Session F: Anomalous and Galactic Cosmic Rays
Chairs: Alan Cummings, Joe Giacalone
This session will focus on observations and theory of ACRs and GCRs. A key issue for ACRs concerns the location and mechanism of their acceleration. For GCRs, a key issue is what is the local interstellar energy spectrum, and where does the influence of the Sun on the GCR spectrum end. This session invites contributions that address these fundamental issues, with a particular emphasis on observations that provide important constraints for theories of GCR and ACR transport and possible acceleration location and mechanisms of ACRs.
Anomalous Cosmic Rays (ACRs):
It is now well known that the intensity of ACRs did not peak at the time that each of the Voyager spacecraft crossed the termination shock. Prior to the Voyager 1 (V1) crossing, the prevailing theory for the origin of ACRs involved acceleration of interstellar pickup ions at the termination shock, but this view was challenged by the results from the shock crossings. A number of theories subsequently emerged to explain the origin of anomalous cosmic rays. It has now been nearly 8 years since Voyager 1 crossed the termination shock and 5 years since Voyager 2 crossed it. Other observations of ACRs, most notably during the recent unusually quiet solar-cycle minimum period, may also provide important constraints on the origin of ACRs. It is a good time to reflect on the puzzle concerning the acceleration mechanism of anomalous cosmic rays with the goal of moving towards a consensus view. Some key issues concerning ACRs include:
- What are the testable predictions from the various theories for the acceleration location and mechanism of ACRs and are these consistent with observations? What are the important observational constraints?
- How do lower-energy suprathermal charged particles relate to anomalous cosmic rays?
- How do solar-cycle variations affect the various proposed acceleration mechanisms and are such effects observed?
Galactic Cosmic Rays (GCRs):
The field of galactic cosmic ray research has been around for 100 years and yet there are still puzzles to be sorted out. Some key issues include:
- There are several estimates of the local interstellar spectra of GCRs. How do they compare? Which one should we believe?
- Will there be modulation beyond the heliopause?
- Why were GCRs at 1 AU at an all-time high in the recent solar minimum, whereas ACRs were not? What does this tell us about the transport processes or acceleration mechanism of ACRs?
We invite scientists interested in these topics to participate, and we also solicit suggestions from the community for any additional topics that would benefit from discussion by the attendees. We plan to divide the time available amongst the topics based on interest expressed. We plan about half the available time for short presentations (3-5 slides) with the remaining time held for discussion. Please send suggestions for topics and/or desires to give a presentation to Alan Cummings (ace@srl.caltech.edu) and Joe Giacalone (giacalon@lpl.arizona.edu).
I plan to attend this session.
Return to the symposium main page
here.
Webmaster: marchant@ssl.berkeley.edu
Last Updated: 27 July 2012
