ASKAP Continuum Surveys of

Local Galaxies

Michael BrownARC Future FellowMonash University

Where are we now?

• NVSS / FIRST / SUMMS• 0.5 mJy RMS per beam• 15”-1’ beam

• ~30 uJy RMS per beam in 12 hours Future ASKAP 12

K<9 Spiral Galaxies

Catalogued sources

Flux density perbeam from NVSS images

K<9 Early-type Galaxies

Brown et al. 2011

K<10.5 Spiral Galaxies & AGNs

Floyd et al. (submitted)

Radio continuum• Continuum detects “hot mode” AGNS.• Continuum can be a good SFR indicator

– Have we been misled by optical colours?– Are SFR indicators properly calibrated?

• ASKAP ADE-12 is great for low z science!– It will detect all* local galaxies (duty cycles, env).– One galaxy per beam and with known locations.– Spectroscopy, morphology, optical, mid-IR

• Done better with completed ASKAP but…

Galaxy Colour Bimodality

Galaxy Evolution

Bonne et al. (in prep.)

K-band Absolute Magnitude

Red

Spi

ral /

Tot

al S

pira

l

Kennicutt et al. 2009 Corrected L Ha

L 1.4

L 1.4 & L Ha

SFRIndicator

RescalingSpectra

Spectra and H-alpha measurements from Moustakas et al. (2006, 2010) need to be increased by 10%.

UGCA 219

NVSS 4.5 mJy Optical g=14.78

UGCA 166 g~16

NVSS 2.0 mJy Optical g=16.05

Dolley et al. (in prep.)High star-formationLow star-formation

Gal

axy

Clu

ster

ing

Str

engt

h

Projected spatial Scale

Are Red Spirals Forming Stars?

• KAB<10.5 spiral galaxies– Bonne et al. (in prep) and Floyd et al. (sub.)

• NVSS 1.4 GHz as a star formation proxy– 1.4 GHz is not impacted by dust obscuration

• WISE mid-IR to search for warm dust– Dust is heated by star formation

• 21-cm to search for neutral hydrogen– Could star formation resume?

Sample SelectionKAB<10.5T-type > -1NVSS 1.4 GHz coverage228 galaxies

Select galaxies with f1.4 < 2.5 mJy42 galaxies

SDSS Optical Colours

KAB<10.5 f1.4<2.5 mJyAll other spiral galaxies

UV-optical similar to passive E

H-alpha lost in the noise

Spiral arms are blue in UV-optical

IR excess

Red and no NVSS, but Star Forming

Radio continuum• Continuum detects “hot mode” AGNS.• Continuum can be a good SFR indicator

– Have we been misled by optical colours?– Are SFR indicators properly calibrated?

• ASKAP ADE-12 is great for low z science!– It will detect all* local galaxies (duty cycles, env).– One galaxy per beam and with known locations.– Spectroscopy, morphology, optical, mid-IR

• Done better with completed ASKAP but…

NGC 2811 f1.4 < 2.5 mJy

X

Summary• Have we been misled by colour bimodality?• Red spirals are not faded blue spirals.

– Red spirals are brighter than blue spirals (Bonne).• High and low SFR spirals live in similar halos

– The large-scale clustering is similar (Dolley).• Low SFR spirals are not passive spirals

– Infrared excess and PAH emission • Red spirals generally have HI

NVSS WISE 11 microns

Spitzer 24 microns SDSS Optical

Infrared SEDsIR excess relative to passive elliptical galaxies

NGC 4725 spectrum shows PAH and dust emission

21-cm

Catalogued HI in redUncatalogued HI in black

228 spirals with KAB < 10.5186 spirals in HI catalogues

42 spirals f1.4 < 2.5 mJy31 spirals in HI catalogues

NGC 5188 f1.4=95 mJy

X

NGC 7727 f1.4<2.5 mJy

X