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Simulated HI observations

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

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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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