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Neutrinos from Gamstars

Neutrinos from Gamstars. G.F. Bignami, IUSS Pavia M. Roncadelli, INFN Pavia. GAMSTAR? = Gamma-Ray (Neutron) Star!. Why now ?. 1- Geminga-like Gamstars can bridge gap e.m.astronomy  n astronomy. ’00s. GAMSTAR? = Gamma-Ray (Neutron) Star!. Why now ?.

margaret-emerson
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Neutrinos from Gamstars

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  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  n astronomy

  3. ’00s

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

  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 1/10th true rate

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

  8. Starting point: ns via p photoproduction p + g n + p+  n + ap+ + b (p+ + p-) •  m + n  e + nenm N.B. pion photoproduction kinematically possible if Ep Eg > 0.3 GeV2 f f= 1/1-cosqgp

  9. Geminga à la Goldreich and Julian Max proton energy = 0.4 103 TeV (P=0.237 s) Proton number density n= 3.2 1011 cm-3 High-energy photons are produced through curvature radiation by e+, e- close to light cylinder RL = c/W = 1.1 109 cm Average photon energy assumes Eg =200 MeV

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

  11. The target energetic photon density ng is ng = 0.7 10 7 cm-3 Introducing a standard cross section s p + g n + p+ = 5 10-28 cm-2 The resulting conversion probability P P= s 0.1 RL ng 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 ICE3 ! 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 3000 271 100 25 3 1 1 1 Think of the number of neutrino sources 50 ys from now!

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