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Growing the Lightest Supermassive Black Holes:Beyond the Major Merger Paradigm
Kelly Holley!BockelmannVanderbilt University
k"holley@vanderbilt"edu
NGC 6240 0402+379 Galaxy Awesome
Monday, April 16, 2012
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
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
We found # classes of black holes:
Massive central
Slowly sinking
Ejected
Monday, April 16, 2012
Is SgrA* an oddball?
If kicks are large:
20% of halos form proper SMBH
small kicks:
SgrA* is common
Massive centralMonday, April 16, 2012
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
Light SMBHs don’t assemble from equal mass (or even nearly equal mass ) mergers
ULIs
Massive central
ultra light inspiral
Monday, April 16, 2012
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
Proof in the Pudding? Heinze $!%&Reines et al. 2011
Monday, April 16, 2012
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
r (kpc)0 300
L (L๏)
104
If they accrete halo gas' some may be uLXs
Slowly sinkingMonday, April 16, 2012
redshift
The ejected population
O(103) per 1000 Mpc3 will wander in the
intergalactic medium
EjectedMonday, April 16, 2012
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
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
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
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
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
Monday, April 16, 2012
A small taste of the assembly of a 1012 M๏ halo
Monday, April 16, 2012
A small taste of the assembly of a 1012 M๏ halo
merger
merger
Monday, April 16, 2012
A small taste of the assembly of a 1012 M๏ halo
flyby
Monday, April 16, 2012
Flyby encounters can happen just as often as mergers -- currently ignored in SMBH
growth scenarios
Sinha + HB 2012, in press
Monday, April 16, 2012
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
Nflyby=2Nmerger=4Mbh~105M๏
Nflyby=17Nmerger=44Mbh~107M๏
Quiet halos have underweight SMBHs
Monday, April 16, 2012
Nflyby=2Nmerger=4Mbh~105M๏
Nflyby=17Nmerger=44Mbh~107M๏
To come: a measure of the SMBH growth
from flybys
Monday, April 16, 2012
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!
Monday, April 16, 2012
Monday, April 16, 2012
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.
Monday, April 16, 2012
The fancy 2LPT method allows structure to collapse earlier -- most massive halos more common
(...uh, by 5% at z=0)
Monday, April 16, 2012
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
Monday, April 16, 2012
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
• The lightest supermassive black holes assemble from minor black hole mergers.
• Flyby encounters are common for Milky Way mass halos, especially at z<3.
• Flybys may be important in early SMBH growth, and for these ‘light’ SMBHs
• We are underestimating the number of PopIII stars, seed BHs.
Recap: it(s time to consider deviations from the major merger paradigm
though it’s not clear that this works all the way to z=0
Monday, April 16, 2012
Thanks!
Collaborators on these projects:
Miroslav Micic Manodeep Sinha
Steinn Sigurdsson John Wise
Monday, April 16, 2012
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