Star Formation Efficiency and Environment

1. Screen shot of the ADRIC program showing 15’ SuperCOSMOS field centred on a HICAT source, with published velocities in red, blue ellipses from SExtractor catalogue (selected galaxy in purple). The buttons classify the selected optical counterpart (allowing cases of poor photometry due to merged objects or poor image segmentation to be noted). Log HIPASS Peak Flux Vs Optical Apparent Magnitude for objects matched by velocities from NED and 6dF, educated guesses without velocity match and velocity matches where multiple galaxies match. Skyplot of the position of each HIPASS radio source co-ordinates. Note the concentration of “blank fields” in the Galactic Plane. Position offset (RA) vs Peak Radio Flux Log Mass HI Vs Log Luminosity for objects matched by velocities from NED and 6dF, educated guesses without velocity match and velocity matches where multiple galaxies match. Position offsets: Radio - Optical Velocity offsets: Radio – Optical vs Peak Flux 6dF HαEquivalent Width Vs B-R Density Ratio Vs B-R for 6dF Galaxy Survey observation -22< dec <-42. Density ratio: ratio of galaxy density within a 10MParsec radius for each optically matched galaxy to the galaxy density of HICAT within 5MParsec radius volumes • Star Formation Efficiency and Environment • Marianne T. Doyle*1, David J. Rohde1, Michael J. Drinkwater1, Mike Read2, Baerbel S Koribalski3 and The HIPASS Team • Department of Physics, University of Queensland, Brisbane, Queensland 4072, Australia. • WFAU, Institute for Astronomy, Royal Observatory, Blackford Hill Edinburgh, EH9 3HJ, UK • ATNF, PO Box 76 Epping NSW 1710 AustraliaEmail: mtdoyle@physics.uq.edu.au SUMMARY OPTICAL COUNTERPARTS OF HIPASS SOURCES • New HIPASS Optical Catalogue (HOPCAT) • Optical counterparts for the HI Parkes All-Sky 21cm Survey (HIPASS) (1) have been identified using SuperCOSMOS optical sky survey images • Using the new optical sample we will investigate • Estimators of Star Formation Rates (SFR) • Dependence of Star Formation on local galaxy density • Input Data • Radio: • HIPASS catalogue (HICAT) (2) - 4329 sources • Optical: • SuperCOSMOS (3): Optical images • SExtractor (4): new image catalogue with BRI photometry • 6dF Galaxy Survey (5): velocity matching • NED Database (6): velocity matching • Matching Process – ADRIC • ADRIC: Matlab Program to display and select optical data for each HIPASS source • Velocities from the NED Database and the 6dF Galaxy Survey were used to match those for the HIPASS radio sources to confirm optical matches • When no velocities were available proximity to the HIPASS co-ordinates and other image features were used to assist optical matching • Results • Analysis of 4329 Radio Sources • 78% identified • Velocity Match 57% • With published velocity • Good Guesses 10% • But no published velocity • Multi Match 11% • Compact group of galaxies • No Guess 15% • Several galaxies no velocities • Blank Field 7% STAR FORMATION AND ENVIRONMENT • Star Formation Estimators • Hα emission line equivalent width from 6dF Galaxy Survey • shows expected weak correlation with colour • 6dF spectra measured using 7 arcsec fibres • Measure only the centre of the galaxy • Future Work • Estimators of TOTAL Star Formation Rate to be investigated: • Radio Continuum • High resolution radio observations • HIPASS continuum catalog in preparation • Mid Infrared • Correlation of SFR with local galaxy density • Tentative evidence that galaxies in high-density regions are redder (see figure) References • Stavely-Smith et al (2001) Stavely-Smith, Lister, 2001, MNRAS, 322, • Zwaan & Meyer et al (in preparation) • Hambly et al, 2001, MNRAS, 326,1279-1294,1295-1314,1315-1327 • Bertin E., Arnouts S., AASS, (1996) 117, 393-404 • Wakamatsu, K., Colless M.M., Jarrett T., Parker Q., Saunders W. and Watson F., 2002, IAU Regional Assembly, ASP Conf. Series (in press) • Madore Barry F., Helou George, Corwin Harold G. Jr.,Schmitz Marion, Wu Xiuqiv and Bennett Judy, 1992, ADASS I ASP Conf Series, 25 • Background: M83: The Southern Pinwheel Galaxy from VLT, FORS Team, 8.2-meter VLT, ESO, http://antwrp.gsfc.nasa.gov/apod/ap030511.html IAU SYMPOSIUM 216 - MAPS OF THE COSMOS – 14 -17 JULY XXV\TH GENERAL ASSEMBLY, SYDNEY JULY 13-26, 2003