LOFARLOFARThe Low-Frequency ArrayThe Low-Frequency Array

HeinoHeino Falcke FalckeLOFAR International Project ScientistLOFAR International Project Scientist

ASTRON, ASTRON, DwingelooDwingeloo(Netherlands Foundation for Research in Astronomy)(Netherlands Foundation for Research in Astronomy)

&&RadboudRadboud University, University, NijmegenNijmegen

Next generationradio telescope

• Telescope the size of theNetherlands plus Germany

• Frequencies: 30 - 240 MHz• 10% Square Kilometer Array (SKA)

prototype at low-frequencies• Interferometer baselines: 100 km

– European Expansion to 1000 km• Aperture array: Replace big dishes

by many cheap dipoles– 100 stations of 100 dipole antennas

+ extra sensors (geo+meteo)– No moving parts: electronic beam

steering– supercomputer synthesizes giant

dish• Current Funding: 74 M€• Two orders of magnitude

improvement in resolution andsensitivity

• Science applications: Big bang,astroparticles and the unknown

construction: 2006-2007

LOFAR - phased array telescope

LOFAR Key Science Programs

• Cosmology (Univ. Groningen, deBruyn)– Epoch of Reionization

• All-Sky Surveys (Univ. Leiden, Rottgering)– Star forming galaxies, AGN, Clusters, etc.

• Transient detection (Univ. Amsterdam,Wijers)– Everything that bursts and varies

• Astroparticle Phyiscs (Univ. Nijmegen,Kuijpers/Falcke)– Direct detection of cosmic rays– Cosmic rays & neutrinos impacting the moon

History of the Universe(condensed version)

Opaque

First Stars

Formation of Earth

Now

LOFAR

Invisible

Cosmological Redshift -Hydrogen line is seen at:

Big Bang Hydrogen

Sun & Earth

1.4 MHz 14 MHz 140 MHz1.4 GHz

protons

LOFAR Deep fieldsBillions of new sources

• LOFAR has a very largeField of View and be anideal survey telescope.

• LOFAR will be an all-skymonitor for detectingbursting (transient) radiosources.

• We expect to find > 100Million new sources:– stars & planets– star forming galaxies– active black holes– first objects in the universe– ???

Simulated radio deep field.

Radio image ofgiant radio galaxy

LOFAR simple-stationprototype:

500 Second All-Sky Map

LOFAR will have 1000 times higher resolution,100 times higher sensitivity, and 105 times

more integration time.

Transients with LOFAR-ITS:Jupiter and Lightning

L. Bähren (ASTRON)

Actual time span: 25 ms, 0.1ms/framePlaying time: 31 secFrequency: 23-26 MHz

Dynamic Spectrum

LOFAR Prototype Station (LOPES):detection of nanosecond radio flashes from

ultra-high energy elementary particles

All-Sky Movie of Radio Flash:200 ns duration

LOFAR Prototype Station:10 LOFAR Antennas

Falcke et al. (2005), Nature, Vol. 435, p. 313

Low-Frequency Observationsof the Moon

• Lunar radio emission isalso produced byCosmic Ray showersimpacting on the moon(Zas, Alvarez-Muniz)

• Low Frequencies havelonger attenuationlengths and samplelarger volume.

• Lunar observationsmay give best limit onsuper GZK CosmicRays!

Cosmic Rays

Scholten, et al. (2005, in prep.)

Ultra-High-Energy Cosmic Rays and Neutrinos:Low-Frequency Observations of the Moon

• Lunar radio emission isalso produced byCosmic Ray showersimpacting on the moon

• Low Frequencies havelonger attenuationlengths and samplelarger volume.

• Lunar observationsmay give best limit onsuper GZK CosmicRays!

Cosmic Rays

Scholten, et al. (2005, in prep.)

IBM Blue Gene/L “Stella” – theheart of LOFAR

• 27,4 Tflop

• ~ 12000 PCs

• Occupying 6 m2

• 150 KW power

consumption

• 0,5 Tbit/s input

• Now operational~1.7% slower than #1 in Europe (Barcelona) …

Dutch minister of science

Blue Gene

LOFAR Stations

• 96 Low Band Antenna’s• Distributed over ~60 m• Optimized for 30-80 MHz

• 96 High Band Tiles• 4x4 antenna’s• Disitributed over ~50m• Optimized ~115-240 MHz

Low Band Antennas

High Band Antennas

LOFAR Station Layout

Low BandHigh Band

60 m 50 m

Other Sensors

LOFAR Configuration

Virtual Core Phase I Layout

Land acquisition:200 out of 400 ha

secured

Network:Exloo – Groningen

link is in place

UV-CoverageVirtual Core 100km Array

Dec 80° Dec 50°

Dec 20° Dec 0°

Dec 80° Dec 50°

Dec 20° Dec 0°

LOFAR Basic Properties

European Expansion …

Current discussions:

Germany ~12 stations

UK ~2-3 stations

Italy ~2 stations

France ~1 station?

Poland ~1 station?

GLOW – German LongWavelength Consortium

German Roadmap

• Informal discussions with a group of universities (twice peryear)

• Writing of a White Paper• Presentation of WP to German Community• Individual grant applications by some institutes for stations

(two already honored)• Presentation of plan to to German ministries• Basic documents describing data rights and access,

involvement of German institutes are being developed• Memorandum of Understanding to create German Long

Wavelength (GLOW) consortium• Effelsberg will get first remote station this summer• Discussions with German supercomputing center (Jülich)

about support for German community (LOFAR science center)

Guidelines for remote stations

• The environment (now and in the future)– Fairly isolated– No power lines within 2 km– No highway within 500 mtr– No urban development within 500 mtr– No railroad, tramway within 2 km– No windmills within 2 km– No forest or high trees within 100 mtr. At south no trees within 500 mtr– No other radio interference sources in the neighborhood– A location in or at the fringe of a nature reserve is favorable but requires good

communication with environmentalists and nature organizations.• The location itself.

– Accessible by at least a macadam or sandy road.– 3 – 4 ha (200 x 200 mtr), however different sizes up to a minimal width of 120 mtr are

possible.– As horizontal as possible– Well drained, some water on the land during heavy rains is no probleme– With respect to the cables which shall be put into the ground look for a piece of land with

low potential for archeological findings.– In the Netherlands no iron fences will be used. However by using natural barriers (ditches,

swamps, hedges) entrance will be difficult.• Communication.

– The experience in the Netherlands learns that early, open en intensive communication withgovernmental organizations, public, neighbors etc will contribute to a fast acceptance of theproject and its location.

RFI/spectrum monitoring ofpotential remote station fields

• Monitoring full responsibility of ASTRON/LOFAR– Procedures

• Field requirements• RFI Monitoring• Field inspection

– Measurement equipment and transport– Datasets and analysis– Summary report

• Measurement data summary• Field inspection summary• Conclusions and recommendations

• Support/logistics required from hosts• Issue formal request for monitoring• Travel & hotel costs• Transport costs• Location coordinates, region, city, village, public or private property,….• Host representative at site location during monitoring• Request permission for spectrum measurements/monitoring in Germany

(approval required from national telecom agency)• communication with governmental organizations, public, neighbors etc

LOFAR Schedule

Jan 2004 2005 2006 2007 2008 2009 2010

CDRConnectionCore - Blue Gene/L Core Ring 2Inner ring

Ultimate Operation Initial Operation

Design & engineering

Procurement

Rollout and Integration

2020

CoreTestStation?

Core Station 1

• Operational May 1,2006 with “final”prototype hardware

• 96 dual-dipoleantennas:– grouped in 4 clusters– with 6 sub-stations– of 4 dipoles each– distributed over up to 1

km.• Emulate LOFAR with 24

micro-stations atreduced bandwidth orsingle station at full BW

Future Directions: Low-Frequency antennas at AUGER

Future directions:LOFAR on the Moon

• Below 10 MHz theatmosphere blocks radioemission.

• Man-made interferencecompletely swamps allsignals.

• No astronomy has everbeen done in this long-wavelength regime.

• The only location where thiscan be explored is the far-side of the moon.

• A single Ariane V couldbring a ~300m LOFARtelescope to the moon!

• Cooperation with EADSSpace Transportation.

EADS/ASTRON study

Summary

• LOFAR is well on track, first science already• It is the first serious aperture array and digital

software telescope in astronomy – excellentpreparation for SKA

• It will open up an almost forgotten frequency rangeand improve by two orders of magnitude

• Future:– European expansion– add multidisciplinary applications– add VLF antennas– put LOFAR antennas near AUGER – the world largest

cosmic ray detector in Argentina– there should be a southern LOFAR eventually …– put LOFAR on the moon …

New digital low-frequencyreceivers (LFFE) at Westerbork

3C147 with WesterborkFrequency: 163 MHzField of View: 20o x 20o

Integration: 12 hrs de Bruyn & Brentjens (2005)

Lightning with ITS

L. Bähren (ASTRON)

Actual time span: 25 ms, 0.1ms/framePlaying time: 31 secFrequency: 23-26 MHz

Dynamic Spectrum

LOFAR Network withGeophones + Infrasound

Precision Agriculture

• Use LOFAR infrastructure astestbed for sensor networksin agriculture

• Test case: Phytophthoradisease in potatoes

• Measure humidity in testfields

• Model spread of diseases incomputer

Þ Give farmer preciseinformation on usage ofpesticides, avoidingunnecessary spraying ofchemicals.

LOFAR top-level architecture:operations view

Catalogues

Modeling

Specificationand

Scheduling

Controland

Monitoring

GraphicalInterface

GraphicalInterface

Data Taking

CalibrationPre

Processing

Correlation /Beamforming

Fringe

Calibration

RFIMitigation

Storage

Archive

Export

OperatorScience OperationCenters

preparation

analysis

visualisation

Calibration

productcreation

Schedule

Central Processing

Raw dataCalibrated dataData productsMeta data

World Wide data AccessSensor fields

Internet & GRID

Archive

LOFAR top-level architecture:dataflow view

LOFAR Basic Parameters

Full Array Imaging: 32 MHzFull Array Imaging: 32 MHz

Core Imaging Mode: ~200 beams (4 MHz, 4kHz)Core Imaging Mode: ~200 beams (4 MHz, 4kHz)Expected Processing CapacityExpected Processing Capacity

100 MHz (10-90, 110-190 and 210-290 MHz)100 MHz (10-90, 110-190 and 210-290 MHz)80 MHz (170-230 MHz)80 MHz (170-230 MHz)

Digitized BandwidthDigitized Bandwidth

Virtual Core:Virtual Core:–– 3200 antennas 3200 antennas–– 32 stations 32 stations

–– baselines 100 m - 2 km baselines 100 m - 2 kmOutside Core:Outside Core:

–– 4500 antennas 4500 antennas–– 45 stations 45 stations–– baselines up to 100 km baselines up to 100 km

ConfigurationConfiguration

Full StokesFull StokesPolarizationPolarization

Low Band: 7700Low Band: 7700High Band: 7700 (4x4)High Band: 7700 (4x4)

Number of AntennasNumber of Antennas

Low Band: 30-80 MHzLow Band: 30-80 MHz

High Band: 110-240 MHzHigh Band: 110-240 MHzFrequency RangeFrequency Range