Neutral Hydrogen Gas in Star Forming Galaxies at z=0.24

Philip Lah

Frank Briggs (ANU)

Jayaram Chengalur (NCRA)

Matthew Colless (AAO)

Roberto De Propris (CTIO)

Michael Pracy (ANU)

Erwin de Blok (ANU)

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

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

The Subaru Field - H emission galaxies

Subaru Field

RA

DEC

24’ × 30’

Fujita et al. 2003 narrow band imaging - H emission

flux

used 2dF to get optical

redshifts

Subaru Field Data

GMRT Obs Time

Frequency Observed

zLook Back

TimeRMS per channel

80.5 hours 1150 MHz 0.24 2.8 Gyr ~130 Jy

Primary Beam Size

Resolution Channel

Width

Number of Channels

~29’ ~3’’ 32.6 kms-1 2 × 128

Subaru Galaxies - B magnitude

Thumbnails 10’’ sq

Ordered by H

luminosity

Subaru Galaxies - redshifts

Thumbnails 10’’ sq

Ordered by H

luminosity

Redshift histogram

Subaru Narrow Band Filter

FWHM (120 Å)

GMRT HI freq range

2dF (& AAOmega) redshift

s

HI spectrum all

121 redshifts

Neutral Hydrogen

measurement

MHI =

(1.47 ± 0.89) ×109 M

HI redshift mine all

• used the Fujita et al. 2003 H Luminosity

function for volume calculation

• comparable error to low z DLA

measurements but required less

observing effort (no need lots of

HST time)

Radio Continuum in the

Subaru Field

Deepest GMRT Image

Sub field

12’ × 12’

RMS ~ 16 Jy

several hundred

continuum sources some with optical counterparts

Sullivan et al. 2003

Sullivan et al. 2001

H Luminosity vs.

1.4 GHz Luminosity

&

UV Luminosity vs.

1.4 GHz Luminosity

Halpha vs. RC

line from Sullivan et al.

2001

10’ × 10’

Conclusions

• measured the neutral gas density at z=0.24 with similar accuracy to the DLA method – with plenty of room for improvement

• made the current deepest GMRT continuum image

• the H emission - radio continuum correlation for star forming galaxies seems to hold true at z=0.24

The End

Additional Slides

HI redshift mine all

taking into account

narrow band (H) filter

shape – brighter

galaxies will be seen over

a larger volume

Model no error

model

UV Plane

Fuzzy RC

IntegratedFlux = 17.035

0.077 mJy

Fuzzy B

galaxyUGC 05849

atredshift

z=0.026045