Super Massive Black Holes The Unknown Astrophysics of their initial formation

Characteristics of SBMH Crit = light cone loss A = accretion radius Coll = stellar disruption radius E = eddington radius; radiation pressure limits accretion; more efficient with larger G T = tidal radius G = Event horzon Important: When G>T no energy can be emitted; quenching mechanism

Evidence for SBMH Perturbed orbits at Galaxy Center Only physically plausible Mechanism for observed Quasar Luminosity

Evidence for SMBH

Only plausible QSO Power Source Much of the Gravitational Infall Energy is converted to Magnetic Field energy and the subsequent production of relativistic particles in what are called Radio Loud QSO. This Conversion process remains mysterious.

Simple BH Growth by Accretion Tidal break up of star requires energy: E b = 3/4 G m 2 /R Orbit of gas radius is: Our 2x10 6 M ; R gas =10 12 km  well outside the event horizon of a black hole so it will take a long time to fall from that initial radius throw some in spiral process. Suggests slow growth. Maximum accretion rate dictated by Eddington Luminosity (radiation pressure limited)  Under typical eddington conditions growth rate is Te= 9.3 x10 7 ln(Mc/M) yr  linear approx: 1 M per 10 years. Time for 1 solar mass to 10 8 solar masses is then 2 Gigayears Predicts QSO emergence Z at z = 2.5 Z=8 QSO = 500 million years at maximum growth rate

Density Limited Accretion This maximum rate, however, is not realistic, since the black hole quickly depletes its environment. Its not at all clear that this depletion can replenishes itself rapidly with new material Then growth rate is limited by density. DM/dt =  V The corresponding time-scale to grow from M to Mc under these conditions is at least 5 GYr SMBH growth can not occur nearly fast enough under either of these conditions

Binary Stars New studies show that binary stars are captured more efficiently; at least one gets disrupted New studies show that binary stars are captured more efficiently; at least one gets disrupted But is the seed population big enough? But is the seed population big enough? Binary Stars might not easily form in the first generation of stars at high redshift.

Possibilities Population III Stars: Collapse of Gas Clouds Collapse of Stellar Clusters Merger of already well formed galaxies

Population III Stars What if you start with 10 4 solar masses to begin with. Growth time is then 800 million years; still not fast enough Mergers of 100 seeds to 10 6 solar masses  Growth time is then 400 million years But this require seeds to exist at z > 100 Very Unlikely Scenario

Wind = Yellow A simulated formation model

Part of Galaxy Formation Process? We find that most copiously accreting black holes at these epochs are buried in significant amounts of gas and dust that absorb most radiation except for the highest-energy X-rays. This suggests that black holes grew significantly more during these early bursts than was previously thought, but because of the obscuration of their ultraviolet emission they did not contribute to re-ionization. We find that most copiously accreting black holes at these epochs are buried in significant amounts of gas and dust that absorb most radiation except for the highest-energy X-rays. This suggests that black holes grew significantly more during these early bursts than was previously thought, but because of the obscuration of their ultraviolet emission they did not contribute to re-ionization. Where does all the dust/gas come from? Where does all the dust/gas come from?

Galaxy interactions accelerate the growth of supermassive black holes Okay, yes, we observe this going on Now via merger induced accretion of by now pretty large galaxies  not likely applicable in the first 1 billion years Okay, yes, we observe this going on Now via merger induced accretion of by now pretty large galaxies  not likely applicable in the first 1 billion years

Outflow Limited Collapse Basic gas physics suggests that collapses slows (greatly) with feedback from when the first stars form. Basic gas physics suggests that collapses slows (greatly) with feedback from when the first stars form. Mass outflows from massive stars have to make everything take longer to form and settle. In some cases – terminal galaxy formation can ensue The right input physics into these simulations is not well known

Monolithic Galaxy Formation Something that doesn’t happen easily in the DM Universe Something that doesn’t happen easily in the DM Universe Massive spheroid Galaxies may have 10 8 to 10 9 solar mass dusty tori within 100 pc of galaxy center. Massive spheroid Galaxies may have 10 8 to 10 9 solar mass dusty tori within 100 pc of galaxy center. But this happens at Z=2 not Z=9 But this happens at Z=2 not Z=9 Z=2 sources can be detected with ALMA Z=2 sources can be detected with ALMA

In sum: All known growth processes are too slow to account for existence of radiating SMBH at z =8. Therefore a special/unknown process is required; likely means there is electromagnetic radiation emitted by sources at z > 100 Are there remnants of these sources in the nearby Universe?