HOPCAT, Dark Galaxies & Star Formation Marianne T. Doyle Ph.D. Project University of Queensland

ASA Meeting 2005 Content  HIPASS Optical Catalogue (HOPCAT)  HOPCAT Science  Isolated Dark Galaxies  Star Formation & Galaxy Density  Summary & Accessing HOPCAT Marianne Doyle Ph.D Project University of Queensland Advisor: Michael J. Drinkwater – UQ Assoc. Advisors: Elaine Sadler – Uni Sydney John Ross - UQ Collaborators David J. Rohde - UQ Kevin Pimbblet - UQ Mike Read – WFAU Edinburgh 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…

ASA Meeting 2005 HIPASS Optical Catalogues  HI Parkes All Sky Survey (HIPASS) & Catalogue (HICAT)  Largest blind HI radio survey of the southern sky to Dec=+2 o  Velocity range: km/s  4315 HI radio detected sources  HIPASS Optical Catalogue (HOPCAT)  3618 (84%) optical galaxies identified  Galaxy Choice category: useful for researchers

ASA Meeting 2005 SuperCOSMOS Image Centred on HICAT positions Original HICAT parameters 1 st Digit: 6 optical galaxy choice Visually matched by 3 people to minimise galaxy selection bias 2 Digit optical galaxy choice - match categories 2 nd Digit: 3 photometry quality 6dF & NED velocities SExtractor Image Analysis ellipses Yellow for correct match

ASA Meeting 2005

HOPCAT Science - Isolated Dark Galaxies  4315 HI radio detected objects  Dust extinction cut at A Bj < 1 mag 3692 objects  Blank fields ( galaxy choice category 30):13 objects  Take out over crowded fields2 objects  2 remaining objects?  1 - very faint previously observed optical galaxy in the Centaurus group – Banks et al (1999)  1- non-detection - Narrow-band follow-up observations at Parkes (Thank you Ivy Wong)  Conclusion: No isolated dark galaxies are present within HIPASS Doyle et al. (MNRAS in press & astro-ph/ )

ASA Meeting 2005 HOPCAT Science Star Formation & Galaxy Density  Previous optical surveys - rapid decrease in star formation with increasing galaxy density (Lewis et al. 2002) WHY??  Morphology-Density Relation - Testing 2 theories In regions of high galaxy density either:  fewer HI rich galaxies OR  HI rich galaxies present but physical process is suppressing star formation  Star Formation Rate  Infrared – IRAS in 12, 25, 60 & 100 μ m  1045 IRAS – HOPCAT matches  Galaxy Density - Local Surface Density Σ 10  SuperCOSMOS Galaxy Catalogue  Σ 10 based on radius to 10 th nearest galaxy neighbour

ASA Meeting ’s 40’s 50’s 10’s SFR calculated from IRAS fluxes

ASA Meeting ’s 40’s 50’s 10’s Σ 10 calculated using SuperCOSMOS Galaxy Catalogue

ASA Meeting 2005 Interesting preliminary results but little time! HI Mass rapidly decrease as density increases however Star Formation efficiency not a rapid change as density increases…….. Afternoon tea bribe required for further discussion……

ASA Meeting 2005 SUMMARY  HIPASS Optical Catalogue – HOPCAT  84% Optical Galaxies identified  HOPCAT Science  No isolated dark galaxies are present within HIPASS  With increasing galaxy density  Star Formation Rate decreases  HI Mass decreases rapidly (preliminary result)  However - Star Formation Efficiency only slight decrease (preliminary result)  HOPCAT available soon at:  – Searchable format  Synergy –MNRAS online – Complete catalogue