=> most distant, high redshift Universe!? Consortium of international partners

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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

2 Dutch View ~ 400 km

3 a Lofar `station

4 LOFAR 10 MHz VLALMA GMRT ATCA 350µ ground based radio techniques

5 LOFAR 10 MHz 350µ ground based radio techniques

6 this workshop mmλ astronomy ALMA LOFAR Simularities: sky noise atmosphere Gal. Synchrotron rapid phase variation atmosphere ionosphere Differences: solid angle of tiny (λ/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 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(?) τ < 1 (Gunn-Peterson Effect) UV Z = cold HI HII 70 MHz 90 MHz MHz

9 WMAP result => Z ~ 15 to 20 2 EoRs??? or prolonged, patchy EoR??? Z = cold HI HII warm HI HII Pop III 500 Solar mass

10 LOFAR and SKA distributed star formation Quasar 10 arcmin

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 (α < -2) => 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 (α < -2) => 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 (α < -2) => 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

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22 Frank s 3 favorites LOFAR astronomical science drivers Highest redshift radio sources - Steep spectrum selection (α < -2) => 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 very radiation tough appear to achieve at redshifts sensitivity: between 7 and high 20(?) risk / high gain 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(?) #3 #1 #2

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24 Dipole + ground plane conducting ground plane

25 Dipole + ground plane i2πft I o e equivalent to dipole plus mirror image -I e o i2πft

26 Dipole element response i2πft I o e h equivalent to dipole plus mirror image h -I e o i2πft

27 Dipole θ = zenith angle h i2πft I o e equivalent to dipole plus mirror image h -I e o i2πft 2 P(θ) ~ sin [2πh cos(θ)/λ] (maximize response at θ=0 if h=λ/4 )

28 Dipole θ i2πft I o e azimuth φ h 2 P(θ) ~ sin [2πh cos(θ)/λ] {1 - sin θ sin φ } 2 2

29 θ φ θ φ φ θ φ θ

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

31 sin projection line of constant zenith angle

32 sin projection

33 sin projection gives little weight to sky close to horizon!

34 Y X

35 Y X

36 Dipole over ground plane Y Tuned for 150 MHz X

37 Dipole Tuned for 150 MHz MHz 240 MHz

38 What are these things?

39 Crossed Dipoles for dual polarization conducting plane

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

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

42 4x4 Tuned for 150 MHz sin projection

43 ZA = 0 deg

44 4x4 Patterns ZA = 30 deg tuned for 150 MHz

45 Lofar stations???

46 Size in λ a `station = 101 `4x4 tiles

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

48 Station Beam: no 4x4 envelope

49 Station Beam: using 4x4 envelope

50 Station Beam: 4x4 envelope and taper

51 Station Beam

52 Offset Station Beam Centered station beam inside the 4x4 beam

53 Latitude: deg Decl 4x4: 45 Offset: p.a. 45

54 Slices through 4x4 Beam And Station beams taper

55 Size in λ 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 south -30 deg north east west

60 North Latitude -30 East

61 North Latitude East

62 south deg north east west

63 south -30 deg north east west

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

67 GAIN db

68 2.5 deg offset GAIN db

69 7.5 deg offset GAIN db

70 GAIN db

71 4x4 ZA = 30 deg GAIN db

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