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

2. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 Content  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 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….......

3. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 The 6dFGS - HIPASS Connection  HI Parkes Sky Survey (H IPASS )  HI blind radio survey of the southern sky up to Dec=+2 o  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. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 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. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 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. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 1 st Part: Optical Counterpart - H OPCAT  HIPASS Catalogue (H ICAT ) 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. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 Optical Data  OPTICAL IMAGES  SuperCOSMOS 15’ x 15’ Images  Parkes beam is 15’  7’ radius Radio-Optical position uncertainty  IMAGE ANALYSIS  SExtractor Image Analysis. Radio-Optical Position Uncertainty

8. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 Is that the right galaxy?  Many images have multiple galaxies  Crosscheck H IPASS 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 Unobserved areas Visually matched by 3 people to minimise galaxy selection bias

9. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 Results Optical counterparts for 84% of HICAT radio sources  Optically Matched with velocity58% 2512  Single Match ( 42% - 1798)  Compact group member (16% - 714)  Optically Matched with no velocity26% 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

10. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 Any Isolated Dark Galaxies in H IPASS ?  4315 HI detected objects  Extinction cut at A B j < 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)

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

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

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

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

19. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005 Superimposed ellipses Yellow for correct match 15 x 15 arcmin images to allow for the 7 arcmin position uncertainty Centred on HICAT positions Selection parameters Original HICAT parameters Superimposed and listed Published velocities ADRIC interactive visual matching program

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