1. Ben Stappers (ASTRON) LOFAR 101 Pizza Lunch

2. LOFAR Technical Concept LOFAR is a very large distributed radio telescope: LOFAR is a very large distributed radio telescope: 13,000 small antennas13,000 small antennas in 77 stations 32 Core / 45 remotein 77 stations 32 Core / 45 remote Core about 2.5 km in diameterCore about 2.5 km in diameter 100 km baselines (European 1000km)100 km baselines (European 1000km) 30 - 240 MHz (10m -- 1.25m)30 - 240 MHz (10m -- 1.25m) 10mNo moving parts: electronic beam steering10mNo moving parts: electronic beam steering >20 Tbit/sec raw data>20 Tbit/sec raw data >40 Tflop supercomputer>40 Tflop supercomputer innovative software systemsinnovative software systems datamining and visualisationdatamining and visualisation Full and exclusive control via the Internet Full and exclusive control via the Internet Instantaneous view of the full sky Instantaneous view of the full sky Multi-beaming:several simultaneous users. Multi-beaming:several simultaneous users.

3. Key Numbers & Antennae Frequency Range Low Band: 30-80 MHz / High Band: 110-240 MHz Number of Antennas Low Band: 7700 / High Band: 7700 (4x4) Polarization Full Stokes Configuration Virtual Core: 3200 antennas, 32 station, baselines 100 m - 2 km 3200 antennas, 32 station, baselines 100 m - 2 km Outside Core: 4500 antennas, 45 station,baselines up to 100 km 4500 antennas, 45 station,baselines up to 100 km Digitized Bandwidth 100 MHz (10-90, 110-190 and 210-290 MHz) 80 MHz (170-230 MHz) Processing Capacity Full Array Imaging: 32 MHz - 12 bit Core Station Beams: up to 32 MHz, 20 beams, 4-bit Can trade bandwidth for station beams. Almost fully sample antenna beam (ASM) with 4 MHz beams. LBA HBA

4. Remote Station Hardware Numbers  96 dual polarization low band antennas  96 dual polarization high band tiles  192 receiver boards  24 digital signal processing boards  12 transient buffer boards  6 backplanes  6 clock boards  Input data rate: ~ 460 Gb/s  Output data rate: ~ 2 Gbps  Processing capacity: ~ 1.5 Tmul/s  Storage capacity (Transient Buffer): 96 Gbyte RAM Multiply by 77!!

5. Transient Buffering LCU Trigger External triggerG. trigger

6. LOFAR top-level architecture: operations view

7. Wide Area Network  Data transport from stations and central core to central processor facility  Dedicated fiber connection between core and central processor Central Processing Facility Central Core  up to 800 Gbps bandwidth  10 GbE CWDM  8 channels  length ~70 km  Remote station connections:  10 GbE technology  data rate 2 Gbps from antennas + monitoring + other sensors

8. CEP Implementation Model  Multiple sub-clusters with task-optimised hardware  BlueGene inside Streaming Data Data Handling Filter and Correlator Storage Export Calibration Imaging end products Dynamic models

9. Subsystems: Blue Gene/L 6 racks 128 IO nodes and 1024 compute nodes 128 IO nodes and 1024 compute nodes Internal Tree and Torus (175 MB/s * 6) )directions) Internal Tree and Torus (175 MB/s * 6) )directions) Compute node Compute node Dual core/512 MB RAMDual core/512 MB RAM IO node IO node 1 GbE connection to 8 compute nodes1 GbE connection to 8 compute nodes Diskless Diskless 27.4 Tflops!

10. Scheduling on subsystems

11. The Calibration Challenge  25 TByte of data 10 13 samples 10 13 samples  Models of Instrument Instrument Ionosphere Ionosphere Sky sources Sky sources  Vary in time, freq., …  ~100 000 parameters  Correctly model physics Image plane effects Image plane effects Instrument behaviour etc. Instrument behaviour etc.  Complex minimalisation problem!

12. Initial Test Station

14. The next deliverable: CS1  Hardware of 1 station  Distributed over 4 station locations  12 Gbps connection to Groningen  Downscaled CEP installation

15. CS-1  Operational Sept. 1, 2006 with final prototype hardware  96 dual-dipole antennas: grouped in 4 clusters grouped in 4 clusters one cluster with 48 dipoles one cluster with 48 dipoles three clusters of 16 dipoles three clusters of 16 dipoles distributed over ~ 500m. distributed over ~ 500m. with 24 microstation in total with 24 microstation in total of 4 dipoles each of 4 dipoles each  Goal: Emulate LOFAR with 24 micro-stations at reduced bandwidth or act as a single station at full BW  TBB & HBA will follow later  Conclude CDR Based on CS-1 Results

17. LOFAR Key Science Programs  Cosmology (Groningen: deBruyn) Epoch of Reionization, first stars in the universe Epoch of Reionization, first stars in the universe  Surveys (Leiden: Miley/Rottgering) Star forming galaxies, AGN, Clusters, etc. Star forming galaxies, AGN, Clusters, etc.  Transient detection (Amsterdam: Wijers/Fender/Braun/Stappers) Everything that bursts, pulses and varies in general Everything that bursts, pulses and varies in general  Astroparticle Physics (Nijmegen: Kuijpers/Falcke) Direct detection of cosmic rays Direct detection of cosmic rays Cosmic rays & neutrinos impacting the moon Cosmic rays & neutrinos impacting the moon

18. Sequence of Events At z=1000 the Universe has cooled down to 3000 K. Hydrogen becomes neutral (“Recombination”). At z < 20 the first “PopIII” star (clusters)/small galaxies form. At z ~ 6-15 these gradually photo-ionize the hydrogen in the IGM (“Reionization”). At z<6 galaxies form most of their stars and grow by merging. At z<1 massive galaxy clusters are assembled. Time Ferrara, 2005 ‘Cosmo05’

19. Main science goals of LOFAR – EoR observations  Determine Epoch (or Era) of Reionization  115 MHz  z = 11.4 (WMAP 3 years: z~11-6)  115 MHz  z = 11.4 (WMAP 3 years: z~11-6)  180 MHz  z = 6.9  180 MHz  z = 6.9  Infer sources of reionization (modeling)  hot (massive) stars in forming galaxies: photons with l < 912 Angstrom  hot (massive) stars in forming galaxies: photons with l < 912 Angstrom  Black Holes in (forming) galaxies: photons up to X-ray energies  Black Holes in (forming) galaxies: photons up to X-ray energies  Measure power spectrum of fluctuations as function of redshift  on angular scales from 1’ - 1 o  on angular scales from 1’ - 1 o  on frequency scales from 0.1 - 10 MHz  on frequency scales from 0.1 - 10 MHz  Search for giant Stromgren holes around luminous QSO’s  Search for 21cm line forest in high z radio sources

20. LOFAR Deep fields Billions of new sources  LOFAR has a very large field of view and be an ideal survey telescope.  We expect to find > 100 Million new sources: stars & planets stars & planets star forming galaxies star forming galaxies active black holes active black holes first objects in the universe first objects in the universe ??? ??? Simulated radio deep field. Radio image of giant radio galaxy When & how did galaxies form? When & how did the first BHs form? When did the large scale structure form? What is the relative timescale of them all?

21. RSM - Detect all radio transients Unique and achievable!!! X-ray binaries, AGN, GRBs… Pulsars Planets - solar and extra-solar Flare stars & Serendipity Transients Lars Baehren - ITS Jupiter Burst Zarka Star-Planet Interaction Study variability on timescales from microseconds to years Osten - Flare Stars

22. Transients PlanetsSynchrotron Sources

23. Pulsars van Leeuwen & Stappers 2006 1500 new pulsars: A full local census of radio emitting NSs Geminga like & AXPs/SGRs Steep spectrum (>-3,B0943) MSPs (unbroken spectra) RRATs (long pointings, low-DM) Mostly off sources (on 10%) First Truly Extragalactic pulsars Sensitive to normal and GP emission from nearby galaxies. M33, 10 h,L> 57 Jy kpc 2, 10 pulsars known Brightest to 1.2 Mpc Depending on SI can detect GPs out to 2-4.5 Mpc

24. Cosmic Rays Cosmic Rays Atmospheric interaction: Geosynchrotron emission (10-100 MHz) Lunar Interatcion: Cerenkov emission (100 - 2000 MHz)

25. Conclusions Conclusions LOFAR is reopening the low-frequency radio astronomical window with unprecedented sensitivity and resolution. This not only provides an exciting new window to study well known phenomena but opens up the possibility to study completely new areas Given the two-orders of magnitude improvement in sensitivity, and the amazing time resolution new sources and phenomena will definitely be discovered! If you are interested and/or have an interesting idea then get involved!!!