Presentation on theme: "Black Holes in Universe - From Stellar Masses to Supramassive Objects in Galaxies Max Camenzind Center for Astronomy Heidelberg Landessternwarte."— Presentation transcript:
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. in Chandrasekhar (1983): „The Mathematical Theory of BHs“
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 R S = 2GM/c² = 3 km M / M S 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
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. 4 Laws of Black Hole Mechanics
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 ! 1978 – 2005: Observations
The Year 1963 and the Physics of Kerr Black Hole
How to Treat Gravity of BHs ? In GR the spacetime is a differentiable manifold. The most natural thing is to to foliate it in t=const spatial hypersurfaces t. Measures the “clocks ticking rates” on two t Measures distances among points on a t unit timelike 4-vector normal to t Measures the “stretching” of coordinates tt 1 4 6
2 Parameters: (i)Mass M (ii)Ang. Mom. a „Charge not relevant in Astrophysics“ Event Horizon r H = M + (M² - a²) 1/2 Spacetime is stationary and axisymmetric
Blandford-Znajek Process Blandford & Znajek (1977) Load at infinity J „Split-Monopole“ magnetosphere coupled to rotating Horizon with Znajek Horizon bc drives closed current system Subject of strong criticism (Punsley)
A Modern Version of BZ Mechanism OLC: Outer Light Surface, compact for Black Holes A: Alfven Surface Plasma injection from near ms orbit; Plasma accretion causal: slow ms, Alfven and fast ms points Proto-Jet Current Sheet wwwww Magnetic fields advected from „Infinity“
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 ! T ~ RB Operates outside horizon
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 ! L Rot = E Rot /t brake ~ 10 46 erg/s (M H /10 9 M S ) (t H /t brake ) ~ 10 46 erg/s (M H /10 9 M S ) (t H /t brake ) L Rot = E Rot /t brake ~ 10 38 erg/s (M H /10 M S ) (t H /t brake ) ~ 10 38 erg/s (M H /10 M S ) (t H /t brake ) t brake = f (a, B,…) [BZ 1977] L BZ = k B H ² r H ²c (a/M)² ( F [ H - F ]/ H ²) ~ M H
Black Holes as Astrophysical Objects [ Primordial Black Holes: M < 2 M S ] Stellar Black Holes: 2.2 M S < M < 100 M S Intermediate Mass Black Holes 100 M S < M < 10 5 M S (?) Supermassive Black Holes: 10 5 M S < M < 10 10 M S reside in center of galaxies at all redshifts, 0 < z < 10 (?).
High-Mass XB Cygnus X-1 Black Holes are formed in stellar Collapse >100.000 BHs in the Galaxy 1971 monitored by UHURU
Cyg X-1 – Activity Cycles (VLA / RXTE) When high in X-rays minimum in radio and vice versa Jet launch Radio X-Rays HX
DIFFERENT BINARY SYSTEMS type of the donor star type of accretion (wind or Roche lobe overflow) very different scales: Every X-ray binary is a possible microquasar! J.A. Orosz
Stellar Mass Spectrum Clear Separation NSs vs BHs NS BHs
X-Ray Emission: VARIABILITY on all Time Scales Variations = changes in the state of the source lightcurves: GX 339-4 / GRS 1915+105 Variations on very different time scales ! “easy” observations for human time scale X (2-10 keV) Radio (2,25 GHz) Rau et al (2003) GX339-4 lightcurve 19962003 GRS 1915+105
accretion / ejection coupling cycles of 30 minutes in GRS 1915+105 : ejections after an X-ray dip refilling of the internal part of the disc ? transient ejections during changes of states same phenomenum in the quasar 3C 120 ? far slower ! Mirabel et al (1998) Marscher et al (2002)
SUPERLUMINAL EJECTIONS Move on the sky plane ~10 3 times faster Jets are two-sided (allow to solve equations max. distance) same Lorentz factor as in Quasars : ~ 5-10 Mirabel & Rodriguez (1994) VLA at 3.5 cm VLBI at 22 GHz ~ 1.3 cm ~ arcsec. scale ~ milliarcsec. scale
QUASARS MICROQUASARS Mirabel et al. 1992 Quasar 3C 223 Microquasar 1E1740.7-2942 radio (VLA) observations at 6 cm VLA at 1477MHz ~ 20 cm
Spectrum of a Microquasar If jet emission extends up to the visible band, the jet has > 10% of the total power Markoff et al. (2001) If jet emission dominates the X-ray band, the jet has > 90% of the total power Synchrotron (jet) thermal (disc) ? MeV emission due to Synch. Self-Compton from the compact jet ? GeV ? (GLAST) shocks with the ISM TeV ?
Black Hole Mass ~ Bulge Mass for Inactive Galaxies 30 Nearby Galaxies: M H ~ 0.14% M B Magorrian Relation (N. Häring & H.-W. Rix: ApJL 2004)
Mass vs Luminosity of Quasars L E = 2 x 10 31 Watt x (M/M S ) ~ 5 x 10 4 L S maximum luminosity minimum mass for BHs
Black Hole „Two-Hair Plane“ RL Quasars, Radio Galaxies BH s in Galactic Centers and QSOs BHs at High Redshifts Microquasars, Stellar BHs, M * > 30 Intermediate Mass BHs ???Population III BHs Neutron Stars
Spin a of a Black Hole can be determined from Photon Propagation Equations of geodesics integrable Carter Integrals
High- Redshift Quasars (SDSS) Form in Primordial Clusters Very massive BHs form very early !
Cosmic Quasar Population H 0 = 70 km/s/Mpc k = 0.0 m = 0.3 = 0.7 QSO densities augmented by factor 3 due to obscuration M. Camenzind 2005
Cosmic History & Black Holes recombination Cosmic Dark Age: no light no star, no quasar; IGM: HI First light: the first galaxies and quasars in the universe Epoch of reionization: radiation from the first object lit up and ionize IGM : HI HII reionization completed, the universe is transpartent and the dark ages ended today
Credit: G. Fishman et al., BATSE, CGRO, NASA BATSE GRB Final Sky Map: Astronomy Picture of the Day 2000 June 28
Gamma-Ray Burst Durations Two Populations: Short – 0.03-3s Long – 3-1000s Possible third Population 1-10s
A Slow Explosion of massive star Formation of rotating BH with JETS long duration burst Credit: Y. Grosdidier (U. Montreal) et al., WFPC2, HST, NASA “Astronomy Picture of the Day: 2003 March 25”
On the Origin of Gold: Astronomy Picture of the Day: 2005 May 15 Merging of 2 neutron stars short bursts formation of a BH
New Paradigm for ADs: Disks are not viscous – Disks are turbulent - Turbulence driven by weak magnetic fields - Radiative MHD key vehicle [Balbus & Hawley 1991,98] 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.
Two different accretion states depending on the accretion rate for given mass
Accretion States of Cyg X-1 High State (HS) [truncation radius near rms] Low State (LS) [truncation radius moves away] Transitions Energy emitted in Comptonized photons
What tell us X-rays? MCG-6-30-15 HST/WFPC-2 XMM-Newton 0.5-10keV light curve (Fabian et al. 2002) Rapid X-ray variability of AGN strongly suggests X-rays come from innermost regions of accretion disk
GRMHD Accretion from a Torus as Initial Condition Non-Radiative Accretion Flows De Villiers, Hawley & Krolik 2003 - 2005 (3D non-conservative GRMHD in BL); Gammie et al. 2003, 2004 (2D conservative GRMHD in BL coordinates) Initial condition (exact mech. equilibrium + weak magnetic fields)
Initial State „Final State“ Meridional Plane through a BH Colour: Density Torus + weak magnetic fields Turbulent Thick Disk Keplerian Gammie et al. 2004 Outflows Funnel
Magnetic Fields (originally confined to torus) evolve towards a completely turbulent state. Angular momentum is transported outwards, some accreted to spin up BH.
Beyond Einstein – Heavy Numerical Computations Robust parallel GRMHD Codes
Beyond Einstein: Is there really a Singularity in the Black Hole ? Vacuum energy is present everywhere in the Universe ( Dark Energy) Change the Interior of a Black Hole Regular state ! Mazur & Mottola 2001, 2004
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 – 10 5 M S ? 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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