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

Content  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 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 6dFGS - HIPASS Connection  HI Parkes Sky Survey (H IPASS )  HI blind radio survey of the southern sky up to Dec=2 o  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  highest priority: multiple matches to radio position main sample faint sample (16.7<R<17)

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.

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

Optical Counterpart - H OPCAT  HIPASS Catalogue (H ICAT ) contains 4315 HI radio sources  Find optical counterparts  Accurate galaxy position needed to measure luminosity to calculate SFR  Search for “Dark Galaxies”

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

Is that the right galaxy?  Many images have multiple galaxies  Crosscheck H IPASS 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 Unobserved areas

Results  Optically Matched with velocity58% 2516  Single Match ( 44% )  Compact group member (14% - 634)  Optically Matched with no velocity26% 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

Any Isolated Dark Galaxies in H IPASS ?  4315 HI detected objects  Extinction cut at A B j < 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

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

Star Formation & Density  SUMSS radio continuum data  304 Sumss – H OPCAT matches  Galaxy Density  10 th Galaxy radius  Galaxy number / degree 2  Star Formation Rate  Star Formation Efficiency

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

 SUMSS – Sydney University Molonglo Sky Survey  304 Sumss – H OPCAT matches  Galaxy Density  10 th Galaxy radius  Galaxy number / degree 2 Star Formation Efficiency Vs Density

Summary  2710 optical galaxies near HIPASS positions were added to the 6dFGS list

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