21-cm Cosmology with GMRT, GBT, CRT - IN2P3moriond.in2p3.fr/J10/transparents/peterson.pdf · 21-cm...
Transcript of 21-cm Cosmology with GMRT, GBT, CRT - IN2P3moriond.in2p3.fr/J10/transparents/peterson.pdf · 21-cm...
21-cm Cosmology with
GMRT, GBT, CRT
Presented at Moriond Cos.
By Jeff Peterson CMU
18 March 2010
CMU Cylinder Telescope Prototype
Outline
• GMRT-EoR program
• Intensity Mapping
• Baryon Acoustic Oscillations
• Green Bank Telescope Results
• Cylinder Telescope Concept
The Giant Metrewave Radio
Telescope EoR Program
“If there be light, then there is darkness”
Pythagoras, ~ BC 510
GMRT EoR TEAM
• Ue-Li Pen, Greg Paciga, Tzu-Ching
Chang, Jon Seivers (CITA),
• Jeff Peterson, Kevin Bandura, Jim
McGee, Bruce Taylor (CMU)
• Yashwant Gupta, Jayanata Roy,
Rajaram Nitanyanda (NCRA)
• Steven Myers (NRAO), Kris Sigurdson
(UBC) Chris Hirata (CIT)
Indian Giant Meterwave Radio Telescope
30 dishes @45m ea.
14 in 2 km central
core with
19,000 sq m dish
area.
We use 150 MHz +-
8 MHz
Cost: $12M in 1995
Features of GMRT-Right UV range for EoR
-Largest collecting area
-Full collecting area across sky
-Strong rejection of Cas A, Cygnus A, etc.
-Excellent Polarization Purity
-Systematic very different from dipole arrays
-If full sensitivity can be achieved,
GMRT can make detailed EoRimages.
Instrumental apparent polarization.
Ellipses stretched by factor 8
~50 times less cross pole than LOFAR/MWA
Simulated VHF sky images
Furlanetto,
et.al2003
142 MHz 144 146
148 150 152
154 156 158
Looking for 20 mK
patches on the sky
that are present only
for ~5 MHz
GMRT 150 MHz image, ca 2005
• RFI noise level 2K RMS…desired signal
20 mK
Improvements to GMRT• Built a PC-based correlator
– 8 bit sampling
– Long lags
– Programmable by mortals
• Installing new LNAs (Tsys 400K -> 100K)
• Developed RFI location algorithms and hardware
GMRT LNA
PC Array
Software corr.
RFI location
Current GMRT EoR limits
RFI in images
Extreme EoR model
Quasar ionization model
Stellar ionization model
Sensitivity possible with GMRT
Next steps for GMRT/EoR
• Continue location/elimination of RFI
sources
• Complete LNA installation
• Use drift scan strategy
• Add full-time Graduate Student (NSF
funding pending)
21 cm power spectrum vs. redshift
Pritchard & Loeb 2008
Dark Energy and structure
Inflationary physics
Reionization/dark ages
Three Dimensional 21-cm
Specific Intensity Mapping
aka
“Intensity Mapping”
-Chang, Pen, JBP, McDonald 2008-Wyithe, Loeb 2008-Sethi 2005
Alfalfa redshift survey
Large scale structure matches
optical surveys
Baryon Acoustic Oscillations – Dark
Energy Probe• Acoustic
oscillations
during ionized
era imprinted
standard ruler,
150 Mpc.
WMAP5 and other, Nolta et al (2008)
Baryon Wiggles
Detected by
SDSS and 2df
Eisenstein etal 2009
Spherical Shell in 3d
correlation space.
Steps Toward a High
Sensitivity Dark Energy Exp’t
• Study existing data (HIPASS result)
– Pen, Smith, JP, Chang (2009)
• Use existing telescopes on well studied
fields. Get 21-cm <-> Optical X-corr.
– GBT, Parkes, ATNF, Westerbork, Arecibo
• Test (and model) cylinder prototype
• Use CRT at vy quiet site to get precise
test
Green Bank Telescope
West Virginia
•DEEP2 Fields 2,4
2 deg x 0.5 deg
fields
•50 hours
observation at z=1
•10 hours at z=1.5
•15 arcmin angular
resolution at z=1
Beam
Size
RA-Long MapBeam
Size
21cm – DEEP2 cross correlation
Chang, Pen, Bandura, JP, submitted
Results from GBT
• 2 x 10^14 solar masses HI detected at
z~0.8
• Omega HI ~4.5 +- 1.0 x 10^-4
• Intensity Mapping seems productive
• Next: try this at Arecibo 700-800 MHz
• Program continues at GBT and Arecibo
• 2000 hrs would be needed to get first
BAO result
Proposed BAO instrument,
a Cylinder Radio Telescope
8192 signals
The Cylinder Radio Telescope Consortium
• Jeff Peterson (CMU)
• Kevin Bandura,
• Bruce Taylor
• Jim McGee
• Blake Conaugher
• Florence Liu
• Deena Kim
• Bruce McWilliams
• Uros Seljak (U. C Berkeley)
• Peter Timbie (U. Wisc.)
• Scott Dodelson (FNAL)
• John Marriner
• Chris Stoughton
• Hee Jong Seo
• Dave McGinnis
• Tzu-Ching Chang (IAA Taipei)
Kris Sigurdson (UBC)
• Ben Wang
• Ue-LI Pen (CITA)
• Gojko Vujanovic
• Hassane Darhmouai (AUI)
• Ahmed Legrouri
• Hassan Bourhous
• Rachid Benmouktar
• Christope Yeche (CEA)
• Christohpe Magneville
• Jim Rich
• 2 FTE engineer
• Reza Ansari (LAL)
• Marc Moniez
• 2 FTE engineer
• Jon Bunton (CSIRO)
CRT Science Goals
-Understand Dark Energy and the
acceleration of the universe, using BAO
technique.
-CRT will also allow study of
-Pulsars and Transients.
-Ionization by the first stars.
-Magnetic fields.
-Large Scale Structure P(k)
-SETI
Simulated Results
N. Gnedin R. Ansari, etal
BAO survey volumes
`CRT 2013CRT 2014
Parameters of CRT
• Aperture filling: nearly full
• Size: 100 m
• Sky coverage: 20,000 sq degrees
• Number of data streams: 64-8,000
• Freq Range: start at ~700 MHz, allow 300-
1500
• Instantaneous Bandwidth >200 MHz
CMU prototype cylinders.
Antenna and LNA
Sampling electronics, LAL,
CEA
Saclay-Irfu engineers: Ph.
Abbon,
E. Delagnes, H.
Deschamps, P. Kestener
Irfu physicists: J.-M. Le
Goff,
Ch. Magneville, J. Rich,
Ch.Yeche
Orsay-LAL engineers:Ch.
Beigbeder, D. Breton, T.
Caceres, D. Charlet,
B. Mansoux, C. Pailler, M.
Taurigna
LAL physicists: R. Ansari,
M. Moniez
Analog
electro
nics Clock distribution
500MHz
ADC board
Correlaltion computer
(Sigurdson)
Preliminary Results
Lag (20µs pixels)Lag (20µs pixels)
Tim
e (
20 s
ec p
ixels
)
Tim
e (
20 s
ec p
ixels
)
SunCassiopeia A
Next steps for CRT
• Numerically model foreground subtraction (FNAL) and compare
to data from prototype.
• Build 2-3 Cylinders 10x50 m
• Use existing 32-64 chan. Correlator
• Set up at an existing reasonably quiet observatory
– DRAO, GT, Ooty, Green Bank, Kalihari, Chihuahua
• Measure 21 cm LSS, velocity distortions
• Demonstrate successful foreground subtraction