growing the lightest supermassive black …...recipe for growing the lightest supermassive black...
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Growing the Lightest Supermassive Black Holes:Beyond the Major Merger Paradigm
Kelly Holley!BockelmannVanderbilt University
k"[email protected]"edu
NGC 6240 0402+379 Galaxy Awesome
Monday, April 16, 2012
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e.g. Micic, HB, Sigurdsson + Abel 2007
First task: Growing the lightest supermassive black holes to get event rates for LISA
The broad approach: zoom-in collisionless n-
body simulations to generate merger trees, and incorporate the
gas physics analytically
Monday, April 16, 2012
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Recipe for growing the lightest supermassive black holes
Our black holes grow by a combination of direct mergers and galaxy merger-driven gas accretion:
After halos merge, we merge the BHs after a dynamical friction timescale -- assume the final parsec is solved.
We add gravitational wave recoil, too -- 106 realizations of possible spins and orientations
We use PopIII stellar remnants as our black hole seeds.
Micic, HB, Sigurdsson 2009HB, Micic, Sigurdsson+ Rubbo 2010
see Hirschmann et al; Tanaka et al model
Monday, April 16, 2012
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We found # classes of black holes:
Massive central
Slowly sinking
Ejected
Monday, April 16, 2012
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Is SgrA* an oddball?
If kicks are large:
20% of halos form proper SMBH
small kicks:
SgrA* is common
Massive centralMonday, April 16, 2012
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Light SMBHs don’t just assemble from equal mass (or even nearly equal mass ) mergers
Not EMRI. Not SMBH
merger.
HB et al. 2010
Massive centralMonday, April 16, 2012
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Light SMBHs don’t assemble from equal mass (or even nearly equal mass ) mergers
ULIs
Massive central
ultra light inspiral
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halo mass M๏
blac
k ho
le m
ass
M๏
108
106
104
102
107 108 109 1010 1011
Dwarf galaxies may also have central black holessee also Micic, HB 2007, Volonteri + Priya 2009, Peng 2010,
your name here?
Monday, April 16, 2012
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Proof in the Pudding? Heinze $!%&Reines et al. 2011
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Rogue Black Holes sit in the outer halo
R/Rvir0 1
๏
see also Micic, HB 2007, Bellovary et al. 2011, your name here?
Slowly sinkingMonday, April 16, 2012
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r (kpc)0 300
L (L๏)
104
If they accrete halo gas' some may be uLXs
Slowly sinkingMonday, April 16, 2012
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redshift
The ejected population
O(103) per 1000 Mpc3 will wander in the
intergalactic medium
EjectedMonday, April 16, 2012
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Milky Way is peppered by IMBHs+shredded halos, and one of these may have transformed the galactic center.
Lang et al. 2012
Monday, April 16, 2012
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Very minor IMBH-embedded satellite accretion at starting at z~8 and ending ~10 Myr ago could have
excited new star formation
...and ejected the old stars
...and fed the SMBH
to make the Fermi Bubble
Monday, April 16, 2012
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Very minor IMBH-embedded satellite accretion at starting at z~8 and ending ~10 Myr ago could have
excited new star formation
...and ejected the old stars
...and fed the SMBH
to make the Fermi Bubble
Monday, April 16, 2012
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Main takeaway so far: MW-like SMBHs in MW-like galaxies may grow more from
minor mergers than from major mergers.
Next up: Flyby encounters
with a prescription built on the merger paradigm....
kpc
kpc
Monday, April 16, 2012
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inspiration: BH mass a product of environment?
a few isolated halos had extremely
underweight bhs compared to halos of the same mass elsewhere
Let’s dig deeper into this environment issue -- Simulate larger volumes and zoom into many regions with better resolution
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A small taste of the assembly of a 1012 M๏ halo
Monday, April 16, 2012
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A small taste of the assembly of a 1012 M๏ halo
merger
merger
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A small taste of the assembly of a 1012 M๏ halo
flyby
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Flyby encounters can happen just as often as mergers -- currently ignored in SMBH
growth scenarios
Sinha + HB 2012, in press
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Why this matters: galaxy flybys can strongly perturb the galaxy
Steinmetz+Navarro 2001
Vesperini+Weinberg 2001
...which can funnel gas to the center, may feed the SMBH...Monday, April 16, 2012
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Nflyby=2Nmerger=4Mbh~105M๏
Nflyby=17Nmerger=44Mbh~107M๏
Quiet halos have underweight SMBHs
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Nflyby=2Nmerger=4Mbh~105M๏
Nflyby=17Nmerger=44Mbh~107M๏
To come: a measure of the SMBH growth
from flybys
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And now, a cautionary note about the first black hole seeds.
Semi-analytic method...linear evolution of overdensities make the
halo mass function we see today
Amazingly, it works!
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Monday, April 16, 2012
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2nd order overdensity
2nd order Lagrangian perturbation approximation
linear overdensity
Buchert 94, Scoccimaro 98, Crocce 06, Jenkins 09
But, adding a 2nd order displacement is more accurate.
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The fancy 2LPT method allows structure to collapse earlier -- most massive halos more common
(...uh, by 5% at z=0)
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However, this makes a big difference in the bh seeding epoch!
10 Mpc box 5123 particles from z=300 to 6
HB, Sinha, Wise in prep
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However, this makes a bigger difference in the first stars era!
10−28 10−27 10−26
Density [g cm−3]
102 103 104
Temperature [K]
10−4 10−3 10−2 10−1 100
Electron Fraction
ZAZA
2LPT2LPT
0.25 Mpc/h
Monday, April 16, 2012
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• The lightest supermassive black holes assemble from minor black hole mergers.
• Flyby encounters are common for Milky Way mass halos, especially at z
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Thanks!
Collaborators on these projects:
Miroslav Micic Manodeep Sinha
Steinn Sigurdsson John Wise
Monday, April 16, 2012