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 producedwhat they are made offexact shape of the

energy spectrum

Potential Sources

Hillas plot: Gyro radius has to fit source size!

Galactic < 1017eVSupernovaeneutron stars & stellar

black holes Extragalactic >1018 eV

Supermassive black holesGamma-Ray burstsIntergalactic shocksTop-down: decay of

primordial superheavy particles (?)

1 EeV = 1018 eV

eBER CR

gyr

Radio Images of Cosmic Accelerators

Cas ACygnus A

Fornax A

NRAO/AUI

1.4 , 5, & 8.4 GHz

The Pierre Auger Observatory

Auger: Clustering of UHECRs

The beginning of “charged particle astronomy”!

AUGER Collaboration (2007), Science9. 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)

prediction for iron nuclei

proton prediction

Auger Data

Dep

th o

f sho

wer

max

imum

in a

tmos

pher

e

Cosmic Rays in the Radio

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 RaysMeasure 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 KSPTransients: 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

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 E∝ e2 N∝ e

2

⇒ GJy flares on 20 ns scales

coherent

E-Field

shower front

e± ~50 MeV

Geo-synchrotron

Falcke & Gorham (2003), Huege & Falcke (2004,2005) Tim Huege, PhD Thesis 2005 (MPIfR+Univ Bonn

Earth

B-Field

~0.3 G

Cross Calibration of LOPES10 and KASCADE

B-field

Distance

UHECR Particle Energy

Horneffer-Formula 2008

Energy and Composition from MC Simulations

Huege et al. 2008, (Astropart. Phys.) - REAS2 code

lateral radio profile Xmax radio flux N

e

~5% shower-to-shower fluctuations

LOPES Data

(Horneffer et al. 2007)

LOPES-KASCADE

Imaging of CR radio pulses with LOPES

See also Falcke et al. (LOPES collaboration) 2005, Nature, 435, 313

Horneffer, LOPES30 event

A. Nigl 2007, PhD

Nanosecond Radio Imaging in 3D

Off-line correlation of radio waves captured in buffer memory

We can map out a 5D image cube:3D: space2D: 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)

Actual 3D radio mapping of a CR burst

No simulation!

UHE Neutrino detection needs large detector volumes!Auger: Aeff=3000 km2, Moon: Aeff=9×106 km2

Back to the moon …

Cosmic Ray

100 MHz Radio Waves

Westerbork antennas

Westerbork Synthesis Radio Telescope

Westerbork (WSRT) Experiment

4 freq.

bands

4 freq.

bands

UHE Neutrino Limits from WSRT νMoon Experiment

nMoonAnita ‘08

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)

A. Corstanje (Radboud)

LOFAR low-band has all-sky visibility!

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

Time

Freq

uenc

y

Dispersed Pulse

Sander ter Veen

LOFAR Air Shower ArrayLayout:

5 clusters of 4 particle detectors

in LOFAR core

RFI measurements in ASTRON’s antenna

chamber

Will provide CR triggers to core stations

Hardware & DAQ software is ready, testing under way, installation is next

Synergies with other KSPs

Technical:Identification of steady nearby and transient RFI sourcesDipole-based antenna calibration and monitoring (gain,

polarization)TBB software (mainly with TKP)

Scientific;TKP: FRATs – triggering and identification of Fast Radio

TransientsSurveys: Make survey products accessible to CR

communityCatalog 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.