The full evolution of supernova remnants in low and high density ambient media (original) (raw)
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Shock evolution in non-radiative supernova remnants
Monthly Notices of the Royal Astronomical Society
We present a new analytical approach to derive approximate solutions describing the shock evolution in non-radiative supernova remnants (SNRs). We focus on the study of the forward shock and contact discontinuity while application to the reverse shock is only discussed briefly. The spherical shock evolution of an SNR in both the interstellar medium with a constant density profile and a circumstellar medium with a wind density profile is investigated. We compared our new analytical solution with numerical simulations and found that a few per cent accuracy is achieved. For the evolution of the forward shock, we also compared our new solution to previous analytical models. In a uniform ambient medium, the accuracy of our analytical approximation is comparable to that in Truelove & McKee. In a wind density profile medium, our solution performs better than that in Micelotta, Dwek & Slavin, especially when the ejecta envelope has a steep density profile. The new solution is significantly simplified compared to previous analytical models, as it only depends on the asymptotic behaviours of the remnant during its evolution.
Astronomy and Astrophysics
The large-scale gradient of the interstellar medium (ISM) density distribution essentially affects the evolution of Supernova remnants (SNRs). In a non-uniform ISM, the shape of SNR becomes essentially non-spherical, and distributions of gas parameters inside the remnant become strongly anisotropic. The well-known self-similar Sedov solutions may not be applied to modelling such non-spherical objects. Therefore we propose a new approximate analytical method for full hydrodynamical description of 3D point-like explosions in non-uniform media with arbitrary density distribution. On the basis of this method, we investigate the general properties of evolution of 2D non-spherical adiabatic SNRs in ISM with large-scale density gradient. It is shown that the real shape of adiabatic SNR becomes more non-spherical with age, but the visible shape remains close to spherical even for strong real asymmetry (ratio of maximal to minimal shock radii) and surface brightness contrast. It is shown als...
2011
The thermal structure of the post-shock region of a young supernova remnant (SNR) is heavily affected by two main physical effects, the back-reaction of accelerated cosmic rays (CRs) and the Rayleigh-Taylor (RT) instabilities developing at the contact discontinuity between the ejecta and the shocked interstellar medium (ISM). Here, we investigate the role played by both physical mechanisms in the evolution of SNRs through detailed 3D MHD modeling. Our model describes the expansion of the remnant through a magnetized ISM, including consistently the initial ejecta clumping and the effects on shock dynamics due to back-reaction of accelerated CRs. We discuss the role of the initial ejecta clumpiness in developing strong instabilities at the contact discontinuity which may extend upstream to the main shock and beyond.
Crushing of interstellar gas clouds in supernova remnants
Astronomy and Astrophysics, 2005
We model the hydrodynamic interaction of a shock wave of an evolved supernova remnant with a small interstellar gas cloud like the ones observed in the Cygnus loop and in the Vela SNR. We investigate the interplay between radiative cooling and thermal conduction during cloud evolution and their effect on the mass and energy exchange between the cloud and the surrounding medium. Through the study of two cases characterized by different Mach numbers of the primary shock ( ¤ and 50, corresponding to a post-shock temperature ¤ !" $ # % & ¤ ' K and ) ( 0 !" $ # % 1 ¤ ' K, respectively), we explore two very different physical regimes: for 2 3 , the radiative losses dominate the evolution of the shocked cloud which fragments into cold, dense, and compact filaments surrounded by a hot corona which is ablated by the thermal conduction; instead, for 4 6 5 7 , the thermal conduction dominates the evolution of the shocked cloud, which evaporates in a few dynamical timescales. In both cases we find that the thermal conduction is very effective in suppressing the hydrodynamic instabilities that would develop at the cloud boundaries.
Dynamics and radiation of young type-Ia supernova remnants: Important physical processes
Astronomy Letters, 2004
We examine and analyze the physical processes that should be taken into account when modeling young type-Ia supernova remnants (SNRs) with ages of several hundred years, in which there are forward (propagating into an interstellar medium) and reverse (propagating into ejecta) shock waves. It is shown, that the energy losses in the metalrich ejecta can be essential for remnants already at this stage of evolution. The influence of electron thermal conduction and the rate of the energy exchange between electrons and ions on the temperature distribution and the X-radiation from such remnants is studied. The data for Tycho SNR from the XMM-Newton space X-ray telescope have been employed for the comparison of calculations with observations. ⋆ sorokina@sai.msu.su Numerical simulations of supernova remnants (SNRs) have been conducted already long ago. However, since the physics of these objects is very complex, it has not yet been completely included in any computer program in the world. Moreover, different physical processes can be essential at different stages of evolution.
The Astrophysical Journal, 2012
To better model the efficient production of cosmic rays (CRs) in supernova remnants (SNRs) with the associated coupling between CR production and SNR dynamics, we have generalized an existing cr-hydro-NEI code (i.e., to include the following processes: (1) an explicit calculation of the upstream precursor structure including the position dependent flow speed, density, temperature, and magnetic field strength;
2016
We investigate the role played by initial clumping of ejecta and by efficient acceleration of cosmic rays (CRs) in determining the density structure of the post-shock region of a Type Ia supernova remnant (SNR) through detailed 3D MHD modeling. Our model describes the expansion of a SNR through a magnetized interstellar medium (ISM), including the initial clumping of ejecta and the effects on shock dynamics due to back-reaction of accelerated CRs. The model predictions are compared to the observations of SN 1006. We found that the back-reaction of accelerated CRs alone cannot reproduce the observed separation between the forward shock (FS) and the contact discontinuity (CD) unless the energy losses through CR acceleration and escape are very large and independent of the obliquity angle. On the contrary, the clumping of ejecta can naturally reproduce the observed small separation and the occurrence of protrusions observed in SN 1006, even without the need of accelerated CRs. We conclude that FS-CD separation is a probe of the ejecta structure at the time of explosion rather than a probe of the efficiency of CR acceleration in young SNRs.
Astronomy and Astrophysics
The results of the 2D modelling of Supernova remnant (SNR) RCW86 are given. Models of this remnant, which for the first time interpret the anisotropy of surface brightness as a result of the evolution of adiabatic SNR in the interstellar medium with a large-scale gradient of density, are considered. Estimations on the basic characteristics of RCW86 and the surrounding medium which follow from these models are found. It is shown that the observed surface brightness distribution of RCW86 may be obtaned in the both proposed up till now models with different initial assumptions: one about a Supernova explosion in 185 A.D. and another about an explosion in the OB-asossiation. In order to obtain the observational contrast of surface brightness it is necessary to have a medium with the characteristic scale of nonuniformity 11 pc if the age of RCW86 is 1800 years or 20-25 pc when the SNR is distant from us on 2.8 kpc. The preshock density contrast between the southwestern and northeastern p...
Energy Input and Mass Redistribution by Supernovae in the Interstellar Medium
The Astrophysical Journal, 1998
We present the results of numerical studies of supernova remnant evolution and their effects on galactic and globular cluster evolution. We show that parameters such as the density and the metallicity of the environment significantly influence the evolution of the remnant, and thus change its effects on the global environment (e.g., globular clusters, galaxies) as a source of thermal and kinetic energy.