1. HOPCAT, 6dFGS & Star Formation Rates
THE MORPHOLOGY-DENSITY RELATION IS THE OBSERVATAION THAT THERE ARE FEW OF THESE SPIRAL GALAXIES IN AREAS OF HIGH GALAXY DENSITY
WHAT WE ARE LOOKING AT IS WHY WE DON’T SEE THESE IN GALAXY DENSE REGIONS
Marianne T. Doyle
Ph.D. Project

2. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
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
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

3. The 6dFGS - HIPASS Connection
HI Parkes Sky Survey (HIPASS)
HI blind radio survey of the southern sky up to Dec=+2o
Velocity range of 300 to 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 < 17 mag
“NOT” already in one of the official optical target lists for 6dFGS
341 - highest priority: multiple matches to radio position main sample faint sample (16.7 < R < 17)
HIPASS
BLIND SURVEY OF THE SOUTHERN SKY
HIPASS CATALOGUE (HICAT)
COVERS HI DETECTIONS OUT TO 300 to 12700KM/S
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

4. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
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.
FIND NO STAR FORMING GALAXIES OR VERY FEW IN GALAXY DENSE REGIONS FIRST PROVED
FIND HI BUT NO STAR FORMATION THEN 2ND IS RIGHT
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

5. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
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
OPTICAL SAMPLE BIASED TOWARD STAR FORMING GALAXIES WHICH IS WHAT WE ARE MEASURING
RADIO GIVES A WIDER COVERAGE OF GALAXY TYPES
SFR
FROM LUMINOSITIES
SFE
SFR / MASS HI
LOCAL GALAXY DENSITY
FIND NO STAR FORMING GALAXIES OR VERY FEW IN GALAXY DENSE REGIONS FIRST PROVED
FIND HI BUT NO STAR FORMATION THEN 2ND IS RIGHT
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

6. 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
“HI SOURCE CONTAINING GAS (AND DARK MATTER)
NO DETECTABLE STARS
SUFFICIENTLY FAR AWAY FROM OTHER GALAXIES, GROUPS OR CLUSTERS
SUCH THAT A TIDAL ORIGIN CAN BE EXCLUDED”
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

7. Radio-Optical Position Uncertainty
Optical Data
OPTICAL IMAGES
SuperCOSMOS 15’ x 15’ Images
Parkes beam is 15’
7’ radius Radio-Optical position uncertainty
IMAGE ANALYSIS
SExtractor Image Analysis.
OPTICAL IMAGES: RADIO–OPTICAL UNCERTAINTY
HIPASS SURVEY HAS 15’ BEAM
WANTED IMAGE BIG ENOUGH TO COVER GALAXY GROUPS
NOT CUT OF EDGES OF LARGER GALAXIES
QUICK TEST SHOWED OPTICAL MATCH CAN BE UP TO 7’ FROM HICAT POSITION
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

8. Is that the right galaxy?
Unobserved areas
Visually matched by 3 people to minimise galaxy selection bias
Is that the right galaxy?
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
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

9. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
Results
Optical counterparts for 84% of HICAT radio sources
Optically Matched with velocity 58%
Single Match (42% )
Compact group member (16% - 714)
Optically Matched with no velocity 26%
Single Match (20% )
Compact group member (6% - 258)
No Guess %
Several galaxies no velocities
Blank Field 5%
No visible galaxy
GO THROUGH THE NUMBERS AND EXPLAIN CATAGORIES
CLASSIFICATION ERROR - EACH IMAGES VIEWED BY 3 PEOPLE AND THE UNANIMOUS % IS LISTED
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

10. Any Isolated Dark Galaxies in HIPASS?
4315 HI detected objects
Extinction cut at ABj < 1: objects
Use only blank fields: 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. (MNRAS in press)
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

11. 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
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

12. HOPCAT’s Galaxy density coverage
Solution?
ATCA high resolution HI observations to find/confirm optical counterpart in regions of high galaxy density
Solution?
ATCA high resolution HI observations to find/confirm optical counterpart in regions of high galaxy density
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

13. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
AS EXPECTED - LARGER THE MHI, HIGHER THE SFR
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

14. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
Distribution of SFR/unit Luminosity - Cluster & Field samples (Lewis et al. 2002)
Cluster sample limited to galaxies within the virial radius
Lewis et al. (2002)
Field galaxies have a higher SFR than those in the clusters
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

15. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

16. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

17. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
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
1. (A) SFR FROM LUMINOSITIES = INFRARED, RADIO CONTINUUM & Sub sample of H-Alpha
(B) LOCAL GALAXY DENSITY MEASURE - 3D & to 10th galaxy density – more work to do
3. (A) SFE - Formula
4. HOW DOES THE CONVERSION OF HYDROGEN TO STARS DEPEND UPON ENVIRONMENT AND OTHER FACTORS?
EITHER - FEWER SF GALAXIES IN REGIONS OF HIGH DENSITY
OR - THERE IS A PHYSICAL PROCESS THAT DIRECTLY SUPPRESSES SF
IF NO DECREASE IN SF = GALAXIES OF DIFFERENT TYPES, WITH FEWER STAR FORMING GALAXIES, FORM IN REGIONS OF HIGH DENSITY.
IF THERE IS A DECREASE IN SF IN REGIONS OF HIGH DENSITY = THEN THE THEORY THAT THERE IS A PHYSICAL PROCESS THAT DIRECTLY SUPPRESSES STAR FORMATION IS SUPPORTED.
!!!!!BUT WE HAVE ATCA OBSERVATIONS IN FEB/MARCH 2005 – VOLUNTEERS??????
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

18. Future Data Resources for SFR Calculations
IRAS
2MASS
HIPASS Continuum
6dFGS Hα
SINGG Hα Survey
Gerhardt Meurer, Johns Hopkins University
Complete Hα imaging for small subset of HIPASS
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

19. 15 x 15 arcmin images to allow for the 7 arcmin position uncertainty
ADRIC
interactive visual matching program
Selection parameters
15 x 15 arcmin images to allow
for the 7 arcmin position uncertainty
Original
HICAT parameters
Superimposed
and listed
Published
velocities
Superimposed
ellipses
Yellow for
correct match
Centred on
HICAT positions
SCREEN SHOT OF THE ADRIC PROGRAM
HICAT PARAMETERS
FIELD CENTRED ON A HICAT SOURCE
15 ARCMIN SQUARE IMAGE – ~7ARCMIN HIPASS POSITION UNCERTAINITY
IMAGES ANALYISED AND FROM DATA ELLIPSES PRODUCED (SELECTED GALAXY IN YELLOW).
WITH 2 SOURCES OF PUBLISHED VELOCITIES
THE BUTTONS CLASSIFY THE SELECTED TYPE OF OPTICAL COUNTERPART & QUALITY
ALLOWING CASES OF POOR PHOTOMETRY – STAR INSIDE ELLIPSES
POOR IMAGE SEGMENTATION – ELLIPSE NOT ENCAPUTLAING THE WHOLE GALAXY
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005

20. Swinburne Galaxy Groups Workshop 24th & 25th May, 2005
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
Swinburne Galaxy Groups Workshop 24th & 25th May, 2005