Hot Accretion Disks Revisited

Bjoernsson, G.; Abramowicz, Marek A.; Chen, Xingming; Lasota, Jean–Pierre

doi:10.1086/177587

Cited by 45 publications

(55 citation statements)

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“…The effect of electron-positron pairs in ADAFs has only been studied very approximately within the framework of a local treatment. In this case, the effect of such pairs was found to be unimportant (e.g., Björnsson et al 1996;Kusunose & Mineshige 1996; see Björnsson 1998 for a review). In the present paper, for simplicity we neglect this effect; however, it should be kept in mind that the inclusion of pairs in global hot accretion flows (including ADAFs and LHAFs) should be investigated carefully in the future.…”

Section: Dynamics Of One-temperature Hot Accretion Flowsmentioning

confidence: 98%

Hot One‐Temperature Accretion Flows Revisited

Yuan¹,

Taam²,

Xue³

et al. 2006

ApJ

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The effectiveness of the thermal coupling of ions and electrons in optically thin, hot accretion flows is investigated in a phenomenological approach. In the limit of complete coupling, we focus on the one-temperature accretion flows around black holes. Based on a global analysis, the results are compared with two-temperature accretion flow models and with the observations of black hole sources. Many features of one-and two-temperature solutions are quite similar. That is, hot one-temperature solutions are found to exist for mass flow rates less than a critical value, i.e.,2 is the Eddington accretion rate. WhenṀ P10 À3 2ṀEdd , the viscous energy is mainly balanced by the advective cooling, i.e., the solution is in the advection-dominated accretion flow (ADAF) regime. On the other hand, when 10 À3 2ṀEdd PṀ P10 2ṀEdd , radiative cooling is effective and is mainly balanced by advective heating, placing the solution in the regime of luminous hot accretion flow (LHAF). WhenṀ k 10 2Ṁ Edd , the accretion flow collapses at a transition radius with only the standard optically thick and geometrically thin disk solution existing in the innermost regions. We have fitted the spectra of the two black hole sources with the one-temperature models, Sgr A Ã and XTE J1118+480, which have been examined successfully with two-temperature models. It is found that the one-temperature models do not provide acceptable fits to the multi-wavelength spectra of Sgr A Ã nor to XTE J1118+480 as a result of the higher temperatures characteristic of the one-temperature models. It is concluded that the thermal coupling of ions and electrons cannot be fully effective and that a two-temperature description is required.

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Section: Dynamics Of One-temperature Hot Accretion Flowsmentioning

confidence: 98%

Hot One‐Temperature Accretion Flows Revisited

Yuan¹,

Taam²,

Xue³

et al. 2006

ApJ

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“…Examples of this include accretion disks [1][2][3], models of the early universe [4,5], pulsar magnetospheres [6,7], hypothetical quark stars [8], ultraintense lasers [9], and laboratory and tokamak plasmas [10,11].…”

Section: Introductionmentioning

confidence: 99%

Self-modulation of nonlinear Alfvén waves in a strongly magnetized relativistic electron-positron plasma

et al. 2013

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We study the self-modulation of a circularly polarized Alfvén wave in a strongly magnetized relativistic electron-positron plasma with finite temperature. This nonlinear wave corresponds to an exact solution of the equations, with a dispersion relation that has two branches. For a large magnetic field, the Alfvén branch has two different zones, which we call the normal dispersion zone (where dω/dk > 0) and the anomalous dispersion zone (where dω/dk < 0). A nonlinear Schrödinger equation is derived in the normal dispersion zone of the Alfvén wave, where the wave envelope can evolve as a periodic wave train or as a solitary wave, depending on the initial condition. The maximum growth rate of the modulational instability decreases as the temperature is increased. We also study the Alfvén wave propagation in the anomalous dispersion zone, where a nonlinear wave equation is obtained. However, in this zone the wave envelope can evolve only as a periodic wave train.

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“…In astrophysics, it has been suggested that electron-positron plasmas can be found in pulsar magnetospheres [1], magnetars [2], accretion disks [3], the early universe [4], and supernovae [5], just to cite some examples. Observational evidence of astrophysical electron-positron plasmas has been obtained in the Cygnus-X1 x-ray binary system, the jet in the M-87 giant elliptical galaxy, and other x-ray sources in the Galactic Center [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Self-modulation of nonlinear waves in a weakly magnetized relativistic electron-positron plasma with temperature

et al. 2012

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We develop a nonlinear theory for self-modulation of a circularly polarized electromagnetic wave in a relativistic hot weakly magnetized electron-positron plasma. The case of parallel propagation along an ambient magnetic field is considered. A nonlinear Schrödinger equation is derived for the complex wave amplitude of a selfmodulated wave packet. We show that the maximum growth rate of the modulational instability decreases as the temperature of the pair plasma increases. Depending on the initial conditions, the unstable wave envelope can evolve nonlinearly to either periodic wave trains or solitary waves. This theory has application to high-energy astrophysics and high-power laser physics.

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Hot Accretion Disks Revisited

Cited by 45 publications

References 0 publications

Hot One‐Temperature Accretion Flows Revisited

Hot One‐Temperature Accretion Flows Revisited

Self-modulation of nonlinear Alfvén waves in a strongly magnetized relativistic electron-positron plasma

Self-modulation of nonlinear waves in a weakly magnetized relativistic electron-positron plasma with temperature

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