Arman KhalatyanAIP 2006GROUP meeting at AIP
Outline• What is AGN?
– Scales• The model
– Multiphase ISM in SPH• SFR
– BH model• Self regulated accretion ?!
• Galaxy mergers– Setup, resolution, numeric's …
• Results• Prospects
The Scales.
A false color composite image of the central parsec of the GC taken by the Very LargeTelescope.Old, intermediate mass cool red giants and young massive hot blue stars.
Genzel et al. 2003
Scales
Galaxy Model• DM Halo-NFW profile• Disk – exponential
– stellar– gaseous
• Bulge – Hernquist profile
Springel et al. 2005
Model-MULTIPHASE ISM, SFR
McKee & Ostriker (1977)McKee & Ostriker (1977)
Model-MULTIPHASE ISM, SFR• First implementation of two phase ISM was by
G.Yepes et al (1997) for Eulerian code.• Modified and extended ISM model were
implemented using SPH formalism by Springel et al 2003.– radiative heating and cooling– cold clouds embedded in an ambient hot medium– star formation – feedback from SN( thermal feedback and cloud
evaporation)– Galactic winds and outflows– Metal enrichment
SFR in MULTIPHASE ISM• Rates at which the masses of
the hot and cold phases evolve can be written:
• Effective EOS:
• Density dependence of the SN evaporation
• SFR:
Springel et al 2005
Note:we use q=0.05
“GOLDEN RULE FOR SFR ?”• Kennicut law for sfr:
• SFR parameters:– t0
* 2.1 Gyr
– A0 1.0e4 K
– TSN 1.0e8 K
Springel et al 2005
Cooling functionKatz et al. 1996
Cooling function including metals
Dopita & Sutherland 2003
x95
Modeling AGN• by Bondi(1952)
• A fraction of the power generated by the accretion of matter onto the black hole heats the surrounding gas at a rate:
• The Cooling rate per unit mass of heated gas is:
Cattaneo 2006
SPH implementation by Springel et al 2005
Energetic efficiency of black hole accretion 0.1
Hydrogen baryon fraction
The BH model• The heating rate per unit mass of the gas
depends on three parameters: – the accretion efficiency with respect to the
Bondi rate : – the fraction of the accretion power converted
into heat: – the mass Mgas on which the heat is distributed
Cattaneo 2006, Springel et al. 2005
Local M – T equilibrium • Black hole – IGM coupling factor:
Cattaneo 2006
Parameter tests• Simulations was done by GAGDET-2 TreeSPH code.• Set of simulations was performed ( ~70 different mergers)
Magorrian relation: MBH - Mbulge
Parameter space study • Model parameters:
– physical: , , gas– numerical: MBH0, , NGB, qToomre
Final BH mass vs and
Mbh vs Mgas
Suppression of SFR
COOLING and BH-growth
Gas temperature surrounding BH
MOVIE
Thank You for Your Attention.
To be continued…
Next Step: CosmologyElliptical galaxy N198, Zoomed simulation in box 50Mpc/h with special resolution 1024^3 particlesMgas=5.9 1e5 M⊙
200 kpc/h
Z = 3.7
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