LOFAR and LOIS Next-generation sensor networks and radio techniques for probing space

Transcription

1 Physics in Space Programme LOFAR Outrigger in Scandinavia LOFAR and LOIS Next-generation sensor networks and radio techniques for probing space Bo Thidé Swedish Institute of Space Physics, Uppsala and Dept. of Astronomy and Space Physics, Uppsala University and LOIS Space Centre, Växjö University EISCAT Radar School, Kiruna, 2005

2 New HF-VHF digital radio system for space radio LOFAR Low Frequency Array ( MHz) Test station at Exloo operational, full scale deployment in progress. Final antenna times more sensitive than any existing comparable facility. LOIS LOFAR In Scandinavia Test station near Växjö operational, fast fibre network, supercomputer Transmitter in Hörby (Teracom) Bo Thidé 2

3 Hydrogen radiates at MHz (21 cm) Very important source of radiation from space Bo Thidé 3

4 The Westerbork array of 14 dishes, each 25 m in diameter sees nearby MHz (21 cm) objects M31 (Andromeda, Local group) Bo Thidé 4

5 Q1: How to observe 21 cm line radio emission from the Epoch of Re-Ionisation? M. Rees Bo Thidé 5

6 The cosmological redshift (z~8-10) Doppler shifts the MHz signal into the HF/VHF band! Bo Thidé 6

7 Predicted EoR spectrum to test Big Bang J. Briggs Bo Thidé 7

8 LOFAR Bo Thidé 8

9 Bo Thidé 9

10 LOFAR will be a very sensitive HF/VHF array Bo Thidé 10

11 Sensor field Fibre data transport Central supercomputer Integrate LOFAR network into regional fibre network, sharing costs with schools, health centres etc. LOFAR Phase 1 - Radio telescope - Seismic imager - Precision weather for agriculture, wind energy Bo Thidé 11

12 LOFAR Initial Test Station (ITS) at Exloo Bo Thidé 12

13 First LOFAR ITS results Bo Thidé 13

14 The paradigm Conjuncture of technologies inexpensive environmental sensors high capacity fibre, wireless networks affordable supercomputers Experience with LOFAR project wide-area, large-scale, sensor network in Europe financed through regional/national/structure funds originated in the astrophysics community Issues extension of the concept to ERA activities of FP7 radio astronomy as a technology platform driver Bo Thidé 14

15 LOFAR Phase 2 into Lower Saxony, Schleswig-Holstein, Nordrhein-Westfalen Ultimate LOFAR to Växjö SE Cambridge UK Potsdam DE Nançay FR etc Bo Thidé 15

16 LOIS The LOFAR Outrigger in Scandinavia Bo Thidé 16

17 Three orthogonal linear dipole antennas probe the 3D electric field vectors Bo Thidé 17

18 Three orthogonal loop antennas probe the 3D magnetic field pseudovectors Bo Thidé 18

19 LOIS resources Supercomputer cluster (SUR grant from IBM) and Part of the LOIS Test Station outside Växjö, SE. Lars Daldorff, Axel Guthmann and the IBM system B.T. and Willem Baan (LOFAR) at the LOIS Test Station. Bo Thidé 19

20 Bo Thidé 20

21 LOIS and LOFAR Bo Thidé 21

22 LOIS first of a series of Science Operation Centres Bo Thidé 22

23 LOFAR and LOIS concept Combine advances in enabling IT inexpensive environmental sensors s of sensors wide area optical broadband networks custom+géant/danté+sunet+... high performance computing IBM BlueGene/L, IBM JS20 Clusters,... to sense and interpret the environment in innovative ways Bo Thidé 23

24 LOFAR and LOIS sensors Sensor type Applications LOFAR was conceived by the astrophysics community as a new way to build radio telescopes HF-antenna: VHF-antenna: Geophones: Weather: Water: Infra-sound: astrophysics, ionospheric/magnetospheric physics, astro-particle physics cosmology, early Universe solar effects on Earth, space weather ground subsidence micro-climate prediction gas/oil extraction precision agriculture wind energy precision agriculture habitat management public safety atmospheric turbulence, meteors, explosions, sonic booms Bo Thidé 24

25 Secondary radiation experiment setup Bo Thidé 25

26 1+2D EM Vlasov-Maxwell simulations Magnetised kinetic plasma model of the ionosphere. Pump at k = 0.05 kdebye i i injected for 600 plasma periods. Temporally moving Fourier transforms of E field in time (angular frequency; vertical) and space (wavenumber; horisontal) provides for the dynamic dispersion curves with colour-coded intensities shown. (Click for animation) (Click for animation) Low frequency region High (UH) frequency region Bo Thidé [Bengt Eliasson, Ph.D. thesis, several articles in Phys. Rev. Lett., J. Comput. Phys, ] 26

27 LOIS/LOFAR beat-wave excitation model Bo Thidé 27

28 HF pump frequency dependence Pump frequency stepped around 4f ce, EISCAT/Heating, Norway Bo Thidé 28

29 HF pump frequency dependence Pump frequency stepped around 7f ce, Sura, Russia Bo Thidé 29

30 HF pump frequency dependence Pump frequency swept continuously up and down across 4f ce, Sura, Russia BUM hysteresis HF excited secondary radiation (SEE) as recorded at the radio facility SURA near Nizhniy Novgorod, Russia, 1999 when the HF pump frequency was swept across the ionospheric 4 th gyroharmonic 60 khz Pump (Click for animation) 5340 khz Bo Thidé 4f ce 5540 khz 30

31 Secondary ionospheric radiation/see pump frequency dependence: the big picture Sideband spectra for SEE in a stationary state as a function of pump frequency f 0. Data collected at the SURA facility. Electron cyclotron harmonics (nf ce, n=4-7) are shown on the top of the figure. Sideband offset Δf=f SEE f 0. Bo Thidé 31

32 Pump frequency dependent Doppler radar returns Bo Thidé 32

33 SEE diagnostic of Langmuir turbulence NCM SEE spectrogram for the first 200 ms of pumping. Left part: frequency resolution δf = 1 khz, time step between Right part: δf = 0.2 khz, time step 500 μs. The black line shows the temporal evolution of the reflected HF. September 26, 1998, 14:52 15:26 LT; f 0 = 6778 khz 5f ce. Pump power ~ 180 MW. B.T. et al., Phys. Rev. Lett., in press, July, 2005 A sequence of separate SEE spectra obtained at different times after HF turn-on. Conclusions: broadening of the spectrum in time; an overshoot; appearance of fine structure (NC m ) possibly same as the DP feature. Bo Thidé 33

34 Statistical nature of radiation components A statistical analysis of numerous secondary radiation (SEE) components in their steady state has shown that they are all are non-sinusoidal and noise-like. Roger Karlsson, Ph.D. thesis, September 30, 2005 Bo Thidé 34

35 Polarimetric signatures of the HF pump and secondary radiation Poincaré spheres of wave polarisation Essentially 2D Lie group: SU(2) Bo Thidé 35

36 3D vector polarimetry and radio imaging Bo Thidé 36

37 3D polarimetry utilising that E(t,x) is a polar vector and B(t,x) an axial vector (pseudovector) Bo Thidé 37

38 Use EM field symmetries and conserved quantities (Noether s theorem) Bo Thidé 38

39 EM symmetries (continued) Bo Thidé 39

40 EM symmetries (continued) Bo Thidé 40

41 EM beam with spin (circular polarisation) No orbital angular momentum (OAM) Courtesy and M. J. Padgett, J. Leach et al., U. Glasgow, UK; Royal Society Bo Thidé 41

42 Field vectors across an antenna array for a radio beam with spin (circular polarisation) Phase 0 deg B. T. et al., preprint, 2005 Phase 45 deg Bo Thidé 42

43 Helical radio beams carry orbital angular momentum (OAM) B. Thidé et al., preprint, 2005 Bo Thidé 43

44 Field vectors across an antenna array for a radio beam with orbital angular momentum Phase 0 deg Phase 45 deg B. Thidé et al., preprint, 2005 Bo Thidé 44

45 EM beams with orbital angular momentum (OAM) l=+1 l=+3 l= -4 Courtesy and M. J. Padgett, J. Leach et al., U. Glasgow, UK; Royal Society Bo Thidé 45

46 OAM as turbulence diagnostic Bo Thidé 46

47 OAM as a new RF modulation technique? Bo Thidé 47

48 Cosmic ray radio flash candidates at LOIS (Dec 2004) Latest news: 27 Dec, 2004, magnetar gamma signatures tentatively observed. Bo Thidé 48

49 Bo Thidé 49

50 LOIS transmission tests Test transmissions (ionospheric interactions, space radar) will be made with Radio Sweden s 500kW HF transmitters and logperiodic antennas at Hörby, 200 km south of the LOIS test station. Will try to include other highpower HF transmitters in Europe. Bo Thidé 50

51 Ultra-High Energy Particle Detection on the Moon Oscar Stål Swedish Institute of Space Physics Uppsala, Sweden To the Moon and Beyond Bo Thidé 51

52 Ultra-High Energy Cosmic Rays CR mostly protons Highest energy observed F ~ E up to ev After knee steeper, F ~ E -3 Origin of UHECR unknown Flux obfuscated by B ev 16 J proton 100 km/h Golf ball (!) Bo Thidé 52

53 Radio methods If wavelength is longer, output will be coherent P prop. Eprimary^2 Radio transparent material required Askaryan proposed the use of ice, permafrost, very dry rock etc. Very dry rock is plentiful on the moon, at E=10^16 ev it becomes opaque Neutrino in moon -> Shower -> Emission Bo Thidé 53