Kinetic
description
Transcript of Kinetic
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KineticCMB
Ionized fraction xi = 1 - xHI
Mean brightness temperature
Spin, TS
Pritchard & Loeb 2008
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3 observational techniques:
1. 21 cm forest2. Power spectrum/tomography3. Global spectrum
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1. 21 cm forest
Carilli et al. (2004)
But not until 2020+
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2. Power spectrum
CMB
21 cm(3D)z~100(2D)
Kleban et al. 2007Loeb & Zaldarriaga 2004
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2. Power spectrum
“Science with the MWA”Greenhill, Bowman, et al. (2010, in prep)
Figure by Matt McQuinn
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2. Power spectrum
[21cmFast simulation]
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3. Global spectrum
J. Pritchard
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3. Global spectrum
Code from J. Pritchard
N_ion
f_esc
f_star
f_lya
f_xray
- Number of ionizing photons per baryon in star formation
- Escape fraction of ionizing photons from galaxies(probably between 0.02 and 0.2)
- Star forming efficiency by mass(uncertain to order of magnitude)
- Number of Ly- photons per baryon in stars (popII)(uncertain to a factor of few)
- X-ray luminosity relative to value extrapolated from Glover and Brand (uncertain to more than order of magnitude)
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3. Global spectrum
Mack & Wesley (2008)
Primordial BH evaporation
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Murchison Widefield Array(MWA)
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Murchison Widefield Array (MWA)
Science: 21 cm cosmology, heliosphere, transients,and Galactic physics
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MWA: Antenna Tile
12
1
2
3
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MWA
150 m
32 tiles32 tiles
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MWA first image with correlator
C. Williams (MIT)
32 MHz multi-frequency synthesis with 32 tiles[13 Jan 2010] – 5 minute snapshot
Parkes reference image
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Radio sources w/ MWA
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MWA full array rendering
1.5 km
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MWA 1-year power spectrum sensitivity
4 redshift bands, 300 hours each
21 cm from Lidz et al. 2009MWA uncertainty from Bowman et al. 2006
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Experiment to Detect the Global Epoch of Reionization Signature
(EDGES)
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EDGES
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EDGES
Bowman & Rogers 2010
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AEER
EDGES block diagram
ou t of band noise injection
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Internally-switched calibration• 3-position switch to measure (cycle every 10s):
• Solve for antenna temperature:
(Tcal > TL 300 K, TA 250 K, TR 20 K)
• Results: >105 dynamic range achieved with EDGES
• Limitations: – Total power differences between TL and TA can leave systematic errors
– Temporal variations: comparing measurements at different times
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Antenna (p2)Internal load (p0)
Noise source (p1)
p1– p0
p2 – p0“Calibrated” sky spectrum
T_A ~ (p2 – p0) / (p1 – p0)
“Calibrated” sky spectrumw/ RFI filtering and integration
Internally-switched calibration
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Measured spectrum
Murchison Radio-astronomy Observatory (MRO)
Aug 20 – Oct 20, 2009
1440 wall-clock hours on sky
500 hours after RFI cuts
50 hours eff. integration
+15 dB
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Orbcomm LEO satellite constellation
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Parameter estimation
#1: 21 cm reionization model
#2: Foreground model
m
n
nnF zaT
0
)1(
Pritchard & Loeb (2010, submitted)2 science parameters: z and zr 4-19 nuisance parameters: an
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Lower limit on duration
Bowman & Rogers, Nature, 468, 7325, pp. 796-798 (2010)
zr > 0.06 for 6 < zr < 13 (95% confidence)
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EDGES reionization forecast
Pritchard & Loeb (2010)
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Why don’t we observe in the U.S.?
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21 cm array site selection
Annotated by F. Briggs1 GHz100 MHz
MRO
Narrabri
Sydney
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US TV and FM radio “pollution”
D1 Array – Haystack Obs.D1 Array – Haystack Obs.
West Forks, Maine
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Catlow Valley, Oregon, US60 dB
10 dB 80 MHz 200
EDGES Memo#052, AEER, JDB, 2009
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Thanks! Questions?