FORMATION OF SUPERMASSIVE BLACK HOLES Nestor M. Lasso

FORMATION OF SUPERMASSIVE BLACK HOLES
Nestor M. Lasso Cabrera
In this presentation the different theories that can explain the
formation of Supermassive Black Holes (SMBH) are presented.
Before focus on these theories, an introduction to Black Hole (BH)
(BH)
and SMBH properties is given, along with a brief explanation of the
different techniques used to find SMBH.
Also a description of what we know about SMBH is in here. In
this part are of remarkably importance the facts that:
¾ High Z and Low Z quasar have similar properties: Then they
should have a common origin.
¾ Mass of SMBH proportional to the mass of the bulge:
Exceptions M33 and NGC205.
The formation of SMBH is a not clear process. It has not been
explained yet what was first: Stars or BH’s,
BH’s, the Galaxy or the central
SMBH. Here the three most plausible explanation of formation of
SMBH are given:
¾Population III stars: Accretion, Mergers or Accretion + Mergers
¾Collapse of Gas Clouds
¾Collapse of Stellar Clusters
1. Population III stars:
A. Accretion:
The process is thought to start with a Population III star as a seed
in the earlier Universe. These stars collapse at the end of their
their lives
to form BH’s.
BH’s. These BH’s emitting at Eddington luminosity and
accreting gas at Eddington limit with a efficiency of 10% would last
about 7x108 yrs. to become a SMBH of mass 3x109 M
M. SMBH at
high Z cannot be explained by this theory.
A plausible explanation for these SMBH’s at high Z is that some
period of time they accrete at SuperSuper-Eddington rate and the
rest of their life at Eddington rate.
B. Mergers:
Again the process is thought to star with a Population III star as
a seed in the earlier Universe which collapse and form a BH. This
This
BH will grow by mergers with others BH and Intermediate BH
(IBH). The total number of mergers depends on the mass of Seeds
and the mass of Dark Matter Halos.
In a normal case a total of 102 – 103 dark matter halos are
needed to form a SMBH. This big number tells us that the theory is
not valid alone.
C. Accretion + Mergers:
The most plausible theory is the combination of Accretion and
Mergers. In this case some authors claim that the proportions would
would
be: 10% Mergers + 90% Accretion
2. Collapse of Gas Clouds:
This theory is based in that a gas cloud can collapse to form a
SMBH via a supermassive star or via a disk. This theory is only valid
if fragmentation of the gas cloud into stars can be avoided.
Conditions necessary to avoid star formation in the gas clouds
are given, along with a possible outcome for the formation of the
the
SMBH.
3. Collapse of Stellar Clusters:
This theory is based in the possibility of that a stellar cluster
cluster
collapse to form a SMBH. Conditions necessary for the collapse are
are
given, so as other possible variation of this theory.
FORMATION OF
SUPERMASSIVE BLACK HOLES
NESTOR M. LASSO CABRERA
AST 7939
High Energy Astrophysics
Jonathan Tan
Outline
What is a Black Hole?
What is a SMBH?
How to find SMBH
What do we know about SMBH?
Formation of SMBH
Population III Stars: Accretion and Mergers
Collapse of Gas Clouds
Collapse of Stellar Clusters
What is a Black Hole?
Stars with M > 5-6 M
Ceases to sustain a nuclear fusion reaction
Collapses under its own gravitational field
Supernova
Black Hole
Nothing escapes its gravitational field
Well known:
Formation
Localization
Mass
What is a SMBH?
SuperMassive Black Hole
Mass ~ 108 - 109 M
Nothing escapes its gravitational field
NOT well known:
Mass
Localization: Center of galaxies ??
Formation ?????????
Quasars
How to find a SMBH?
X-Ray Emission
Radial Velocity
106 - 109 M
NO STAR
Rotational Velocity
Gravitational lensing
Radio
“Light”
Centaurus A
~1350 Km s-1
Visible
Light
0
M .8
pc
What do we know about SMBH?
Present in nearly all active and non-active luminous galaxies
Quasar population
High z and Low z quasar similar properties – indistinguishable
Mass proportional to the mass of bulge
M ~ 0.2% M galaxy
(Miyaji et al. 2000)
What do we know about SMBH?
Mass proportional to the mass of bulge EXCEPTIONS:
M33 and NGC 205
(Ferrarese et al. 2006)
Formation of SMBH
Not clear:
First nonlinear objects: Stars or BH ?
Galaxies or Central BH ?
THEORIES:
Population III stars:
Accretion
Mergers
Accretion + Mergers
Collapse of Gas Clouds
Collapse of Stellar Clusters
1 - Population III stars: Accretion
Seed: Early massive star - Population III stars
Free metal
~100 M
(Abel et al. 2002 and Bromm et al. 2002)
BH
(Heger et al. 2003 and Carr et al. 1984)
Eddington limit
.M
Eddington Luminosity
LEdd = (4πmpcGM)/σTh
Gas Accretion:
Edd
= 10 LEdd / c2
Radiative Efficiency of 10% η = 0.1
MSMBH = 3x109 M
tSMBH ~ 7x108 yr.
(Haiman et al. 2001)
tΛCMD Uni (z=6) ~ 8x108 yr.
SEEDS at z ≥ 15
SMBH at high z NO PAUSIBLE
1 - Population III stars: Accretion
Eddington rate:
MBH = 108 M
.M
Radiative Efficiency of 10% η = 0.1
Edd
= 10 LEdd / c2 ≈ 1.7 M yr-1
.
.
Super-Eddington rate: M >> M
Edd
SMBH at high z PLAUSIBLES
Thick disk (Radiative inefficient flow RIAF)
Eddington luminosity
Energy not radiate away
(Begelman et al. 1982)
1 - Population III stars: Accretion
Super-Eddington rate + Eddington rate (Cavaliere et al. 2000)
If
.M >> M.
Edd
Outflows of mass
Little mass reach the BH (Stone et al. 1999)
SMBH at high z NO PAUSIBLE
.M ~ 10 -100 M.
Edd
(Begelman 2002)
SMBH at high z PAUSIBLE
1 - Population III stars: Mergers
Seed: Early massive star - Population III stars
Free metal
z ~ 20
In dark matter halos of 106 M (min. to form stars)
~100 M
(Abel et al. 2002 and Bromm et al. 2002)
BH
(Heger et al. 2003 and Carr et al. 1984)
Mergers:
Total Mergers depend on: mass of Seeds and mass of Dark Matter Halos
Mergers of ~ 104 IMBH (105 M)
NO VALID ALONE
102 – 103 Dark Matter Halos
1 - Population III stars: Mergers
NGC 6240
First evidence of SMBH Mergers
3000 light years apart
1 - Population III stars: Accretion +
Mergers
10% Mergers
(Combes 2005)
90% Accretion
2 – Collapse of Gas Clouds
Could form SMBH’s directly at high z via:
Supermassive Star (SMS)
Disk
Only if fragmentation of the gas cloud into stars can be avoided
Contracting gas becomes:
Optically thick
Radiation pressure supported
If self-gravitating
Less susceptible to
Star Formation
(Loeb et al. 1994)
Prone to Star Formation (Goodman 2003)
2 – Collapse of Gas Clouds
How to stabilize the cloud and avoid Star Formation?
Keep disk at high temperature:
Only in metal free, high z halos
H2 dissociated by UV light
No cooling
No molecules
No star formation
Gas collapses at ~ 8000K
~ 106 M SMBH (Oh et al. 2003)
Angular momentum (even with cooling particles):
From gravitational instabilities, spiral waves, bars, …
Drive a fraction of the gas to smaller scales in nucleus
2 – Collapse of Gas Clouds
A possible outcome for the formation of the SMBH:
Gas flows in
Disk becomes optically thick
Radiation pressure dominates for sufficiently massive objects
Radiation pressure may temporarily balance gravity
Forming a SMS
SMS radiates at Eddington limit and continue contracting
When SMS sufficiently compact, star becomes dynamically unstable
For M ≤ 105 M Start stops collapsing and explode
For M > 105 M Start collapses directly to a SMBH (Shapiro 2004)
3 – Collapse of Stellar Clusters
Negative heat capacity of self-gravitating stellar systems makes them
vulnerable to gravitational collapse (Binney & Tremaine 1987)
If core collapse continues
SMS
SMBH
Depends on number of stars in cluster N ≥ 106 – 107 stars (Lee 1987)
A different theory: (Begelman et al. 1978)
Massive stars dominate the dynamics of the cluster
Massive stars collapse faster than cluster as a whole
IMBH
IMBH + Accretion + Mergers
References:
Haiman, Z. 2004 arXiv:astro-ph/0403225v1
Greenwood, C.J. “Supermassive Black Holes at the Center of Galaxies
Kormendy et al. 2001 arXiv:astro-ph/0105230v1
Miyaji, T., Hasinger, G., & Schmidt, M. 2000, A&A, 353, 25
Begelman, M. C., & Meier, D. L. 1982, ApJ, 253, 87
Combes, F. 2005 arXiv:astro-ph/0505463
THE LOW MASS END OF THE
SUPERMASSIVE BLACK HOLE POPULATION
M33
Nestor M. Lasso Cabrera
This presentation is base in the low mass end of the SMBH
population. In particular it is based on M33 and its particular nuclei.
After see in the former presentation the particularities of the
nuclei of M33 compare with other luminous galaxies, here is
presented a study of M33 compare with M32, a galaxy with bulge,
and with NGC4395, a similar galaxy with bulge.
Curves of Surface brightness profile, radial velocity and velocity
dispersion of M33 are compared with that of M32, a typical galaxy
galaxy
with bulge. This curves place the upper limit of M33 in 3000M for
Merrit et al.,2001 and in 1500 M for Gebhardt et al., 2001.
Also the relation mass BH vs. velocity dispersion is shown for
different galaxy and both upper limits of M33 are place in the plot,
plot,
showing that M33 does not follow the relation.
Finally M33 is compare with NGC 4395. A galaxy pretty similar
to M33 but that shows a BH of about 33-4 x 105M.
THE LOW MASS END OF THE
SUPERMASSIVE BLACK HOLE
POPULATION
M33
NESTOR M. LASSO CABRERA
AST 7939
High Energy Astrophysics
Jonathan Tan
FORMATION OF
SUPERMASSIVE BLACK HOLES
What is a SMBH?
How to find SMBH
X-Ray Emission
Radial Velocity
Rotational Velocity
Gravitational Lensing
What do we know about SMBH?
Present in almost all luminous galaxies
Quasar Population
High and Low z quasar with similar properties
Mass proportional to the mass of bulge
M ~ 0.2% M galaxy
FORMATION OF
SUPERMASSIVE BLACK HOLES
Formation of SMBH
Population III Stars: Accretion and Mergers
Collapse of Gas Clouds
Collapse of Stellar Clusters
Mass proportional to the mass of bulge EXCEPTIONS:
M33 and NGC 205
Brightest Galaxies => SMBH
Intermediate and Lowest Galaxies => Stellar Nucleus
50%-70% late-type galaxies contain Stellar Nucleus (Balcells et al. 2003)
Stellar Nuclei ~20 times brighter than typical globular cluster
(Ferrarese et al. 2006)
M33
Surface brightness profile
M32
Gebhardt et al., 2001
Michard & Nieto, 1991
M33
Merrit et al.,2001
M33
Gebhardt et al., 2001
21km/s ≤ σ ≤ 35km/s
σ ~ 24km/s
M• ≤ 7x104 M‫סּ‬
M• ≤ 5x104 M‫סּ‬
Upper limit: M• ≤ 3000 M‫סּ‬
M• ≤ 1500 M‫סּ‬
M32
Bender, Kormendy & Dehnen 1996
Gebhardt
Merrit et al.,2001
M•=1.3x108 M‫( סּ‬σ/200)3.65 Gebhardt et al., 2001
M•=1.3x108 M‫( סּ‬σ/200)4.8 Ferrarese & Merrit 2000
σ < 35Km/s ~ Glob. cluster σ => No evidence BH (Merrit et al., 2001)
σ ~ 24Km/s ~ Glob. cluster σ => No evidence BH (Gebhardt et al., 2001)
Upper limit on the Mass ~3000M Merrit et al.,2001
Upper limit on the Mass ~1500M Gebhardt et al.,2001
Stellar central ρ ~ 106 M/pc3 ~ BH ρ >> Globular cluster ρ
Stellar Nuclei ~20 times brighter than typical globular cluster
NO BH or Globular cluster in Bulgeless galaxies => WHAT????
Barth et al. 2005
Filippenko & Ho, 2003
σ ≤ 30km/s
THERE IS A BH!!!
M• ~ 3-4x105 M‫סּ‬
Reverberation Mapping
Conclusions
Some Bulgeless galaxies have BH
Other Bulgeless galaxies: NO BH or Globular cluster
=> WHAT????
Luminous Galaxies with Bulge (L, σ ): SMBH
M• - σ relation for luminous galaxies with bulges
M• - σ relation for bulgeless galaxies ????
References:
Ferrarese et al. 2006, ApJ 644,L21
Merritt et al. 2001, arXiv:astro-ph/0107359v2
Gebhardt et al. 2001, ApJ 122:2469
Greene and Ho 2007, arXiv:astro-ph/0707.2617v1
Barth et al. 2005, ApJ 619:L151