1 / 17

Update on Solar Science

Update on Solar Science. Jim Ryan, Abe Falcone, James Ledoux. Huge X28 solar flare occurred on 29 October 2003, largest on record. Major signal (decrease) in Milagro, even, arguably, in the raw trigger rate (middle panel below).

rhiannon-briallen
Download Presentation

Update on Solar Science

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Update on Solar Science Jim Ryan, Abe Falcone, James Ledoux Milagro Collaboration

  2. Huge X28 solar flare occurred on 29 October 2003, largest on record. Major signal (decrease) in Milagro, even, arguably, in the raw trigger rate (middle panel below). Signal is in the form of a Forbush Decrease—a “sweeping up” of galactic CR in the heliosphere by the CME. Direct solar particles are small component (in valley). Milagro Collaboration

  3. Signal shows up in other NMs. (Time scaling of Apatity data by eyeball.) Milagro Collaboration

  4. Direct Solar Particles? • Yes, but effect is not large • Need to correlate structure at lowest point with signals in NMs. • Whopping signal from some low cutoff stations, i.e., South Pole. Milagro Collaboration

  5. South Pole NM The solar origin of the bumps in the valley of the scaler data could be confirmed with some careful correlation with several stations. Sorry for compressing the plots to match time scales. Milagro HT scalers Milagro Collaboration

  6. Long term effects of CMEs 12.9 GV 3.0 GV 1995-2004 Haleakala (red) and Climax (blue) have significantly different cutoffs and see different responses of the heliosphere to solar activity on a long term basis. Haleakala modulates less but still sees isolated events, e.g. 10/03 at right edge. Milagro Collaboration

  7. Shorter term effects: Climax (bottom) stays down longer w.r.t. Haleakala and recovers more slowly (effect not large on these time scales over cutoff range). How does Milagro add to this? Trigger threshold is possibly much higher than Haleakala cutoff (12.9 GV). Milagro Collaboration

  8. Significant Items • Solar protons at depth of Forbush decrease on 29 October, with no big onset like 15 April 2001. • Significant Forbush decrease even in triggered rate, but seemingly short-lived w.r.t. scalars and NMs. Milagro Collaboration

  9. Scientific Pay Dirt • Forbush decreases are poorly understood above 15 GV. • Previous identifications from underground detectors are dubious. • Which trigger rate of ours is > 15 GV? • If our triggered threshold corresponds to ~20-50 GV, then we are measuring the differential backfilling of the heliosphere with galactic cosmic rays, never seen before on these time scales. Milagro Collaboration

  10. Thumbnail Hypothesis for Forbush Decrease Publication • At ~50 GV the gyroradius at 1 AU is about 0.2 AU compared to 0.02 AU for a 5 GV proton. • The diffusion of galactic protons back into 1 AU is therefore more rapid (on scale of hours not days, months or years). • Finally, a new probe into the transport of galactic cosmic rays in the heliosphere. Milagro Collaboration

  11. Evidence • The duration of the decrease and its recovery are typically momentum independent. We see that the triggered rate (middle) (assuming small corrections) recovers faster. Milagro Collaboration

  12. Further Work (growing list) • Look at other trigger-criteria rates (different cutoffs). • Need longer baseline to study recovery (met corrections critical here). • Model effective proton threshold for different channels. • Compare to Climax, Haleakala, IMP to obtain direct solar particle spectrum from 50 MeV to 50 GeV. • Analyze event data to quantify azimuthal anisotropy of decrease (unprecedented). Milagro Collaboration

  13. Meeting Opportunities • “When the Sun Went Wild” session at the Denver Solar Physics Division Meeting of the AAS in Denver in June (1). Abstracts due March 17! Will have to circulate draft abstract next week (ouch). Will probably be a bit bland at this stage. Milagro Collaboration

  14. Missed Opportunities • Late May AGU meeting in Montreal, but others are coming along. JR might go anyhow (semester ended) to hear what’s going on perhaps with TBD data in hand. Milagro Collaboration

  15. Journal Opportunities • Call for a special volume of J. Geophys. Res. on this period of solar activity. Call went out for someone to organize and has been deathly quiet since. It will probably happen one way or the other. Milagro Collaboration

  16. Collaborations • Approached by Cliff Lopate (UNH, Climax, Haleakala), Jack Lockwood (UNH, Durham, Mt. Washington) and Bill Webber (NMSU, IMP) to collaborate on an analysis of the direct solar particles. Our signal is not huge, but is probably there when compared to timing of increases at NMs and spacecraft. Yet to be demonstrated, but at least we see the end of the spectrum. Milagro Collaboration

  17. Need to get our data out first somehow prior to multi-instrument paper. • I suggest first a Forbush decrease analysis, since our direct particle signal is weak and would be best used in the context of other data. • Milagro direct solar particle data might be publishable alone but should wait to see. • Decrease anisotropy paper should be strictly Milagro, or at least lead. Milagro Collaboration

More Related