Why Massive Black Holes are Small in Disk Galaxies ?

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Why Massive Black Holes Why Massive Black Holes are Small in Disk are Small in Disk Galaxies ? Galaxies ? Formation of the First Generation of Galaxies: Strategy for the Observational Corroboration of Physical Scenarios, 2-5 December 2003, Niigata University, Niigata, Japan Nozomu KAWAKATU Center for Computational Physics, University of Ts ukuba Masayuki UMEMURA Collabora tor Center for Computational Physics, University of Tsukuba

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Why Massive Black Holes are Small in Disk Galaxies ?. Nozomu KAWAKATU Center for Computational Physics, University of Tsukuba. Collaborator. Masayuki UMEMURA. Center for Computational Physics, University of Tsukuba. - PowerPoint PPT Presentation

Transcript of Why Massive Black Holes are Small in Disk Galaxies ?

Page 1: Why Massive Black Holes are Small in Disk Galaxies ?

Why Massive Black HolesWhy Massive Black Holes

are Small in Disk Galaxies ?are Small in Disk Galaxies ?

Formation of the First Generation of Galaxies: Strategy for the Observational Corroboration of Physical Scenarios, 2-5 December 2003, Niigata University, Niigata, Japan

Nozomu KAWAKATU

Center for Computational Physics, University of Tsukuba

Masayuki UMEMURA

Collaborator

Center for Computational Physics, University of Tsukuba

Page 2: Why Massive Black Holes are Small in Disk Galaxies ?

Contents• Introduction

• Physical mechanism for formation of Supermassive Black Holes

• Model for Disk galaxies

Radiation drag (Poynting-Robertson) effect

• Basic Equation

• Results

• Summary

Recent observational results ( BH mass-to-bulge mass correlation )Angular momentum transfer problem for supermassive black holes

Equation of angular momentum transferTreatment for extinction by dusty gas

Relationship between the final BH mass and bulge-to-disk ratio of host galaxy

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IntroductionRecent high quality observations of galactic centers1) BH mass-to-galaxy mass ratio is considerably smaller than 0.002 for Disk.

(Salucci et al. 2000; Sarzi et al. 2001; Ferrarese 2002; Baes et al. 2003)

0.1 1

10-4

10-3

bulge galaxyM M

MB

H /

Mga

laxy

0.03

10-2

10-5

Normal spiral and barred galaxies

Sy1

×▲ NLSy1Sy2

2) BH mass-to-galaxy mass ratio is reduced by more than an order of magnitude with a smaller bulge-to-disk ratio.

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0.1 1

10-4

10-3

bulge galaxyM M

MB

H /

Mbu

lge

0.03

10-2

10-5Normal spiral and barred galaxies

Sy1

×▲ NLSy1Sy2

3) BH mass-to-bulge mass ratio lies at a level of 0.001, which is similar to that found in elliptical galaxies.

Formation of SMBHs Formation of Bulges

Physical relation!Physical relation!

=

(e.g., Kormendy & Richstone 1995)

ellipticals

Page 5: Why Massive Black Holes are Small in Disk Galaxies ?

It has not been clear

why the BH mass is smaller in disk physically!!

BH galaxy 0.002M M

BH galaxy 0.002M M

Elliptical Galaxies

Disk Galaxies

BH bulge( 0.002)M M

Summary of observational results in galactic centers

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The physics on the angular momentum transfer is essential !

SMBH Formation: Angular Momentum Problem

Hydrodynamical Mechanisms for Ang. Mom. Transfer( From galactic scale to BH horizontal scale )

1) Gravitational torque by a bar or non-axisymmetric mode But, this mechanism is effective only beyond ~ 1kpc.

2) Turbulent viscosity But, the timescale is longer than the Hubble time in galactic scale ! (e.g. A galactic disk cannot shrink via turbulent viscosity.)

1 21 11 210

vis kpc2 11 4s

3 10 yr0.1 10 10

j M Tt R

c M K

¤

(Wada & Habe 1995, Fukuda 1998)

3) Radiation drag (present work)

The timescale is shorter than the Hubble time in galactic scale.1 12 2

27drag kpc12

8.6 10 yr10

c R L Zt R

L L Z

¤ ¤

BH galaxy max0.007M M theoretical upper limit: (Umemura 2001)

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Radiation Drag – Poynting-Robertson Effect –

< Absorption process >

Lab.Frame

2 2final mc t m c

final final

t v

mv m vc c

m0 

v0

E t

finalm

finaalv

t vp

c c

< Re-emission process >

Lab.Frame

final 0 ,m m final v vMatter slowdowns ! v0v <

m

v“radiation drag”

E t

2 20 mc t mc

0 0 mv mv

In practice, optically thin surface layer is stripped by radiation drag, and loses angular momentum (Sato-san talks in details).

Page 8: Why Massive Black Holes are Small in Disk Galaxies ?

1) The BH-to-bulge mass ratio is basically determined by the energy conversion efficiency of nuclear fusion from hydrogen to helium, i.e., 0.007.

Radiation Drag efficiency in galactic bulges Radiation Drag efficiency in galactic bulges

(Umemura 2001)

bulgeBH 2

LM dt

c

“Radiation drag efficiency is determined by the total number of photons ”

bulgeL :total luminosity of the bulge

2) The inhomogeneity of ISM helps the radiation drag to sustain the maximal efficiency.

3) By incorporating the realistic chemical evolution, we predicted .

(Kawakatu & Umemura 2002 )

(Kawakatu, Umemura & Mori 2003 )

ISM is observed to highly inhomogeneous in active star-forming galaxies ! covering factor O(1)

Optically thick regime

BH bulge 0.002M M

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Radiation drag - Geometrical Dilution -

(Umemura et al. 1997,1998; Ohsuga et al. 1999)

low drag efficiency

high drag efficiency

Spherical System

Disk-like System

However, the details are not clear quantitatively !

Page 10: Why Massive Black Holes are Small in Disk Galaxies ?

This Work

We investigate the efficiency of radiation drag in disk galaxies.

To investigate the relation between the morphology of host galaxies and the angular momentum transfer efficiency due to the radiation drag

We solve the 3D radiation transfer in an inhomogeneous ISM.

We have disclosed the physical reasonsWe have disclosed the physical reasons

why the BHs are smaller in disk galaxies!why the BHs are smaller in disk galaxies!

Page 11: Why Massive Black Holes are Small in Disk Galaxies ?

Model

bulge bulge galaxyf M M

The difference of morphology is expressed by changing “ bulge fraction (fbulge)” .

1

0.03

0.5 fbulge

11galaxy( 10 )M M ¤

disk disk0.01 0.1h r r “disk scale height “

Inhomogeneous ISM covering factor is unity.

Page 12: Why Massive Black Holes are Small in Disk Galaxies ?

Basic Equations

The gain and loss of total angular momentum is regulated by this equation.

1( )

d rvF E P v

r dt c c

The Eq.of Ang.Mom.Transfer

Radiation DragRadiation Flux

:F :P:E d d gn : mass extinction due to dust opaci

tyradiation energy density radiation flux radiation stress tensor

The contribution of the radiation from distant stars is essential to radiation drag

since these stars have different velocities from absorbing clouds.

Page 13: Why Massive Black Holes are Small in Disk Galaxies ?

Treatment of the radiation tranfser

-,0 er

jdF

0, 0, 0,1 1 1

, ,N N N

j j jj j j

e E dE e P dP e

F dF

1 22

c2 1 b r

gas cr :optical depth of a gas cloud

: the optical depth for all intervening clouds along the light ray

,0r

jdF

b

cr

opacity : dust in clumpy gas clouds

All radiative quantities are determined by radiation from stars diluted by dusty ISM.

We calculate the radiation fields by the direct integration of the radiation transfer.

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Mass Accretion Rate

g g

JM M

J

Total mass of the ISM

Angular Momentum Extraction

Estimate for BH mass

0 0

BH g g0 0

t t JM M dt M dt

J

Angular momentum transfer in an Inhomogeneous ISM

( t0:Hubble time; J: total angular momentum )

dragrot

1

( )cN

i i ii

J r F Fc

 

Total angular momentum loss rate

( Nc:Number of clouds)

Page 15: Why Massive Black Holes are Small in Disk Galaxies ?

~ 1/20

~ 1/50

~ 1/200

disk0.01h r

disk0.04h r

disk0.1h r

BH galaxyM M

0.1 1

10-4

10-3

Mas

s ra

tio

bu lge bulge galaxyf M M0.03

10-5

Sd Sc Sb Sa S0 EHubble Type

BH bulgeM M

BH galaxyM M

disk0.01h rdisk0.04h r disk0.1h r

disk0.01h r

disk0.04h r

disk0.1h r

Almost constant

Result.1: BH mass-to-morphology relation

3BH galaxy bu lge10M M f

Page 16: Why Massive Black Holes are Small in Disk Galaxies ?

Why MBH are small in disk galaxies? ① & ②

Radiation drag cannot work effectively in disk galaxies !

pole on viewpole on view

“radiation”

② Radiation from disk stars is heavily diminished across the disk (optically thick disk)

① A number of photons escaped from the system (Surface-to-volume ratio )

③ The velocity difference stars and absorbing clouds becomes closer to zero (optically thick disk)

Page 17: Why Massive Black Holes are Small in Disk Galaxies ?

0.1 1

10-4

10-3

bulge galaxyM M

MB

H /

Mga

laxy

NGC3245

NGC4151

NGC3516

NGC5548

NGC4593

NGC7469

Mrk590

NGC3783

3C120

NGC4051

Mrk509

M81

NGC1023

M31

Fairall 9

Galaxy

NGC4258

NGC7457

NGC4395

NGC1068

(Sy1/Starburst)

NGC3227

(Sy2/Starburst)

(Sy2/Starburst)

Circinus (Sy2/Starburst)

Normal spiral and barred galaxiesSy1

×▲ NLSy1Sy2

0.03

10-5

10-2

Result.2-1: Comparison with the observations

Normal spiral and barred galaxiesSy1

×

NGC3245

NGC4151

NGC3516

NGC5548

NGC4593

NGC7469Mrk590

NGC3783

3C120

NGC4051

Mrk509

M81

NGC1023

M31

Fairall 9

Galaxy

NGC4258

NGC7457

NGC4395

NGC1068

(Sy1/Starburst)

▲ NLSy1NGC3227

(Sy2/Starburst)

(Sy2/Starburst)

Circinus (Sy2/Starburst)

Sy2 Normal spiral and barred galaxiesSy1

×

NGC3245

NGC4151

NGC5548

NGC4593

NGC3783

Mrk509

M81

NGC1023

M31

Fairall 9

Galaxy

NGC4258

NGC7457

NGC4395

▲ NLSy1NGC3227

(Sy2/Starburst)

NGC7469Mrk590

3C120

NGC4051

NGC1068

(Sy1/Starburst)

(Sy2/Starburst)

Circinus (Sy2/Starburst)

Sy2

This trend is broadly consistent with theoretical prediction.These objects have relatively small BHs compared with the predictions.

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Result.2-2: Comparison with the observations

0.1 1

10-4

10-3

bulge galaxyM M

MB

H /

Mbu

lge

NGC3245NGC4151

NGC3516

NGC5548

NGC4593

NGC7469

Mrk590

NGC3783

3C120

NGC4051

Mrk509

M81

NGC1023

M31

Fairall 9

Galaxy

NGC4258

NGC7457

NGC4395

NGC1068

(Sy1/Starburst)

NGC3227

(Sy2/Starburst)

(Sy2/Starburst)

Circinus (Sy2/Starburst)

Normal spiral and barred galaxies×NLSy1Sy2 ▲

0.03

Sy1

10-2

10-5

NGC3245NGC4151

NGC3516

NGC5548

NGC4593

NGC7469Mrk590

NGC3783

3C120

NGC4051

Mrk509

M81

NGC1023

M31

Fairall 9

Galaxy

NGC4258

NGC7457

NGC4395

NGC1068

(Sy1/Starburst)

NGC3227

(Sy2/Starburst)

(Sy2/Starburst)

Circinus (Sy2/Starburst)

Normal spiral and barred galaxies×NLSy1Sy2 ▲Sy1

NGC3245NGC4151

NGC3516

NGC5548

NGC4593

NGC7469Mrk590

NGC3783

3C120

NGC4051

Mrk509

M81

NGC1023

M31

Fairall 9

Galaxy

NGC4258

NGC7457

NGC4395

NGC1068

(Sy1/Starburst)

NGC3227

(Sy2/Starburst)

(Sy2/Starburst)

Circinus (Sy2/Starburst)

Normal spiral and barred galaxies×NLSy1Sy2 ▲Sy1

Observational data roughly agree with the prediction .Sy1 with SB & NLSy1 fall appreciably below 0.001 again.

Page 19: Why Massive Black Holes are Small in Disk Galaxies ?

Summary1. BH-to-galaxy mass ratio decreases with a smaller bulge-to-disk ratio, and is reduced maximally by two orders of magnitude, resulting in .

• Almost all photons can escape from a disk-like system, owing to the effect of geometrical dilution.

• The radiation from stars in disk galaxies is considerably reduced in the optically-thick disk.

< Physical Reasons>

2. In disk galaxies, the BH-to-bulge mass ratio is about 0.001 .

The BH-to-bulge mass ratio is fundamentally determined by physical The BH-to-bulge mass ratio is fundamentally determined by physical constantε=0.007, regardless of morphology of host galaxies.constantε=0.007, regardless of morphology of host galaxies.

It turns out that the formation of SMBH is not basically determined by disk components, but bulge components, consistently observational data.

5BH galaxy 10M M

The present model also predict BH-to-galaxy mass ratio depends on the disk scale-height (h), 3

BH galaxy disk10 / 2M M h r

• The velocity difference stars and absorbing clouds becomes closer to zero

Page 20: Why Massive Black Holes are Small in Disk Galaxies ?

Grazie mille!どうもありがとう ございました!