Magnetohydrodynamic simulations of outflows from accretion disks

Ustyugova, G. V.; Koldoba, A. V.; Romanova, M. M.; Чечеткин, В. М.; Lovelace, R. V. E.

doi:10.1086/187739

Cited by 134 publications

(149 citation statements)

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“…In the former, the jet velocity (V jet ) and mass outflow rate (Ṁ w ¼ dM w /dt) depend on the magnetic energy (E mg ) as V jet / E 1 = 3 mg ;Ṁ w $ constant, and in the latter V jet / E 1 = 6 mg ;Ṁ w / E 0:5 mg . This mass flux scaling law was confirmed by Ustyugova et al (1999).…”

Section: Introductionsupporting

confidence: 60%

“…Can jets be ejected in the same manner in the axisymmetric cases? The stability of propagating jets has been studied by taking the accretion disk as the fixed boundary condition in twodimensional MHD (e.g., Ustyugova et al 1995;Ouyed & Pudritz 1997a, 1999Romanova et al 1998;Hardee & Rosen 1999Frank et al 2000), three-dimensional MHD ( Nakamura et al 2001;Ouyed et al 2003;Nakamura & Meier 2004), and three-dimensional SPMHD (smoothed particle MHD) simulations (Cerqueira & de Gouveia Dal Pino 2001). The three-dimensional treatment is necessary for investigating the stability of the jet against the nonaxisymmetric modes.…”

Section: Introductionmentioning

confidence: 99%

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Three‐dimensional Magnetohydrodynamic Simulations of Jets from Accretion Disks

Kigure

Shibata

2005

ApJ

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We report the results of three-dimensional magnetohydrodynamic ( MHD) simulations of a jet formation by the interaction between an accretion disk and a large-scale magnetic field. The disk is not treated as a boundary condition but is solved self-consistently. To investigate the stability of the MHD jet, the accretion disk is perturbed with a nonaxisymmetric sinusoidal or random fluctuation of the rotational velocity. The dependences of the jet velocity (v z ), mass outflow rate (Ṁ w ), and mass accretion rate (Ṁ a ) on the initial magnetic field strength in both nonaxisymmetric cases are similar to those in the axisymmetric case. That is, v z / B 1 = 3 0 ,Ṁ w / B 0 , anḋ M a / B 1:4 0 , where B 0 is the initial magnetic field strength. The former two relations are consistent with Michel's steady solution, v z / (B 2 0 /Ṁ w ) 1 = 3 , although the jet and accretion do not reach the steady state. In both perturbation cases, a nonaxisymmetric structure with m ¼ 2 appears in the jet, where m is the azimuthal wavenumber. This structure cannot be explained by Kelvin-Helmholtz instability and seems to originate in the accretion disk. Nonaxisymmetric modes in the jet reach almost constant levels after about 1.5 orbital periods of the accretion disk, while all modes in the accretion disk grow with oscillation. As for the angular momentum transport by Maxwell stress, the vertical component, hB B z /4 i, is comparable to the radial component, hB B r /4 i, in the wide range of initial magnetic field strength.

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Section: Introductionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Three‐dimensional Magnetohydrodynamic Simulations of Jets from Accretion Disks

Kigure

Shibata

2005

ApJ

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“…The solutions are Notes. a In the work of Ustyugova et al (1995), mass flux as free parameter by allowing the disk density to evolve. b Pudritz (1997) andFendt &Čemeljić (2002) allow no feedback from the jet to the disk and seem to overdetermine their simulations.…”

Section: Appendix a Zero Current Boundarymentioning

confidence: 99%

“…c Romanova et al (1997) perform isothermal simulations without solving the energy equation. Since the subslow injection, constraints on the following three quantities are given, v z , E φ , E r -just as Ustyugova et al (1995). d Krasnopolsky et al (1999) prescribe mass flux with the choice (E φ , E r , s, ρ, v z ) and superslow injection.…”

Section: Appendix a Zero Current Boundarymentioning

confidence: 99%

Acceleration and Collimation of Relativistic Magnetohydrodynamic Disk Winds

Porth

Fendt

2010

ApJ

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We perform axisymmetric relativistic magnetohydrodynamic simulations to investigate the acceleration and collimation of jets and outflows from disks around compact objects. Newtonian gravity is added to the relativistic treatment in order to establish the physical boundary condition of an underlying accretion disk in centrifugal and pressure equilibrium. The fiducial disk surface (respectively a slow disk wind) is prescribed as boundary condition for the outflow. We apply this technique for the first time in the context of relativistic jets. The strength of this approach is that it allows us to run a parameter study in order to investigate how the accretion disk conditions govern the outflow formation. Substantial effort has been made to implement a current-free, numerical outflow boundary condition in order to avoid artificial collimation present in the standard outflow conditions. Our simulations using the PLUTO code run for 500 inner disk rotations and on a physical grid size of 100 × 200 inner disk radii. The simulations evolve from an initial state in hydrostatic equilibrium and an initially force-free magnetic field configuration. Two options for the initial field geometries are applied-an hourglass-shaped potential magnetic field and a split monopole field. Most of our parameter runs evolve into a steady state solution which can be further analyzed concerning the physical mechanism at work. In general, we obtain collimated beams of mildly relativistic speed with Lorentz factors up to 6 and mass-weighted half-opening angles of 3-7 deg. The split-monopole initial setup usually results in less collimated outflows. The light surface of the outflow magnetosphere tends to align vertically-implying three relativistically distinct regimes in the flow-an inner subrelativistic domain close to the jet axis, a (rather narrow) relativistic jet and a surrounding subrelativistic outflow launched from the outer disk surface-similar to the spine-sheath structure currently discussed for asymptotic jet propagation and stability. The outer subrelativistic disk-wind is a promising candidate for the X-ray absorption winds that are observed in many radio-quiet active galactic nuclei. The hot winds under investigation acquire only low Lorentz factors due to the rather high plasma-β we have applied in order to provide an initial force-balance in the disk corona. When we increase the outflow Poynting flux by injecting an additional disk toroidal field into the outflow, the jet velocities achieved are higher. These flows gain super-magnetosonic speed and remain Poynting flux dominated.

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“…Pelletier & Pudritz 1992;Ferreira 1997; Krasnopolsky & Königl 2002), advanced sim-⋆ E-mail: jan.staff@mq.edu.au ulations in 2 dimensions (e.g. Ustyugova et al 1995;Ouyed et al 1997;Kato et al 2002;Ramsey & Clarke 2011) and 3 dimensions (e.g. Ouyed et al 2003;Anderson et al 2006;Moll 2009;Staff et al 2010), and tested against the ever increasing high resolution observations (e.g.…”

Section: Introductionmentioning

confidence: 99%

Hubble Space Telescope scale 3D simulations of MHD disc winds: a rotating two-component jet structure

Staff

Koning

Ouyed

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present the results of large scale, three-dimensional magneto-hydrodynamics simulations of disc-winds for different initial magnetic field configurations. The jets are followed from the source to 90 AU scale, which covers several pixels of HST images of nearby protostellar jets. Our simulations show that jets are heated along their length by many shocks. We compute the emission lines that are produced, and find excellent agreement with observations. The jet width is found to be between 20 and 30 AU while the maximum velocities perpendicular to the jet is found to be up to above 100km/s. The initially less open magnetic field configuration simulations results in a wider, two-component jet; a cylindrically shaped outer jet surrounding a narrow and much faster, inner jet. These simulations preserve the underlying Keplerian rotation profile of the inner jet to large distances from the source. However, for the initially most open magnetic field configuration the kink mode creates a narrow corkscrewlike jet without a clear Keplerian rotation profile and even regions where we observe rotation opposite to the disc (counter-rotating). The RW Aur jet is narrow, indicating that the disc field in that case is very open meaning the jet can contain a counterrotating component that we suggests explains why observations of rotation in this jet has given confusing results. Thus magnetized disc winds from underlying Keplerian discs can develop rotation profiles far down the jet that are not Keplerian.

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Magnetohydrodynamic simulations of outflows from accretion disks

Cited by 134 publications

References 0 publications

Three‐dimensional Magnetohydrodynamic Simulations of Jets from Accretion Disks

Three‐dimensional Magnetohydrodynamic Simulations of Jets from Accretion Disks

Acceleration and Collimation of Relativistic Magnetohydrodynamic Disk Winds

Hubble Space Telescope scale 3D simulations of MHD disc winds: a rotating two-component jet structure

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