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H OPCAT , 6dF & Star Formation Rates

H OPCAT , 6dF & Star Formation Rates. Marianne T. Doyle Ph.D. Project. Content. Supervisor : Michael J. Drinkwater – UQ Assoc. Supervisors : Elaine Sadler – Uni Sydney John Ross - UQ Collaborators David J. Rohde - UQ Mike Read – WFAU Edinburgh Baerbel Koribalski – ATNF, Epping

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H OPCAT , 6dF & Star Formation Rates

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  1. HOPCAT, 6dF & Star Formation Rates Marianne T. Doyle Ph.D. Project

  2. Content Supervisor: Michael J. Drinkwater – UQ Assoc. Supervisors: Elaine Sadler – Uni Sydney John Ross - UQ Collaborators David J. Rohde - UQ Mike Read – WFAU Edinburgh Baerbel Koribalski – ATNF, Epping HIPASS Team – ATNF Parkes & Epping, Universities of : Melbourne, Cardiff, Western Sydney Macarthur, Wales, Swinburne, Technology Sydney, New Mexico, Manchester, Colorado, Sydney, Leicester ASTRON The Netherlands, AAO Sydney, WIYN Tucson etc…....... • The HIPASS - 6dFGS Connection • My Project • Investigate the question: How does star formation depend upon environment and other factors? • Finding optical counterparts for the HIPASS catalogue • Investigating the Morphology-density relation using Star Formation Rates, Star Formation Efficiency and Galaxy Density

  3. The 6dFGS - HIPASS Connection • HI Parkes Sky Survey (HIPASS) • HI blind radio survey of the southern sky up to Dec=2o • October 2001: 2710 “additional” targets were added to the 6dfGS (Thank you Michael Drinkwater) • Optical objects included are: • within 5 arcmin of the HIPASS positions • R mag < 17 • “NOT” already in one of the official optical target lists for 6dF • 341 - highest priority: multiple matches to radio position 1558 - main sample 811 - faint sample (16.7<R<17)

  4. My PhD Project • The question: How does the conversion of hydrogen to stars (star formation) depend upon environment and other factors? • Testing two theories: • Either fewer “star forming galaxies” actually form in regions of high galaxy density, OR • There are physical processes that directly suppresses star formation.

  5. Steps • Use radio detected galaxy sample instead of optical sample • Optical samples are biased towards star forming galaxies which is what we are trying to measure. • Star Formation Rate (SFR) • Star Formation Efficiency (SFE) • Local galaxy density

  6. Optical Counterpart - HOPCAT • HIPASS Catalogue (HICAT) contains 4315 HI radio sources • Find optical counterparts • Accurate galaxy position needed to measure luminosity to calculate SFR • Search for “Dark Galaxies”

  7. Radio-Optical Position Uncertainty Optical Data • OPTICAL IMAGES • SuperCOSMOS 15’ x 15’ Images • 7’ radius Radio-Optical position uncertainty • IMAGE ANALYSIS • SExtractor Image Analysis.

  8. Unobserved areas Is that the right galaxy? • Many images have multiple galaxies • Crosscheck HIPASS velocity with optical or high resolution radio velocities • Published velocities – NED • Information from catalogues, surveys & the literature Data varies in quality • Need a high quality dataset • 6dF velocities (Kindly supplied by Heath) • Developed an automated visual interactive program ADRIC

  9. Results • Optically Matched with velocity 58% 2516 • Single Match (44% - 1882) • Compact group member (14% - 634) • Optically Matched with no velocity 26% 1107 • Single Match (20% - 851) • Compact group member (6% - 256) • No Guess 11% 476 • Several galaxies no velocities • Blank Field 5%216 • No visible galaxy

  10. Any Isolated Dark Galaxies in HIPASS? • 4315 HI detected objects • Extinction cut at ABj < 1 - 3692 objects • Use only blank fields - 13 objects • Take out over crowded fields - 2 object remaining • 2 remaining objects? • 1 is a very faint previously observed galaxy in the Centaurus group • 1 ruled out with Narrow-band follow-up observations at Parkes as a non-detection • Conclusion: No isolated dark galaxies are present in the HIPASS survey

  11. HOPCAT’s Galaxy density coverage • Solution? • ATCA high resolution HI observations to find/confirm optical counterpart in regions of high galaxy density • Galaxies in regions with Low galaxy density? • Large sample • Galaxies in regions with High galaxy density? • Very small sample

  12. Star Formation & Density • SUMSS radio continuum data • 304 Sumss – HOPCAT matches • Galaxy Density • 10th Galaxy radius • Galaxy number / degree2 • Star Formation Rate • Star Formation Efficiency

  13. Ave density = 86 Ave SFR = 1.2 Ave density = 12 Ave SFR = 0.5 Ave density =0.9 Ave SFR = 0.34 Ave density=0.07 SFR ave=1.3 Star Formation Rate Vs Density

  14. Star Formation Efficiency Vs Density • SUMSS – Sydney University Molonglo Sky Survey • 304 Sumss – HOPCAT matches • Galaxy Density • 10th Galaxy radius • Galaxy number / degree2

  15. Summary • 2710 optical galaxies near HIPASS positions were added to the 6dFGS list

  16. Selectionparameters Original HICAT parameters 15 x 15 arcmin images to allow for the 7 arcmin position uncertainty Centred on HICAT positions Superimposed ellipses Yellow for correct match Superimposed and listed Published velocities ADRIC interactivevisual matching program

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