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It is known that ultrasound techniques yield non-intrusive measurements of hydrodynamic flows. For example, the study of the echoes produced by a large number of particle insonified by pulsed wavetrains has led to a now standard velocimetry…
A sample of radio-loud active galactic nuclei (AGN) at 2cm is studied to test the isotropic distribution of radio sources in the sky and their uniform distribution in space. The sample is complete flux-density limits of 1.5Jy for positive…
Flat radio spectra with large brightness temperatures at the core of AGN and X-ray binaries are usually interpreted as the partially self-absorbed bases of jet flows emitting synchrotron radiation. Here we extend previous models of jets…
Deep X-ray surveys by Chandra and XMM-Newton have resolved about 80% of the 2-10 keV cosmic extragalactic X-ray background (CXRB) into point sources, the majority of which are obscured AGN. The obscuration might be connected to processes…
We present results on the spectral decomposition of 118 Spitzer Infrared Spectrograph (IRS) spectra from local active galactic nuclei (AGN) using a large set of Spitzer/IRS spectra as templates. The templates are themselves IRS spectra from…
Radiative transfer is a key bottleneck in computational astrophysics: it is nonlocal, stiff, and tightly coupled to hydrodynamics. We introduce Ray-trax, a GPU-oriented, fully differentiable 3D ray tracer written in JAX that solves the…
Numerical simulation of a relativistic runaway electron breakdown in the upper atmosphere is performed using GEANT4 simulation toolkit. General features of a relativistic runaway electron avalanche are reconstructed and properties of…
Active galactic nuclei (AGN) are typically identified through their distinctive X-ray or radio emissions, mid-infrared (MIR) colors, or emission lines. However, each method captures different subsets of AGN due to signal-to-noise (SNR)…
This paper concerns the derivation of radiative transfer equations for acoustic waves propagating in a randomly fluctuating half-space in the weak-scattering regime, and the study of boundary effects through an asymptotic analysis of the…
Context. NRAO 150 is one of the brightest radio and mm AGN sources on the northern sky. It has been revealed as an interesting source where to study extreme relativistic jet phenomena. However, its cosmological distance has not been…
We study an inverse problem where an unknown radiating source is observed with collimated detectors along a single line and the medium has a known attenuation. The research is motivated by applications in SPECT and beam hardening. If…
Recent hydrodynamic simulations and observations of radio jets have shown that the surrounding environment has a large effect on their resulting morphology. To investigate this we use a sample of 50 Extended Radio Active Galactic Nuclei…
We have studied the nuclear emission detected in high-resolution radio and optical data of carefully selected samples of low luminosity AGN (LLAGN) in the local universe. When the Eddington ratio is plotted against the nuclear…
Radio relics are arc-like synchrotron sources at the periphery of galaxy clusters, produced by cosmic-ray electrons in a $\mu$G magnetic field which are believed to have been (re-)accelerated by merger shock fronts. However, not all relics…
We examine the rest-frame far-infrared emission from powerful radio sources with 1.4GHz luminosity densities of 25<=log(L_1.4/WHz^-1)<=26.5 in the extragalactic Spitzer First Look Survey field. We combine Herschel/SPIRE flux densities with…
We show that radiation from complex and inherently random but correlated wave sources can be modelled efficiently by using an approach based on the Wigner distribution function. Our method exploits the connection between correlation…
We study the cosmic evolution of radio-loud active galactic nuclei (AGNs) using a beaming-minimized sample of 4{,}555 steep-spectrum sources over $0<z\lesssim4$, compiled from the XXL survey, VLA-COSMOS, and other wide-field data sets. We…
High-energy emission of extragalactic objects is known to take place in relativistic jets, but the nature, the location, and the emission processes of the emitting particles are still unknown. One of the models proposed to explain the…
We study the standard spectral line radiative transfer equation for media consisting of resonant atoms and non-resonant components (the dust grains and the atoms without considered spectral transition). Our goal is to study the intensity…
$^{222}$Rn is a noble radioactive gas produced along the $^{238}$U decay chain, which is present in the majority of soils and rocks. As $^{222}$Rn is the most relevant source of natural background radiation, understanding its distribution…