BLACK HOLES: FROM STARS TO GALAXIES

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BLACK HOLES FROM STARS TO GALAXIES ACROSS THE
RANGE OF MASSES
Felix Mirabel
European Southern Observatory.
Chile (on
leave from CEA. France)

• In last decade there have been overwhelming
  evidences
• for the existence of BHs as stellar remnants in
  binaries,
• as supermassive objects at the centers of
  galaxies, and
• possibly, as intermediate-mass compact objects
  in
• ultraluminous X-ray sources.
• BHs are real physical entities that play an
  important role
• in several areas of modern astrophysics

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STELLAR BLACK HOLES

• Compact objects in stellar binaries with mass
  functions greater than 4.
• 20 known out of a total population that could be
  as large as 100 million.
• Is there a real gap for MBH 2.2 - 4 M? ?
• Why in the Milky Way has not been found a stellar
  BH with MBH gt18 M? ?
• Is this due to poor statistics or to the metal
  content of BH progenitors ?
• Are BHs always form in energetic supernovae as
  suggested by the chemical composition of some
  donors, or could they also be form directly ?
• Does explosion vs. implosion depend on the mass
  of the collapsing core ?
• The observation of GRBs of long duration should
  shed light for our understanding of the
  mechanisms of stellar-mass black hole formation.

Synergy needed
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SUPERMASSIVE BLACK HOLES

• Dynamics is the most direct method to determine
  the masses of compact objects, and therefore, the
  best evidence for their existence.
• First dynamic evidence by the motion of H2O
  masers in NGC 4258.
• Best dynamic evidence by the motion of stars
  around the dormant BH of 3-4 x 106 M? at the
  center of our Galaxy.
• Presence of a cluster of massive stars
  distributed along randomly inclined disks of 0.04
  pc and 0.5 pc radii.
• This cluster seems to have been formed in situ
  and its study may open new horizons for our
  understanding of the formation of massive BHs and
  its relation with massive formation of stars in
  galactic centers.
• SMBHs are ubiquitous. Their mass is proportional
  to that of the bulge.
• The most massive are at z gt 6 and must have
  assembled in t lt 109 yr.
• Lower mass SMBHs formed more slowly by mergers at
  z lt 3.
• The peak accretion rate took place at z0.7 as
  the peak IR background.
• Due to gravitational recoil SMBHs could be off
  center and running away.
• HOW WERE SMBHs
  FORMED ?

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BHs OF INTERMEDIATE MASS

• Possible existence of BHs with M gt 100 M? in ULXs
  because of X-ray spectra properties, QPOs, and
  injected energy in surrounding nebulae.
  Furthermore, stellar BHs show luminosity
  saturation.
• The luminosity of ULXs fits the luminosity
  function of BHXRBs.
• No dynamic evidence found so far by the motion of
  satellite objects.
• No hyper-luminous stellar BH such as SS433 or GRS
  1915105 has been found in our Galaxy hosting an
  IMBHs. Upper limit is M 20 M?
• Why in our Galaxy -where the determination of the
  mass functions is possible-, no IMBH is found ?
• IMBHs may be there but are difficult to identify.

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ANALOGOUS PHENOMENA IN BHs ACROSS THE RANGE OF
MASSES

• Accretion-ejection coupling in microquasars and
  quasars (e.g. 3C120).
• Analogous time lags in adiabatically expanding
  clouds in quasi-periodic flares of Sgr A and
  microquasars. Rotating blobs or jets ?
• At low accretion rates the power is dominated by
  synchrotron, compact, flat spectrum jets, and
  universal correlations are being found.
• In high accretion states there are
  non-relativistic outflows with masses as large as
  30 the accreting mass.
• The joint action of massive outflows and jets
  heat and blow away the surrounding medium
  (ISM/IGM). Solve the cooling flow problem.
• Bended disks re-direct the jets. This geometry
  could account for the unified model of AGN, and
  the large fraction of obscured AGN.
• Inflow of mass jet collimation close to the BH
  in terms of the gravitational radius can be
  zoomed with better angular resolution in SMBH
  than in stellar-mass BHs.

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BHs AS PROBES OF GRAVITY IN THE STRONG-FIELD
REGIME

• Much of the radiation emerges within 6 Rg
• BHs are determined by mass, spin and electric
  charge.
• THE SPIN CAN BE DERIVED FROM
• X-ray flux and temperature.
• Skewed fluorescence iron lines.
• QPOs of maximum fix frequency.

BH ASTROPHYSICS IS TODAY IN SIMILAR SITUATION AS
STELLAR ASTROPHYSICS IN THE FIRST DECADES OF THE
XX CENTURY. EMPIRICAL CORRELATIONS PRECEEDS THE
PHYSICAL UNDERSTANDING OF STARS AND BHs.
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• Thank to G. Matt, V. Karas and the local
  support !
• have a good trip back home !