5 research outputs found
High- and low energy nonthermal X-ray emission from the cluster of galaxies A 2199
We report the detection of both soft and hard excess X-ray emission in the
cluster of galaxies A 2199, based upon spatially resolved spectroscopy with
data from the BeppoSAX, EUVE and ROSAT missions. The excess emission is visible
at radii larger than 300 kpc and increases in strength relative to the
isothermal component. The total 0.1-100 keV luminosity of this component is 15
% of the cluster luminosity, but it dominates the cluster luminosity at high
and low energies. We argue that the most plausible interpretation of the excess
emission is an inverse Compton interaction between the cosmic microwave
background and relativistic electrons in the cluster. The observed spatial
distribution of the non-thermal component implies that there is a large halo of
cosmic ray electrons between 0.5-1.5 Mpc surrounding the cluster core. The
prominent existence of this component has cosmological implications, as it is
significantly changing our picture of a clusters's particle acceleration
history, dynamics between the thermal and relativistic media, and total mass
budgets.Comment: Accepted for publication in Astrophysical Journal, Letter
Detection of the Neupert Effect in the Corona of an RS CVn Binary System by XMM-Newton and the VLA
The RS CVn-type binary Geminorum was observed during a large,
long-duration flare simultaneously with {\it XMM-Newton} and the VLA. The light
curves show a characteristic time dependence that is compatible with the
Neupert effect observed in solar flares: The time derivative of the X-ray light
curve resembles the radio light curve. This observation can be interpreted in
terms of a standard flare scenario in which accelerated coronal electrons reach
the chromosphere where they heat the cool plasma and induce chromospheric
evaporation. Such a scenario can only hold if the amount of energy in the fast
electrons is sufficient to explain the X-ray radiative losses. We present a
plausibility analysis that supports the chromospheric evaporation model.Comment: Accepted for publication in Ap