HOPCAT, 6dF

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HOPCAT, 6dF Star Formation Rates

• Marianne T. Doyle
• Ph.D. Project

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Content
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 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

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The 6dFGS - HIPASS Connection

• HI Parkes Sky Survey (HIPASS)
• HI blind radio survey of the southern sky up to
  Dec2o
• 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 lt 17
• NOT already in one of the official optical
  target lists for 6dF
• 341 - highest priority multiple matches to radio
  position 1558 - main sample 811 - faint sample
  (16.7ltRlt17)

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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.

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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

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Optical Counterpart - HOPCAT

• HIPASS Catalogue (HICAT) contains 4315 HI radio
  sources
• Find optical counterparts
• Accurate galaxy position needed to measure
  luminosity to calculate SFR
• Search for Dark Galaxies

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Optical Data

• OPTICAL IMAGES
• SuperCOSMOS 15 x 15 Images
• 7 radius Radio-Optical position uncertainty
• IMAGE ANALYSIS
• SExtractor Image Analysis.

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Is that the right galaxy?

• Many images have multiple galaxies
• Crosscheck HIPASS 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

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Results

• Optically Matched with velocity 58 2516
• Single Match (44 - 1882)
• Compact group member (14 - 634)
• Optically Matched with no velocity 26 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

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Any Isolated Dark Galaxies in HIPASS?

• 4315 HI detected objects
• Extinction cut at ABj lt 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
• 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

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HOPCATs Galaxy density coverage

• Solution?
• ATCA high resolution HI observations to
  find/confirm optical counterpart in regions of
  high galaxy density

• Galaxies in regions with Low galaxy density?
• Large sample
• Galaxies in regions with High galaxy density?
• Very small sample

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Star Formation Density

• SUMSS radio continuum data
• 304 Sumss HOPCAT matches
• Galaxy Density
• 10th Galaxy radius
• Galaxy number / degree2
• Star Formation Rate
• Star Formation Efficiency

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Star Formation Rate Vs Density
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Star Formation Efficiency Vs Density

• SUMSS Sydney University Molonglo Sky Survey
• 304 Sumss HOPCAT matches
• Galaxy Density
• 10th Galaxy radius
• Galaxy number / degree2

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Summary

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

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ADRIC interactive visual matching program