A MODEL FOR THE RADIO EMISSION FROM SNR 1987A

We report an up-turn in the soft X-ray light curve of supernova remnant (SNR) 1987A in late 2003 (~6200 days after the explosion), as observed with the Chandra X-ray Observatory. Since early 2004, the rapid increase of the 0.5-2 keV band X-ray light curve can no longer be described by the exponential density distribution model with which we successfully fitted the data between 1990 and 2003. Around day ~6200, we also find that the fractional contribution to the observed soft ...

A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants is employed to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5--100 yr. It is shown that an efficient production of nuclear CRs leads to a strong modification of the outer supernova remnant shock and to a large downstream magnetic field $B_\mathrm{d}\approx 20$ mG. The shock modification and the strong field are required to yield the steep ...

The emission of supernova remnants reflects the properties of both the progenitor supernovae 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 supernova. We performed high-resolution hydrodynamic simulations describing SN 1987A soon afte...

We present radio imaging observations of supernova remnant 1987A at 9 GHz, taken with the Australia Telescope Compact Array over 21 years from 1992 to 2013. By employing a Fourier modeling technique to fit the visibility data, we show that the remnant structure has evolved significantly since day 7000 (mid-2006): the emission latitude has gradually decreased, such that the overall geometry has become more similar to a ring structure. Around the same time, we find a decreasing...

Shell-type supernova remnants (SNRs) exhibit correlations between radio surface brightness, SNR diameter, and ambient medium density. We investigate these correlations, to extract useful information about the typical evolutionary stage of radio SNRs, and to obtain insight into the origin of the relativistic electrons and magnetic fields responsible for the radio emission. We propose a scenario, according to which the observed correlations are the combined effect of SNRs evolv...

$\sim$18 yr after the supernova explosion, the blast wave of SNR 1987A is entering the main body of the equatorial circumstellar material, which is causing a dramatic brightening of the remnant. We recently reported the observational evidence for this event from our {\it Chandra} data (Park et al. 2005b; P05 hereafter). We present here the temporal evolution of the X-ray emitting shock parameters and the detailed description of the spectral and image analysis of SNR 1987A, on...

We continue to explore the validity of the reflected shock structure (RSS) picture in SNR 1987A that was proposed in our previous analyses of the X-ray emission from this object. We used an improved version of our RSS model in a global analysis of 14 CCD spectra from the monitoring program with Chandra. In the framework of the RSS picture, we are able to match both the expansion velocity curve deduced from the analysis of the X-ray images and light curve. Using a simplified a...

We study properties of early radio emission from stripped-envelope supernovae (those of type IIb/Ib/Ic). We suggest there is a sub-class of stripped-envelope supernovae in their radio properties, including optically well-studied type Ic supernovae (SNe Ic) 2002ap and 2007gr, showing a rapid rise to a radio peak within ~ 10 days reaching to a low luminosity (at least an order of magnitude fainter than a majority of SNe IIb/Ib/Ic). They show a decline after the peak shallower t...

We present detailed Fourier modeling of the radio remnant of Supernova 1987A, using high-resolution 9 GHz and 18 GHz data taken with the Australia Telescope Compact Array over the period 1992 to 2008. We develop a parameterized three-dimensional torus model for the expanding radio shell, in which the emission is confined to an inclined equatorial belt; our model also incorporates both a correction for light travel-time effects and an overall east-west gradient in the radio em...

A new numerical model of the nonlinear diffusive shock acceleration is presented. It is used for modeling of particle acceleration in supernova remnants. The model contains coupled spherically symmetric hydrodynamic equations and the transport equations for energetic protons, ions and electrons. The forward and reverse shocks are included in the consideration. The spectra of cosmic rays released into interstellar medium from a supernova remnant are determined. The role of the...