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A theory is presented for the frequency dependence of the power spectrum of photon current fluctuations originating from a disordered medium. Both the cases of an absorbing medium (``grey body'') and of an amplifying medium (``random…
We carry out 1D hydrodynamical simulations of the evolution of a spherically symmetric supernova remnant (SNR) subject to an external radiation field (ERF) that influences the cooling and heating rates of the gas. We consider homogeneous…
We derive new constraints on light CP-even scalars using old gamma-ray observations in the direction of SN1987A by the Solar Maximum Mission (SMM) satellite. Light scalars can be abundantly produced in the supernova core via the nucleon…
The bright circles observed around stars are usually considered as produced by shock waves; but this interpretation does not explain easily the bright spots of the "pearl necklace" of NS 1987A supernova. Assuming that the central object of…
Simple analytic formulas are considered for the energy radiated in low frequency bremsstrahlung from fully ionized gases. A formula that has been frequently cited over many years turns out to have only a limited range of validity, more…
A goal of supernova remnant (SNR) evolution models is to relate fundamental parameters of a supernova (SN) explosion and progenitor star to the current state of its SNR. The SNR hot plasma is characterized by its observed X-ray spectrum,…
Currently, no light source exists which is both narrow-band and speckle-free with sufficient brightness for full-field imaging applications. Light emitting diodes (LEDs) are excellent spatially incoherent sources, but are tens of nanometers…
The light curves of 'hypernovae', i.e. very energetic supernovae with $E_{51} \equiv E/10^{51}$ergs $\gsim 5-10$ are characterized at epochs of a few months by a phase of linear decline. Classical, one-dimensional explosion models fail to…
Supernova remnants (SNRs) are the outcome of supernovae (SNe, either core-collapse or thermonuclear). The remnant results from the interaction between the stellar ejecta and the ambient medium around the progenitor star. Young SNRs are…
In supernova spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of…
Scattering relativistic electrons with optical lasers can result in a significant frequency upshift for the photons, potentially producing $\gamma$-rays. This is what linear Compton scattering taught us. Ultra-intense lasers offer nowadays…
Within low-mass star formation, water vapor plays a key role in the chemistry and energy balance of the circumstellar material. The Herschel Space Observatory will open up the possibility to observe water lines originating from a wide range…
We study theoretically the concept of homogenization in optics using an ensemble of randomly distributed resonant stationary atoms with density $\rho$. The ensemble is dense enough for the usual condition for homogenization, viz.…
High-brightness electron sources are a key ingredient to the development of compact accelerator-based light sources. The electron sources are commonly based on (linear) photoemission process where a laser pulse with proper wavelength…
Free electron radiation such as Cerenkov, Smith--Purcell, and transition radiation can be greatly affected by structured optical environments, as has been demonstrated in a variety of polaritonic, photonic-crystal, and metamaterial systems.…
We investigate theoretically a scheme for spectroscopy of electrons emitted by an on-demand single particle source. The total system, with an electron turnstile source and a single level quantum dot spectrometer, is implemented with edge…
Concatenating data from the millimetre regime to the infrared, we have performed spectral energy distribution modelling for 227 of the 405 millimetre continuum sources of Hill et al. (2005) which are thought to contain young massive stars…
We define the Schr\"odinger equation with focusing, cubic nonlinearity on one-vertex graphs. We prove global well-posedness in the energy domain and conservation laws for some self-adjoint boundary conditions at the vertex, i.e. Kirchhoff…
Superluminous supernovae are among the most energetic stellar explosions in the Universe, but their energy sources remain an open question. Here we present long-term observations of one of the closest examples of the hydrogen-poor subclass…
A detailed analysis of the bremsstrahlung spectrum at nonrelativistic electron scattering on argon and xenon is carried out. It is shown that the approximate formulas widely used for the description of bremsstrahlung spectra lead to…