Download presentation
Presentation is loading. Please wait.
1
The Evolution of Stars and Gas in Galaxies PhD Thesis Proposal Philip Lah
2
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)
3
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
4
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.
5
Background
6
Star Formation Rate Subaru Field Hα Spectroscopy Hα Narrow Band Imaging UV (with no dust correction)
7
Stellar Mass Density Dickenson et al. 2003
8
Neutral Hydrogen Gas Mass
9
HIPASS HI 21cm Rao & Turnshek 2003 Storrie- Lombardi & Wolfe 2000
10
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?
11
HI 21cm Emission at High Redshift
12
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
13
Giant Metrewave Radio Telescope
23
GMRT Antenna Positions
24
GMRT Collecting Area 30 dishes of 45 m diameter GMRT Collecting Area 21 × ATCA 15 × Parkes 6.9 × WSRT 3.6 × VLA
25
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
26
Observational Targets
27
Table of Targets Targetz Look Back Time ν HI GMRT Obs Time Subaru Field0.242.8 Gyr1142 MHz90 hours Abell 3700.374.0 Gyr1033 MHz70 hours Cl0024+16540.394.2 Gyr1022 MHz18 + 45 hours
28
Galaxy Cluster Abell 370 RA DEC 27’ × 27’ Cluster Centre
29
Galaxy Cluster Abell 370 RA DEC ~3’ × 3’
30
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. 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]
31
Radio Data Cube RA DEC
32
Spectrum through Cube galaxy redshift
33
Spectrum around Redshift galaxy redshift
34
Flux around Galaxy in Velocity Space galaxy redshift
35
HI Abell 370
36
RMS decrease
37
Mass HI Assuming an optically thin neutral hydrogen cloud M HI * = 6.2 ×10 9 M (Zwaan et al. 2003)
38
Abell 370 HI Mass No. Redshifts HI Mass Upper Limit (with 95% certainty) 33 8.0 × 10 9 M 1.3 M HI * Estimates: 100 2.5 × 10 9 M 0.42 M HI * 300 1.7 × 10 9 M 0.28 M HI *
39
Galaxy Cluster Cl0024+1654 RA DEC 21’ × 21’ Cluster Centre
40
Galaxy Cluster Cl0024+1654 RA DEC ~1’ × 1’
41
Cl0024+1654 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
42
Subaru Field RA DEC 24’ × 30’
43
Subaru Field Redshifts Subaru Filter FWHM (120 Å) GMRT HI Freq Range
44
Subaru Field Redshifts No. Redshifts Estimated HI Mass Upper Limit (with 95% certainty) 166 3.1 × 10 8 M 0.052 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
45
Past and Future Work
46
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 Cl0024+1652 Sept to mid-Nov 2 nd Three Month Project - 6dFGS working with Robert Proctor and Duncan Forbes (Swinburne University) and Matthew Colless (AAO)
47
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
48
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]
49
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
50
Future Work 2007: first 6 months - finish write up thesis / finish off anything left over from previous years
51
The End
53
Additional Slides
54
The UV Plane
55
Abell 370 UV plane
56
UV Plane
57
GMRT Beam
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.