Transcript thesis_proposal

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