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Co-evolution of Black Holes and Galaxies: Small Scales
Issues
Andrés Escala AstorquizaDAS, U. de Chile
Observational Evidence for Coevolution
MBH-σ (Ferrarese & Merrit/Gebhardt et al. 2000), MBH-Mbulge (Marconi & Hunt 2003) relations.
Co-evolution of cosmic SFR (Madau plot) and AGN activity.
AGN Heating needed for Galaxy Luminosity Function (Croton et al. 06’).
MBHs must be included in Standard Hierarchical Galaxy Formation within ΛCDM
Cosmology
Small Scale Issues:
Two basic unsolved issues that needs to be understood for a comprehensive scenario for MBH-Galaxy co-evolution are:
MBHs Mergers vs Last Parsec Stalling (->GW Recoil vs Three body problem).
MBH growth and its feedback on the environment (SF shutoff?).
Massive Black Hole Mergers
Mergers of Galaxies & MBHs (Begelman, Blandford & Rees 1980’)
Stellar loss-cone depletion by 3-body kicks implies stalling of MBH binary coalescence at sub-parsec separations.
MBHs-Disk Interactions• Gaseous disks are main candidates for
extracting angular momentum from MBH binaries and drive the final coalescence.
• Simulations in the literature of binary-disk interactions can be divided in 2 groups:
tmerge ~ 1000 torb(Type II)
tmerge ~ torb(Type I)
Escala et al. 04,05Dotti et al. 09
Artymowicz & Lubow 94Shi, Krolig et al. 12
Binary Proto-stars. Different
stages in the process of formation of binary stars shows different interactions with the gaseous envelopes.
This will not only affect their final separation but also in their final masses since accretion also varies dramatically in both cases.
Relevant to investigate when starts the type II stage.
Boss (1984) & more …
Artymowicz & Lubow (1994) & more…
Analytic Estimates Analytical estimates for a Gap Opening
Condition can be computed by comparing the timescales for closing (~∆R2/νturb) and opening (~∆L/T) a Gap.
Computed for torques from a Global Non-axisymmetric Density Enhancement instead from the Resonances that appears in the linear theory (not applicable for q≈1, only for q<<1).
Gives a criteria that can be expressed on 2 dimensionless quantities of the binary-disk system: h/rbin Mgas(<rbin)/Mbin
Time gap opening/ Time gap closing
If
SPH Simulations for Testing the Criteria (del Valle & Escala
12’)
del Valle & Escala (2012)
Can’t be explained by Lin & Papaloizou 86’:
Comparison of the Literature with del Valle & Escala 12’.
Are both types present in the real Universe? Probably YES
Type IIType I
Type I interaction should be more frequent in wet mergers and Type II in dry ones:
MBH accretion, its feedback and possible SF shutoff.
AGN Feedback: SF Shutoff?
• Proposed by several authors, based on simple analytical estimates of BH growth/feedback (e.g. Silk and Rees 98, King 03, Wyithe & Loeb 03, Begelman & Nath 05).
• DiMatteo et al (2005); Hopkins et al ++++++:
However …..• Resolution ≈ 100 RBH
inf (all BH-physics totally unresolved).
• These simulations have almost the same assumptions that simple analytical estimates (-> do not test them).
• A better approach is to perform smaller scale simulations that test these hypothesis.
• An example: hypothesis of Eddington Limited growth can be exceed thru Photon Trapping (Begelman 78), Super-Eddington Atmospheres due to unstable photon-bubbles (Begelman 02; Krumholz et al 05, 09).
Measuring AGN Feedback:
• Several ongoing attempts to quantify AGN feedback in both wind & jet modes (Krongold et al. 07,10; Rupke & Veilleux 11’; Harrison et al. 12’) .
• However, total momentum and energy observed in the outflow is still lower than required (~1/10) .
• Energy & momentum comes in the form of ionized gas Can this component transfer its momentum into heating the molecular ISM and stopping SF.
Mrk 573
If it is not feedback, what can set MBH-σ/MBH-MBulge relations?
Two Possibilties:
•No physical link between BH and Galaxies (Jahnke & Macciò 11’), relations are just a N vs N plot.
•Such link exists and we need to look for alternatives. Any galactic problem relevant in controlling MBH growth will work.
Implicit assumption of huge number of MBH mergers!
A personal Candidate: Galactic-Scale Fueling
Unavoidable step in the growth of Massive Black Holes and it is indeed a galactic problem!
Fueling Flowchart (Wada 2004):
Transport Supersonically Turbulent Disk (Final Kpc)
Becerra, M.Sc. 12’ Levine et al (2008)
Mass transport in turbulent disk (assuming a power-law inertial range):
BH ~ vrot 3 (Escala 06’,07’)
G
KS Law BH α Bulge
E(k)~k-3
E(k)~k-5/3
THANKS!
Motivation: fate of MBHs after Galaxy Mergers
Galaxy mergers are common events in
the universe.
Each galaxy with a sizeable bulge is
expected to have a MBH.
What is the fate of the BHs? Will also
Coalesce?
NGC 6240
MBH inclusion in Standard Hierarchical ΛCDM Cosmology
Di matteo
Gap Opening Condition• The migration timescales predicts completely
different behaviours (in the two cases) in terms of an eventual coalescence.
• Crucial to predict whether a Gap will be opened or not and apply it for different scenarios for binary MBHs/Protostars growth.
• Since Type I disks are generally thicker and more massive than Type II ones, M and H will be parameters to explore.
Summary I• We have studied under which
conditions the interaction of a disk with a binary will open a gap.
• We successfully test our analytical expectations against full 3-D hydrodynamic simulations.
• We are now in the position to predict under which scenarios we expect an efficient MBH merging.
• Also in a position to study when starts the type II stage in binary proto-stars.
Star Formation Triggering in Disc Galaxies
Part of Fernando Becerra´s Masters Thesis (work currently in progress)
KS Law
SFR-Mrot relation (Escala 2011)
SFR-Σgas/tdyn (Silk)
Our work• Explore the possibility of second
parameters
• Example: Escala (2011)
Star Formation Triggering
Aim: Study galactic-scale triggering of star formation.
In particular the role of Mrot (maximum mass scale not stabilized by rotation)
Compare different star formation laws: Kennicutt Law vs SFR-Mrot relation (Escala 2011).
Summary
Differences with terrestrial fluids:
Nontrivial Flows: on the Earth generated by solid bodies. In space also by gravitational forces, radiation field and explosions.
Astrophysical fluids are frequently partially ionized. Thus, electromagnetic forces can play a role in the macroscopic dynamics.
Why Numerical Simulations are so important in
Astronomy Most problems requires a large dynamic
range (4, 5, 6 and more orders of magnitude).
A broad variety of physical processes involved (gravity, hydro, radiation, B, etc) in complex geometries (full 3-d).
HPC needed! (Software & Hardware solutions ).
Astrophysical Fluids Basic Ingredients:
Gravity: always.
Hydrodynamics: gas, stars only when collisions are not negligible.
Many More: Radiation Fields, G.R. corrections, Chemical/Nuclear Reactions, etc. -> generally included as sub-grid physics.
Hydro Methods Used
Eulerian: Adaptive Mesh Refinement (AMR).
Lagrangian: Smooth Particle Hydrodynamics (SPH).
Methods: SPH The fluid its sampled and represented by
particles smoothed by a kernel W. Allows any function to be expressed in
terms of its values at a set of disordered points, i.e.:
hj is the variable smoothing length, adjusted to keep the number of neighbors N constant.
ρ (r) = Σ mj W(r-rj;hj)j=1
N
adaptive spatial resolution
SPH Example: Large Scale Struc.
Methods: AMR Grid-based Technique.
Uses a criteria for automatic increase of the resolution.
Criterias can be chosen to guarantee resolve: density contrast, jeans length , shocks, etc.
AMR Example: detonations
SPH Simulations using Gadget-2 code.
Galaxy Mergers
Para ver esta pel cula, debeメdisponer de QuickTime y deᆰ
un descompresor YUV420 codec.
Para ver esta pel cula, debeメdisponer de QuickTime y deᆰ
un descompresor YUV420 codec.
AMR Simulations using ENZO code.