H OPCAT, 6dFGS & Star Formation Rates Marianne T. Doyle Ph.D. Project

HOPCAT, 6dFGS & Star Formation Rates

Marianne T. DoylePh.D. Project

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

Content 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

Advisor:Michael J. Drinkwater – UQAssoc. Advisors: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

Velocity range of 300 to 12700 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 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 Part 1

Use radio detected galaxy sample instead of optical sampleOptical 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


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


Optical Data

OPTICAL IMAGES SuperCOSMOS 15’ x 15’ Images

Parkes beam is 15’7’ 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:

High quality dataset - 6dFGS velocities (Kindly supplied by Heath)

Published velocities – NEDInformation from catalogues, surveys & the literatureData varies in quality

Developed ADRIC Automated visual interactive program

Unobserved areas

Visually matched by 3 people to minimise galaxy selection bias


ResultsOptical counterparts for 84% of HICAT radio sources

Optically Matched with velocity 58% 2512 Single Match (42% - 1798) Compact group member (16% - 714)

Optically Matched with no velocity 26% 1106 Single Match (20% - 848) Compact group member (6% - 258)

No Guess 11% 481 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 – 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)


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

11-22

/Hz W 102.3

Lum

YrMSFR Solar

1

YrMass

SFRSFE

HI

2

10

11

DegGalArea RadiusGalaxyth

Galaxy


HOPCAT’s Galaxy density coverage Solution?

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



Distribution of SFR/unit Luminosity - Cluster & Field samples (Lewis et al. 2002)Cluster sample limited to galaxies within the virial radius




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


Future Data Resources for SFR Calculations

IRAS2MASS HIPASS Continuum6dFGS HαSINGG Hα Survey

Gerhardt Meurer, Johns Hopkins University Complete Hα imaging for small subset of HIPASS


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


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

Documents

H OPCAT, 6dFGS & Star Formation Rates Marianne T. Doyle Ph.D. Project