1. LOFAR LOw Frequency Array => most distant, high redshift Universe !? Consortium of international partners… Dutch ASTRON USA Haystack Observatory (MIT) USA Naval Research Lab … `best site’ = WA … … … Novel `technology telescope’ - array design => no moving parts (cheap) - huge, fast data network - huge collecting area multi-beaming - multi-beaming

2. Dutch View ~ 400 km

3. a Lofar `station’

4. ground based radio techniques 10 MHz 350  VLAALMA ATCA GMRT LOFAR

5. ground based radio techniques 10 MHz 350  LOFAR

6. …this workshop… mm astronomy… ALMA LOFAR Simularities: sky noise atmosphere Gal. Synchrotron rapid phase variation atmosphere ionosphere Differences: solid angle of tiny ( /D of dish) nearly all sky receiving element survey …. mosaic all-sky calibration

7. Top 4 LOFAR astronomical science drivers 21cm emission/absorption from Epoch of Reionisation -mapping the neutral clouds in IGM as first sources of ionising radiation appear at redshifts between 7 and 20(?)

8. Z = 20 ……………. 15 ………. 10 8 7 6 cold H I H II Top LOFAR astronomical science drivers 21cm emission/absorption from Epoch of Reionisation -mapping of neutral residue of IGM as first sources of ionising radiation appear at redshifts between 7 and 20(?)  < 1 … (Gunn-Peterson Effect) UV 70 MHz 90 MHz 130 160 190 MHz

9. Z = 20 15 10 8 7 6 cold H I warm H I 2 EoRs ??? … or… prolonged, patchy EoR ??? Pop III stars: @ 500 Solar mass H II WMAP result => Z ~ 15 to 20

10. 10 arcmin LOFAR and SKA … Quasar distributed star formation

11. Top 4 LOFAR astronomical science drivers 21cm emission/absorption from Epoch of Reionisation -mapping of neutral clouds in IGM as first sources of ionising radiation appear at redshifts between 7 and 20(?) Highest redshift radio sources -Steep spectrum selection (  1 source per sample of ~30,000 -=> catalog of background radio sources for intervening HI absorption

12. Spectral Index Redshift

13. Spectral Index Redshift

14. Mapping intervening protogalaxies in 21cm absorption SKAMP-III compatible !

15. Top 4 LOFAR astronomical science drivers 21cm emission/absorption from Epoch of Reionisation -mapping of neutral clouds in IGM as first sources of ionising radiation appear at redshifts between 7 and 20(?) Highest redshift radio sources -Steep spectrum selection (  1 source per sample of ~30,000 -=> catalog of background radio sources for intervening HI absorption 3-D mapping of the Galactic non-thermal emission -uses free-free absorption by known extended thermal sources -will determine the origin of the Galactic cosmic ray flux

16. Radio sky in 408 MHz continuum (Haslam et al) (Dominated by synchrotron emission from relativistic electrons)

17. holes in the Galactic radio sky… Optically thick thermal plasma … HII regions

18. mapping the synchrotron emission in front of … and behind the opaque thermal sources ….

19. Top 4 LOFAR astronomical science drivers 21cm emission/absorption from Epoch of Reionisation -Mapping of neutral clouds in IGM as first sources of ionising radiation appear at redshifts between 7 and 20(?) Highest redshift radio sources -Steep spectrum selection (  1 source per sample of ~30,000 -=> catalog of background radio sources for intervening HI absorption 3-D mapping of the Galactic non-thermal emission -uses free-free absorption by known extended thermal sources -will determine the origin of the Galactic cosmic ray flux Transient and bursting sources -no moving parts => nearly instantaneous response to trigger events -central core is an all-sky (hemisphere) monitor -sensitive to non-thermal, coherent emission events, should they exist(?)

20. The SUN Coronal Mass Ejections, CMEs

22. Highest redshift radio sources -Steep spectrum selection (  1 source per sample of 10,000 -=> catalog of background radio sources for intervening HI absorption 21cm emission/absorption from Epoch of Reionisation -Tomography of neutral residue of IGM as first sources of ionising radiation appear at redshifts between 7 and 20(?) 3-D mapping of the Galactic non-thermal emission -uses free-free absorption by known extended thermal sources -will determine the origin of the Galactic cosmic ray flux Transient and bursting sources -no moving parts => nearly instantaneous response to trigger events -central core is an all-sky (hemisphere) monitor -sensitive to non-thermal, coherent emission events, should they exist(?) LOFAR astronomical science drivers Frank’s 3 favorites very tough to achieve sensitivity: high risk / high gain #1 #2 #3

24. Dipole + ground plane conducting ground plane

25. Dipole + ground plane equivalent to dipole plus mirror image I e o i 2  ft - I e o i 2  ft

26. h Dipole element element response response equivalent to dipole plus mirror image I e o i 2  ft - I e o i 2  ft h

27. h Dipole equivalent to dipole plus mirror image I e o i 2  ft - I e o i 2  ft h  P(  ) ~ sin [ 2  h cos(  )/ ] 2 = zenith angle (maximize response at  =0 if h= /4 )

28. Dipole I e o i 2  ft h  P(  ) ~ sin [ 2  h cos(  )/ ] {1 - sin  sin  } 2  azimuth 2 2

29.        

30. The Sky above dipole The `sin projection’ of hemisphere onto a plane:

31. ‘sin projection’ line of constant zenith angle

32. ‘sin projection’

33. gives little weight to sky close to horizon !

34. X Y

35. X Y

36. Dipole Tuned for 150 MHz over ground plane X Y

37. 120 150 180 210 MHz 240 MHz Dipole Tuned for 150 MHz

38. What are these things?

39. Crossed Dipoles for dual polarization conducting plane

40. Droopy Dipoles for broad-band, dual polarization LOFAR-Low Band dipole element

41. h s s 4x4 array 4x4 array of dipoles on ground plane - the ‘LOFAR-High band’ element (many analogies to gratings for optical wavelengths)

42. 4x4 Tuned for 150 MHz sin projection

43. ZA = 0 deg 15 30 45 60 75

44. 4x4 Patterns 120 150 180 210 240 ZA = 30 deg tuned for 150 MHz

45. Lofar stations ???

46. Size in a `station’ = 101 `4x4 tiles’

47. Size in a `station’ as 101 omni-directional elements

48. no Station Beam: no 4x4 envelope

49. Station Beam: using 4x4 envelope

50. Station Beam: 4x4 envelope and taper

51. Station Beam

52. OffsetStationBeam inside the 4x4 beam Centered station beam

53. Latitude: +53.5 deg Decl 4x4: 45 Offset: 5 @ p.a. 45

54. Slices through 4x4 Beam And Station beams taper

55. Size in a `station’ = 101 `4x4 tiles’

56. Zenith no offset

57. o Zenith + 5 offset

58. Radio sky in 408 MHz continuum (Haslam et al)

59. north south west east - 30 deg

60. East North Latitude -30

61. East North Latitude +53.5

62. north south west east +53.5 deg

63. north south west east - 30 deg

64. Top 4 LOFAR astronomical science drivers 21cm emission/absorption from Epoch of Reionisation Highest redshift radio sources [ => catalog of background radio sources for intervening HI absorption ] 3-D mapping of the Galactic non-thermal emission Transient and bursting sources

65. Top 4 LOFAR astronomical science drivers 21cm emission/absorption from Epoch of Reionisation Highest redshift radio sources [ => catalog of background radio sources for intervening HI absorption ] 3-D mapping of the Galactic non-thermal emission Transient and bursting sources

66. ZA = 30 deg for 4x4 5 deg Offset for station beam Effect of moving station beam w.r.t. 4x4 beam

67. GAIN dB

68. 2.5 deg offset GAIN dB

69. 7.5 deg offset

70. GAIN dB

71. 4x4 ZA = 30 deg