LOFAR LOw Frequency Array most distant high redshift
- Slides: 74
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 - huge, fast data network huge collecting area multi-beaming (cheap)
Dutch View ~ 400 km
a Lofar `station’
LOFAR ATCA GMRT VLA ALMA 350 m 10 MHz ground based radio techniques
LOFAR 350 m 10 MHz ground based radio techniques
…this workshop… mml astronomy… Simularities: sky noise rapid phase variation Differences: solid angle of receiving element survey …. ALMA atmosphere LOFAR Gal. Synchrotron ionosphere tiny (l/D of dish) nearly all sky mosaic all-sky calibration
Top 4 LOFAR astronomical science drivers • 21 cm 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(? )
Top LOFAR astronomical science drivers • 21 cm 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(? ) t. UV< 1 … (Gunn-Peterson Effect) Z = 20 ……………. 15 ………. 10 8 cold HI 7 6 HII 70 MHz 90 MHz 130 160 190 MHz
WMAP result => Z ~ 15 to 20 2 Eo. Rs ? ? ? … or… prolonged, patchy Eo. R ? ? ? Z = 20 cold HI HII 15 10 8 7 warm HI Pop III stars: @ 500 Solar mass 6 HII
LOFAR and SKA distributed star formation … Quasar 10 arcmin
Top 4 LOFAR astronomical science drivers • 21 cm 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 (a < -2) => 1 source per sample of ~30, 000 => catalog of background radio sources for intervening HI absorption
Spectral Index Redshift
Spectral Index Redshift
Mapping intervening protogalaxies in 21 cm absorption SKAMP-III compatible !
Top 4 LOFAR astronomical science drivers • 21 cm 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 (a < -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
Radio sky in 408 MHz continuum (Haslam et al) (Dominated by synchrotron emission from relativistic electrons)
holes in the Galactic radio sky… Optically thick thermal plasma … HII regions
mapping the synchrotron emission in front of … and behind the opaque thermal sources ….
Top 4 LOFAR astronomical science drivers • 21 cm 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 (a < -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(? )
The SUN Coronal Mass Ejections, CMEs
Frank’s 3 favorites LOFAR astronomical science drivers • Highest redshift radio sources - • Steep spectrum selection (a < -2) => 1 source per sample of 10, 000 => catalog of background radio sources for intervening HI absorption #3 #1 21 cm emission/absorption from Epoch of Reionisation - • Tomography of neutral residue of IGM as first sources of ionising very tough to achieve sensitivity: high risk / high gain 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 - #2 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(? )
Dipole + ground plane conducting ground plane
Dipole + ground plane Ioe i 2 pft equivalent to dipole plus mirror image -Ioe i 2 pft
Dipole element response Ioe i 2 pft h equivalent to dipole plus mirror image h -Ioe i 2 pft
q = zenith angle Dipole Ioe i 2 pft h h equivalent to dipole plus mirror image -Ioe i 2 pft 2 P(q) ~ sin [2 ph cos(q)/l] (maximize response at q=0 if h=l/4 )
Dipole q Ioe i 2 pft azimuth 2 f h 2 P(q) ~ sin [2 ph cos(q)/l] {1 - sin q sin 2 f }
q q f q f f
The `sin projection’ of hemisphere onto a plane: The Sky above dipole
‘sin projection’ line of constant zenith angle
‘sin projection’
‘sin projection’ gives little weight to sky close to horizon !
X Y
Y X
Dipole over ground plane Tuned for 150 MHz Y X
Dipole Tuned for 150 MHz 120 180 150 210 MHz 240 MHz
What are these things?
Crossed Dipoles for dual polarization conducting plane
Droopy Dipoles for broad-band, dual polarization LOFAR-Low Band dipole element
4 x 4 array of dipoles on ground plane - the ‘LOFAR-High band’ element h s s (many analogies to gratings for optical wavelengths)
4 x 4 Tuned for 150 MHz sin projection
ZA = 0 deg 45 15 60 30 75
4 x 4 Patterns • • ZA = 30 deg tuned for 150 MHz 120 150 180 210 240
Lofar stations ? ? ?
a `station’ = 101 `4 x 4 tiles’ Size in l
a `station’ as 101 omni-directional elements Size in l
Station Beam: no 4 x 4 envelope
Station Beam: using 4 x 4 envelope
Station Beam: 4 x 4 envelope and taper
Station Beam
Offset Station Beam Centered station beam inside the 4 x 4 beam
Latitude: +53. 5 deg Decl 4 x 4: 45 Offset: 5 @ p. a. 45
Slices through 4 x 4 Beam And Station beams taper
a `station’ = 101 `4 x 4 tiles’ Size in l
Zenith no offset
Zenith + o 5 offset
Radio sky in 408 MHz continuum (Haslam et al)
-30 deg north east west south
North Latitude -30 East
North Latitude +53. 5 East
+53. 5 deg north east west south
-30 deg north east west south
Top 4 LOFAR astronomical science drivers • 21 cm 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
Top 4 LOFAR astronomical science drivers • 21 cm 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
Effect of moving station beam w. r. t. 4 x 4 beam ZA = 30 deg for 4 x 4 5 deg Offset for station beam
GAIN d. B
GAIN d. B 2. 5 deg offset
GAIN d. B 7. 5 deg offset
GAIN d. B
GAIN d. B 4 x 4 ZA = 30 deg
- Lofar technologies
- Lofar
- Middle = low + (high - low) / 2
- Do electromagnetic waves require a medium
- Types of medium frequency current
- Apparent vs absolute magnitude
- Dwu
- The universe expanding than
- Redshift deadlock detected
- Big bang solar system
- Classmethod aws
- Redshift create index
- Cannibal inhabitants of a distant land
- Onomatopoeia in caged bird
- Bare willows and distant mountains
- Distant
- Distant retrograde orbit
- Lod example
- Interpreting motion graphs
- Distant
- Aims are
- Peace is not merely a distant goal
- Distant past tense
- Emotive style communication
- Significant figures
- Low voltage hazards
- Lga pga
- Array 3 dimensi adalah
- Jagged array
- Associative array vs indexed array
- Difference between broadside and endfire array
- Apa itu menginisialisasi
- Array yang sangat banyak elemen nol-nya
- Array satu dimensi dan dua dimensi
- Photovoltaic array maximum power point tracking array
- Define low frequency current
- Low frequency current in physiotherapy
- Low frequency attenuation
- Low frequency algorithmic trading
- Low frequency attenuation
- Low frequency attenuation
- Extreme low frequency
- What is a conditional relative frequency
- Probability with relative frequency
- Average of sine wave
- Vmax= aw
- Relative frequency bar chart
- What is a marginal frequency
- Joint relative frequency
- High low birthday guesser
- Facilitated diffusion high to low
- Low german vs high german
- High art vs low art
- Conflict with interest
- High surface tension vs low surface tension
- 3 to 8 decoder truth table
- R22 pt chart low side
- Gearing ratios
- High context vs low context culture ppt
- High context vs low context culture ppt
- Oxygen flow rate chart
- Venturi mask
- Non rebreather mask definition
- High low method cost equation
- What is a low spin complex
- High low method formula
- High bypass turbofan vs low bypass
- Archer risk assessment
- High vs low small bowel obstruction
- Low wages high rent political cartoon meaning
- Low and high uncertainty avoidance
- Heat budget of earth
- High art vs low art examples
- Where should there be low friction on a mountain bike
- Low floor high ceiling math tasks