scholarly journals On the role of magnetic reconnection in jet/accretion disk systems

2009 ◽  
Vol 5 (H15) ◽  
pp. 247-248 ◽  
Author(s):  
Elisabete M. de Gouveia Dal Pino ◽  
Pamela Piovezan ◽  
Luis Kadowaki ◽  
Grzegorz Kowal ◽  
Alex Lazarian
Keyword(s):  
Active Galactic Nuclei ◽  
Magnetic Reconnection ◽  
Accretion Disk ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Astrophysical Jet ◽  
Radio Flare

AbstractThe most accepted model for jet production is based on the magneto-centrifugal acceleration out off an accretion disk that surrounds the central source (Blandford & Payne, 1982). This scenario, however, does not explain, e.g., the quasi-periodic ejection phenomena often observed in different astrophysical jet classes. de Gouveia Dal Pino & Lazarian (2005) (hereafter GDPL) have proposed that the large scale superluminal ejections observed in microquasars during radio flare events could be produced by violent magnetic reconnection (MR) episodes. Here, we extend this model to other accretion disk systems, namely: active galactic nuclei (AGNs) and young stellar objects (YSOs), and also discuss its hole on jet heating and particle acceleration.

scholarly journals MAGNETIC FIELD EFFECTS NEAR THE LAUNCHING REGION OF ASTROPHYSICAL JETS

2010 ◽  
Vol 19 (06) ◽  
pp. 729-739 ◽  
Author(s):  
E. M. DE GOUVEIA DAL PINO ◽  
G. KOWAL ◽  
L. H. S. KADOWAKI ◽  
P. PIOVEZAN ◽  
A. LAZARIAN
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Magnetic Energy ◽  
Galactic Nuclei ◽  
Young Stellar Objects ◽  
Magnetic Field Effects ◽  
Astrophysical Jets ◽  
Stellar Objects ◽  
Fundamental Properties

One of the fundamental properties of astrophysical magnetic fields is their ability to change topology through reconnection and in doing so, to release magnetic energy, sometimes violently. In this work, we review recent results on the role of magnetic reconnection and associated heating and particle acceleration in jet/accretion disk systems, namely young stellar objects (YSOs), microquasars, and active galactic nuclei (AGNs).

scholarly journals Numerical Studies of Astrophysical Objects at Fesenkov Astrophysical Institute (FAI)

2018 ◽  
Vol 2 (1) ◽  
pp. 124-134
Author(s):  
Assylkhan Bibossinov ◽  
◽  
Denis Yurin ◽  
Chingis Omarov ◽  
◽  
...  
Keyword(s):  
Black Hole ◽  
Numerical Simulations ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Large Scale ◽  
International Workshop ◽  
Star Clusters ◽  
Galactic Nuclei ◽  
Numerical Studies ◽  
Astrophysical Objects

Numerical studies of astrophysical objects are a relatively new direction in Fesenkov Astrophysical Institute (FAI) and is mainly represented by the Laboratory of Cosmology, Stellar Dynamics and Computational Astrophysics. The lab seeks to understand the evolution of gravitating systems at various scales – from star clusters to galaxies to large-scale structure of the universe as a whole, and tackles these problems both through analytical methods and through numerical simulations. The particular focus is on numerical simulations of star clusters, especially those found in active galactic nuclei – this is a topic of oldestablished collaboration with colleagues from Astronomisches Rechen-Institut (Heidelberg) and National Astronomical Observatories of China (Beijing). The prominent example is STARDISK project dedicated to the numerical research of active galactic nuclei as multicomponent systems composed of compact stellar cluster, gaseous accretion disk and a supermassive black hole. It is demonstrated that an accretion disk can noticeably decelerate stars and thus enhance the accretion rate onto the black hole. In 2013 FAI hosted the MODEST-13 International Workshop dedicated to modeling of star clusters. Recently a new project has been approved aimed at construction of triaxial equilibrium N-body systems that can be of great help in various numerical experiments with disk galaxies. There are also long standing plans to perform cosmological simulations of large scale structures to test a new approach to dark matter and energy actively developed at FAI. For numerical calculations, FAI has a small, but growing computer cluster consisting of several high-performance computing servers equipped with computational GPU cards.

scholarly journals Water fountains: bipolar fast stellar jets traced by water vapor maser emission

2012 ◽  
Vol 8 (S290) ◽  
pp. 227-228
Author(s):  
Hiroshi Imai
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Asymptotic Giant Branch ◽  
Young Stellar Objects ◽  
Agb Stars ◽  
Stellar Objects ◽  
Stellar Jets ◽  
The Masses ◽  
Host Stars ◽  
Maser Sources

AbstractHighly collimated, bipolar fast jets are found in asymptotic giant branch (AGB) and post-AGB stars as well as in active galactic nuclei and young stellar objects. It is still unclear how to launch such jets from dying stars that were originally spherically symmetric. Exploration of the stellar jet evolution is also expected to probe its role in shaping a planetary nebula. Interestingly, some of stellar H2O maser sources — water fountains — exhibit stellar jets with spatially and kinematically high collimation in the earliest phase (<1000 years) of the jet evolution. Such water fountains have been identified in 14 sources to date. We have recently conducted interferometric (VLBA, EVN, VERA, VLA) maser and the single-dish (ASTE) CO J = 3 → 2 line observations of the water fountains. They have revealed a typical dynamical age (< 100 yr) and the detailed kinematical structures of the water fountains, possibility of the coexistence of “equatorial flows”, and their locations and kinematics in the Milky Way. Based on these results, the masses and evolutionary statuses of the host stars are also estimated.

scholarly journals THE ROLE OF THE ACCRETION DISK, DUST, AND JETS IN THE IR EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

2013 ◽  
Vol 777 (2) ◽  
pp. 164 ◽  
Author(s):  
R. E. Mason ◽  
C. Ramos Almeida ◽  
N. A. Levenson ◽  
R. Nemmen ◽  
A. Alonso-Herrero
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Galactic Nuclei ◽  
Ir Emission

scholarly journals The Radiative Impact of FU Orionis Outbursts on Protostellar Envelopes

1997 ◽  
Vol 182 ◽  
pp. 407-416
Author(s):  
K. R. Bell ◽  
K. M. Chick
Keyword(s):  
Point Source ◽  
Accretion Disk ◽  
Large Scale ◽  
Polar Axis ◽  
Equilibrium Structure ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Circumstellar Material ◽  
Isotropic Point ◽  
Radiative Impact

We present preliminary results of an investigation into the radiative impact of FU Orionis outbursts on protostellar envelopes. In the thermal accretion disk instability model, the inner portion of the disk is inflated in such a way as to funnel most of the outburst luminosity along the poles of the system. A multidimensional radiative transfer code is employed to derive the thermal equilibrium structure of the surrounding protostellar envelope and the backheated accretion disk during outburst. The radiation emitted during outburst is modeled as a combination of a self-luminous accretion disk and a central point source. We compare the relative heating of circumstellar material due to (1) an isotropic point source and (2) an anisotropic point source in which the emitted radiation is confined to a 30° cone about the polar axis. The isotropic point source creates a spherical dust cavity, while the anisotropic source naturally results in a cavity which is hourglass-shaped. Repeated outbursts may ultimately be responsible for the large-scale polar cavities commonly inferred to exist around young stellar objects. We also show that due to the anisotropy of the radiation expected during outburst, disk annuli within a few au will be shielded from the radiation of the outburst.

RADIATIVE PROCESSES IN JETS

2010 ◽  
Vol 19 (06) ◽  
pp. 659-669 ◽  
Author(s):  
GABRIELA S. VILA
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Electromagnetic Spectrum ◽  
Physical Processes ◽  
Energy Distributions ◽  
Stellar Objects ◽  
Radiative Processes ◽  
Relativistic Particles

Relativistic jets and collimated outflows are ubiquitous phenomena in astrophysical settings, from young stellar objects up to Active Galactic Nuclei. The observed emission from some of these jets can cover the whole electromagnetic spectrum, from radio to gamma-rays. The relevant features of the spectral energy distributions depend on the nature of the source and on the characteristics of the surrounding environment. Here the author reviews the main physical processes that command the interactions between populations of relativistic particles locally accelerated in the jets, with matter, radiation and magnetic fields. Special attention is given to the conditions that lead to the dominance of the different radiative mechanisms. Examples from various types of sources are used to illustrate these effects.

The Formation of Astrophysical Jets

1997 ◽  
Vol 163 ◽  
pp. 845-866 ◽  
Author(s):  
Mario Livio
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Young Stellar Objects ◽  
Astrophysical Jets ◽  
Stellar Objects ◽  
X Ray ◽  
Astrophysical Objects ◽  
Low Mass ◽  
Wind Source ◽  
X Ray Binaries

AbstractIt is assumed that the acceleration and collimation mechanisms of jets are the same in all the classes of astrophysical objects which are observed to produce jets. These classes now include: active galactic nuclei, young stellar objects, massive x-ray binaries, low mass x-ray binaries, black hole x-ray transients, symbiotic systems, planetary nebulae, and supersoft x-ray sources.On the basis of this assumption, an attempt is made, to identify the necessary ingredients for the acceleration and collimation mechanism. It is argued that: (i) jets are produced at the center of accretion disks which are threaded by a vertical magnetic field, (ii) the production of powerful jets requires, in addition, an energy/wind source associated with the central object. Tentative explanations for the presence of jets in some classes of objects and absence in others are given. Some critical observation that can test the ideas presented in this paper are suggested.

Sign in / Sign up

Export Citation Format

Share Document