Experimental Evidence of Black Holes

Transcription

1 Experimental Evidence of Black Holes School on Particle Physics, Gravity and Cosmology Dubrovnik 2006 September 1 st Andreas Müller Max-Planck-Institute for Extraterrestrial Physics Garching, Germany amueller@mpe.mpg.de

2 Plan of the talk Black hole basics Stellar-mass BHs Active galactic nuclei (AGN) Accretion onto BHs Ray tracing techniques Detection methods Probing BH spin What do we observe? Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 2

3 Black hole basics Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 3

4 Schwarzschild vs. Kerr Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 4

5 Kerr solution Roy P. Kerr (1963) in Boyer-Lindquist-Form (1967) (G = c = 1) lapse function delta potential generalized radius sigma potential frame-dragging frequency black hole mass M spin parameter a cylindrical radius Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 5

6 Black Hole mass scale TeV (particle-like): 1000 protons ~ g intermediate-mass: M? primordial: g ~ mountain mass? stellar: M? M80 M74 supermassive: M XTE J SS433 M83 3C273 M87 images: Chandra, HST, NASA Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 6

7 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 7

8 Gravitational collapse of stars collapsing star stellar rest mass compact object white dwarf neutron star black hole Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 8

9 X-ray binary Cyg X-1 Black hole Giant star kev Sketch from Chandra Website M BH ~ 10 M D ~ 2 kpc Observation: Integral, ESA, Beckmann et al Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 9

10 Candidate η Carinae Southern sky: Carina Super star M >100 M distance: 7500 Lj Luminous Blue Variable (LBV) Gigantic stellar explosion: hypernova E ~ erg = x E SN expected relic object: stellar black hole Hubble space telescope 1996 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 10

11 Gamma ray bursts (GRBs) Animations from Swift website I) short duration II) long duration (0.01s < t < 2s) (2s < t < 1000s) merging compact objects collapse of a massive star e.g. NS-NS GRBs: forming black holes caught in the act! isotropic distribution over sky cosmological origin Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 11

12 Anisotropic fireball model for GRBs Γ ~ γ-rays shock wave optical IR radio Model established by Meszaros & Rees 1993, 1997; Paczynski & Rhoads 1993 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 12

13 GRB observation Example GRB t ~ 20 s E γ ~ kev X-ray afterglow 8 hr after prompt emission Optical afterglow 12 hr after prompt emission observation: Integral, ESA, Beckmann et al Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 13

14 Active galactic nuclei (AGN) Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 14

15 dichotomy into AGN type 1 and AGN type 2 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 15

16 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 16

17 Accretion onto black holes Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 17

18 Eddington s argument observed luminosity hints for BH mass accretion rate related to luminosity Super-Eddington accretion possible e.g. in disk accretion Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 18

19 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 19

20 Jet launching: Need for Kerr Supercomputer simulations: nonradiative, ideal general relativistic magneto-- hydrodynamics Poynting flux from rapidly spinning BH drives funnel-wall outflow! becomes > 10% restmass accretion rate at high spins however outflow has Γ sim ~ 2 only whereas Γ obs ~ 10 Krolik et al Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 20

21 Ray tracing techniques Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 21

22 Kerr ray tracing - render disk images i = 60 a = 0.99 M r in r out = r H = 30.0 r g Keplerian kinematics Müller, diploma thesis 2000 Doppler effect distorted by beaming (SR) and gravitational redshift (GR) fully relativistic generalized Doppler factor effects influence any emission in black hole systems! Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 22

23 Kerr ray tracing Event horizon, Black hole Beaming spot rotation Computer simulation of rotating thin gas disk Müller PhD 2004 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 23

24 Kinematical methods Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 24

25 Hightech in Atacama desert Very Large Telescope, ESO, Chile four 8m-telescopes on 2635m mountain, optical and near-infrared interferometry resolving power comparable to space telescope (0.05 to mas! Full moon / 40000) Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 25

26 Stellar Orbits at Sgr A* kinematical probe stellar motion of stars in NIR S stars Keplerian laws: M = 3.6 x 10 6 M Genzel group MPE: Eckart et al Schödel et al Eisenhauer et al Ghez et al. 1998, 2000, 2003 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 26

27 kinematical M-σ relation tight correlations between black hole and surrounding spheroid Magorrian et al Hähnelt & Kauffmann 2000 Tremaine et al Ferrarese & Merritt 2002 conflicts with M-L V Lauer et al. astro-ph/ curved M-σ, brightest cluster galaxies: low σ for their high L Wyithe 2006 M ~ σ 4 M31, Andromeda Sgr A*, Milkyway M87, Virgo Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 27

28 Other kinematical methods QPOs at microquasars Abramowicz et al Aschenbach et al Flares (NIR + X at Sgr A*) Genzel et al Aschenbach et al reverberation mapping optical orbit at ISCO suggests a/m~0.5 Peterson et al. X-rays Reynolds et al. Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 28

29 Obscurative methods obscura, Latin: darkness Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 29

30 Measurements of Black spot obscurative Kerr ray tracing: a/m = 0.1 i = 40 r in = r H+ = r g r out = 30.0 r g R trunc = 6.0 r g Kepler rotation + radial drift truncated emissivity black spot ~ 2 R S Müller & Camenzind, A&A 2004 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 30

31 obscurative Candidate: Sgr A* best BH candidates for obscurative: Sgr A*, M87* + Krichbaum et al Takahashi 2004 Falcke et al Bardeen 1970ies VLT, NACO 2002 Baganoff et al Chandra Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 31

32 obscurative Spot depends on orientation & spin Müller PhD 2004 gravitational redshift causes BH main characteristic black spot is smaller if disk is present (here) as cp. to non-disk case inclination and spin deform shape of the event horizont (spherical vs. ellipsoidal) Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 32

33 obscurative An analogue solar X-rays are scattered of the Moon high S/N: shadow of the moon in X-rays detected as immersed in bright XRB this is really a shadow Schmitt et al similar: isolated BHs immersed into CMB Carter 2006 bremsstrahlung of solar wind e - Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 33

34 Spectro-relativistic methods Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 34

35 spectro-relativistic Broad Iron K lines relativistically broadened emission lines near BHs dominant: Fe Kα at 6.4 kev rest frame energy observed in AGN, and GBH with ASCA, RXTE, XMM, Chandra, Suzaku precondition: primary HX source illuminates cold accretion disk probe {M, a} Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 35

36 spectro-relativistic A Fe Line Gallery observations: subtract power law and fit relativistic broad disk line here: ray tracing simulations a = M i = 30 r in = 1.24 M r out = M β = 3.0 a = M i = 75 r in = 1.24 M r out = M β = 3.0 a = M i = 30 r in = 6.0 M r out = M β = 3.0 a = M i = 30 r in = 20.0 M r out = M β = 3.0 a = M i = 1 r in = 1.24 M r out = M β = 3.0 a = M i = 30 r in = 1.24 M r out = M β = 4.0 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 36

37 Gravitational redshift spectro-relativistic i = 75 a/m = Keplerian rotating rings, Strong gravity! Gaussian emissivity: ~ 1 r g narrow g = ν obs / ν em Müller & Wold 2006, A&A in press, astro-ph/ Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 37

38 spectro-relativistic Redshift gradient relativistic emission lines from Keplerian rotating rings are characterised by line core redshift z core Fe K X-rays opt. BLR lines gravitational redshift decays linearly in far-field probe {M, a, i} Mrk 110: opt. BLR lines suggests multi-wavelength search for gravitationally redshifted features Müller & Wold 2006 A&A in press astro-ph/ Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 38

39 Hightech in Earth orbit XMM-Newton, ESA X-ray range kev Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 39

40 Cosmic X-ray Background spectro-relativistic stacked relativistic broad emission lines from ~100 active SMBHs in X-ray background Fe Kα feature at 6-7 kev for AGN type-1 and 2 type-1 type-2 Lockman Hole Hasinger et al. XMM, 770 ks Streblyanska et al Brusa et al Müller & Hasinger 2005 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 40

41 Aberrative methods Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 41

42 Lensing of orbital shapes aberrative use relativistic light bending effects (lensing) right: tight intrinsically circular orbits around a Kerr BH deformation of classical Kepler ellipses to skewed shapes dependence on inclination of orbital plane pioneering papers: Luminet 1972 Cunningham & Bardeen 1973 also microlensing (indirect method using light curve) higher order images neglected Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 42

43 Schwarzschild vs. Kerr aberrative r orb = 6 r g lensed orbits: discriminate Schwarzschild (symmetric) from Kerr (asymmetric) i = 30 i = 60 spin breaks mirror symmetry i = 85 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 43

44 Accretive methods Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 44

45 accretive AGN activity M87 Eddington s argument: use luminosity to estimate BH mass M BH ~ 3 x 10 9 M D ~ 16 Mpc Outflow drivers: relativistic AGN-Jets hint for active rotating SMBH Blandford & Znajek 1977 alternative: rotating MHD disk Blandford & Payne kpc M87 HST Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 45

46 AGN activity Cyg A Cyg A X-rays Chandra Cyg A radio VLA M BH ~ 2.5 x 10 9 M D ~ 230 Mpc Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 46 Sketch

47 Eruptive methods Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 47

48 eruptive Stellar tidal disruption accretion burst event: X-ray flare L X decay with t -5/3 ROSAT, Chandra detected in 2004 at RX J , z = 0.05 happens every 10 4 yrs tidal radius: X-rays optical Komossa et al Halpern et al Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 48

49 Other eruptive methods GRBs flares see kinematical methods Hawking radiation tough job for cosmic BHs 2008 in reach with particle accelerators (LHC)? Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 49

50 Gravitational-wave induced method characteristic GW spectrum and GW frequencies e.g. BH-BH merger in 10 to 500 Hz range chirp, inspiral, ringdown Courtesy: W. Benger, MPI for Gravitational Physics Is there a chance to prove event horizons with GW signals? Is there a chance to probe BH spin with GW spectra? Yes, indeed! (Berti & Cardoso 2006, gr-qc/ ) Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 50

51 Most confidental methods need to come close to BH to probe ergosphere and event horizon, r < R S strongest clues for BH existence from: GRBs (no alternative according to current knowledge) stellar orbits (i.e. Galactic Centre) Quasi-periodic Oscillations (QPOs) broad iron K lines Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 51

52 Black hole spin Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 52

53 Probing BH spin Study orbital and other characteristic frequencies QPOs Coupling of r ms and a widely used in broad line business flare orbiting at r ms BH growth argument (e.g. Shapiro 2005) spin-up by accretion and merging, a ~ Jet launching argument GRMHD in the Kerr geometry Proximity required: steep gradient of frame-dragging frequency: ω ~ r -3 Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 53

54 What do we observe? Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 54

55 What do we observe? it is massive it is compact it is dark neither event horizon, nor curvature singularity observed can we do? Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 55

56 Black Hole Observability dissipation argument to distinguish NS from BH ADAF argument: BHs are dimmer g ~ 0 suppresses any electromagnetic signal testing BHs vs. BH alternatives by em impossible claim for evidence Narayan et al Remillard et al Broderick & Narayan 2006 claim for non-observability Abramowicz et al Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 56

57 Static black hole alternatives Petri 2003 Mazur & Mottola 2001 only anisotropic version is stable (Cattoen et al. 2005) Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 57

58 Curvature invariants Kretschmann scalar ring singularity cosmic censorship? current observations (fits with iron K lines) reach r min ~ few r g a/m = r H+ = r g Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 58

59 The LQG back bounce Wheeler: emergence of true singularities signals breakdown of classical GR Loop effects: negative pressure develops in gravitational collapse to avoid singularity classical classical LQG LQG Goswami et al Bojowald et al evolution of area radius and energy density (inset) Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 59

60 Conclusions Observations hint for massive dark objects (MDOs) Event horizons and singularities are NOT yet proven Kerr black hole currently best choice Be open-minded for new Gravity issues! 2008: mini BHs at LHC? Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 60

61 Einstein & Holes Why socks? They only get holes! photo: Summer School Dubrovnik 2006 Andreas Müller (MPE Garching) 61