Transcript Formation of Disk Galaxies

Multivariate Properties of
Galaxies at Low Redshift
Galaxy Properties from Imaging
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Luminosity functions
Star formation rate
Stellar mass
Morphology
Color-magnitude
relation
Environment
Photometric redshift
2-D Clustering
2 6-color SDSS scans of 2.5°x2.5°.
Galaxy Properties from Spectroscopy
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Detailed star
formation
history
Dynamical mass
Metallicity
Dust content
3-D clustering
AGN activity
Galaxy Surveys: Optical & NIR
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DEEP2
AEGIS
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COMBO17
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Steidel
ELAIS-S1
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MUSYC
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MS1054
Where is the stellar mass?
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Galaxies at
~1010.5-1011.5M
contain most of
stellar mass.
SFR and Dn show
bimodality.
Some, not much,
environmental
dependence
Kauffmann et al. 2004
Bivariate LF’s:
Morphology
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Sersic index n:
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n=4: elliptical
n=1: spiral
Ellipticals dominate
bright end; later types
at faint end.
Faint end slope varies
with n; Bright end
truncation invariant.
SB trends similar; high
SB’s have higher n.
Ball et al 2005
Ball et al 2005
Bivariate LF’s:
Color
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u-r measures (roughly)
ratio of current to past
star formation.
Red galaxies dominate
at bright end.
Blue galaxies have
steeper faint-end
slope.
r-z distribution shows
less trend, because
fewer blue galaxies.
LF’s in Field vs.
Clusters
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Cortese et al. 2005
Field R-band LF
(SDSS) well-fit by
Schechter function,
with a~-1.26.
Clusters show an
excess population of
small galaxies.
GALEX data shows
faint-end upturn is
from passive dwarfs.
Trentham et al 2005
Stellar Mass Fcn in
Field vs. Clusters
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Near-IR (J, K) allow
more direct tracer of
M*.
Clusters show
steeper faint end,
field is shallow.
Non-emission line
field galaxies show
very shallow slope.
Balogh et al 2001
Morphology-Density
Relation
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Ellipticals prefer denser
environments.
Discovered in the 80’s,
regarded as a fundamental
aspect of environment.
Why does it occur?
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Ram-pressure stripping?
Merging?
Harassment?
Starvation?
Goto et al. 2004
It’s star formation
history, stupid!
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At fixed luminosity
and color, there is no
strong relationship
between density and
either Sersic index or
surface brightness.
It’s not morphologydensity, it’s colordensity, or perhaps
star formation
history-density
relation.
Blanton et al. 2005
Color, magnitude, morphology
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Ellipticals (highn) tend to be
red and high-SB.
CMD shows
bimodality:
“red sequence”
& “blue cloud”.
Color-SB relation
shows similar
bimodality.
Red sequence evolution
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Red sequence in
place at z~1 (10
Gyr ago).
Gets slowly
redder with
time; zf~2+.
Dominated by
early-types (not
dusty spirals).
Mass-Metallicity Relation
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Lee et al. 2006
SDSS emission line
galaxies, central
regions.
M*-Z shows a strong
trend up to
M*~1010.5M, then
flattens to higher M*.
Scatter is small: 0.2
dex at low-M, 0.07 dex
at high-M.
Origin yet unclear, but
outflows likely needed.
Tremonti et al. 2004
Tully-Fisher and M*/L
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Stellar/baryonic mass vs.
dynamical mass.
~x7 M*/L variation in B,
~x2 in K (for spirals).
Tightest with B-R color.
With M*/L(color), TF has
M*v4.5.
With HI data, baryonic TF
Mbv3.5±0.2.
Extending to lower
masses suggests Mbv4:
variation with Mb?
Recall Mhalov3, so at face
value small halos have
less baryons: Mb/Mhv0.5.
Bell & de Jong 2001
Lv4
Lv3
McGaugh
2004
AGNs: Where do they live?
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In M*>1010M.
Morphologically
similar to earlytypes.
OTOH, recent SF
similar to latetypes (esp. in
strong AGN).
Kauffmann et al 2003
AGNs and galaxy
evolution
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AGNs roughly occupy
“green valley”.
Black hole growth
occuring in M*~1010.51011 M galaxies.
Same M* as transition
in colors, SFRs, etc.
Cause or effect?
Kauffmann et al 2004
Clustering: 2PCF
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x=(r/r0)-g, g~1.8 and
r0~5 Mpc/h.
Departs significantly
from pure power law.
Red galaxies have
steeper x slope.
Mild luminosity
dependence, strongest
at luminous end.
Norberg et al 2001
Zehavi et al. 2003, 2004
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Halo Occupation Distribution
Zehavi et al 2003
HOD = P(Ng,Mh).
Made up of “1-halo”
and “2-halo” terms.
From this, get bias:
b≡(xgg/xmm)1/2.
<N(M)> has characteristic shape; can derive
by matching x(r).
Yang et al 2004
Conditional Luminosity Function
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F(L|M)dL:
Luminosity fcn
in bins of halo
mass.
Tune F(L|M) to
reproduce LF,
x(L), and T-F.
Depends on
cosmology, or
anything that
affects halo
abundance.
Yang et al 2003