The Evolution of Stars and Gas in Galaxies:

PhD Midterm

Philip Lah

A journey with noise and astrometry

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 (Cerro Tololo Inter-American Observatory, Chile)

Those that deserve special mentions:

• Brian Schmidt

• Agris Kalnajs

• Michael Pracy

• Tony Martin-Jones

• Scott Croom (AAO) & Rob Sharp (AAO)

• Nissim Kanekar (NRAO)

Goal of PhD

• to relate the star formation rate, the stellar mass and the mass in neutral hydrogen gas in galaxies as they evolve

• to examine galaxy evolution over last 4 Gyr, (a third of the age of the universe, z~0.4)

• to study galaxies in a variety of different environments

• UNIQUE PART to study galaxy properties in the same systems – optically selected galaxies

Background

Star Formation Rate

SubaruField

Hα Spectroscopy

Hα Narrow Band Imaging

UV (with no dust correction)

HI redshift

Zwaan et al. 2005HIPASSHI 21cm

Rao et al. 2006

Prochaska et al. 2005

HI look back

HI 21cm Emission at

High Redshift

HI emission• HI – single atom of hydrogen – radiation from an excited state were proton & electron have the same spin - 10 million year half life• Assuming an optically thin neutral hydrogen cloud

• MHI* = 6.3 ×109 M (HIPASS, Zwaan et al. 2005)

1

2

1

236

kms

V

Mpc

d

mJy

S

zM

M LHI

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

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

RA

DEC

Radio Data Cube

• pick out HI signal using optical redshifts

• coadd faint signals to make measurement

Observational Targets

Table of Targets

Target Type zLook Back

TimeGMRT Obs

Time

Subaru Fieldfield galaxies

with H emission

0.24 2.8 Gyr 80.5 hours

Abell 370cluster and

surroundings0.37 4.0 Gyr 70 hours

Cl0024+1654cluster and

surroundings0.39 4.2 Gyr 18 + 45 hours

Galaxy Cluster Abell 370

Galaxy Cluster Abell 370

RA

DEC 27’ × 27’

Cluster Centre

Galaxy Cluster Abell 370

RA

DEC ~3’ × 3’

HI Abell 37033 literature

redshifts but σz ≥ ± 300 kms-1

Upper limit MHI = 1.3 MHI

*

with 95% confidence

Galaxy Cluster Abell 370

• need more redshifts for reasonable analysis

• the plan is to use WFI on SSO 40 inch for imaging – Mike Pracy took some data last year and hopefully take more this year

• hopefully use AAOmega for spectroscopic follow-up in October/November 2006

• also made improvements to my data reduction methods so redo reduction

The Subaru Field - H emission galaxies

Subaru Field

RA

DEC

24’ × 30’

Fujita et al. 2003 narrow band imaging - H emission

flux

We used 2dF to get redshifts

SDF positions

GMRT beam 10% level

GMRT beam 50% level

Blue Points Subaru galaxies

Red Points NVSS Radio Continuum

Sources

SDF uv coverage

Subaru Field is

equatorial

Image of Dirty Beam

image

7’ × 7’

radio equivalent of optical point

spread function

Self Calibration

Deepest GMRT Image

Field 10

12’ × 12’

RMS ~ 16 Jy

Sad cont sources

From AIPS auto detection routine -

SAD

Blue > 5 mJyRed > 1 mJy

Black > 0.32 mJyGrey > 80 Jy

RMS ~ 16 Jy

SubaruField

boundary

Continuum Images

Thumbnails 20’’ sq

Fuzzy RC

IntegratedFlux = 17.035

0.077 mJy

Fuzzy B

galaxyUGC 05849

atredshift

z=0.026045

Astrometry

• need optical and radio positions to agree to a high level of precision

• shift in radio data – corrected by comparing with FIRST continuum source positions

• optical data – PROBLEM coordinates that I had been given for the Subaru galaxies rounded to the 5th decimal place before converting to degrees/hours, minutes, seconds format

eg. 10.56479302 10.56479 10h 33m 53.24s

Position change

Rounding error:

0.18’’ DEC2.7’’ RA

PROBLEMS2dF fibre

diameter is 2’’

many galaxies

smaller than 2’’

Radio Continuum of the

Subaru Galaxies

Sullivan et al. 2003

Sullivan et al. 2001

H Luminosity vs.

1.4 GHz Luminosity

&

UV Luminosity vs.

1.4 GHz Luminosity

Subaru Galaxies - B magnitude

Thumbnails 10’’ sq

Ordered by H

luminosity

Subaru Galaxies – Continuum

Thumbnails 10’’ sq

Halpha vs. RC

line from Sullivan et al.

2001

Neutral Hydrogen in the

Subaru Galaxies

Subaru Galaxies - B magnitude

Thumbnails 10’’ sq

Ordered by H

luminosity

Subaru Galaxies - redshifts

Thumbnails 10’’ sq

Ordered by H

luminosity

2dF spectrum good

good spectrum

2dF spectrum poornot so greatspectrum

Redshift histogram

Subaru Narrow Band Filter

FWHM (120 Å)

GMRT HI freq range

112 redshifts in GMRT data

Galaxy Sizes

Thumbnails 10’’ sq

Ordered by H

luminosity

Variety of sizes –

measured size at 25th

mag arcsec-2 isophote

Diameter HI

unsmoothed beam

FWHM ~3’ (10 kpc)

smoothed beam FWHM ~5.3’

(20 kpc)

smoothed beam FWHM ~8.0’

(30 kpc)

HI spectrum all

112 redshifts

Neutral Hydrogen

measurement

MHI = 0.071

0.12 MHI*

HI spectrum bright

Log H Luminosity

> 41 erg s-1

36 redshifts

Neutral Hydrogen

measurement

MHI = 0.57

0.26 MHI*

HI spectrum faint

Log H Luminosity

40.4 erg s-1

33 redshifts

Neutral Hydrogen

measurement

MHI = 0.31

0.19 MHI*

HI spectrum mid

40.4 < Log H Luminosity

41 erg s-1

43 redshifts

Neutral Hydrogen

measurement

MHI = 0.44 0.20 MHI

*

HI redshift mine all

taking into account

narrow band (H) filter

shape – brighter

galaxies will be seen over

a larger volume

Future Work: Galaxy Cluster Cl0024+1654

Galaxy Cluster Cl0024+1654

RA

DEC 21’ × 21’

Cluster Centre

Galaxy Cluster Cl0024+1654

RA

DEC ~1’ × 1’

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)

• 18 + 45 hours GMRT observations

Cl0024 positions

GMRT Beam 50% level

Cl0024 z slice GMRT HI freq limits

PhD Timetable of CompletionRest of 2006:

• finish analysis of the Subaru Field (to be completed by the end of August 2006)

• analysis of galaxy cluster Cl0024+1652 (analysis to be finished by January 2007)

• optical imaging of galaxy cluster Abell 370 using SSO 40 inch and AAOmega follow-up to get redshifts – Mike Pracy doing much of this but I will be involved

2007:

• complete analysis of galaxy cluster Abell 370 (to be finished no later than June 2007)

• write up my thesis throughout 2007 finish between September 2007 & March 2008 (3½ - 4 year mark)

The End

Additional Slides

The UV Plane

Model no error

model

B mag vs. Halpha Lum

UV Plane

Stellar Mass Density

Dickenson et al. 2003

HI spectrum bright faintMHI= 0.41 0.15

MHI*

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

Galaxy Cluster Abell 370

• originally started working on this data in 3 month project – worked on to learn radio astronomy

• 42 literature redshifts for Abell 370 cluster members 33 are usable – large error in σz ≥ ± 300 kms-1 (from Soucail et al. 1988 )

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?