HOPCAT, 6dF & Star Formation Rates

Marianne T. DoylePh.D. Project

ContentThe HIPASS - 6dFGS Connection

My Project

Investigate the question: How does star

formation depend upon environment

and other factors?

Finding optical counterparts for the HIPASS

catalogue

Investigating the Morphology-density

relation using Star Formation Rates, Star

Formation Efficiency and Galaxy Density

Supervisor:Michael J. Drinkwater – UQAssoc. Supervisors:Elaine Sadler – Uni SydneyJohn Ross - UQCollaborators David J. Rohde - UQMike Read – WFAU

EdinburghBaerbel Koribalski – ATNF,

EppingHIPASS Team – ATNF Parkes

& Epping, Universities of : Melbourne, Cardiff, Western Sydney Macarthur, Wales, Swinburne, Technology Sydney, New Mexico, Manchester, Colorado, Sydney, LeicesterASTRON The Netherlands,AAO Sydney,WIYN Tucson etc….......

The 6dFGS - HIPASS Connection HI Parkes Sky Survey (HIPASS)

HI blind radio survey of the southern sky up to Dec=2o

October 2001: 2710 “additional” targets were added to the 6dfGS (Thank you Michael Drinkwater)

Optical objects included are: within 5 arcmin of the HIPASS positions R mag < 17“NOT” already in one of the official optical target lists for 6dF

341 - highest priority: multiple matches to radio position 1558 - main sample 811 - faint sample (16.7<R<17)

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.

Steps 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.

Star Formation Rate (SFR)

Star Formation Efficiency (SFE)

Local galaxy density

YrMSFR Solar /Hz W 2.3

Lum1-22

1.4GHz

1

YrMass

SFRSFE

HI

2

10

11DegGal

Area RadiusGalaxythGalaxy

Optical Counterpart - HOPCAT

HIPASS Catalogue (HICAT) contains 4315 HI radio sources

Find optical counterparts Accurate galaxy position needed to measure

luminosity to calculate SFR

Search for “Dark Galaxies”

Optical Data

OPTICAL IMAGES SuperCOSMOS 15’ x 15’ Images

7’ radius Radio-Optical position uncertainty

IMAGE ANALYSIS SExtractor Image Analysis.

Radio-Optical Position Uncertainty

Is that the right galaxy? Many images have multiple galaxies Crosscheck HIPASS velocity with optical or high

resolution radio velocities Published velocities – NED

Information from catalogues, surveys & the literatureData varies in quality

Need a high quality dataset6dF velocities (Kindly supplied by Heath)

Developed an automated visual interactive program

ADRIC

Unobserved areas

Results 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

Any Isolated Dark Galaxies in HIPASS? 4315 HI detected objects Extinction cut at ABj < 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

1 ruled out with Narrow-band follow-up observations at Parkes as a non-detection

Conclusion: No isolated dark galaxies are present in the HIPASS survey

HOPCAT’s Galaxy density coverage Galaxies in

regions with Low galaxy density? Large sample

Galaxies in regions with High galaxy density? Very small

sample

Solution?ATCA high resolution HI observations to find/confirm optical counterpart in regions of high galaxy density

Star Formation & Density SUMSS radio continuum data

304 Sumss – HOPCAT matches

Galaxy Density 10th Galaxy radius Galaxy number / degree2

Star Formation Rate Star Formation Efficiency

Star Formation Rate Vs Density

Ave density=0.07

SFR ave=1.3

Ave density =0.9

Ave SFR = 0.34

Ave density = 12

Ave SFR = 0.5

Ave density = 86

Ave SFR = 1.2

SUMSS – Sydney University Molonglo Sky Survey 304 Sumss –

HOPCAT matches

Galaxy Density 10th Galaxy radius Galaxy number /

degree2

Star Formation Efficiency Vs Density

Summary

2710 optical galaxies near HIPASS positions were added to the 6dFGS list

Superimposed ellipses

Yellow for correct match

15 x 15 arcmin images to allow

for the 7 arcmin position uncertaintyCentred on

HICAT positions

Selection parameters

Original

HICAT parameters

Superimposed and listedPublished velocities

ADRIC

interactive visual matching program