Related papers: Science Objectives for an X-Ray Microcalorimeter O…
The hard X-ray (HXR) emission in solar flares comes almost exclusively from a very small part of the flaring region, the footpoints of magnetic loops. Using RHESSI observations of solar flare footpoints, we determine the radial positions…
Galaxies are key objects for the study of cosmology, the life cycle of matter, and stellar evolution. X-ray observations have given us a new key window into these building blocks of the Universe, that allows us to investigate their hot…
Three generations of the Miniature X-ray Solar Spectrometer (MinXSS) have flown on small satellites with the goal "to explore the energy distribution of soft X-ray (SXR) emissions from the quiescent Sun, active regions, and during solar…
Extending previous studies of nonthermal electron transport in solar flares which include the effects of collisional energy diffusion and thermalization of fast electrons, we present an analytic method to infer more accurate estimates of…
Recent progress in the diagnosis of flare fast particles is critically discussed with the main emphasis on high resolution Hard X-Ray (HXR) data from RHESSI and coordinated data from other instruments. Spectacular new photon data findings…
Following a CME which started on 2002 November 26, RHESSI, the Ramaty High Energy Solar Spectroscopic Imager, observed for 12 hours an X-ray source above the solar limb, at altitudes between 0.1 and 0.3 RS above the photosphere. The GOES…
Broad-band spectra of accreting X-ray binary pulsars can be fit by a phenomenological model composed by a power law with a high energy rollover above 10 keV, plus a blackbody component with a temperature of few hundred eV. While, at least…
We review the terms, spectral radiance and spectral irradiance, and show how their precise definitions are crucial for interpreting observations made with different instruments covering widely different energy or wavelength ranges. We show…
We review recent examples where the synergy between radio and X-ray observations has led to substantial progress in understanding astronomical systems. The sub-arcsecond imaging capabilities of the Chandra X-ray observatory provides a…
Context. Stellar coronae are unresolved in X-rays, so inferences about their structure rely on spectral analysis. The "Sun-as-an-X-ray-star" (SaXS) approach uses the Sun as a spatially resolved template to interpret stellar spectra, but…
The X-ray telescopes on board BeppoSAX are an optimal set of instruments to observe bright galactic binary pulsars. These sources emit very hard and quite complex X-ray spectra that can be accurately measured with BeppoSAX between 0.1 and…
The Micro Solar-Flare Apparatus (MiSolFA) is a compact X-ray imaging spectrometer designed for a small 6U micro-satellite. As a relatively inexpensive yet capable Earth-orbiting instrument, MiSolFA is designed to image the high-energy…
Abridged) We model the X-ray properties of millisecond pulsars (MSPs) by considering hot spot emission from a weakly magnetized rotating neutron star (NS) covered by an optically-thick hydrogen atmosphere. We investigate the limitations of…
Over the past 16 years, NASA's Chandra X-ray Observatory has provided an unparalleled means for exploring the universe with its half-arcsecond angular resolution. Chandra studies have deepened our understanding of galaxy clusters, active…
A setup of a unique x-ray source is put forward employing a relativistic electron beam interacting with two counter-propagating laser pulses in the nonlinear few-photon regime. In contrast to Compton scattering sources, the envisaged x-ray…
This review surveys the statistics of solar X-ray flares, emphasising the new views that RHESSI has given us of the weaker events (the microflares). The new data reveal that these microflares strongly resemble more energetic events in most…
The aim of the thesis is the study of properties of solar flares via reconstruction of energy distributions of accelerated/heated electrons, diagnostics of flare plasma based on EUV and X-ray observations, as well as the estimation of the…
X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from…
A great deal of emphasis on timing in the RXTE era has been on pushing toward higher and higher frequency phenomena, particularly kHz QPOs. However, the large areas of the RXTE pointed instruments provide another capability which is key for…
In previous works we have developed a method to convert solar X-ray data, collected with the Yohkoh/SXT, into templates of stellar coronal observations. Here we apply the method to several solar flares, for comparison with stellar X-ray…