Prospects of Identifying the Sources of the Galactic Cosmic Rays with IceCube Alexander Kappes Francis Halzen Aongus O’Murchadha University Wisconsin-Madison 3 rd VLVnT Workshop April , Toulon France

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France2 Outline  Cosmic rays and gamma/neutrino production  Which are the accelerators of the Galactic cosmic rays?  Can we see them with neutrino telescopes (IceCube)?

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France3 The Cosmic Ray Spectrum  Cosmic ray spectrum measured over more than 12 decades  Spectrum steepens at ~3 PeV  Transition between Galactic and extra-Galactic component at eV  Form of spectrum requires Galactic accelerators up to 3 PeV (PeVatrons)  Not identifiable with cosmic ray experiments (magnetic fields) extragalacticgalactic

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France4 The Cosmic-Ray Gamma/Neutrino Connection  Relation  / spectrum parameters (pp interactions) (at Earth  mixing leads to (1 : 1 : 1))  CR “knee” produce  -rays of ~300 TeV p + p(  ) →   + X   +   e + e +  p + p(  ) →  0 + X    Hadronic neutrino and  ray production: ( e :     Norm: Index: Cut-off: Kappes etal: ApJ,656: ,2007

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France5 The Mystery of the Missing PeVatrons  SNRs best candidates for Galactic cosmic ray accelerators  But no SNR  spectrum extends above a few 10 TeV  Possible reason: “Direct” high energy  -ray emission only in first few hundred years  Detection still possible by observing secondary  -rays produced in nearby clouds  Milagro better suited than Cherenkov telescopes 400 yr 2000 yr 8000 yr yr (10 4 solar masses) at 1 Kpc 8000 yr 2000 yr Cherenkov telescopes (e.g. HESS, Magic) Air shower arrays (Milagro) Gabici, Aharonian: arXiv:

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France Milagro Sky Survey At 12 TeV MGRO J MGRO J MGRO J MGRO J MGRO J MGRO J  MGRO : not seen by VERITAS in first observation  consistency requires  < 2.2  MGRO J : Magic measures E -2 spectrum Abdo thesis defense, March 2007 VERITAS observation

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France7 Gamma-ray Spectrum of MGRO J  Again E -2 spectrum; extends up to 100 TeV !  Strong indicator of proton acceleration in this source

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France8 The Role of Neutrino Telescopes  Air shower array currently only in Northern Hemisphere  Photon production ambiguous  Cherenkov telescopes have only small field of view (few deg 2 ) cover only small part of sky (at a time) large photon background in star forming region (e.g. Cygnus) can hide sources  Neutrinos unambiguous sign for hadronic acceleration  Neutrino telescope properties fit well to air shower arrays “all sky” sensitivity increasing sensitivity with energy (small background) angular resolution O (1º)

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France9 Gamma and Neutrino Spectra Neutrino spectra for all sources Spectra for MGRO J  Assumed E -2 with Milagro normaliztion (MGRO J index = 2.1)   spectrum 180 TeV Halzen, Kappes, O’Murchadha: arXiv: neutrino flux gamma flux MGRO J MGRO J MGRO J MGRO J MGRO J MGRO J E thresh (TeV) E thresh (TeV) E 2  flux (TeV s -1 cm -2 )

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France10 Significance for MGRO J (5 years) Milagro measurements favor lower sensitivity curve (dashed line)   after 5 years  IceCube (80 strings) effective area (with quality cuts)  Search window: observed events signal + atm. calculated signal events Halzen, Kappes, O’Murchadha: arXiv: 1 22 33 1 10 E thresh (TeV) E thresh (TeV) # events p value

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France11 Significance for all 6 Milagro sources after 5 years  p-value = after 5 years but large error band (not shown)  Optimal 30 TeV (determined by loss of signal events) Halzen, Kappes, O’Murchadha: arXiv:

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France12 Simulated Neutrino Skymaps IC80 (5 years) # events (arb. units) Correlated Skymap Not actual way to analyse data !

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France13 Summary  Cosmic ray sources (PeVatrons) should leave imprint on Milagro sky map  Milagro observes several hotspots with apparently hard spectra  maybe first PeVatron(s) discovered (MGRO J )  If these are the cosmic ray sources IceCube will be able to see them with time (best sensitivity above several 10 TeV)  MGRO J and MGRO J also visible (50%) by Mediterranean detectors More information in Halzen, Kappes, O’Murchadha: arXiv:

April 23, 2008Alexander Kappes, 3rd VLVnT Workshop, Toulon France14 The TeV Gamma-Ray Sky