Star-Massive Black Holes Encounters J.-P.Luminet Observatoire de Paris (LUTH) Tidal Disruption Events Esa, Madrid 2012

Supermassive black holes (M > 106 MS) in active galactic nuclei quasars radiogalaxies Supermassive black holes (M > 106 MS) in active galactic nuclei Seyfert 2

Massive black holes (M > 106 MS) in quiescent galactic nuclei Sagittarius A* 2,7 106 MS < M < 3,5  106 MS)

Intermediate mass black holes (103 < M < 106 MS) in globular clusters M15 4000 MS G1/M31 20 000 MS

The « octopus » model for AGN Luminet (1986)

BH’s gravitational radius Characteristic distances Accretion radius Collision radius Hills limit 108 MO Ablation radius Tidal radius BH’s gravitational radius 6

Tidal field = relative acceleration between elements of matter Newtonian tidal field Tidal field = relative acceleration between elements of matter tidal potential tidal tensor deviation tensor

(planet-satellite couple in circular orbit) • For incompressible homogeneous bodies • static field (planet-satellite couple in circular orbit) Edouard Roche Roche limit (1847)

• incompressible bodies in dynamical field (asteroid-black hole encounter in parabolic orbit) Luminet & Carter (1986) Kostic et al. (2009) Cigar-like regime Disk-like regime 0.16 RT ≤ Rp ≤ RT Rp ≤ 0.16 RT

Luminet et al. 1982-1986 : « affine » model • compressible bodies in dynamical field (star-black hole encounter in parabolic orbit) Luminet et al. 1982-1986 : « affine » model Non-disruptive regime Oscillating Riemann ellipsoid => variable star ?

From equilibrium to stellar disruption Compare : timescale of varying tidal field / internal timescale of the star Far from the tidal radius : Star adjusts its equilibium configuration Close to and inside the tidal radius : Pionneer work : Hills, 1975 ; Frank & Rees, 1976 Strongly dynamical tidal field => Star cannot respond

the penetration factor Parabolic orbit Crucial parameter : the penetration factor Carter & Luminet (Nature, 1982) Tidal radius Black hole RP RT

Slight penetration (b ~ 1) in the tidal radius Disruption process in the ellipsoidal model (Luminet & Carter, 1986) « cigar-like » configuration after leaving the tidal radius

Disruption process reproduced by hydrodynamical simulations Slight penetration in the tidal radius Disruption process reproduced by hydrodynamical simulations Ejected matter « cigar-like » configuration after leaving the tidal radius « S-like » configuration at the periastron

Lidskii & Ozernoy (1979), Rees (1988) Accretion of stellar debris (50%)  Tidal Flares Lidskii & Ozernoy (1979), Rees (1988) Tidal radius Massive black hole

UV flare in NGC 4252 (Renzini et al. 1995) X-ray flare in RXJ 1242-11 (Komossa & Greiner, 1999) UV flare in NGC 4252 (Renzini et al. 1995)

Giant X-UV luminous flares Detection (ROSAT, Chandra, Galex…) of X-UV flares from (non active) galactic nuclei

X-UV-optical luminous flares Detection (Chandra, Galex, Pan-starrs…) of flares from (non active) galactic nuclei (Komossa et al., Saxton et al. , Esquej et al., Gezari et al., etc.) « Relativistic » Tidal Flares Detection (Swift) of hard-X flares (Lx ~1047 ergs) (Zauderer et al. 2011, Cenko et al. 2012) Relativistic jets from tidal ejecta ?

(Carter & Luminet, Nature, 1982) The Pancake Effect (Carter & Luminet, Nature, 1982) Fixed compressive principal direction of the tidal tensor in the « vertical » direction ==> For deep penetration ( > 3)

The « Rolling Mill » Effect Cartoon version fixed compressive point after periastron But relativistc velocity at periastron => almost instantenous flattening

Disruption process in the ellipsoidal model (Luminet & Carter, 1986) Deep penetration (b > 3) in the tidal radius Disruption process in the ellipsoidal model (Luminet & Carter, 1986)

Explosive stellar disruption ? Compression and heating strongly dependent from the penetration factor Maximum values for an ideal gas with polytropic index 5/3 : Conditions required for explosive thermonuclear reactions

Detonation of metals (C, N, O, …) by radiative proton captures (Luminet & Pichon 1989) Helium detonation by triple alpha (Pichon 1985)

Tidally induced supernovae? Luminet, 1986 Rosswog et al., 2008 A special type of GRB ? Carter, 1992 Lu et al. 2008; Gao et al. 2011

The pancake triangle (solar type stars) Star enters the Black hole Black hole enters the star 107 K 108 K 109 K log ( No disruption log(M•/M*)

Shock waves in stellar pancakes (Brassart & Luminet, 2008-2010)

Problematics Stellar pancakes calculated in the affine model (Luminet et al. 1983- 1989) ==> Elliptical deformations of the star • Stellar pancakes calculated by 3D hydro (Bicknell & Gingold 1983; Laguna et al. 1993; Fulbright 1996) ==> SPH method (uses artificial viscosity to simulate shock waves) N.B. : Generalized affine model (Ivanov et al. 2001-2003)

Due to shock waves occuring during the phase of vertical direction ?? Disagreement : compression of the stellar core less than in the affine model: max ~ 1.5 for  < 10 max ~ const for  > 10 Due to shock waves occuring during the phase of vertical direction ?? Or bad treatment (SPH) of shock waves ?

New Hydrodynamical Model Euler eqs. + Godunov methods 1D approximation valid from the tidal radius to periastron Principal axes of the tidal tensor

 = 7 velocity Phase1: collapse Tidal radius periastron max.compression Phase1: collapse

 = 7 velocity Phase 2: bounce max.compression Subsonic expansion Subsonic collapse Supersonic collapse Subsonic expansion

collapse Shock  = 7 density (after bounce) Tidal radius periastron max.compression and bounce Shock (after bounce)

 = 7 temperature shock

= 15 shock 1 (before bounce) velocity shock 2 (after bounce)

 = 15 shock 1 (before bounce) density shock 2 (after bounce)

maximum central density maximum central temperature

Shock-driven maximum temperature  = 10 Shock-driven maximum temperature

Number of disruption events: Wang & Merritt (2004), Tal (2005) BH binaries : Chen et al (2009) UV/X/gamma-ray flares

Modelisation of Gamma-Ray Bursts jet Long GRB Short GRB 41

• g-ray transients Swift J1644+57 and Swift J2058+05 (Zauderer 2011, Cenko 2012) interpreted as a relativistic outflow from transient accretion onto a 106 Ms black hole • GRB 060614 (long ~100 s) without SN remnant : disruption of a WD by an intermediate mass BH ? (Lu et al. 2008) • A new class of g-ray bursts from stellar disruptions by IMBH ? (Gao et al., 2010)  From a total of 328 Swift GRBs with accurate measured durations and without SN association, 25 GRBs satisfying the criteria for GRB060614-type bursts…

Relativistic tidal field Luminet & Marck, 1985 E = specific total energy L = specific angular momentum for parabolic orbits : E = 1

Precession effect : self-crossing orbit

Double point inside the tidal radius: Luminet & Marck, 1985

Double point inside the tidal radius Brassart & Luminet, 2011 Double point inside the tidal radius Several compressions

Multi-pancake effect and X/ bursts • Multi-peak structure and timescales compatible with GRB 970815 (and others ?)

Recent hydro models … • 3D simulations coupling hydrodynamics and nuclear network (Guillochon et al., 2011): Confirm the occurrence of tidally induced supernovae • Red giants / BH interactions (Mac Leod et al., 2012): Tidal stripping of atmosphere • White dwarfs / IM BH strong encounters (Rosswog et al. 2010, Hass et al. 2012): Confirm nuclear ignition (e.g. helium detonation)

Supermassive BH > 108 MS Analogy with stellar collisions Around a 109 MS black hole, the typical collisional velocities are > 5000 km/s within a distance 0.1 pc from the black hole b = vcoll/v* crushing factor b = RT/Rp Massive BH (104 - 108 MS) Supermassive BH > 108 MS Glob. Clusters, GN, Seyfert Quasars, Giant elliptical …

 : disruption /  : pancake effect High velocity head-on collisions, polytropes 5/3 Barnes, 2003 Makino, 1999

The End