State transitions in black hole Xray binaries are likely caused by gas evaporation from a thin accretion disk into a hot corona. We present a heightintegrated version of this process, which is suitable for analytical and numerical studies. With radius
The conventional accretion disk lore is that magnetized turbulence is the principal angular momentum transport process that drives accretion. However, when dynamically important largescale magnetic fields thread an accretion disk, they can produce mass and angular momentum outflows, known as winds
 NSFPAR ID:
 10501262
 Publisher / Repository:
 DOI PREFIX: 10.3847
 Date Published:
 Journal Name:
 The Astrophysical Journal
 Volume:
 965
 Issue:
 2
 ISSN:
 0004637X
 Format(s):
 Medium: X Size: Article No. 175
 Size(s):
 ["Article No. 175"]
 Sponsoring Org:
 National Science Foundation
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Abstract r scaled to Schwarzschild units and coronal mass accretion rate to Eddington units, the results of the model are independent of black hole mass. State transitions should thus be similar in Xray binaries and an active galactic nucleus. The corona solution consists of two powerlaw segments separated at a break radius ${\stackrel{\u0307}{m}}_{c}$r _{b}∼ 10^{3}(α /0.3)^{−2}, whereα is the viscosity parameter. Gas evaporates from the disk to the corona forr >r _{b}, and condenses back forr <r _{b}. Atr _{b}, reaches its maximum, ${\stackrel{\u0307}{m}}_{c}$ . If at ${\stackrel{\u0307}{m}}_{c,\mathrm{max}}\approx 0.02\phantom{\rule{0.25em}{0ex}}{(\alpha /0.3)}^{3}$r ≫r _{b}the thin disk accretes with , then the disk evaporates fully before reaching ${\stackrel{\u0307}{m}}_{d}<{\stackrel{\u0307}{m}}_{c,\mathrm{max}}$r _{b}, giving the hard state. Otherwise, the disk survives at all radii, giving the thermal state. While the basic model considers only bremsstrahlung cooling and viscous heating, we also discuss a more realistic model that includes Compton cooling and direct coronal heating by energy transport from the disk. Solutions are again independent of black hole mass, andr _{b}remains unchanged. This model predicts strong coronal winds forr >r _{b}, and aT ∼ 5 × 10^{8}K Comptoncooled corona forr <r _{b}. Twotemperature effects are ignored, but may be important at small radii. 
Abstract Spinning supermassive black holes (BHs) in active galactic nuclei magnetically launch relativistic collimated outflows, or jets. Without angular momentum supply, such jets are thought to perish within 3 orders of magnitude in distance from the BH, well before reaching kiloparsec scales. We study the survival of such jets at the largest scale separation to date, via 3D general relativistic magnetohydrodynamic simulations of rapidly spinning BHs immersed into uniform zeroangularmomentum gas threaded by a weak vertical magnetic field. We place the gas outside the BH sphere of influence, or the Bondi radius, chosen to be much larger than the BH gravitational radius,
R _{B}= 10^{3}R _{g}. The BH develops dynamically important largescale magnetic fields, forms a magnetically arrested disk (MAD), and launches relativistic jets that propagate well outsideR _{B}and suppress BH accretion to 1.5% of the Bondi rate, . Thus, lowangularmomentum accretion in the MAD state can form largescale jets in Fanaroff–Riley (FR) type I and II galaxies. Subsequently, the disk shrinks and exits the MAD state: barely a disk (BAD), it rapidly precesses, whips the jets around, globally destroys them, and lets 5%–10% of ${\stackrel{\u0307}{M}}_{\mathrm{B}}$ reach the BH. Thereafter, the disk starts rocking back and forth by angles 90°–180°: the rocking accretion disk (RAD) launches weak intermittent jets that spread their energy over a large area and suppress BH accretion to ≲2% ${\stackrel{\u0307}{M}}_{\mathrm{B}}$ . Because the BAD and RAD states tangle up the jets and destroy them well inside ${\stackrel{\u0307}{M}}_{\mathrm{B}}$R _{B}, they are promising candidates for the more abundant, but less luminous, class of FR0 galaxies. 
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R _{B}≈ 2 × 10^{5}GM _{•}/c ^{2}, whereM _{•}is the SMBH mass. For the classic idealized Bondi problem, spherical gas accretion without magnetic fields, our simulation results agree very well with the general relativistic analytic solution. Meanwhile, when the accreting gas is magnetized, the SMBH magnetosphere becomes saturated with a strong magnetic field. The density profile varies as ∼r ^{−1}rather thanr ^{−3/2}and the accretion rate is consequently suppressed by over 2 orders of magnitude below the Bondi rate $\stackrel{\u0307}{M}$ . We find continuous energy feedback from the accretion flow to the external medium at a level of ${\stackrel{\u0307}{M}}_{\mathrm{B}}$ . Energy transport across these widely disparate scales occurs via turbulent convection triggered by magnetic field reconnection near the SMBH. Thus, strong magnetic fields that accumulate on horizon scales transform the flow dynamics far from the SMBH and naturally explain observed extremely low accretion rates compared to the Bondi rate, as well as at least part of the energy feedback. $\sim {10}^{2}\stackrel{\u0307}{M}{c}^{2}\sim 5\phantom{\rule{0.15em}{0ex}}\times \phantom{\rule{0.15em}{0ex}}{10}^{5}{\stackrel{\u0307}{M}}_{\mathrm{B}}{c}^{2}$ 
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, several orders of magnitude higher than the ${\stackrel{\u0307}{M}}_{\mathrm{acc}}=1.8\times {10}^{11}\phantom{\rule{0.25em}{0ex}}\mathrm{g}\phantom{\rule{0.25em}{0ex}}{\mathrm{s}}^{1}$ estimate obtained in earlier efforts. The larger mass accretion rate implies that the minimum estimated radius of the orbiting solid body is ${\stackrel{\u0307}{M}}_{\mathrm{acc}}=5.6\times {10}^{8}\phantom{\rule{0.25em}{0ex}}\mathrm{g}\phantom{\rule{0.25em}{0ex}}{\mathrm{s}}^{1}$ = 72 km, which, although significantly larger than prior estimates, still lies within the upper bounds (a few hundred kilometers) for which the internal strength could no longer withstand the tidal forces from the gravity of the WD. ${r}_{\mathrm{min}}$ 
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