On the Non-Thermal Energy Content of Cosmic Structures

1) Background: the budget of non-thermal energy in galaxy clusters is not well constrained, owing to the observational and theoretical difficulties in studying these diluted plasmas on large scales. 2) Method: we use recent cosmological simulations with complex physics in order to connect the emergence of non-thermal energy to the underlying evolution of gas and dark matter. 3) Results: the impact of non-thermal energy (e.g. cosmic rays, magnetic fields and turbulent motions) is found to increase in the outer region of galaxy clusters. Within numerical and theoretical uncertainties, turbulent motions dominate the budget of non-thermal energy in most of the cosmic volume. 4) Conclusion: assessing the distribution non-thermal energy in galaxy clusters is crucial to perform high-precision cosmology in the future. Constraining the level of non-thermal energy in cluster outskirts will improve our understanding of the acceleration of relativistic particles by cosmic shocks and of the origin of extragalactic magnetic fields.

Multitemperature analysis of solar flare observed on 2003 March 29

We present results of multitemperature analysis of GOES C7.2 class flare SOL2003-03-29T10:15. This event occurred close to the centre of the solar disk and had two maxima in soft X-rays. We have performed analysis of physical parameters characterizing evolution of conditions in the flaring plasma. The temperature diagnostics have been carried out using the differential emission measure (DEM) approach based on the soft X-ray spectra collected by RESIK Bragg spectrometer. Analysis of data obtained by RHESSI provided opportunity to estimate the volume and thus calculating the density and thermal energy content of hot flaring plasma.

A possible heating mechanism for the X-ray-emitting plasma within clusters of galaxies

X-ray and extreme ultraviolet emission from galaxy clusters can be interpreted as thermal emission from a hot plasma gravitationally bound to the cluster and constituting a significant amount of the mass of the cluster. The origin of this plasma and its thermal energy content can be linked to the formation process through the theory of self-organization of these structures.

The X-ray Properties of Supernova Remnants in the Large Magellanic Cloud

There are at least 25 supernova remnants (SNR) in the Large Magellanic Cloud (LMC) with X-ray luminosities exceeding 2 × 1035 erg s−1. As many as 25 other SNR may be contained in the X-ray survey conducted with the Einstein Observatory of the LMC. The X-ray spectra of the 6 SNR observed with the Solid State Spectrometer (SSS) resemble their galactic counterparts; two SNR, N157B and 0540–69.3, may emit X-rays primarily by synchrotron radiation. The density of the medium in which SNR are expanding inferred from the X-ray data appears to decrease with SNR diameter; the density of the ISM inferred from the Balmer lines of 4 new SNR in the LMC is much lower than that inferred from X-ray observations. The apparent thermal energy content of LMC SNR evolves with diameter, peaking at ∼5 × 1050 ergs. The ratio of the densities of the X-ray and [SII] emitting plasmas is consistent with their being in pressure equilibrium. The SN rate in the LMC is ∼1 per 100–200 years. This is the number of SN expected from other considerations. The number diameter relation of LMC SNR is consistent with free expansion. The X-ray data are difficult to understand in terms of traditional Sedov models on SNR evolution; probably ejecta and multiphase ISM are required to explain the X-ray properties of LMC SNR.