Numerical simulations of dissipationless disk accretion

Bogovalov, S. V.; Tronin, I. V.

doi:10.1134/s1063773717090018

Cited by 13 publications

(16 citation statements)

References 28 publications

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“…For magnetically accelerated jets from rotating bodies this is well known (e.g. Bogovalov 1995;Beskin & Nokhrina 2009). In our models, there is no rotation and the slow expansion of the jet core is of a somewhat different nature.…”

Section: Discussionmentioning

confidence: 71%

Causality and stability of cosmic jets

Porth¹,

Komissarov²

2015

Mon. Not. R. Astron. Soc.

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In stark contrast to their laboratory and terrestrial counterparts, cosmic jets appear to be very stable. They are able to penetrate vast spaces, which exceed by up to a billion times the size of their central engines. We propose that the reason behind this remarkable property is the loss of causal connectivity across these jets, caused by their rapid expansion in response to fast decline of external pressure with the distance from the "jet engine". In atmospheres with power-law pressure distribution, p ext ∝ z −κ , the total loss of causal connectivity occurs, when κ > 2 -the steepness which is expected to be quite common for many astrophysical environments. This conclusion does not seem to depend on the physical nature of jets -it applies both to relativistic and non-relativistic flows, both magnetically-dominated and unmagnetised jets. In order to verify it, we have carried out numerical simulations of moderately magnetised and moderately relativistic jets. The results give strong support to our hypothesis and provide with valuable insights. In particular, we find that the z-pinched inner cores of magnetic jets expand slower than their envelopes and become susceptible to instabilities even when the whole jet is stable. This may result in local dissipation and emission without global disintegration of the flow. Cosmic jets may become globally unstable when they enter flat sections of external atmospheres. We propose that the Fanaroff-Riley morphological division of extragalactic radio sources into two classes is related to this issue. In particular, we argue that the low power FR-I jets become re-confined, causally connected and globally unstable on the scale of galactic X-ray coronas, whereas more powerful FR-II jets re-confine much further out, already on the scale of radio lobes, and remain largely intact until they terminate at hot spots. Using this idea, we derived the relationship between the critical jet power and the optical luminosity of the host galaxy, which is in a very good agreement with the observations.

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Section: Discussionmentioning

confidence: 71%

Causality and stability of cosmic jets

Porth¹,

Komissarov²

2015

Mon. Not. R. Astron. Soc.

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“…The point is that two terms in the numerator have the same order of magnitude, the first one being related to the sliding along the magnetic surface, and the second one being related to the angular momentum. E.g., for monopole magnetic field (and for slow rotation) the toroidal velocity vanishes (Bogovalov 1992;Beskin & Okamoto 2000). For this reason it is not surprising that vϕ can change sign.…”

Section: Resultsmentioning

confidence: 99%

On the radio image of relativistic jets – I. Internal structure, Doppler boosting, and polarization maps

Chernoglazov

Бескин

Pariev

2019

Monthly Notices of the Royal Astronomical Society

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In this first paper from forthcoming series of works devoted to radio image of relativistic jets from active galactic nuclei the role of internal structure of a flow is discussed. We determine the radial profiles of all physical values for reasonable Michel magnetisation parameter σ M and ambient pressure P ext . Maps of Doppler boosting factor δ and observed directions of linear polarisation of synchrotron emission are also constructed.

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“…Tian et al (2011) found that the QPPs are correlated with line intensity, Doppler velocity, and line width from the observations of Hinode EUV Imaging Spectrometer (EIS). In the X-ray and γ-ray channels, the QPPs with a short period of a few seconds are detected by Hoyng et al (1976) and Bogovalov et al (1983). Using Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) observations, the 2005 January 19 solar flare displays the QPPs with a period of 2−4 minutes at HXR emissions (Ofman & Sui 2006), while the 2002 December 26 solar flare exhibits the 2-min QPPs at the soft X-ray (SXR) emissions (Ning 2014).…”

Section: Introductionmentioning

confidence: 99%

Imaging and Spectral Observations of Quasi-Periodic Pulsations in a Solar Flare

Ning

Zhang

2015

ApJ

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We explore the Quasi-Periodic Pulsations (QPPs) in a solar flare observed by Fermi Gamma-ray Burst Monitor (GBM), Solar Dynamics Observatory (SDO), Solar Terrestrial Relations Observatory (STEREO), and Interface Region Imaging Spectrograph (IRIS) on 2014 September 10. QPPs are identified as the regular and periodic peaks on the rapidly-varying components, which are the light curves after removing the slowly-varying components. The QPPs display only three peaks at the beginning on the hard X-ray (HXR) emissions, but ten peaks on the chromospheric and coronal line emissions, and more than seven peaks (each peak is corresponding to a type III burst on the dynamic spectra) at the radio emissions. An uniform quasi-period about 4 minutes are detected among them. AIA imaging observations exhibit that the 4-min QPPs originate from the flare ribbon, and tend to appear on the ribbon front. IRIS spectral observations show that each peak of the QPPs tends to a broad line width and a red Doppler velocity at C I , O IV , Si IV , and Fe XXI lines. Our findings indicate that the QPPs are produced by the non-thermal electrons which are accelerated by the induced quasi-periodic magnetic reconnections in this flare.

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Numerical simulations of dissipationless disk accretion

Cited by 13 publications

References 28 publications

Causality and stability of cosmic jets

Causality and stability of cosmic jets

On the radio image of relativistic jets – I. Internal structure, Doppler boosting, and polarization maps

Imaging and Spectral Observations of Quasi-Periodic Pulsations in a Solar Flare

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