1 / 11

Pervasive Field Model

Evidence For A Weak Galactic Center Magnetic Field : T. N. LaRosa (Kennesaw St. Univ.) Crystal Brogan (U. of Hawaii) S.N. Shore (U. of Pisa) T. J. W. Lazio, N. Kassim, M. Nord, (NRL). Pervasive Field Model.

cheryl
Download Presentation

Pervasive Field Model

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. Evidence For A Weak Galactic Center Magnetic Field: T. N. LaRosa (Kennesaw St. Univ.)Crystal Brogan (U. of Hawaii) S.N. Shore (U. of Pisa) T. J. W. Lazio, N. Kassim, M. Nord, (NRL)

  2. Pervasive Field Model • NTF magnetic fields of order 1 mG. Magnetic pressure exceeds the thermal pressure, therefore unless confined the filaments would expand on a timescale short compared to their synchrotron lifetime • NTFs are the illuminated flux tubes of a space-filling, globally organized field. A local interaction (magnetic reconnection) is responsible for the electron acceleration • Large magnetic field energy required – 5 x 1054 ergs, equipartition with local ISM turbulence

  3. Minimum Energy Analysis 327/74 MHz spectral index  =0.7 Luminosity  2.5 x 1036 ergs/s Minimum energy  1 4/7 x 1052 ergs Magnetic field  6 (/f)-2/7G Particle energy density 1.3 f-2/7 eV/cm3 ( is the proton to electron energy ratio, f is the filling factor)

  4. Energy Requirements • 1 SNe every 3 x 105 years • The higher star formation rate in the GC (Figer et al 2004) gives an expected SN rate in the inner 50 pc of 1 SNe every 105 years • Consistent with the energy requirements to account for the soft X-ray emission (Muno et al 2004)

  5. Discussion: • A strong 1 mG field with a solar value for the cosmic ray energy density (1.8 eV/cm3) would generate a 327 MHz emissivity of 41 KJy/beam - orders of magnitude more emission than the observed, 229 Jy/beam • Radiative lifetime of an electron emitting at 74 MHz in a 1 mG is 105 years. Requires that the source by resupplied at an implausibly high rate

  6. Conclusions • The derived particle energy density is consistent with the EGRET data • Evidence from H3+, Li and B, and cloud heating all suggest a GC cosmic ray energy comparable with the solar values • A strong 1 mG space filling global magnetic field is not consistent with the radio emission

More Related