growing the lightest supermassive black …...recipe for growing the lightest supermassive black...

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

mailto:[email protected]

mailto:[email protected]

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


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


We found # classes of black holes:

Massive central

Slowly sinking

Ejected


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


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?


Proof in the Pudding? Heinze $!%&Reines et al. 2011


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


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


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


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


A small taste of the assembly of a 1012 M๏ halo



merger

merger



flyby


Flyby encounters can happen just as often as mergers -- currently ignored in SMBH

growth scenarios

Sinha + HB 2012, in press


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๏


Quiet halos have underweight SMBHs




To come: a measure of the SMBH growth

from flybys


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!


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.


The fancy 2LPT method allows structure to collapse earlier -- most massive halos more common

(...uh, by 5% at z=0)


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


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


• 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


Thanks!

Collaborators on these projects:

Miroslav Micic Manodeep Sinha

Steinn Sigurdsson John Wise


growing the lightest supermassive black …...recipe for growing the lightest supermassive black...

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