Constraining feedback
by satellite galaxies
岡本 崇 (Durham・筑波)

理論懇 16 Dec 2008

ΛCDM & galaxy formation
Constant L/M

AGN?

Supernova?

Benson+’03

Baryonic physics is akey!

理論懇 16 Dec 2008

Satellite problem

Simulated
sub-halos

Observedsatellites

Moor+’99, Klypin+’99

理論懇 16 Dec 2008

Previous studies
LF of MW satellites

Somerville`02

Benson+`02• Semi-analytic models
suggested that theinclusion of theeffects ofreionization-heating,photo-heating, and SN
feedback can solve thesatellite problem.

Koposov+`08
理論懇 16 Dec 2008

However• These SA models overestimated the effects
of a UV-background.
Filtering mass

Simulations

Okamoto, Gao, Theuns ‘08

理論懇 16 Dec 2008

Cosmological simulations• 3 MW-candidate halos from the Aquarius
project (Springel+’08)– Aq-A, Aq-C, and Aq-D

• Resolution– Reference:– High-resolution:• ISM– Standard– Multiphase-model (Okamoto+’08)• Harder EOS for star-forming gas:

– Star formation is normalized to reproduce theKennicutt relation
理論懇 16 Dec 2008

Phase diagrams
StandardMultiphase

理論懇 16 Dec 2008

Phenomenological modelsfor feedback• Assuming 100% of the SN energy is converted
to the kinetic energy of winds• Two types of energy conserving winds– Wind models are characterised by the windspeed,, and the mass loading factor,where.

,(Similar to SA models)(a la Springel & Hernquist)

理論懇 16 Dec 2008

Simulations• 3 MW candidate halos• WMAP1 cosmology• Time dependent, spatially uniform UV-background(Haardt & Madau ‘01; zreion = 9)
• Chemical evolution by Type II and Ia SNe and AGB
stars• Metallicity dependent cooling• SF is normalized to reproduce the Kennicutt
relation• FB is modeled as winds

理論懇 16 Dec 2008

Models
Modelmultiphasevw

σ0 or η

5σ

No

5σ

σ0~217 km/s

5σ, ismYes

5σσ0~217 km/s

4σ, ismYes

4σ

σ0~271 km/s

700 km s-1

Yes

700 km s-1

η ~ 2.4600 km s-1

Yes

600 km s-1

η ~ 3.3

η and σ0 are computed by considering only contribution from SNeII. Thereis also contribution from SNeIa in the simulations.
理論懇 16 Dec 2008

Central galaxies• Edge-on views of B-band
surface brightness• Z-axis is defined byangular momentum ofstars within 0.05 Rvir.

50 h-1 kpc
理論懇 16 Dec 2008

Morphology of
the centralgalaxies• Orbital circularity(Jz/Jc(E)) of stars
within Rvir on the disk
plane (stars belonging
to satellites areexcluded).
• z-axes are defined by
the angular momentum ofstars within 0.05 Rvir.

理論懇 16 Dec 2008

Star formation
histories of
the centralgalaxies• Formation histories ofstars within 0.1 Rvir.
Stars belonging to thesatellites areexcluded.
• Simulations with andwithout the multiphasemodel are very similar.

理論懇 16 Dec 2008

Satellite
luminosity
functions• V-band luminosityfunctions• Blue: local groupsatellites• Red (and light blue):
simulated satellites•
is favored• Larger mass loading isneeded for smaller
galaxies.
理論懇 16 Dec 2008

Metallicityluminosity
relations• [Fe/H] vs. Mv• Blue: local groupsatellites• Red (and green):
simulated satellites•
is again favored.

理論懇 16 Dec 2008

Convergencetests• Reference:• High-resolution:• Upper: SFHs of the central
galaxies• Lower: V-band satellite
luminosity functions– dotted: Observational data
for the bright satellites– dot-dashed: Fit to thefaint MW satellites byKoposov et al.
• Excellently converged!!
理論懇 16 Dec 2008

Conclusion• CDM model can reproduce the observed
properties of the MW satellites.
•
is preferred to theconstant wind speed models(constant)– Physics?

• Most of SN energy should be converted tothe kinetic energy of winds.
– Other energy sources?

理論懇 16 Dec 2008