1. 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

2. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
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?
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

3. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
In The Beginning………
SFR
-Density
Relation
Lewis et al (2002)
Morphology
-Density
Relation
Dressler et al. (1980)
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

4. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
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?
FIND NO STAR FORMING GALAXIES OR VERY FEW IN GALAXY DENSE REGIONS FIRST PROVED
FIND HI BUT NO STAR FORMATION THEN 2ND IS RIGHT
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

5. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
Local Galaxy Density
3D Local Galaxy Density → No Redshifts → Not Possible
2D - Local Surface Density – Σ10
HIPASS Catalogue (HICAT) Optical Catalogue - HOPCAT
Reliable radio-optical galaxy matches
Centred on
HICAT positions
HICAT Information
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

6. Star Formation Rate & Efficiency
Star Formation Rate – SFR
Infrared Fluxes from IRAS
Radio Fluxes from SUMSS & NVSS
Star Formation Efficiency - SFE
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

7. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
SFR-Density Relation
Infrared SFRs
SFR-Density Relation
Radio SFRs
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

8. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
SFR-Density Relation
Infrared SFRs
Separated into 1000 km s-1 Velocity Ranges
6dF2MASS-IRAS
1180 galaxies
SFR-Density Relation
Radio SFRs
Separated into 1000 km s-1 Velocity Ranges
SCosGC-SUMSS/NVSS
339 galaxies
339 (172 & 167) 478 (275 & 203)
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

9. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
SFE-Density Relation
Infrared SFEs
Separated into 1000 km s-1 Velocity Ranges
6dF2MASS-IRAS
1180 galaxies
SFE-Density Relation
Radio SFEs
Separated into 1000 km s-1 Velocity Ranges
SCosGC-SUMSS/NVSS
339 galaxies
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

10. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
Optical
vs.
Radio
Samples
KS test confirms 2 populations are different
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

11. Comparing SFR vs. Σ10 Results
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

12. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
Conclusion
So……..
SFR & SFE of HI Galaxies does not depend on Σ10
Population of HI galaxies decreases with increasing Σ10 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.
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

13. 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……..
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

14. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
EXTRA SLIDES
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

15. 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)
Original
HICAT parameters
6dF & NED
velocities
SuperCOSMOS Image Centred on
HICAT positions
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

16. Local Galaxy Density Problems?
Density Corrections for edge affects
> 50% edge affected - galaxy removed
Density Corrected
Northern & Galactic Plane edge affected – trigonometry
SMC & LMC edge affected – Monte Carlo integral method
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
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

17. Star Formation Rate & Efficiency Radio & Infrared Fluxes
Infrared Fluxes from IRAS
Radio Fluxes from SUMSS & NVSS
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

18. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
Data Sets
Fluxes HOPCAT-SCosGC HOPCAT-6dF2MASS
SFR vs MHI (vel<10000 km s-1)
IRAS
SUMSS
SN6I
Σ10 Plots ( 1000<vel<6000 km s-1)
IRAS
SUMSS
SN6I
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

19. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
HI Mass vs. SFR
But is this to good to be true?
Flux Limited Sample?
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney

20. ASA Scientific Meeting 1 – 5th July, 2007 Macquarie University, Sydney
HI Mass
vs.
SFR
Separated
into
1000 km s-1
Velocity
Ranges
ASA Scientific Meeting 1 – 5th July, Macquarie University, Sydney