Jets in Magnetically Arrested Hot Accretion Flows: Geometry, Power and Black Hole Spindown. (arXiv:2108.12380v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Narayan_R/0/1/0/all/0/1">Ramesh Narayan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chael_A/0/1/0/all/0/1">Andrew Chael</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chatterjee_K/0/1/0/all/0/1">Koushik Chatterjee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ricarte_A/0/1/0/all/0/1">Angelo Ricarte</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Curd_B/0/1/0/all/0/1">Brandon Curd</a>
We present the results of nine simulations of radiatively-inefficient
magnetically arrested disks (MADs) across different values of the black hole
spin parameter $a_*$: $-0.9$, $-0.7$, $-0.5$, $-0.3$, 0, 0.3, 0.5, 0.7, and
0.9. Each simulation was run up to $t gtrsim 100,000,GM/c^3$ to ensure disk
inflow equilibrium out to large radii. We find that the saturated magnetic flux
level, and consequently also jet power, of MAD disks depends strongly on the
black hole spin, confirming previous results. Prograde disks saturate at a much
higher relative magnetic flux and have more powerful jets than their retrograde
counterparts. MADs with spinning black holes naturally launch jets with
generalized parabolic profiles whose widths vary as a power of distance from
the black hole. For distances up to $100;GM/c^2$, the power-law index is $k
approx 0.27-0.42$. There is a strong correlation between the disk-jet geometry
and the dimensionless magnetic flux, resulting in prograde systems displaying
thinner equatorial accretion flows near the black hole and wider jets, compared
to retrograde systems. Prograde and retrograde MADs also exhibit different
trends in disk variability: accretion rate variability increases with
increasing spin for $a_*>0$ and remains almost constant for $a_*lesssim 0$,
while magnetic flux variability shows the opposite trend. Jets in the MAD state
remove more angular momentum from black holes than is accreted, effectively
spinning down the black hole. If powerful jets from MAD systems in Nature are
persistent, this loss of angular momentum will notably reduce the black hole
spin over cosmic time.
We present the results of nine simulations of radiatively-inefficient
magnetically arrested disks (MADs) across different values of the black hole
spin parameter $a_*$: $-0.9$, $-0.7$, $-0.5$, $-0.3$, 0, 0.3, 0.5, 0.7, and
0.9. Each simulation was run up to $t gtrsim 100,000,GM/c^3$ to ensure disk
inflow equilibrium out to large radii. We find that the saturated magnetic flux
level, and consequently also jet power, of MAD disks depends strongly on the
black hole spin, confirming previous results. Prograde disks saturate at a much
higher relative magnetic flux and have more powerful jets than their retrograde
counterparts. MADs with spinning black holes naturally launch jets with
generalized parabolic profiles whose widths vary as a power of distance from
the black hole. For distances up to $100;GM/c^2$, the power-law index is $k
approx 0.27-0.42$. There is a strong correlation between the disk-jet geometry
and the dimensionless magnetic flux, resulting in prograde systems displaying
thinner equatorial accretion flows near the black hole and wider jets, compared
to retrograde systems. Prograde and retrograde MADs also exhibit different
trends in disk variability: accretion rate variability increases with
increasing spin for $a_*>0$ and remains almost constant for $a_*lesssim 0$,
while magnetic flux variability shows the opposite trend. Jets in the MAD state
remove more angular momentum from black holes than is accreted, effectively
spinning down the black hole. If powerful jets from MAD systems in Nature are
persistent, this loss of angular momentum will notably reduce the black hole
spin over cosmic time.
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