The Evolution of Supernovae Embedded in Stellar Groups

The Astrophysical Journal, 2001

The evolution of type Ia supernova binary system progenitors is highly uncertain. Several evolutionary models predict that the accretion of mass onto the white dwarf is accompanied by mass ejection from the binary in the form of a powerful wind, but very few observations have been made during the initial phase of formation of supernovae remnants, when the interaction of supernova ejecta with presupernova wind could be tested. Here we present hydrodynamical simulations of supernova ejecta interaction with an ambient medium modified by presupernova wind. The structure of the ambient medium when the supernova explodes is very sensitive to the details of wind history, and the evolution of the supernova remnant can be affected during several thousand years. We have found that the forward shock expansion parameter is a good tool for discriminating between several wind models. The evolution of the supernova remnant in the presence of an ambient medium modified by interaction with pre-supernova wind cannot be described by a similarity solution. We also rule out simple models based on a circumstellar medium that merges smoothly with a uniform density ambient medium.

International Astronomical Union Colloquium

The time dependent ionization and temperature structure of the circumstellar medium around supernovae has been calculated, in order to interpret recent supernova radio observations. For a stellar wind origin of the circumstellar medium, we relate the time of radio turn-on to the progenitor mass loss rate. We also show that large column densities for the UV resonance lines are expected. The results are applied to SN 1979c, SN 1980k and SN 1987A.

Monthly Notices of the Royal Astronomical Society, 2013

Monthly Notices of the Royal Astronomical Society

Heating of the interstellar medium by multiple supernovae (SNe) explosions is at the heart of producing galaxy-scale outflows in starburst galaxies. Standard models of outflows assume a high efficiency of SNe in heating the gas to X-ray emitting temperatures and to fill the central region of starburst with hot gas, in order to launch vigorous outflows. We study the efficiency of multiple SNe in heating the interstellar medium (ISM) and filling the volume with gas of high temperatures, with 2-D and 3-D hydrodynamic simulations. We argue that SNe have to be clustered in space and time (and be coherent) in order to compensate for the radiative loss. In particular, we find that in coherent cases, the filling factor of gas with 3 × 10 6 K can be at the most 0.3 and the total heating efficiency 0.3, for gas with density 1 cm -3 and 0.1-1 Z ⊙ . The heating efficiency and filling factors are much smaller in incoherent cases. Comparing our results to the commonly adopted efficiency (0.1-0.3) and large filling factor of hot gas in models of starburst driven galactic outflows, we therefore conclude that outflows can be driven by multiple SNe if the coherency condition is satisfied.

Monthly Notices of The Royal Astronomical Society, 1998

We report the detection of the slow moving wind into which the compact supernova remnant SN 1997ab is expanding. Echelle spectroscopy provides clear evidence for a well resolved narrow (Full Width at Zero Intensity, FWZI ~ 180 km/s) P-Cygni profile, both in Ha and Hb, superimposed on the broad emission lines of this compact supernova remnant. From theoretical arguments we know that the broad and strong emission lines imply a circumstellar density (n ~ 10^7 cm^-3). This, together with our detection, implies a massive and slow stellar wind experienced by the progenitor star shortly prior to the explosion.

Physics of Plasmas, 2006

The evolution of supernova remnants ͑SNRs͒ represents a useful and natural laboratory for gasdynamics studies. In this paper the results of several hydrodynamical simulations of the propagation and early phases of interaction of two SNRs embedded in a homogeneous interstellar environment are shown. In particular, the hydrodynamic evolution and collision of twin SNRs during their self-similar stage has been simulated using a two-dimensional Lagrangian hydrocode. In addition, the results of a detailed simulation that attempts to set the adequate conditions to reproduce the same phenomenon through laser ablation of two plastic plugs at the laboratory scale are presented. These results indicate that both large-scale and small-scale simulations display several common features that can be used to design an experiment aimed to validate the hydrodynamical codes. Of particular interest are the structures found around the juncture of the two colliding shells produced by the interaction of the remnants.

The Astrophysical Journal, 2015

The emission of supernova remnants (SNRs) reflects the properties of both the progenitor supernovae (SNe) and the surrounding environment. The complex morphology of the remnants, however, hampers the disentanglement of the two contributions. Here, we aim at identifying the imprint of SN 1987A on the X-ray emission of its remnant and at constraining the structure of the environment surrounding the SN. We performed high-resolution hydrodynamic simulations describing SN 1987A soon after the core-collapse and the following three-dimensional expansion of its remnant between days 1 and 15,000 after the SN. We demonstrated that the physical model reproducing the main observables of SN 1987A during the first 250 days of evolution also reproduces the X-ray emission of the subsequent expanding remnant, thus bridging the gap between SNe and SNRs. By comparing model results with observations, we constrained the explosion energy in the range 1.2-1.4 × 10 51 erg and the envelope mass in the range 15-17 M e. We found that the shape of X-ray lightcurves and spectra at early epochs (<15 years) reflects the structure of outer ejecta: our model reproduces the observations if the outermost ejecta have a post-explosion radial profile of density approximated by a power law with index α = −8. At later epochs, the shapes of X-ray lightcurves and spectra reflect the density structure of the nebula around SN 1987A. This enabled us to ascertain the origin of the multi-thermal X-ray emission, disentangle the imprint of the SN on the remnant emission from the effects of the remnant interaction with the environment, and constrain the pre-supernova structure of the nebula.

The Astrophysical Journal, 2012

We study the properties of low-velocity material in the line of sight toward nearby Type Ia supernovae (SNe Ia) that have measured late phase nebular velocity shifts (v neb ), thought to be an environment-independent observable. We have found that the distribution of equivalent widths of narrow blended Na i D1 and D2 and Ca ii H and K absorption lines differs significantly between those SNe Ia with negative and positive v neb , with generally stronger absorption for SNe Ia with v neb 0. A similar result had been found previously for the distribution of colors of SNe Ia, which was interpreted as a dependence of the temperature of the ejecta with viewing angle. Our work suggests that (1) a significant part of these differences in color should be attributed to extinction, (2) this extinction is caused by an asymmetric distribution of circumstellar material (CSM), and (3) the CSM absorption is generally stronger on the side of the ejecta opposite to where the ignition occurs. Since it is difficult to explain (3) via any known physical processes that occur before explosion, we argue that the asymmetry of the CSM is originated after explosion by a stronger ionizing flux on the side of the ejecta where ignition occurs, probably due to a stronger shock breakout and/or more exposed radioactive material on one side of the ejecta. This result has important implications for both progenitor and explosion models.

2002

We present ground-based near-infrared imaging and HST optical imaging and spectroscopy of the interaction between the ejecta of SN 1987A and its equatorial circumstellar ring. This interaction has made a transition, from emission originating in just a few “hot spots ” at restricted locations in position angle around the ring, to a collision producing optical emission over a nearly continuous distribution, with few breaks larger than 45 degrees. The centroids of the first three spots are measured to move at 2000 −3000 km s −1, which we interpret as a lower limit of the velocity of the forward blast front. Multi-wavelength light curves of – 2 – the spots show that they do not evolve uniformly, and change significantly on timescales as short as one month; in particular the first spot shows a significant break in its lightcurve. Implications of observed delays between spots appearances are discussed, which leads to a generalized model of hot spot evolution, and suggests that the early a...

Monthly Notices of the Royal Astronomical Society

Supernova explosions and their remnants (SNRs) drive important feedback mechanisms that impact considerably the galaxies that host them. Then, the knowledge of the SNRs evolution is of paramount importance in the understanding of the structure of the interstellar medium and the formation and evolution of galaxies. Here, we study the evolution of SNRs in homogeneous ambient media from the initial, ejecta-dominated phase, to the final, momentum-dominated stage. The numerical model is based on the Thin-Shell approximation and takes into account the configuration of the ejected gas and radiative cooling. It accurately reproduces well-known analytic and numerical results and allows one to study the SNR evolution in ambient media with a wide range of densities n0. It is shown that in the high-density cases, strong radiative cooling alters noticeably the shock dynamics and inhibits the Sedov-Taylor stage, thus limiting significantly the feedback that SNRs provide to such environments. For ...