HOPCAT, 6dFGS

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HOPCAT, 6dFGS Star Formation Rates

• Marianne T. Doyle
• Ph.D. Project

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Content
Advisor Michael J. Drinkwater UQ Assoc.
Advisors 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 PhD Project 6dFGS
• Investigate the question How does star formation
  depend upon environment and other factors?
• Part 1 Finding optical counterparts for the
  HIPASS catalogue
• Part 2 Investigate the 2 possible explanations
  for 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
• Velocity range of 300 to 12700 km s-1
• October 2001
• 2710 additional targets were added to the
  6dFGS (Thank you Mike Read Michael Drinkwater)
• Optical objects included are
• within 5 arcmin of the HIPASS positions
• R lt 17 mag
• NOT already in one of the official optical
  target lists for 6dFGS
• 341 - highest priority multiple matches to radio
  position 1558 - main sample 811 - faint sample
  (16.7 lt R lt 17)

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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

• Part 1
• 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.
• Find optical counterparts for radio sample
• Part 2
• Star Formation Rate (SFR)
• Star Formation Efficiency (SFE)
• Local galaxy density
• Which theory is correct to explain the
  Morphology-density relation

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1st Part Optical Counterpart - HOPCAT

• HIPASS Catalogue (HICAT) contains 4315 HI radio
  sources
• Parkes beam 15 - Radio-Optical position
  uncertainty 7
• Find optical counterparts
• Accurate optical positions are needed to measure
  luminosity to estimate SFR
• Search for Isolate Dark Galaxies
• HI source containing gas (and dark matter)
• No detectable stars
• Sufficiently far away from other galaxies, groups
  or clusters

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Optical Data

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

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Is that the right galaxy?
Visually matched by 3 people to minimise galaxy
selection bias

• Many images have multiple galaxies
• Crosscheck HIPASS velocity with
• High quality dataset - 6dFGS velocities (Kindly
  supplied by Heath)
• Published velocities NED
• Information from catalogues, surveys the
  literature
• Data varies in quality
• Developed ADRIC
• Automated visual interactive program

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Results

• Optical counterparts for 84 of HICAT radio
  sources
• 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 Banks et al (1999)
• 1 ruled out with Narrow-band follow-up
  observations at Parkes as a non-detection (Thank
  you Ivy)
• Conclusion No isolated dark galaxies are present
  in the HIPASS survey
• Doyle et al (submitted MNRAS)

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Part 2 Star Formation Density (Preliminary
work)

• First Pass
• Sydney University Molonglo Sky Survey (SUMSS)
  843MHz radio continuum data
• 304 SUMSS HOPCAT matches
• Star Formation Rate
• Star Formation Efficiency
• Galaxy Density
• Galaxy separation between HICAT SuperCOSMOS
  Galaxy Catalogue positions
• Area based on a radius to the
• 10th nearest galaxy
• Galaxy number / degree2

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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

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Distribution of SFR/unit Luminosity - Cluster
Field samples (Lewis et al. 2002) Cluster sample
limited to galaxies within the virial radius
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SUMMARY

• Positions for 2710 optical galaxies near HIPASS
  positions added to 6dFGS observing list
• HIPASS Optical Catalogue
• Used 6dFGS velocities
• Optical Counterparts for 84
• Preliminary Work - SUMSS
• SFR vs. HI mass Larger the HI mass the larger
  the SFR
• SFR vs. Density Decreased SFR in galaxy dense
  regions? More analysis needed
• SFE vs. Density Decreased SFE in galaxy dense
  regions? More analysis needed

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Future Data Resources for SFR Calculations

• IRAS
• 2MASS
• HIPASS Continuum
• 6dFGS Ha
• SINGG Ha Survey
• Gerhardt Meurer, Johns Hopkins University
• Complete Ha imaging for small subset of HIPASS

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ADRIC interactive visual matching program
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Analysis of SuperCOSMOS Images

• SExtractor Image Analysis
• SuperCOSMOS data catalogue?
• Ellipse segmentation problem for extended objects
• SExtractor Segmentation problems?
• Used 2 sets of ellipse analysis parameters