H OPCAT , 6dFGS & Star Formation Rates

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

2. Content Advisor: Michael J. Drinkwater – UQ Assoc. Advisors: 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 PhD Project & 6dFGS • Investigate the question: How does star formation depend upon environment and other factors? • Part 1: Finding optical counterparts for the HIPASS catalogue • Part 2: Investigate the 2 possible explanations for the Morphology-density Relation using Star Formation Rates, Star Formation Efficiency and Galaxy Density Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

3. The 6dFGS - HIPASS Connection • HI Parkes Sky Survey (HIPASS) • HI blind radio survey of the southern sky up to Dec=+2o • Velocity range of 300 to 12700 km s-1 • October 2001: 2710 “additional” targets were added to the 6dFGS (Thank you Mike Read & Michael Drinkwater) • Optical objects included are: • within 5 arcmin of the HIPASS positions • R < 17 mag • “NOT” already in one of the official optical target lists for 6dFGS • 341 - highest priority: multiple matches to radio position 1558 - main sample 811 - faint sample (16.7 < R < 17) Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

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. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

5. Steps • Part 1 • 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. • Find optical counterparts for radio sample • Part 2 • Star Formation Rate (SFR) • Star Formation Efficiency (SFE) • Local galaxy density • Which theory is correct to explain the Morphology-density relation Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

6. 1st Part: Optical Counterpart - HOPCAT • HIPASS Catalogue (HICAT) contains 4315 HI radio sources • Parkes beam 15’ - Radio-Optical position uncertainty 7’ • Find optical counterparts • Accurate optical positions are needed to measure luminosity to estimate SFR • Search for Isolate Dark Galaxies • HI source containing gas (and dark matter) • No detectable stars • Sufficiently far away from other galaxies, groups or clusters Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

7. Radio-Optical Position Uncertainty Optical Data • OPTICAL IMAGES • SuperCOSMOS 15’ x 15’ Images • Parkes beam is 15’ • 7’ radius Radio-Optical position uncertainty • IMAGE ANALYSIS • SExtractor Image Analysis. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

8. Unobserved areas Visually matched by 3 people to minimise galaxy selection bias Is that the right galaxy? • Many images have multiple galaxies • Crosscheck HIPASS velocity with: • High quality dataset - 6dFGS velocities (Kindly supplied by Heath) • Published velocities – NED • Information from catalogues, surveys & the literature • Data varies in quality • Developed ADRIC • Automated visual interactive program Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

9. Results Optical counterparts for 84% of HICAT radio sources • Optically Matched with velocity 58% 2512 • Single Match (42% - 1798) • Compact group member (16% - 714) • Optically Matched with no velocity 26% 1106 • Single Match (20% - 848) • Compact group member (6% - 258) • No Guess 11% 481 • Several galaxies no velocities • Blank Field 5%216 • No visible galaxy Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

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 – Banks et al (1999) • 1 ruled out with Narrow-band follow-up observations at Parkes as a non-detection (Thank you Ivy) • Conclusion: No isolated dark galaxies are present in the HIPASS survey Doyle et al. (MNRAS in press) Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

11. Part 2: Star Formation & Density (Preliminary work) • First Pass: • Sydney University Molonglo Sky Survey (SUMSS) 843MHz radio continuum data • 304 SUMSS – HOPCAT matches • Star Formation Rate • Star Formation Efficiency • Galaxy Density • Galaxy separation between HICAT & SuperCOSMOS Galaxy Catalogue positions • Area based on a radius to the 10th nearest galaxy • Galaxy number / degree2 Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

12. HOPCAT’s Galaxy density coverage • Solution? • ATCA high resolution HI observations to find/confirm optical counterpart in regions of high galaxy density Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

13. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

14. Distribution of SFR/unit Luminosity - Cluster & Field samples (Lewis et al. 2002) Cluster sample limited to galaxies within the virial radius Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

15. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

16. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

17. SUMMARY • Positions for 2710 optical galaxies near HIPASS positions added to 6dFGS observing list • HIPASS Optical Catalogue • Used6dFGS velocities • Optical Counterparts for 84% • Preliminary Work - SUMSS • SFR vs. HI mass : Larger the HI mass the larger the SFR • SFR vs. Density : Decreased SFR in galaxy dense regions? More analysis needed • SFE vs. Density : Decreased SFE in galaxy dense regions? More analysis needed Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

18. Future Data Resources for SFR Calculations • IRAS • 2MASS • HIPASS Continuum • 6dFGS Hα • SINGG Hα Survey • Gerhardt Meurer, Johns Hopkins University • Complete Hα imaging for small subset of HIPASS Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

19. 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 Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

20. SExtractor Image Analysis SuperCOSMOS data catalogue? Ellipse segmentation problem for extended objects SExtractor Segmentation problems? Used 2 sets of ellipse analysis parameters Analysis of SuperCOSMOS Images Swinburne Galaxy Groups Workshop 24th & 25th May, 2005