Black Holes in Universe From Stellar Masses to Supramassive Objects in Galaxies Max Camenzind



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Black Holes in Universe - From Stellar Masses to Supramassive Objects in Galaxies

  • Max Camenzind

  • Center for Astronomy Heidelberg (ZAH)

  • @ Landessternwarte (2005)


Prologue: Chandrasekhar 1983

  • „The black holes of nature are the most perfect macroscopic objects there are in the universe: the only elements in their construction are our concepts of space and time. And since the general theory of relativity provides only a single unique family of solutions for their descriptions, they are the simplest objects as well.“

  •  No matter is involved in their construction [i.e. no EOS], a Black Hole is a global vacuum solution with horizon, a kind of gravitational soliton.



Topics

  • The Long History of Black Hole Physics.

  • The Year 1963 and Kerr Black Hole  Gravitational field is not Newtonian !

  • Evidence for the Existence of Black Holes  4 Classes of Astrophysical Objects.  „No Hair Plane (Glatzenebene)“ (M,a).

  • Accretion: New Paradigm of disk accretion onto Black Holes (Balbus & Hawley 1991).

  • Magnetic Fields - The Spin Paradigm: The Ergosphere as a Source of Energy  Launch Jets (Blandford & Znajek 1977)  still largely not understood.

  • Beyond Einstein ? Dreams and Future



The Long Way towards BHs

  • 1915: Einstein postulates the field equations (together with Hilbert).

  • 1916: Schwarzschild Solution  Schwarzschild radius RS = 2GM/c² = 3 km M / MS

  • Einstein denied the reality of Black Holes … He considered Black Holes as a mere mathematical curiosity.

  • This view changed after his death  detection of Quasars (> 1963)  observation of Cygnus X-1 (1971)



1963 – Foundation of Black Holes

  • 1923 - Milestone 1: George Birkhoff: Schwarzschild spacetime geometry is the unique spherically symmetric solution of the Einstein vacuum field equations

  • 1939 - Robert Oppenheimer & Hartland Snyder show gravitational collapse of a pressureless homogeneous fluid sphere  formation of a trapped region

  • 1963 – Milestone 2: Roy Kerr solves the Einstein vacuum field equations for uncharged symmetric rotating systems

  • 1963 – Milestone 3: Quasars are detected  fuelled by accretion onto Black Holes

  • 1965 - Ezra Newman and collaborators solve the Einstein-Maxwell equations for charged rotating systems

  • 1967 - Werner Israel presents proof of a "no hair" theorem



1968 – 1977: Golden Age

  • 1968 – Brandon Carter uses Hamilton-Jacobi theory to derive 1st-order equations of motion for particle moving in Kerr black holes  Kerr Ray-Tracing

  • 1969 - Roger Penrose discusses the Penrose process for the extraction of the spin energy from a Kerr black hole  Free energy of BHs

  • 1971 – Milestone 4: Identification of Cygnus X-1/HDE 226868 as a binary black hole candidate system.

  • 1973 - David Robinson completes the proof of the uniqueness theorem for Kerr black holes

  • 1977 – Milestone 5: Blandford-Znajek Process  electromagnetic spin energy extraction from rotating black holes



4 Laws of Black Hole Mechanics

  • 1972 - Stephen Hawking proves that the area of a classical black hole's event horizon cannot decrease.

  • 1972 - Jacob Bekenstein suggests that black holes have an entropy proportional to their surface area due to information loss effects

  • 1973 - James Bardeen, Brandon Carter, and Stephen Hawking propose 4 laws of black hole mechanics in analogy with laws of thermodynamics  Free energy

  • 1973 - Stephen Hawking applies quantum field theory to black hole spacetimes and shows that black holes will radiate particles with a black-body spectrum which can cause black hole evaporation  concept is important, but astrophysically not relevant, and still debated.



1978 – 2005: Observations

  • 1978 – Sargent et al. show evidence for a supermassive BH in the center of Messier 87 (“serious possibility”). This has been very much debated  but confirmed !

  • 1992 – Microquasar GRS 1915+105 found.

  • 1997 – Fe line redshifts of the innermost portions of accretion disks around rotating supermassive black holes

  • 2000 - Evidence for the hypothesis that Sagittarius A* is a supermassive black hole at the centre of the Milky Way galaxy

  • 2002 – The most distant Black Hole found:  Cosmological Redshift z = 6.43 ! (< 1 Gyear old)

  • 2005 – BHs confirmed in ~ 20 X-Ray Binary Systems !

  • 2005 – BHs confirmed in ~ 30 nearby galactic centers !

  • 2005 – BHs found in ~ 100,000 Quasars !



The Year 1963 and the Physics of Kerr Black Hole















4 Laws of BH Mechanics









Blandford-Znajek Process



A Modern Version of BZ Mechanism



Twisting of Magnetic Fields

  • Except for induction terms, evolution of toroidal magnetic field ~ Newtonian MHD

  •  Source: Differential plasma rotation

  •  Schwarzschild: no shear !

  •  Extreme Kerr: biggest effect !



Black Holes  2 Energy Reservoirs

  • Potential energy  tapped by accretion  X-rays

  • Rotational energy  tapped by magnetic fields, similar to rotating neutron stars (Blandford & Znajek 1977)  will feed energy of JETS !



Anatomy of Black Holes



Black Hole Ergosphere  Extended Boundary Layer



Each form of matter will be driven to corotation within the ergosphere !  Boundary Layer near Horizon ~ rH





Outflows in Quasars & Micro- Quasars ?  „Stochastic Funnel- Flow“



Field Line Twisting by Rotating Black Holes



Astrophysical Black Holes in the Universe



Black Holes as Astrophysical Objects

  • [ Primordial Black Holes: M < 2 MS]

  • Stellar Black Holes: 2.2 MS < M < 100 MS

  • Intermediate Mass Black Holes 100 MS < M < 105 MS (?)

  • Supermassive Black Holes: 105 MS < M < 1010 MS  reside in center of galaxies at all redshifts, 0 < z < 10 (?).





Cyg X-1 – Activity Cycles (VLA / RXTE)



Low-Mass X-Ray Binaries



DIFFERENT BINARY SYSTEMS



Stellar Mass Spectrum  Clear Separation NSs vs BHs



X-Ray Emission: VARIABILITY on all Time Scales



accretion / ejection coupling



GRS 1915+105 Microquasar



SUPERLUMINAL EJECTIONS



QUASARS  MICROQUASARS



GRS 1915+105 Disk Evolution



Spectrum of a Microquasar



Quasars 3C 273



Spectrum of a Quasar





Black Holes in E-Galaxies Drive Jets Cygnus A (VLA) 3C 219 (VLA)



Quasar Spectra





Black Hole Mass ~ Bulge Mass for Inactive Galaxies



Mass vs Luminosity of Quasars



Black Hole „Two-Hair Plane“



Spin a of a Black Hole can be determined from Photon Propagation



Image of a Ring



Line Emission from BH Accretion





High-Redshift Quasars (SDSS) Form in Primordial Clusters



Cosmic Quasar Population



Cosmic History & Black Holes











New Insight: Accretion is Turbulent - not Viscous



New Paradigm: BHs in Different Accretion States

  • BHs grow by accretion processes.

  • MHD turbulence drives angular momentum transport in acretion disks (Balbus & Hawley magnetorotational instability, MRI). Disks are turbulent, not viscous !

  • The well-known thin disk accretion model (Shakura & Sunyaev) only applies for high accretion rates, typically more than a few percent Eddington.

  •  Truncated accretion at lower rates.









Accretion States of Cyg X-1



What tell us X-rays?



GRMHD Accretion from a Torus as Initial Condition  Non-Radiative Accretion Flows











Beyond Einstein – The Observer‘s Dreams



XEUS - ESA





Beyond Einstein – Heavy Numerical Computations



Beyond Einstein: Is there really a Singularity in the Black Hole ?



Mottola-Mazur Gravastar  5 Layers

  • External Schwarzschild vacuum, r>2M

  • Thin shell at r > 2M, surface density + and surface tension.

  • [ Finite-thickness shell at r = 2M, stiff matter. ]

  • [ Second thin shell at r < 2M, surface density -, surface tension. ]

  • de Sitter vacuum inside: P = -c²  bulk of mass  no singularity r=0



Conclusions - Visions

  • Mass spectrum is continuous from stellar to 10 billion solar masses. Gap from 100 – 105 MS ?

  • But Kerr parameter a is not yet measurable !

  • GRMHD (> 2000) Plasma dynamics near BHs can be successfully treated within Godunov schemes  Use Kerr coordinates, bc within horizon !  MRI accretion theory is now tractable !

  • Strong B-field limit (which is unphysical !): GR Magnetodynamics confirms BZ mechanism of energy extraction out of the ergosphere  Jets are ergospheric plasma flows ?

  • Weak field limit of GRMHD (relevant for MRI) is in unsatisfactory state, most results based on non-conservative methods  Turbulent accretion to rotating BHs essentially unsolved, but now tractable with modern methods.

  • Also include radiation effects, which is important for high accretion rates at high z.



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