Heino Falcke Radboud University, Nijmegen ASTRON, Dwingeloo LOFAR Cosmic Ray KSP Heino Falcke Radboud University, Nijmegen ASTRON, Dwingeloo

What we (don’t) know about UHECRs We know: their energies (up to 1020 eV). their overall energy spectrum We don’t know: where they are produced how they are produced what they are made off exact shape of the energy spectrum

Potential Sources Hillas plot: Gyro radius has to fit source size! Galactic < 1017eV Supernovae neutron stars & stellar black holes Extragalactic >1018 eV Supermassive black holes Gamma-Ray bursts Intergalactic shocks Top-down: decay of primordial superheavy particles (?) 1 EeV = 1018 eV

Radio Images of Cosmic Accelerators Cygnus A Cas A NRAO/AUI Fornax A 1.4 , 5, & 8.4 GHz

The Pierre Auger Observatory

Auger: Clustering of UHECRs The beginning of “charged particle astronomy”! 1set until May 24: 12/15 correlate 2ns set until May 24- August: 8/12 correlate (2.7 expected) For combined set: 20 out of 27 cosmic rays events 236 correlate with at least one of the 442 selected AGN (292 in the eld of view 237 of the Observatory), while only 5.6 are expected on average to do so if the 238 ux were isotropic (p = 0:21) µG B-fields and kpc scales needed AUGER Collaboration (2007), Science 9. Nov. (2007)

Ultra-high Energy Cosmic Ray Spectrum ? The Pierre Auger Collaboration, Physics Letters B  (2010) 

Auger Composition Results Looks like CR primaries become more heavy. NB: HiRes experiment interprets this differently (=> only protons) proton prediction Depth of shower maximum in atmosphere Auger Data prediction for iron nuclei

Cosmic Rays in the Radio Countrate at 10^17eV: 10^5 events 10^18 eV: ~600-1000 (lower and upper curve) 10^19 eV: 4 cnv[3 10^15 /(Meter^2 Second sr eV^-1.5)/(10^18 eV)^2.5 Pi sr (Pi km^2)* Year 10^18 eV] νMoon S. Lafebre

Radio Astroparticle Physics: Cosmic Rays in atmosphere: Geosynchrotron emission (10-100 MHz) Radio fluorescence and Bremsstrahlung (~GHz) Radar reflection signals (any?) VLF emission, process unclear (<1 MHz) Neutrinos and cosmic rays in solids: “Cherenkov emission” (100 MHz - 2 GHz) polar ice cap (balloon or satellite) inclined neutrinos through earth crust (radio array) CRs and Neutrinos hitting the moon (telescope)

LOFAR Cosmic Ray KSP: Main Goals Understand High-Cosmic Rays Measure and fully characterize radio signals of extensive air showers (e.g., reference calibration for LOFAR and AUGER). Understand effects of and on lightning Use radio technique in transition region from Galactic to extragalactic CRs to clarify their nature (i.e., composition) Search for radio flashes from the moon to characterize UHECR spectrum at highest energies (NuMoon) Develop the techniques to work on raw time series data on dipole-level (transient buffer board & tied-array beam) in near field and far-field. Science Synergy with other KSP Transients: Identify and understand other sporadic signals (“RFI”, lightning, SETI, astrophysical sub-ms pulses, e.g. giant pulses) Survey: Identify sources of UHECRs

Coherent Geosynchrotron Radio Pulses in Earth Atmosphere Earth B-Field ~0.3 G UHECRs produce particle showers in atmosphere Shower front is ~2-3 m thick ~ wavelength at 100 MHz e± emit synchrotron in geomagnetic field Emission from all e± (Ne) add up coherently Radio power grows quadratically with Ne Etotal=Ne*Ee Power ∝Ee2 ∝ Ne2 GJy flares on 20 ns scales shower front e± ~50 MeV Geo- synchrotron coherent E-Field Falcke & Gorham (2003), Huege & Falcke (2004,2005) Tim Huege, PhD Thesis 2005 (MPIfR+Univ Bonn

Cross Calibration of LOPES10 and KASCADE UHECR Particle Energy B-field Distance Horneffer-Formula 2008

Energy and Composition from MC Simulations lateral radio profile  Xmax radio flux  Ne LOPES Data (Horneffer et al. 2007) ~5% shower-to-shower fluctuations LOPES-KASCADE Huege et al. 2008, (Astropart. Phys.) - REAS2 code

Imaging of CR radio pulses with LOPES A. Nigl 2007, PhD Horneffer, LOPES30 event See also Falcke et al. (LOPES collaboration) 2005, Nature, 435, 313

Nanosecond Radio Imaging in 3D Actual 3D radio mapping of a CR burst No simulation! Off-line correlation of radio waves captured in buffer memory We can map out a 5D image cube: 3D: space 2D: frequency & time Image shows brightest part of a radio airshower in a 3D volume at t=tmax and all freq. Bähren, Horneffer, Falcke et al. (RU Nijmegen)

UHE Neutrino detection needs large detector volumes! Auger: Aeff=3000 km2, Moon: Aeff=9×106 km2 Back to the moon …

Cosmic Ray Westerbork antennas 100 MHz Radio Waves

Westerbork (WSRT) Experiment 4 freq. bands 4 freq. bands Westerbork Synthesis Radio Telescope

UHE Neutrino Limits from WSRT νMoon Experiment Anita ‘08 nMoon Buitink et al. (2009), A&A - Scholten et al. (2009), Phys. Rev. Lett.

LOFAR Sensitivity to Neutrinos Singh et al. (2009)

LOFAR sensitivity to CRs Singh et al. (2009)

Commissioning Results: Triggering finally works Horneffer/Corstanje/Falcke (Radboud)

Station Pulse Triggers in a Day (Sky Distribution) LOFAR low-band has all-sky visibility! A. Corstanje (Radboud)

5ms All-Sky Imaging with LOFAR TBBs Single LBA station S. Welles L. Bähren (Radboud)

5ms All-Sky Imaging with LOFAR TBBs Single LBA station S. Welles L. Bähren (Radboud)

Real-Time Detection and TBB Dumping of Crab Giant pulse Frequency  Dispersed Pulse Time  Sander ter Veen

LOFAR Air Shower Array Layout: 5 clusters of 4 particle detectors in LOFAR core RFI measurements in ASTRON’s antenna chamber Hardware & DAQ software is ready, testing under way, installation is next Will provide CR triggers to core stations

Synergies with other KSPs Technical: Identification of steady nearby and transient RFI sources Dipole-based antenna calibration and monitoring (gain, polarization) TBB software (mainly with TKP) Scientific; TKP: FRATs – triggering and identification of Fast Radio Transients Surveys: Make survey products accessible to CR community Catalog of radio sources with estimates of sizes, magnetic fields, jet powers …

Summary & Conclusions We want to explore the fastest time scales in LOFAR (down to 5ns) and develop novel techniques in radio astronomy Real-time triggering Transient Buffer-Board (TBB) utilization 3D all-sky imaging on buffered data (1sec observation needs 1TB of data to be processed…) Transient signal extraction detect airshowers from UHECRs between 1017 and 1019 eV determine radio properties with unprecedented quality (e.g., input for AUGER) determine precisely energy and composition in the suspected transition region form Galactic to Extragalactic CRs search for UHECRs and Neutrinos >1021 eV hitting the moon Verify GZK-cutoff at the very least place the best limits on super-GZK CRs and neutrinos (which SKA will surely detect) investigate and search for other sub-second signals in buffered data and collaborate with Transient KSP Giant pulses of pulsars coherent burst from exploding neutron stars, etc. Lightning SETI (One Second All-Sky Survey) provide a catalog of northern UHECR source candidates with Survey KSP.