Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.
-
Upload
cordelia-nash -
Category
Documents
-
view
218 -
download
0
Transcript of Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.
![Page 1: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/1.jpg)
CCosmographyosmographyAAndndRRadioadioPPulsarulsarEExperimentxperiment
Judd D. BowmanJudd D. Bowman
October 10, 2009October 10, 2009
![Page 2: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/2.jpg)
CARPE collaboration
Judd Bowman (Caltech)
Rich Bradley (NRAO/UVA)
Jacqueline Hewitt (MIT)
David Kaplan (UCSB/Milwaukee)
Avi Loeb (Harvard)
Maura McLaughlin (WVU)
Miguel Morales (U. Washington)
Stuart Wyithe (Melbourne)
Students:
Eli Visbal (Harvard)
Paul Geil (Melbourne)
Alex Fry (U. Washington)
Christian Boutan (U. Washington)
![Page 3: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/3.jpg)
Outline
1. Overview and motivation2. Reference antenna concept3. Performance
4. Sites and RFI5. Foreground subtraction
![Page 4: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/4.jpg)
Dark energy
• 1 < z < 4: beneficial for models poorly described by w and w’ at z=1
• Transverse and line-of-sight BAO scales: spectroscopic and photometric galaxy surveys are mostly sensitive to transverse
• 2D BAO spectrum gives better constraints than spherically binned
• Sensitive to only dark matter power spectrum and four additional parameters:
– Mass weighted neutral hydrogen fraction x_HI
– HI mass weighted halo bias <b>
– Ionizing photon mean free path k_mfp
– Fluctuations in the ionizing background K_0 (<1% suppression on large scales since UV field is nearly uniform after reionization )
• Robust against non-linear effects in the linear and quasi-linear regimes
![Page 5: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/5.jpg)
Pulsars
Searches
• Local sources at low luminosities at lower frequencies
• Distant brighter objects at higher frequencies
• Deep searches of the Magellanic clouds in single pointings
• Repeated survey the entire sky: sporadic sources, intermittent sources, rapidly precessing systems (e.g. binaries)
• Better RFI rejection with many beams
Timing
• Dedicated observations: probe emission physics, establish orbital parameters, and test gravity
• Multiple pulsars timed simultaneously: refine pulsar ephemerides, remove systematics effects, improving gravitational wave studies
![Page 6: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/6.jpg)
Approach
1. Dark Energy IM is exactly same problem as reionization
2. Leverage existing MWA, LOFAR, PAPER efforts
3. To minimize risk and development overhead:
– Design a Dark Energy array that closely builds on low-frequency heritage– Incorporate lessons learned on foreground subtraction and calibration
4. Be ready to start construction as soon as reionization arrays prove technique is successful
![Page 7: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/7.jpg)
The MWA as an example
150 m
![Page 8: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/8.jpg)
The MWA as an example
![Page 9: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/9.jpg)
CARPE reference design
Number of antennas: 2500 (steerable)
Antenna effective area: 1.28 - 5.14 m2
Total collecting area: 3000 - 12,500 m2
Field of view: ~20 deg
Available bands: high: 0.2 - 0.5 m (600-1500 MHz)
low: 0.4 - 1.0 m (300-700 MHz)
Redshift range: 0 < z < 4
Instantaneous bandwidth: 300 MHz
Maximum baseline: 250 m
Angular resolution: 3 to 11 arcmin
MOFF dimension: 512 x 512
Observing strategy: 3 fields, each for 2000 hours per year
(2x more efficient than drifting)
Target cost: $50M
![Page 10: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/10.jpg)
Sensitivity scaling laws
![Page 11: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/11.jpg)
FOV and resolution requirements
z = 1: 150 Mpc > 2.5 deg
> 25 MHz
8 Mpc < 4 arcmin< 1 MHz
z = 4: 150 Mpc > 1.5 deg
> 15 MHz
8 Mpc < 2 arcmin< 0.5 MHz
Largest angular scale retained = largest spectral scale after foreground subtraction
![Page 12: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/12.jpg)
CARPE reference design
![Page 13: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/13.jpg)
Instantaneous UV coverage
Antennas Baselines
![Page 14: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/14.jpg)
Instantaneous UV redundancybaselines/m
2
![Page 15: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/15.jpg)
Point source (mis-)subtraction
• Must localize sources to 0.1” for MWA– Scales with number of antennas, so close to ~1” for CARPE – Only 0.5% of beam, so need SNR~200
Datta et al. 2009 (in press)
post-subtractionbefore polynomial subtraction
![Page 16: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/16.jpg)
Calibration error limits
• MWA residual calibration errors should be ~0.01% in amplitude or ~0.01 degree in phase at end of integration– Scales with number of antennas, 5x easier for CARPE– 0.2% in amplitude and 0.2 degree in phase per day
Datta et al. 2009 (in press)
post-subtractionpre-subtraction
![Page 17: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/17.jpg)
Key technologies
1. MOFF correlator2. Inexpensive broadband antennas3. Precision calibration techniques from reionization arrays
![Page 18: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/18.jpg)
MOFF
• Output image has the equivalent information of the FX correlator visibilities, allowing precision deconvolution and polarimetry.
• Antennas do not need to be placed on a regular grid.
• Computationally efficient for compact arrays with a high spatial density of antennas: CARPE MOFF correlator is 14 times more efficient than FX (2.7e14 CMAC/s compared to 3.7e15 CMAC/s for FX)
• MOFF correlation depends on the physical size of the array and not the number of antennas: easily scale to ~10000 antennas with fractional increase in computational load
• A fully calibrated electric field image is created as an intermediate product. The number of calibrated pulsar beams available is limited only by the output bandwidth, and hardware de-dispersion can be easily incorporated.
![Page 19: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/19.jpg)
CARPE Antenna ConceptRichard Bradley (NRAO/UVA)
![Page 20: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/20.jpg)
Sierpinski carpet fractal
![Page 21: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/21.jpg)
Dual level: 4x4 low – 8x8 high
1.6 m
1.0 m
![Page 22: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/22.jpg)
Sinuous cone
• Inexpensive photolithographic printing• >20 dB rear rejection w/ no ground plane
![Page 23: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/23.jpg)
Example return loss for 2-4 GHz case
![Page 24: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/24.jpg)
Trapezoidal-tooth pyramidal-type
![Page 25: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/25.jpg)
Green Bank Solar Radio Burst Spectrometer
70-300 MHz
300-3000 MHz
![Page 26: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/26.jpg)
HEFT LNA noise (unmatched)
![Page 27: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/27.jpg)
System temperature
Sky (GC
)
Total (cold region)
Sky (cold)CMB
LNA
5.22
K21
GHzCMBLNA
sys TT
T
![Page 28: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/28.jpg)
Imaging sensitivity v. angular scale
![Page 29: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/29.jpg)
Observing strategy
• 3 fields, 1000-2000 hours each
• Tracking more efficient than drifting:
- SNR 2x lower for same time
- Not sample variance limited until >1000 hours, then only on largest scales
![Page 30: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/30.jpg)
Estimated uncertainty
![Page 31: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/31.jpg)
Cosmology parameter estimation
![Page 32: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/32.jpg)
Roadmap
2010-2011:• Full antenna simulation• MOFF FPGA prototype implementation• Prototype antenna tile• Detailed design and cost
2012-2013:• End-to-end demonstration
Looking for a mid-Decade start
![Page 33: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/33.jpg)
Site selection
![Page 34: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/34.jpg)
CARPE reference site
Annotated by F. Briggs1 GHz100 MHz
MRO
Narrabri
Sydney
![Page 35: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/35.jpg)
New England radio interference
Rogers et al. 2005
![Page 36: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/36.jpg)
Owens Valley radio interference
Dale Gary
![Page 37: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/37.jpg)
FM and TV Strength
![Page 38: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/38.jpg)
A bit more on foregrounds
![Page 39: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/39.jpg)
Foreground 2D power spectra
![Page 40: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/40.jpg)
Foreground subtraction removes signal
![Page 41: Cosmography And Radio Pulsar Experiment Judd D. Bowman October 10, 2009.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649d005503460f949d2d79/html5/thumbnails/41.jpg)
CARPE summary
• Large-N, small-D, high-dwell
• Complementary science goals: DE, Pulsars
• Leverage significant effort in reionization arrays to mitigate calibration and foreground risks
• Exploit new correlator and DSP capabilities