1. Black Hole Accretion Theoretical Limits And Observational Implications Dominikus Heinzeller Institute for Theoretical Astrophysics Center for Astronomy Heidelberg Albert-Ueberle-Str. 2, 69120 Heidelberg dh@ita.uni-heidelberg.de Dominikus Heinzeller Institute for Theoretical Astrophysics Center for Astronomy Heidelberg Albert-Ueberle-Str. 2, 69120 Heidelberg dh@ita.uni-heidelberg.de Credit: Michael Owen, John Blondin

2. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 2 Outline 1.Black hole accretion and the Eddington limit 2.Spectral energy distribution of super-Eddington flows 3.Conclusions In collaboration with W.J. Duschl, S. Mineshige, K. Ohsuga Supported by: Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook

3. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 3 Classical Eddington limit global upper limit for the luminosity of a star spherical approximation often used in accretion discs: spherical symmetry homogeneous isotropic radiation no relativistic effects Thomson scattering no gas pressure Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook

4. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 4 Contradictions cosmology: SMBHs in the early universe accretion scenarios require super-Eddington accretion observation of super-Eddington luminosities: ULXs –sub-Eddington IMBHs? too hot accretion disc problem –super-Eddington stellar mass BHs? Current and previous work: modification of global classical Eddington limit local deviations –leaky discs (Begelman 2002) –critical accretion discs (Fukue 2000, 2004) Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook

5. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 5 Local Eddington limit in discs local Eddington limit for radial and vertical direction thin -discs (Shakura & Sunjaev 1973) slim discs: advection (Abramowicz et al. 1980/1988) Thomson scattering and interpolated opacities (Gail, priv comm.) spherical symmetry homogeneous isotropic radiation no relativistic effects Thomson scattering no gas pressure ? Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook

6. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 6 Local Eddington limit in discs radial upper limit on vertical upper limit unimportant for high (advection), otherwise crucial inner boundary? (here: torque-free) slim disc, : while Vertical Eddington limit Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook

7. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 7 SED of super-Eddington flows based on 2D RHD simulations (Ohsuga et al. 2005) –high accretion rates –energy transport via radiation and advection –consideration for photon trapping observer at inclination parallel line of sight calculation of radiative transfer –relativistic effects –electron scattering – -dependent ff-absorption Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook

8. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 8 SED of super-Eddington flows Blackbody temperature fit to peak: Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook

9. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 9 SED of super-Eddington flows mild relativistic beaming Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook Blackbody temperature fit to peak:

10. D. Heinzeller: Black Hole Accretion; IAU 2006, 08/23/2006 slide 10 Conclusions Black hole accretion: classical Eddington-limit not applicable in discs –depends on disc model –varies with distance from central object –inner disc region/boundary decisive bottle-neck in inner disc region super-Eddington accretion and luminosities Spectral energy distribution: modelling of disc and its environment necessary for interpretation of spectra mild relativistic beaming –increased photon number for small –enhanced average photon energy –high temperatures Influence on BH growth? Outflows, jets? Evidence for IMBH? NGC 4261 Credit: R.M. Elowitz Outline Black hole accretion SED of super- Eddington flows Conclusions and outlook