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Simulated HI observations

This project outlines the data pipeline for simulated HI observations, focusing on the Sky Simulation Engine (SEX) and Telescope Simulation processes. It details the detection techniques employed and compares the output of HIPASS and SEX. Future work will involve using IC 2574 data pipelines and S3 simulations to explore array configurations in the galaxy's neighborhood. Additionally, the research utilizes the Duchamp source finder for detecting and processing data cubes, addressing shortcomings in the differential number counts and enhancing data reliability.

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Simulated HI observations

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  1. Robbie Auld Cardiff University collaborating with Oxford SKADS team Simulated HI observations

  2. Outline • Description of the data pipeline • Sky simulation (SEX)‏ • Telescope Simulation • Detection Technique • Comparisons: HIPASS vs. SEX • dN/dz – SEX vs. SAX • Future THINGS: IC 2574

  3. Data Pipeline Web query S3 simulation (RW & FL) Query generated via the web interface, source list and datacube generated locally with S3 Tools. Sky model SKA simulator ParselTongue script (HRK) that uses AIPS routines. Includes: antenna Tsys, antenna layout, gain factors, integration time per visibility, total observation time Corrupted cube Cleaned datacube Source Finder Duchamp source finder package (ATNF)‏

  4. Resulting datacube Filled UV plane!

  5. Source detector: Duchamp • Locates sets of contiguous voxels (3D pixels) above some threshold. • Threshold determination: • Manual (absolute value / S/N value)‏ • Automatic (False Discovery Rate method)‏ • Enhancement • Spectral smoothing (Hanning)‏ • Spatial smoothing (Gaussian convolution)‏ • A trous (wavelet procedure)‏ • Voxels above threshold are flagged, merging algorithm rejects multiple detections

  6. Duchamp output Postscript file of all detections VO compatible catalogue file

  7. Comparisons with HIPASS

  8. SEX shortcomings • HIMF (0 < z < 0.1)‏ Wilman et al. 2008

  9. SEX vs. SAX: dn/dz Abdalla & Rawlings (2005)‏ Diamonds – SAX Stars – SEX SEX differential number counts too low.

  10. Future THINGS: IC 2574 Integrated intensity Velocity Field Explore effects of different array configurations with the galaxy in the local neighbourhood and then try moving it further away.

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