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The Evolution of Stars and Gas in Galaxies PhD Thesis Proposal Philip Lah Supervisor: Frank Briggs Supervisory Panel: • Erwin de Blok (RSAA) • Jayaram Chengalur (National Centre for Radio Astrophysics, India) • Matthew Colless (Anglo-Australian Observatory) • Roberto De Propris (University of Bristol, UK) Goal of PhD • to relate the evolution in galaxies of their star formation rate, their stellar mass and their mass of neutral hydrogen gas (the fuel of star formation) • examine galaxy evolution over last 4 Gyr (going back third age of the universe) • study galaxies environments in a variety of different • UNIQUE PART study galaxy properties in same systems – optically selected galaxies Why do this? Should give a clearer picture of how, when and where stars and their host galaxies form. Improves our understanding of our place in the universe, residing in our galaxy, the Milky Way, and orbiting our star, the Sun. Background Star Formation Rate Hα Spectroscopy Subaru Field Hα Narrow Band Imaging UV (with no dust correction) Stellar Mass Density Dickenson et al. 2003 Neutral Hydrogen Gas Mass Neutral Hydrogen Gas Mass Rao & Turnshek 2003 HIPASS HI 21cm StorrieLombardi & Wolfe 2000 Galaxy Environment galaxy environment cluster, cluster outskirts and the field • density - morphology relation • density - star formation relation • density - neutral hydrogen relation Cause of density relations? HI 21cm Emission at High Redshift Previous highest redshift HI Westerbork Synthesis Radio Telescope (WSRT) Netherlands Abell 2218 z = 0.18 integration time 36 days, Zwaan et al. 2001 Very Large Array (VLA) Abell 2192 z = 0.1887 integration time ~80 hours, Veheijen et al. 2004 Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope GMRT Antenna Positions GMRT Collecting Area 30 dishes of 45 m diameter GMRT Collecting Area 21 × ATCA 15 × Parkes 6.9 × WSRT 3.6 × VLA Method of HI Detection • individual galaxies HI 21cm emission below radio observational detection limits • large sample of galaxies with known positions & precise redshifts (from optical observations) • coadd weak HI signals isolated in position & redshift (velocity) space • measure integrated HI signal – total HI mass of whole galaxy population – can calculate the average HI galaxy mass Observational Targets Table of Targets Target z Look Back Time Subaru Field 0.24 2.8 Gyr 1142 MHz 90 hours Abell 370 0.37 4.0 Gyr 1033 MHz 70 hours Cl0024+1654 0.39 4.2 Gyr 1022 MHz 18 + 45 hours νHI GMRT Obs Time Galaxy Cluster Abell 370 27’ × 27’ DEC Cluster Centre RA Galaxy Cluster Abell 370 ~3’ × 3’ DEC RA Abell 370 Data • 42 literature redshifts for Abell 370 cluster members 33 are usable – large error in σz ≥ ± 300 kms-1 (from Soucail et al. 1988 ) • obtaining imaging data ESO 2.2m/WFI with VRI filters 34’ × 33’ (queue scheduled by Sept) use to select sample for spectroscopic follow-up • using AF2/WYFFOS 4.2m William Herschel Telescope, La Palma (sometime in Oct to Dec) for redshifts and star formation rate from [OII] Radio Data Cube DEC RA Spectrum through galaxy redshiftCube Spectrum around Redshift galaxy redshift Flux around Galaxy in Velocity galaxy redshift Space HI Abell 370 RMS decrease Mass HI Assuming an optically thin neutral hydrogen cloud M HI M 2 236 S d L V 1 1 z mJy Mpc kms MHI* = 6.2 ×109 M (Zwaan et al. 2003) Abell 370 HI Mass HI Mass Upper Limit No. Redshifts 33 (with 95% certainty) 8.0 × 109 M 1.3 MHI* Estimates: 100 2.5 × 109 M 0.42 MHI* 300 1.7 × 109 M 0.28 MHI* Galaxy Cluster Cl0024+1654 21’ × 21’ DEC Cluster Centre RA Galaxy Cluster Cl0024+1654 ~1’ × 1’ DEC RA Cl0024+1654 Data • HST imaging 2181 galaxies with morphologies of which 195 spectroscopically confirmed cluster members (Treu et al. 2003) • Hα narrow band imaging with Subaru star formation rates (Kodama et al. 2004) • 296 literature redshifts within HI frequency limits of the GMRT observation (Cszoke et al. 2001) • estimated HI Mass Upper Limit similar to Abell 370: ~1.7 × 109 M Subaru Field 24’ × 30’ RA DEC Subaru Field Redshifts GMRT HI Freq Range Subaru Filter FWHM (120 Å) Subaru Field Redshifts number of target Hα emitting galaxies = 347 number of galaxies with quality ≥ 3 redshifts = 183 number of galaxies in GMRT HI freq range = 166 No. Redshifts 166 Estimated HI Mass Upper Limit (with 95% certainty) 3.1 × 108 M 0.052 MHI* Past and Future Work Previous Work started PhD 1st March 2004 • Mar to mid-July 1st Three Month Project preliminary work on reducing Abell 370 GMRT data - creating data reduction pipeline • mid-July to Aug completed reduction of one sideband of the 7 days of data - prepared results for a GMRT telescope proposal for galaxy cluster Cl0024+1652 • Sept to mid-Nov 2nd Three Month Project 6dFGS working with Robert Proctor and Duncan Forbes (Swinburne University) and Matthew Colless (AAO) Previous Work • mid Nov to Dec Literature Review for Thesis Proposal • Jan 2005 traveled to India for GMRT observations galaxy cluster Cl0024+1652 • beginning of March 5 nights 2dF AAT redshift observations of the Subaru Field • have been working on adapting and revising data reduction code for all GMRT data sets – developing partially automated flagging of data Future Work rest 2005: • finish data reduction code • reduce Subaru data and publish results • reduce Cl0024+1652 data and publish results • Abell 370 spectroscopic observations using AF2/WYFFOS 4.2m William Herschel Telescope, La Palma (sometime in Oct to Dec) – for redshifts and star formation rate from [OII] Future Work 2006: • beginning year finish reducing Abell 370 data and publish results • once published Subaru results may go back to GMRT TAC for another sample of field galaxies • other possibilities: - obtain more redshifts for coadding particularly on the outskirts of the clusters - stellar mass measurements using redshifts and additional near-infrared imaging Future Work 2007: • first 6 months - finish write up thesis / finish off anything left over from previous years The End Additional Slides The UV Plane Abell 370 UV plane UV Plane GMRT Beam