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Low Frequency Observations of the ISM and Pulsar Timing Joris Verbiest Xiaopeng You (Southwest University, China) William Coles (UCSD) George Hobbs (ATNF) PPTA team Swinburne University & ATNF, Australia
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Outline Brief intro to PPTA DM variations and the turbulent ISM PSR J0437-4715’s DM Structure Function TOA-intensity correlation Summary
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Australia Telescope National Facility, CSIRO, Sydney Dick Manchester, George Hobbs, David Champion, John Sarkissian, John Reynolds, Mike Kesteven, Warwick Wilson, Grant Hampson, Andrew Brown, David Smith, Jonathan Khoo, (Russell Edwards) Swinburne University of Technology, Melbourne Matthew Bailes, Willem van Straten, Joris Verbiest, Ramesh Bhat, Sarah Burke, Andrew Jameson University of Texas, Brownsville Rick Jenet University of California, San Diego Bill Coles Franklin & Marshall College, Lancaster PA Andrea Lommen University of Sydney, Sydney Daniel Yardley National Observatories of China, Beijing Johnny Wen Peking University, Beijing Kejia Lee Southwest University, Chongqing Xiaopeng You Curtin University, Perth Aidan Hotan PPTA Team Members
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Pulsar Timing Arrays Main goal: Detect gravitational waves Secondary goals: Investigate time standards Investigate Solar System Investigate ISM …
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DM Variations in Timing 50cm 20cm 10cm 20cm
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PPTA DM Variations You et al., MNRAS, 2007
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DM Structure Function Measure of turbulent power at different scales Expected to be exponential with spectral index α = 5/3 for Kolmogorov model
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Typical SF You et al., MNRAS, 2007
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Kolmogorov Slope (1000 days ≈ 7.8 AU) You et al., MNRAS, 2007
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Large Inner Scale (10 days ≈ 0.4 AU) You et al., MNRAS, 2007
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PSR J0437-4715 SF 1000 days ≈ 61 AU You et al., MNRAS, 2007
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0437 DM Variations ~500 days ≈ 30 AU 2004 2008
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Scintillation & TOAs PSR J0437-4715 685 MHz 2 hours, 8sec integrations TOA residual Signal-to-Noise -1
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Scintillation/TOA - Simulations Coles et al., in preparation
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Grad DM - Simulations Coles et al., in preparation
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Correlation - Real Data Coles et al., in preparation
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Conclusions PTAs need high timing precision. ISM effects need to be corrected Most easily measured at low frequencies ISM: an interesting place that keeps surprising…
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