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 in a variety of different environments 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 Subaru Field  Hα Spectroscopy  Hα Narrow Band Imaging  UV (with no dust correction)

Stellar Mass Density Dickenson et al. 2003

Neutral Hydrogen Gas Mass

HIPASS HI 21cm Rao & Turnshek 2003 Storrie- Lombardi & 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 Very Large Array (VLA) Abell 2192 z = integration time ~80 hours, Veheijen et al. 2004

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 Targetz Look Back Time ν HI GMRT Obs Time Subaru Field Gyr1142 MHz90 hours Abell Gyr1033 MHz70 hours Cl Gyr1022 MHz hours

Galaxy Cluster Abell 370 RA DEC 27’ × 27’ Cluster Centre

Galaxy Cluster Abell 370 RA DEC ~3’ × 3’

Abell 370 Data 42 literature redshifts for Abell 370 cluster members  33 are usable – large error in σ z ≥ ± 300 kms -1 (from Soucail et al ) 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 RA DEC

Spectrum through Cube galaxy redshift

Spectrum around Redshift galaxy redshift

Flux around Galaxy in Velocity Space galaxy redshift

HI Abell 370

RMS decrease

Mass HI Assuming an optically thin neutral hydrogen cloud M HI * = 6.2 ×10 9 M  (Zwaan et al. 2003)

Abell 370 HI Mass No. Redshifts HI Mass Upper Limit (with 95% certainty) × 10 9 M  1.3 M HI * Estimates: × 10 9 M  0.42 M HI * × 10 9 M  0.28 M HI *

Galaxy Cluster Cl RA DEC 21’ × 21’ Cluster Centre

Galaxy Cluster Cl RA DEC ~1’ × 1’

Cl Data HST imaging  2181 galaxies with morphologies of which 195 spectroscopically confirmed cluster members (Treu et al. 2003) H α 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 × 10 9 M 

Subaru Field RA DEC 24’ × 30’

Subaru Field Redshifts Subaru Filter FWHM (120 Å) GMRT HI Freq Range

Subaru Field Redshifts No. Redshifts Estimated HI Mass Upper Limit (with 95% certainty) × 10 8 M  M HI * number of target Hα emitting galaxies = 347 number of galaxies with quality ≥ 3 redshifts = 183 number of galaxies in GMRT HI freq range = 166

Past and Future Work

Previous Work started PhD 1st March 2004 Mar to mid-July  1 st 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 Cl Sept to mid-Nov  2 nd 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 Cl 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 Cl 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