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

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)

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 • 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

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

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.

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

9. Results Optical counterparts for 84% of HICAT radio sources • 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 – 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 (submitted MNRAS)

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

12. HOPCAT’s Galaxy density coverage • Solution? • ATCA high resolution HI observations to find/confirm optical counterpart in regions of high galaxy density

14. Distribution of SFR/unit Luminosity - Cluster & Field samples (Lewis et al. 2002) Cluster sample limited to galaxies within the virial radius

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

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

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

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