Origins of superluminous supernovae (SLSNe) discovered by recent SN surveys are still not known well. One idea to explain the huge luminosity is the collision of dense CSM and SN ejecta. If SN ejecta is surrounded by dense CSM, the kinetic energy of SN ejecta is efficiently converted to radiation energy, making them very bright. To see how well this idea works quantitatively, we performed numerical simulations of collisions of SN ejecta and dense CSM by using one-dimensional radiation hydrodynamics code STELLA and obtained light curves (LCs) resulting from the collision. First, we show the results of our LC modeling of SLSN 2006gy. We find that physical parameters of dense CSM estimated by using the idea of shock breakout in dense CSM (e.g., Chevalier & Irwin 2011, Moriya & Tominaga 2012) can explain the LC properties of SN 2006gy well. The dense CSM's radius is about 1016 cm and its mass about 15 M⊙. It should be ejected within a few decades before the explosion of the progenitor. We also discuss how LCs change with different CSM and SN ejecta properties and origins of the diversity of H-rich SLSNe. This can potentially be a probe to see diversities in mass-loss properties of the progenitors. Finally, we also discuss a possible signature of SN ejecta-CSM interaction which can be found in H-poor SLSN.

Supernova remnants have long been considered to be the dominant sources of Galactic cosmic rays. For a long time the prime evidence consisted of radio synchrotron radiation from supernova remnants, indicating the presence of electrons with energies of several GeV. However, in order to explain the cosmic ray energy density and spectrum in the Galaxy supernova remnant should use 10% of the explosion energy to accelerate particles, and about 99% of the accelerated particles should be protons and other atomic nuclei.

Over the last decade a lot of progress has been made in providing evidence that supernova remnant can accelerate protons to very high energies. The evidence consists of, among others, X-ray synchrotron radiation from narrow regions close to supernova remnant shock fronts, indicating the presence of 10-100 TeV electrons, and providing evidence for amplified magnetic fields, gamma-ray emission from both young and mature supernova remnants. The high magnetic fields indicate that the condition for accelerating protons to >1015 eV are there, whereas the gamma-ray emission from some mature remnants indicate that protons have been accelerated.

Type Ibn supernovae (SNIbn) are a small group of core-collapse events whose ejecta interact with a He-rich and H-deprived circumstellar medium. The explosion of the prototype of this family, SN 2006jc, was heralded by a major stellar eruption two years before its core collapse. This unexpected discovery increased significantly the interest of the astronomical community toward these unusual events. A number of other objects have been included to the SNIbn zoo. In these contribution we review our current knowledge on this rare family of interacting, stripped-envelope supernovae (SE-SNe).

During the last few years, overionized (recombining) plasmas were unexpectedly discovered in a few supernova remnants, but the origin is still unclear. In this contribution, we present a preliminary spectroscopic analysis of the X-ray emission from the north central region of IC443, one of the “recombining” remnants. An overionized NEI plasma model can reproduce well the Ly-alpha lines and the recombination edges in the spectrum. The ionization temperatures for the metals Mg, Si and S are much higher than the electron temperatures. which is a strong indication of overionization of these elements. The different spectral features of the recombining plasma are characterized on scales of a few arcmin, such as the increasing trend of the pre-cooling temperature and the ionization time from south to north, which may imply a pre-heating direction.

We present three studies that use supernova (SN) environments within host galaxies (HGs) to constrain SNe properties. These studies are ordered from an indirect approximation to a direct determination of the environmental parameters of the SN. We find correlations between the galactocentric distance and several parameters measured from both the SN light-curve (LC) and the host galaxy spectroscopy. We are able to recover and strength previous results pointing to a sequence on the progenitor mass of different SN types. We also confirm no significant difference in the elemental abundances of the environment where different SN types exploded, measured with a more powerful technique such as Integral Field Spectroscopy (IFS).

Outflows from galaxies play a crucial role in the evolution of galaxies and also affect the surrounding medium. The standard scenario of explaining these outflows with the help of supernovae driven wind has recently come under criticism, and other processes such as radiation pressure and cosmic-rays have been invoked. We examine the relative importance of supernovae as the driving mechanism of galactic outflows in light of these competing processes.

Type IIn supernovae have bright optical emission and high bolometric luminosities. Due to their high mass loss, their are expected to have dense circumstellar interaction, thus produce bright radio and X-ray emission. We aim to carry out systematic study to understand their circumstellar interaction, mass loss properties. Here, I provide specific examples of two Type IIn supernovae, 2006jd and 2010jl.

We have measured HI absorption distance to the youngest Galactic supernova remnant G1.9+0.3. Absorption by known anomalous velocity features near the Galactic centre (GC) puts a lower limit on its distance from Sun as 10 kpc, 2 kpc further away from the GC. We have found a small diameter (1.6′) shell like structure G354.4+0.0, that shows polarised emission in the NVSS. Based on its morphology, angular size, HI distance and its spectrum between 1.4 GHz and 330 MHz, it is perhaps the second youngest SNR in the Galaxy that is expanding in a dense environment of an HII region surrounding it. Our pilot observation of the inner Galactic 4th quadrant within 337° < l < 354° with a fixed Galactic latitude of 0.37° has confirmed G345.1−0.2 as an SNR.

Studying the environments in which core-collapse supernovae (SNe) explode and then subsequently evolve is essential to establish the nature of the mass loss and the explosion of the progenitor star. The spatial structure of the outer shock in young core-collapse SNRs provides an opportunity to study the nature of the medium into which the remnant has been expanding. We present our X-ray study of the outer shocks in young core-collapse SNRs in our Galaxy. For Cas A and G292.0+1.8, we find that both remnants have been likely interacting with dense red supergiant winds. For other remnants with bright thermal X-ray emission from the shell, we suggest that they are interacting with pre-existing circumstellar structure. We discuss the nature of the winds and the progenitor stars.

We present the largest sample of multi-wavelength Supernova Remnants (SNRs) in six nearby galaxies, based on Chandra archival data and deep optical narrow-band Hα and [Sii] images as well as spectroscopic observations. We have identified 37 X-ray selected thermal SNRs, 30 of which are new identifications and ~ 400 optical SNRs, for 67 of which we spectroscopically verified their shock-excited nature. We discuss the properties of the X-ray/optically detected SNRs in different types of galaxies and hence different environments, in order to address their dependence on their Interstellar Medium (ISM). We also discuss the SNR populations in the context of the star formation rate of their host galaxies. We cross-correlate parameters of the optically detected SNRs with parameters of coincident X-ray emitting SNRs in order to understand their evolution and investigate possible selection effects.

Type IIP SNe constitute a major fraction of all core-collapse supernovae and arise from massive stars that end their lives close to Red Supergiants. The blastwave from the SN interacting with the progenitor's circumstellar matter produces a hot region bounded by a forward and a reverse shock from which most of the X-ray emission originates. Analysis of archival Chandra observations of SN 2004dj, one of the nearest supernovae since SN 1987A, together with published data from radio and optical bands determines the pre-explosion mass-loss rate, blastwave speed, electron acceleration and magnetic field amplification efficiencies. X-ray emission arises from both inverse Compton scattering by non-thermal electrons accelerated in the forward shock and from thermal emission from the supernova ejecta hit by the reverse shock. Determination of the properties of the radiating plasma based on the separation of thermal and non-thermal radiation differentiates different types of supernovae and their environments.

Smoothed particle hydrodynamics (SPH) models of the recurrent nova RS Ophiuchi are presented, along with simple models for circumstellar absorption lines. The evolution of the model sodium line is similar to the behaviour in some Type Ia SNe, e.g. SN2006X.

Supernovae constitute a critical source of energy input to the interstellar medium (ISM). In this short review, we focus on their latest phase of evolution, the supernova remnants (SNRs). We present observations of three old SNRs that have reached the phase where they interact with the ambient interstellar medium: W28, IC443, and 3C391. We show that such objects make up clean laboratories to constrain the physical and chemical processes at work in molecular shock environments. Our studies subsequently allow us to quantify the impact of SNRs on their environment in terms of mass, momentum, and energy dissipation. In turn, their contribution to the energy balance of galaxies can be assessed. Their potential to trigger a further generation of star formation can also be investigated. Finally, our studies provide strong support for the interpretation of γ-ray emission in SNRs, a crucial step to answer questions related to cosmic rays population and acceleration.

We examine excess emission at high positive and negative velocities toward known Galactic supernova remnants (SNRs) in the “Inner-Galaxy Arecibo L-band Feed Array (I-GALFA)” Hi 21-cm survey data. The I-GALFA survey covers ℓ = 32° to 77°, and has a velocity range of ±700 km s−1 with high angular and velocity resolutions (4′ and 0.18 km s−1, respectively) and good sensitivity (0.2 K). The excess emission which is thought to be part of a fast-expanding Hi shell of a SNR is detected from four among 39 SNRs in the I-GALFA area: W44, G54.4–0.3, W51C, and CTB 80. Although the Hi shells of the four SNRs were already reported in low-resolution studies, the first detection of both sides of an expanding Hi shell associated with W44 is very inspiring. We discuss physical properties of these four SNRs and their statistical nature.

It is not straightforward to determine the distribution of supernova remnants (SNRs) in the Galaxy. The two main difficulties are that there are observational selection effects that mean that catalogues of SNRs are incomplete, and distances are not available for most remnants. Here I discuss the selection effects that apply to the latest catalogue of Galactic SNRs. I then compare the observed distribution of ‘bright’ SNRs in Galactic longitude with that expected from models in order to constrain the Galactic distribution of SNRs.

SN 2012AW is a type-IIP supernova which exploded in M95. In this paper we discuss the radio observations of this supernova and model them to determine the important parameters relevant to the explosion and the evolution of blast wave. We also determine the dominant cooling process important to this source.

Three-dimensional kinematic reconstructions of optically emitting ejecta in the young Galactic supernova remnant Cassiopeia A (Cas A) are discussed. The reconstructions encompass the remnant's faint outlying ejecta knots, including the exceptionally high-velocity NE and SW streams of debris often referred to as ‘jets’. The bulk of Cas A's ejecta are arranged in several circular rings with diameters between approximately 30″ (0.5 pc) and 2′ (2 pc). We suggest that similar large-scale ejecta rings may be a common phenomenon of young core-collapse remnants and may explain lumpy emission line profile substructure sometimes observed in spectra of extragalactic core-collapse supernovae years after explosion. A likely origin for these large ejecta rings is post-explosion input of energy from plumes of radioactive 56Ni-rich ejecta that rise, expand, and compress non-radioactive material to form bubble-like structures.

Since the discovery of nonthermal X-rays in the shell-type supernova remnant SN1006 almost 20 years ago, the field has developed considerably, owing significant progress to our understanding of particle acceleration. Key to the characterization of the nonthermal emission is the ability of current satellites, XMM-Newton and Chandra, to perform spatially resolved spectroscopy at a relatively small spatial scale.

In this review, I intend to present the main contributions of the study of nonthermal X-rays from supernova remnants to the understanding of particle acceleration.

Tycho is one of nearly a dozen Galactic supernova remnants which are suggested to emit hadronic γ-ray emission. Among them, however, it is the only one in which the hadronic emission is proposed to arise from the interaction with low-density ambient medium. Based on the multi-band observations, we suggest that Tycho is encountering dense cloud at the northeastern boundary. The γ-ray emissions can be explained by hadronic process with self-consistent parameters, such as a modest energy conversion efficiency. In this SNR-cloud association scenario, the distance can be estimated as ~2.5 kpc.