اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدRadiatively driven electron-positron jets from two component accretion flows
208
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Matter accreting onto black holes has long been known to have standing or oscillating shock waves. The post-shock matter puffs up in the form of a torus, which intercepts soft photons from the outer Keplerian disc and inverse Comptonizes to produce hard photons. The post-shock region also produces jets. We study the interaction of both hard photons and soft photons, with on-axis electron-positron jets. We show that the radiation from post-shock torus accelerates the flow to relativistic velocities, while that from the Keplerian disc has marginal effect. We also show that, the velocity at infinity or terminal velocity ${vartheta}$, depends on the shock location in the disc.
قيم البحث
اقرأ أيضاً
The first laboratory astrophysics experiments to produce a radiatively cooled plasma jet with dynamically significant angular momentum are discussed. A new configuration of wire array z-pinch, the twisted conical wire array, is used to produce conver
gent plasma flows each rotating about the central axis. Collision of the flows produces a standing shock and jet that each have supersonic azimuthal velocities. By varying the twist angle of the array, the rotation velocity of the system can be controlled, with jet rotation velocities reaching ~20% of the propagation velocity.
We explore the effect of momentum-driven winds representing radiation pressure driven outflows from accretion onto supermassive black holes in a set of numerical hydrodynamical simulations. We explore two matched sets of cosmological zoom-in runs of
24 halos with masses ~$10^{12.0}-10^{13.4}$ M_sun run with two different feedback models. Our `NoAGN model includes stellar feedback via UV heating, stellar winds and supernovae, photoelectric heating and cosmic X-ray background heating from a meta-galactic background. Our fiducial `MrAGN model is identical except that it also includes a model for black hole seeding and accretion, as well as heating and momentum injection associated with the radiation from black hole accretion. Our MrAGN model launches galactic outflows which result in both `ejective feedback - the outflows themselves which drive gas out of galaxies - and `preventative feedback, which suppresses the inflow of new and recycling gas. As much as 80 % of outflowing galactic gas can be expelled, and accretion can be suppressed by as much as a factor of 30 in the MrAGN runs when compared with the NoAGN runs. The histories of NoAGN galaxies are recycling-dominated, with ~70% of material that leaves the galaxy eventually returning, and the majority of outflowing gas re-accretes on 1 Gyr timescales without AGN feedback. Outflowing gas in the MrAGN runs has higher characteristic velocity (500 - 1,000 km/s versus 100-300 km/s for outflowing NoAGN gas) and travels as far as a few Mpcs. Only ~10% of ejected material is re-accreted in the MrAGN galaxies.
The fundamental difference between accretion around black holes and neutron stars is the inner boundary condition, which affects the behavior of matter very close to the compact objects. This leads to formation of additional shocks and boundary layer
s for neutron stars. Previous studies on the formation of such boundary layers focused on Keplerian flows that reached the surface of the star, either directly or through the formation of a transition layer. However, behavior of sub-Keplerian matter near the surface of a neutron star has not been studied in detail. Here, we study the effect of viscosity, in presence of cooling, on the sub-Keplerian flows around neutron stars, using Smoothed Particle Hydrodynamics. Our time-dependent study shows that multiple shocks, transition and boundary layers form in such type of accretion, when viscosity is significant, and one or more layers are absent when the viscosity is moderate. These flows are particularly of interest for the wind dominated systems such as Cir X-1. We also report the formation of a generalized flow configuration, Two-Component Advective Flow, for the first time.
We present a theoretical model for driving jets by accretion onto Kerr black holes and try to give an answer to the following question: How much energy could be extracted from a rotating black hole and its accretion disk in order to power relativistic jets in Active Galactic Nuclei?
We present magnetohydrodynamic simulations of a resistive accretion disk continuously launching transmagnetosonic, collimated jets. We time-evolve the full set of magnetohydrodynamic equations, but neglect radiative losses in the energetics (radiativ
ely inefficient). Our calculations demonstrate that a jet is self-consistently produced by the interaction of an accretion disk with an open, initially bent large-scale magnetic field. A constant fraction of heated disk material is launched in the inner equipartition disk regions, leading to the formation of a hot corona and a bright collimated, super-fastmagnetosonic jet. We illustrate the complete dynamics of the ``hot near steady-state outflow (where thermal pressure $simeq$ magnetic pressure) by showing force balance, energy budget and current circuits. The evolution to this near stationary state is analyzed in terms of the temporal variation of energy fluxes controlling the energetics of the accretion disk. We find that unlike advection-dominated accretion flow, the energy released by accretion is mainly sent into the jet rather than transformed into disk enthalpy. These magnetized, radiatively inefficient accretion-ejection structures can account for under-luminous thin disks supporting bright fast collimated jets as seen in many systems displaying jets (for instance M87).
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
