HI Galaxies

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HI Galaxies the Star Formation Rate-Density
Relation
Dr Marianne T. Doyle - My PhD Michael J.
Drinkwater UQ - Principle Advisor Elaine
Sadler, Uni Sydney John Ross - Assoc. Advisors
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Content

• Morphology-Density Star Formation
  Rate-Density Relations
• A New way to Investigating the SFR-Density
  Relation - HI Galaxy Sample
• HI Parkes All Sky Survey Optical Catalogue
  HOPCAT
• Results
• Conclusions
• What Next?

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In The Beginning
Morphology -Density Relation Dressler et al.
(1980)
SFR -Density Relation Lewis et al (2002)
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My PhD Project

• Past studies are based on optical samples
• Different Investigation of SFR-Density Relation -
  HI Galaxies Sample to answer the question
• Are there fewer HI star forming galaxies in
  regions of high galaxy density
• OR
• Are there physical processes that directly
  suppresses star formation in these galaxies?

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Local Galaxy Density

• 3D Local Galaxy Density ? No Redshifts ? Not
  Possible
• 2D - Local Surface Density S10
• HIPASS Catalogue (HICAT) Optical Catalogue -
  HOPCAT
• Reliable radio-optical galaxy matches

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Star Formation Rate Efficiency

• Star Formation Rate SFR
• Infrared Fluxes from IRAS
• Radio Fluxes from SUMSS NVSS
• Star Formation Efficiency - SFE

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SFR-Density Relation Infrared SFRs
SFR-Density Relation Radio SFRs
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Optical vs. Radio Samples KS test confirms 2
populations are different
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Comparing SFR vs. S10 Results
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Conclusion

• So..
• SFR SFE of HI Galaxies does not depend on S10
• Population of HI galaxies decreases with
  increasing S10 compared to past optical samples
• There are fewer HI star-forming galaxies in
  regions with increasing local surface density.
• It is the HI galaxy population that decreases,
  not their SFR, with increasing local surface
  density.
• Confirming the Morphology-Density Relation.
• Previous SFR-Density Relation results are due to
  the optical data samples used.

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PhD completed! (Sigh of relief)

• Wish List for Post Doctoral Research?
• Star Formation in Galaxies /or Galaxy
  Groups/Clusters.
• Intergalactic galaxy/cluster research.
• SKA/Radio Astronomy.
• Multi-wavelength extragalactic research.
• Optical Astronomy.
• To be or not to be a Dark Galaxy..

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EXTRA SLIDES
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A New way to Investigating the SFR-Density
Relation HI Galaxies

• HI Galaxy Sample - HOPCAT
• Optical Catalogue based on the HI Parkes All Sky
  Survey Catalogue (HICAT)

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Local Galaxy Density Problems?

• No redshifts Fore Background galaxy
  contamination?
• Arbitrary MBj bright faint limits (-21-17mags
  respectively)
• Corresponding mbj limits calculated using target
  galaxies velocity
• Only use galaxies with this range of mbj

• Density Corrections for edge affects
• gt 50 edge affected - galaxy removed
• Density Corrected
• Northern Galactic Plane edge affected
  trigonometry
• SMC LMC edge affected Monte Carlo integral
  method

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Star Formation Rate Efficiency Radio
Infrared Fluxes

• Infrared Fluxes from IRAS
• Radio Fluxes from SUMSS NVSS

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Data Sets

• Fluxes HOPCAT-SCosGC HOPCAT-6dF2MASS
• SFR vs MHI (vellt10000 km s-1)
• IRAS 1405 1405
• SUMSS 340 340
• SN6I 221 221
• S10 Plots ( 1000ltvellt6000 km s-1)
• IRAS 923 1180
• SUMSS 172 275
• SN6I 167 203

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HI Mass vs. SFR
But is this to good to be true? Flux Limited
Sample?
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HI Mass vs. SFR
Separated into 1000 km s-1 Velocity Ranges