By Avi Loeb, slides here.
- why most of the matter is not BHs? Due to angular momentum of collapsing matter <- tidal torques from neighbours near turnaround <- non-spherical collapse
- you can check in, you can't check out
- fill the orbit of Earth w/ water -> black hole from a huge swimming pool in space
- pathological point in space-time
- 'string theorists still get paid, get prizes, they give prizes to each other'
- no hair theorem: charge is not important in astrophysics, only mass and spin
- cosmic censorship conjecture (no naked singularities)
- Beckenstein-Hawking radiation: negligible in astrophysics
- whenever there is a horizon, there are quantum fluctuations
- SgrA* 3D star orbits
- horizon commercial
- Broderick & Loeb 2006 - imaging SgrA*, cosmological beaming due to lensing
- BH spin parameter - max value is c, a = 1, normalisation (spin matters!)
- shadow of the BH: the region behind it has its light obscured
- gas is optically thin for wavelengths < 1mm
- ISM does not blur the image due to free e- scattering (turbulence), blurring is smaller than horizon scale
- VLBA can resolve SgrA* and M87 (~10 u-arcsecs)
- the Event-Horizon Telescope
- radio: Fourier space imaging, Broderick, Loeb 2010
- M87: huge BH, jet base images, Doeleman 2012
- feeding BH: MR instabilities, funnel (empty region for outflow, collimated by outflowing jet)
- Eddington limit: Thompson scattering due to luminosity of BH accretion -> outward force, momentum flux, Thompson cross-section. Protons are pulled by gravity create inward force, they are balanced at Eddington luminosity L_E = 1.3x 10^{38} erg/s (M/M_{\odot})
- BH luminosity: L_E x \eta: mass of BH grows exponentially
- Eddington timescale: short, we can grow a small seed to large value quickly. By trapping radiation, timescales shorten
- hot haloes collapse to supermassive stars -> BHs
- 1% of galaxies are quasars, BH mass is way lower than the total mass of the host: why are quasars short-lived? Because they are suicidal, self-regulating their growth, unbinding the gas that is feeding them.
- 10% quasars have jets (are radio loud)
- Binary AGN (Shen 2011)
- BL regions: characteristic speeds ~0.01c, UV radiation is converted into broad line emission
- NL regions: ~1kpc distance, gass is illuminated by quasar
- merger: at some stage, it can have 1 NL region and 2 BL region. Blech, Loeb 2012
- reverberation mapping, Koessis, Heiman, Loeb
- residence time of BHB - types of migration, shrinks the orbit differently from GWs
- Kulkarni & Loeb: excursion set formalism, multiple BHs: 3 body system is unstable (like human beings)
- SF in outer regions of accretion disk - you're likely to make stars - it may explain why quasar spectra have metal lines!
- extreme mass ratio inspiral stellar mass BH or NS [LISA]
- gravitational waves - time-dependent quadrupoles, BH/NS binaries, LIGO, eLISA (detects virtual GWs, generated by people playing WoW) -> precision: 1/1000th diameter of proton
- BH recoils: if the BHs have different masses, they recoil at hundreds km/s - they get out of the galaxy or move away from the center. GW emission is beamed at one direction, momentum is conserved
- > kick, candidate CID-42
- Star clusters around recoiled BHs in the MW halo: ~100 BHs ejected during assembly of MW halo, carrying SCs from cusp of host dwarf galaxy - there should be some unusual clusters in halo clusters, O'Leary & Loeb 2008. Stars are moving around BH Keplerian potential, BH gets a kick, stars may remain bound by E = -1/2 v^2 - GM/r^2 = 0.5(v - v_{kick} - GM/r^2) (vector addition), if E remains negative
- tidal disruption of stars by BHs ('this is an illustration from NASA, so it has no scientific value')
- loss cone: tidal disruption 1/10^{-5}
- BHs larger than 10^8 M_{\odot} swallow the whole stars - Hayasaki, Stone, Loeb 2012
- for binaries: loss cone filled by GW recoil, star disruption once every 10-100 years
- miniquasar 2013 - cloud falling into SgrA*, pericenter of highly elliptical, almost radial orbit with T == 200 yr, imsged in Br\gamma -- Burkert 2012 simulation
- is the cloud pressure-confined? There seems to be no evidence of ambient ram pressure? Maybe this cloud is produced by low mass star with protoplanetary disk - Murray-Clay & Loeb 2012
- hypervelocity planets from tidal disruption of stellar binaries
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