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Motivation #1: verification of performance of array

First Exploration of MWA Deep Field Point Source Population C. Williams - PhD Thesis J. Hewitt – reporting some analysis. Motivation #1: verification of performance of array . Compare to existing catalogs – source by source Compare to existing catalogs – statistics

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Motivation #1: verification of performance of array

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  1. First Exploration of MWA Deep Field Point Source PopulationC. Williams - PhD ThesisJ. Hewitt – reporting some analysis

  2. Motivation #1: verification of performance of array • Compare to existing catalogs – source by source • Compare to existing catalogs – statistics • Compare multiply observed sources • Source injection (uv data)

  3. Motivation #2: deeper southernsample of Ultra-Steep Spectrum Sources Spectral index distribution for low-frequency-selected and high-frequency-selected sources (De Breuck et al. 2000) “Ultra-Steep-Spectrum” is alpha < -1.3 (between frequencies of 1420 and ~300 MHz)

  4. Motivation #2: new sample of Ultra-Steep Spectrum Sources De Breuck et al. 2004

  5. Motivation #3: know your enemy – we want to subtract this foreground

  6. Comparison Catalogs • Molonglo Reference Catalog (MRC): 408 MHz, southern sky excluding Galactic plan, complete above 1 Jy, goes to 700 mJy, about 3 arc min resolution • Culgoora Catalog: 80 and 160 MHz, not really a catalog, rather flux measurements of known sources • Parkes-MIT-NRAO 5 GHz survey • Source counts from Cambridge 150 MHz surveys

  7. Comparison of individual sources Galactic plane

  8. Comparison of individual sources: Molonglo-MWA

  9. Comparison of individual sources: Molonglo-MWA Histogram of differences in source positions Note declination shift

  10. Comparison of individual sources: Molonglo-MWA Histogram of differences in source positions, normalized

  11. Comparison of individual sources: Molonglo-MWA Differences in source positions Plotted vs. distance from phase center

  12. Comparison of individual sources: Molonglo-MWA Differences in source positions, normalized Plotted vs. distance from phase center

  13. Comparison of individual sources: Molonglo-MWA Working on comparison of flux densities (Chris Williams and FakhriZahedy, work in progress)

  14. Comparison of statistics: Cambridge-MWA source counts MWA sample Flux density vs. distance from phase center

  15. Comparison of statistics: Cambridge-MWA source counts MWA sample Choose “complete” region

  16. Comparison of statistics: Cambridge-MWA source counts MWA sample (very preliminary) Fits give power law index of -1.75 and -2.12 Cambridge -1.8 (Gower 1966); -1.51 (de Mateo et al. 2002)

  17. Comparison of statistics: Distribution of PMN-MWA spectral indices

  18. Deepersample of Ultra-Steep Spectrum Sources 5 GHz – 150 MHz spectral indices MWA Ultra- Steep Spectrum Sources 128-tile array will be MUCH more capable than this 32-tile array!

  19. Comparison to other catalogs for verification • Positions look good but • Shift • Increased error with distance from phase center • Source counts in the right ballpark but • Correction for varying sensitivity across field needed • Careful fitting needed • Spectral index distribution looks very plausible • Science • New sample of Ultra Steep Spectrum sources • Learning about the EoR enemy SUMMARY

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