Transcript Does Every Early-Type Galaxy Host a Radio AGN?

ASKAP Continuum Surveys
of
Local Galaxies
Michael Brown
ARC Future Fellow
Monash University
Where are we now?
• NVSS / FIRST / SUMMS
• 0.5 mJy RMS per beam
• 15”-1’ beam
Future ASKAP 12
• ~30 uJy RMS per beam in 12 hours
K<9 Spiral Galaxies
Catalogued sources
Flux density per
beam from NVSS images
K<9 Early-type Galaxies
Brown et al. 2011
log (P1 4 / W Hz 1)
K<10.5 Spiral Galaxies & AGNs
10 10 yr
10 11 yr
10 12 yr
Mean fit
Type 1
Type 2
75% WISE AGN
90% WISE AGN
100% WISE AGN
23
1
1
1
22
21
20
19
21
22
23
24
MK
Floyd et al. (submitted)
25
26
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
Red
Blue
Colour
Galaxy Evolution
Dwarf
Faint
SF
Red spiral
Blue Spiral
SF
Merger
Fading
Luminosity
Elliptical
Blue Spiral
Bright
Red Spiral / Total Spiral
Bonne et al. (in prep.)
K-band Absolute Magnitude
SFR
Indicator
L 1.4
L 1.4 & L Ha
Kennicutt et al. 2009
Corrected L Ha
Rescaling
Spectra
Spectra and Halpha
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
Galaxy Clustering Strength
Dolley et al. (in prep.)
High star-formation
Low star-formation
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 Selection
KAB<10.5
T-type > -1
NVSS 1.4 GHz coverage
228 galaxies
Select galaxies with
f1.4 < 2.5 mJy
42 galaxies
SDSS Optical Colours
KAB<10.5 f1.4<2.5 mJy
All other spiral galaxies
Red and no NVSS, but Star Forming
UV-optical
similar to
passive E
H-alpha lost
in the noise
Spiral arms
are blue in
UV-optical
IR excess
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
Spitzer 24 microns
WISE 11 microns
SDSS Optical
Infrared SEDs
IR excess relative to
passive elliptical galaxies
NGC 4725 spectrum
shows PAH and dust
emission
21-cm
Catalogued HI in red
Uncatalogued HI in black
228 spirals with KAB < 10.5
186 spirals in HI
catalogues
42 spirals f1.4 < 2.5 mJy
31 spirals in HI catalogues
NGC 5188 f1.4=95 mJy
X
NGC 7727 f1.4<2.5 mJy
X