the magnetic field geometry around
the heliosphere allow us to set a bound on the distance beyond which a puzzling
10-TeV “bump” and certain related spectral features emph{cannot} originate.
The sharpness of the spectral breaks associated with the bump, the abrupt
change of the CR intensity across the local magnetic equator ($90^{circ}$
pitch angle), and the similarity between the primary and secondary CR spectral
patterns point to a local reacceleration of the bump particles out of the
background CRs. We argue that, owing to a steep preexisting CR spectrum, a
nearby shock may generate such a bump by boosting particle rigidity by a mere
factor of $sim$1.5 in the range below 50 TV. Reaccelerated particles below
$sim$0.5 TV are convected with the interstellar medium flow and do not reach
the Sun. The particles above this rigidity then form the bump. This single
universal process is responsible for the observed spectral features of all CR
nuclei, primary and secondary, in the rigidity range below 100 TV. We propose
that one viable candidate is the system of shocks associated with $epsilon$
Eridani star at 3.2 pc of the Sun, which is well aligned with the direction of
the local magnetic field. Other shocks, such as old supernova shells, may
produce a similar effect. We provide a simple formula that reproduces the
spectra of all CR species with only three parameters uniquely derived from the
CR proton data. We show how our formalism predicts helium, boron, carbon,
oxygen, and iron spectra. Our model thus unifies all the CR spectral features
observed below 50 TV.
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