1. Neutrinos from Gamstars G.F. Bignami, IUSS Pavia M. Roncadelli, INFN Pavia

2. GAMSTAR? = Gamma-Ray (Neutron) Star! Why now ? 1- Geminga-like Gamstars can bridge gap e.m.astronomy  astronomy

3. ’00s

4. GAMSTAR? = Gamma-Ray (Neutron) Star! Why now ? 2- Fermi Discovers tens of new Gemingas 1- Geminga-like Gamstars can bridge gap e.m.astronomy  astronomy

5. LAT discovers a radio-quiet pulsar! P ~ 317 ms Pdot ~ 3.6E-13 Characteristic age ~ 10,000 yrs

6. The Pulsing Sky Pulses at 1/10 th true rate

7. GAMSTAR? = Gamma-Ray (Neutron) Star! Why now ? 2- Fermi Discovers tens of new Gemingas 1- Geminga-like Gamstars can bridge gap e.m.astronomy  astronomy 3- Ice Cube 40 is now coming of age

8. Starting point:  s via  photoproduction p +   n +  +  n + a  + + b (  + +  - )    +  e + e  N.B. pion photoproduction kinematically possible if E p E  > 0.3 GeV 2 f f= 1/1-cos   p

9. Geminga à la Goldreich and Julian Max proton energy = 0.4 10 3 TeV (P=0.237 s) Proton number density n= 3.2 10 11 cm -3 High-energy photons are produced through curvature radiation by e +, e - close to light cylinder R L = c/  = 1.1 10 9 cm Average photon energy assumes E  =200 MeV

10. Simple geometry tranform cylinder in spherical shell 0.9 R L < r < R L The GJ energetic protons, accelerated close to the star, interact with  s around R L Production of energetic neutrinos is boosted well above that on thermal target photons !

11. The target energetic photon density n  is n  = 0.7 10 7 cm -3 Introducing a standard cross section  p +   n +  + = 5 10 -28 cm -2 The resulting conversion probability P P=  0.1 R L n  or 3.9 10 -13

12. Thus, the resulting Geminga neutrino flux in Ice Cube above 1 TeV for its measured distance is 1-10 km -2 y -1 magic # 4 ICE 3 ! Bonus #1 : contrary to our rough approximation, neutrinos will be pulsed, just like gamma-rays

13. Bonus #2 : Geminga will be the first and the brightest, but a list of Gamstar as candidate neutrino sources will soon be provided by Fermi 3 25 271 3000 111 100 Think of the number of neutrino sources 50 ys from now!