I also discuss some related issues in the dynamics of the current sheet separating the closed and open field regions within pulsars' magnetospheres, and relate these dissipative structures to pulsed gamma ray emission. Results from H. VHE observations are an invaluable tool to study the acceleration and propagation of energetic particles in many astrophysical systems where relativistic outflows are the main drivers of the emission, such as AGNs, GRBs and galactic binary systems.
In this talk we will review the main results of H.
Athena: revealing the Hot and Energetic Universe
We will also comment on some prospects for future investigations with H. The structure of its relativistic plasma jet is resolved at radio, optical and X-ray wavelengths. M 87 belongs to the class of active galactic nuclei AGN and is one of the few extragalactic TeV gamma-ray source not belonging to the class of blazars. During the last 10 years M 87 has been regularly detected by several experiments at VHE.
The current status as well as the prospects of future simultaneous multi-wavelength observations are discussed.
MHD processes at the jet base Elisabete Gouveia Dal Pino, Universidade de Sao Paulo, Brazil One of the fundamental properties of astrophysical magnetic fields is their ability to change their topology through magnetic reconnection and in doing so, to release magnetic energy, sometimes violently. The resulting power-law electron distribution is compatible with the synchrotron radio spectrum observed during the outbursts of these sources. In addition, the magnetic reconnection events cause the heating of the coronal gas which can be conducted back to the disk to enhance its thermal soft x-ray emission as observed during outbursts in microquasars.
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The decay of the hard x-ray emission after a radio flare could also be explained in this model due to the escape of relativistic electrons with the evolving jet outburst. In the case of YSOs, a similar magnetic configuration can be reached that can produce the observed x-ray flares in some sources and provide the heating at the jet launching base.
Fully 3D MHD-particle-in-cell simulations of turbulent reconnection and particle acceleration will be also presented. Recent progress in particle acceleration theory Luke Drury, Dublin Institute for Advanced Studies, Ireland In this review I will survey the current state of particle acceleration theory as applied to astrophysical systems with relativistic outflows.
Although certainly not the only mechanism for particle acceleration, discussion tends to be dominated by diffusive shock acceleration because this is the best understood process, at least for non-relativistic shocks. The exciting new development here is the growing appreciation and understanding of magnetic field amplification. In the relativistic regime shock acceleration is much less secure, but here also recent PIC simulations offer interesting insights and hope for progress in the near future.
The Swift observatory is detecting bursts per year, providing arcsecond localizations and sensitive observations of the prompt and afterglow emission. The Fermi observatory is observing bursts per year with its medium-energy GRB instrument and about 10 bursts per year with its high-energy LAT instrument. In addition, rapid-response telescopes on the ground are providing new capabilities to study optical emission during the prompt phase and spectral signatures of the host galaxies. The combined data set is enabling great advances in our understanding of GRBs including afterglow physics, short burst origin, and high energy emission.
This talk will highlight recent findings. This is consistent with the prediction that cosmic rays with larger energies can only arrive from nearby sources since they must surmount the losses caused by propagation through the cosmic microwave background. Correlations are observed with the positions of active galactic nuclei within Mpc, and with other distributions of local extragalactic objects. An excess of events is observed from a region of the sky close to the location of the radio source Cen A.
Current measurements do not identify neither individual sources nor a specific class of sites of origin.
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We review these results and discuss the perspectives that similar studies with future data, complemented with further measurements of composition of the cosmic rays, may identify their astrophysical sources. In a sense, jets might be easier to understand if they were featureless. However we observe a wide variety of structures which we call 'knots'. By considering the ramifications of the various scenarios for the creation of knots, we determine which ones or which classes are favored by the currently available multiwavelength data.
Black-hole jets begin to reveal their antimatter secrets
In particular, I will consider the implications of the most recent observations in gamma- and X-ray energy bands. Discussing different scenarios for gamma-ray production in such sources, I will the mostly focus on the formation of non-thermal emission in relativistic outflows, which are natural components of microquasars and binary pulsar systems.
In addition to the results of general relativistic MHD simulations, which have allowed to clarify particular aspects of the launch of black hole jets in the collapsar scenario, I will also discuss the possibility of explaining the "shallow decay phase" in the afterglows of LGRBs discovered by the Swift observatory.
- Astrophysical jet!
- Databases demystified.
- Bristol University | School of Physics | Astrophysics!
- Accretion Disks, Jets and High-Energy Phenomena in Astrophysics.
This talk will review our current understanding of the acceleration and collimation of such outflows -- with emphasis on recent developments - and will proceed to discuss the key open questions on this subject. The discussion will address both purely theoretical issues and the confrontation between theory and observations. Among the topics that will be considered are: the appropriate theoretical framework for modeling relativistic outflows magnetodynamics or magnetohydrodynamics?
The scaling of conditions in the central engine and of jet properties with the controlling parameters: black hole mass and spin, accretion rate and strength of magnetic field on the horizon, will be discussed. Environmental effects on jet propagation, collimation and dissipation in different systems will also be considered. In this talk, I will review the general properties of these sources and highlight the results of MW studies carried out on bright sources.
Magnetic Acceleration of Relativistic Jets Ramesh Narayan, Harvard-Smithsonian Center for Astrophysics, USA We describe numerical simulations of magnetized relativistic jets, focusing in particular on the efficiency with which Poynting flux is converted to bulk kinetic energy of the outflowing gas.
We show that efficient conversion occurs only for certain geometries. We also discuss the stability of jets to the kink mode. Non-thermal processes in black hole coronae Juri Poutanen, University of Oulu, Finland The origin of dramatically different electron distributions responsible for Comptonization in black hole X-ray binaries BHBs in their various states is discussed. We solve the coupled kinetic equations for photons and electron-positron pairs without approximations on the relevant cross-sections accounting for Compton scattering, synchrotron radiation, pairp production and Coulomb collisions.
In the absence of external soft photons, the pairs are efficiently thermalized by synchrotron self-absorption and Coulomb scattering even for pure nonthermal electron injection. Galaxy NGC , an extragalactic jet of material moving at nearly the speed of light can be seen at the three o'clock position.
From Wikipedia, the free encyclopedia. Proceedings of Science : Bibcode : mbhe. Retrieved 19 February H Retrieved 26 May Yale University — Office of Public Affairs. Archived from the original on Bibcode : Sci The Astrophysical Journal. Bibcode : ApJ Monthly Notices of the Royal Astronomical Society.
Rivista del Nuovo Cimento. Bibcode : NCimR Reprinted in: Penrose, R.
General Relativity and Gravitation. Bibcode : GReGr.. Physical Review. Bibcode : PhRvD.. Categories : Astrophysics Plasma physics Black holes. Hidden categories: All articles with unsourced statements Articles with unsourced statements from February Namespaces Article Talk. Views Read Edit View history.
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