HOPCAT, Dark Galaxies & Star Formation

Marianne T. Doyle Ph.D. Project University of Queensland

Content

Marianne Doyle Ph.D Project University of Queensland

  HIPASS Optical Catalogue (HOPCAT) HOPCAT Science

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  Isolated Dark Galaxies  Star Formation & Galaxy Density HIPASS Team – ATNF Parkes & Epping, Universities of : Melbourne, Cardiff, Western Sydney Macarthur, Wales, Swinburne, Technology Sydney, New Mexico, Manchester, Colorado, Sydney, Leicester  Summary & Accessing HOPCAT 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: 300 - 12700 km/s 4315 HI radio detected sources  HIPASS Optical Catalogue (HOPCAT)  3618 (84%) optical galaxies identified  Galaxy Choice category: useful for researchers

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

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HOPCAT Science - Isolated Dark Galaxies

 4315 HI radio detected objects     Dust extinction cut at A Bj

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Take out over crowded fields 1 mag 3692 objects Blank fields ( galaxy choice category 30): 13 objects 2 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/0505591)

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   SuperCOSMOS Galaxy Catalogue Σ 10 based on radius to 10 th nearest galaxy neighbour 10

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60’s 40’s 50’s 10’s

SFR calculated from IRAS fluxes

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60’s 40’s 50’s 10’s

Σ 10 calculated using SuperCOSMOS Galaxy Catalogue

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Interesting preliminary results but little time!

HI Mass rapidly decrease as density increases however Star Formation efficiency

SFE

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SFR Yr Mass HI

not a rapid change as density increases……..

 1 Afternoon tea bribe required for further discussion……

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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:   http://HIPASS.aus-vo.org – Searchable format Synergy –MNRAS online – Complete catalogue

ASA Meeting 2005