HOPCAT, Dark Galaxies & Star Formation

Marianne T. DoylePh.D. Project

University of Queensland

ASA Meeting 2005

ContentHIPASS Optical Catalogue

(HOPCAT)

HOPCAT Science

Isolated Dark Galaxies

Star Formation & Galaxy Density

Summary & Accessing HOPCAT

Marianne Doyle Ph.D ProjectUniversity of

QueenslandAdvisor:Michael J. Drinkwater – UQAssoc. Advisors:Elaine Sadler – Uni SydneyJohn Ross - UQCollaborators David J. Rohde - UQKevin Pimbblet - UQMike Read – WFAU EdinburghHIPASS Team – ATNF Parkes &

Epping, Universities of : Melbourne, Cardiff, Western Sydney Macarthur, Wales, Swinburne, Technology Sydney, New Mexico, Manchester, Colorado, Sydney, LeicesterASTRON 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=+2o

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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SuperCOSMOS Image Centred on HICAT positions

Original

HICAT parameters

1st Digit: 6 optical galaxy choice

Visually matched by 3 people to minimise galaxy selection bias

2 Digit optical galaxy choice - match categories

2nd Digit: 3 photometry quality

6dF & NED velocities

SExtractorImage

Analysisellipses

Yellow for correct match

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HOPCAT Science - Isolated Dark Galaxies 4315 HI radio detected objects Dust extinction cut at ABj < 1 mag 3692 objects

Blank fields (galaxy choice category 30): 13 objects Take out over crowded fields 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 HIPASSDoyle 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 μm

1045 IRAS – HOPCAT matches

Galaxy Density - Local Surface Density Σ10 SuperCOSMOS Galaxy Catalogue

Σ10 based on radius to 10th nearest galaxy neighbour

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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

Σ10 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

not a rapid change as density increases……..

Afternoon tea bribe required for further discussion……

1

YrMass

SFRSFE

HI

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