HI Galaxies & the Star Formation Rate-Density

Relation

Dr Marianne T. Doyle - My PhDMichael J. Drinkwater – UQ - Principle Advisor

Elaine Sadler, Uni Sydney & John Ross - Assoc. Advisors

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, 2007 Macquarie University, Sydney

Morphology

-Density

RelationDressler et al. (1980)

SFR

-Density

RelationLewis et al (2002)

In The Beginning………

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?

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, 2007 Macquarie University, Sydney

Star Formation Rate & Efficiency

Star Formation Rate – SFR Infrared Fluxes from IRAS Radio Fluxes from SUMSS & NVSS

Star Formation Efficiency - SFE

HIMass

SFRYrSFE )( 1

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

SFR-Density RelationInfrared SFRs

SFR-Density RelationRadio SFRs

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

SFR-Density RelationRadio SFRs

Separated into 1000 km s-1 Velocity Ranges

SCosGC-SUMSS/NVSS

339 galaxies

SFR-Density RelationInfrared SFRs

Separated into 1000 km s-1 Velocity Ranges

6dF2MASS-IRAS

1180 galaxies

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

SFE-Density RelationInfrared SFEs

Separated into 1000 km s-1 Velocity Ranges

6dF2MASS-IRAS

1180 galaxies

SFE-Density RelationRadio SFEs

Separated into 1000 km s-1 Velocity Ranges

SCosGC-SUMSS/NVSS

339 galaxies

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, 2007 Macquarie University, Sydney

Comparing SFR vs. Σ10 Results

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, 2007 Macquarie University, Sydney

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, 2007 Macquarie University, Sydney

EXTRA SLIDES

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

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)

SuperCOSMOS Image Centred on

HICAT positions6dF & NED velocities

Original

HICAT parameters

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

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

Local Galaxy Density Problems?Density

Corrections for edge affects> 50% edge

affected - galaxy removed

Density CorrectedNorthern &

Galactic Plane edge affected – trigonometry

SMC & LMC edge affected – Monte Carlo integral method

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

Star Formation Rate & Efficiency Radio & Infrared Fluxes

Infrared Fluxes from IRAS Radio Fluxes from SUMSS & NVSS

1-221.4GHz1

4.1Hz W 102.3

Lum)( yrMSFR solarGHz

)s (ergs Lum105.4)( 1-IR

441 yrMSFR solarIR

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 1405 1405

SUMSS 340 340

SN6I 221 221

Σ10 Plots ( 1000<vel<6000 km s-1)

IRAS 923 1180

SUMSS 172 275

SN6I 167 203

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, 2007 Macquarie University, Sydney

HI Mass

vs.

SFR

Separated

into

1000 km s-1

Velocity

Ranges