Related papers: RHESSI as a Hard X-Ray Polarimeter
We investigate accelerated electron energy spectra for different sources in a large flare using simultaneous observations obtained with two instruments, the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz, and the Reuven Ramaty High…
At hard X-ray energies, the bright footpoint emission from solar flare loops often prevents a detailed analysis of the weaker loop-top source morphology due to the limited dynamic range available for X-ray imaging. Here, we study the X1.3…
We present the first results using the Reuven Ramaty High-Energy Solar Spectroscopic Imager, RHESSI, to observe solar X-ray emission not associated with active regions, sunspots or flares (the quiet Sun). Using a newly developed chopping…
The imaging spectroscopy capabilities of the Reuven Ramaty high energy solar spectroscopic imager (RHESSI) enable the examination of the accelerated electron distribution throughout a solar flare region. In particular, it has been revealed…
We present new RHESSI upper limits in the 3-200 keV energy range for solar hard X-ray emission in the absence of flares and active regions, i.e. the quiet Sun, using data obtained between July 2005 and April 2009. These new limits,…
Recent progress in solar Hard X-ray (HXR) observations with RHESSI data and methods for spectral inversion allow us to study model-independent mean electron flux spectra in solar flares. We report several hard X-ray events observed by…
Investigate particle acceleration and heating in a solar microflare. In a microflare with non-thermal emission to remarkably high energies ($>50$ keV), we investigate the hard X-rays with RHESSI imaging and spectroscopy and the resulting…
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…
The Reuven Ramaty High Energy Spectroscopic Solar Imager (RHESSI) uses the rotational modulation principle to observe temporally, spatially, and spectrally resolved hard X ray and gamma ray images of solar flares. In order to track the…
RHESSI observations are used to quantitatively study the hard X-ray evolution in 5 large solar flares selected for spectral hardening in the course of the event. The X-ray bremsstrahlung emission from non-thermal electrons is characterized…
Polarimetry is widely considered a powerful observational technique in X-ray astronomy, useful to enhance our understanding of the emission mechanisms, geometry and magnetic field arrangement of many compact objects. However, the lack of…
Solar flare X-ray spectra are typically dominated by thermal bremsstrahlung emission in the soft X-ray ($\lesssim$10 keV) energy range; for hard X-ray energies ($\gtrsim$30 keV), emission is typically non-thermal from beams of electrons.…
We study the nature of energy release and transfer for two sub-A class solar microflares observed during the second flight of the Focusing Optics X-ray Solar Imager (FOXSI-2) sounding rocket experiment on 2014 December 11. FOXSI is the…
In this paper, we analyze hard X-ray spikes observed by RHESSI to understand their temporal, spectral, and spatial properties. A recently developed demodulation code was applied to hard X-ray light curves in several energy bands observed by…
Measurements of the linear polarization of high-energy emission from pulsars, accreting black holes, and gamma-ray bursts (GRBs) provide an opportunity for constraining the emission mechanisms and geometries (e.g., of the accretion disk,…
X-ray polarization should provide new probes of magnetic field geometry and acceleration physics near the base of blazar jets, but near-future missions will have limited sensitivity. We thus use existing lower energy data and X-ray…
The hard X-ray polarimeter POLAR aims to measure the linear polarization of the 50-500 keV photons arriving from the prompt emission of gamma-ray bursts (GRBs). The position in the sky of the detected GRBs is needed to determine their level…
We present X-ray imaging and spectral analysis of all microflares the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observed between March 2002 and March 2007, a total of 25,705 events. These microflares are small flares,…
Resonant Inelastic X-ray Scattering (RIXS) in the soft x-ray range is an element-specific energy-loss spectroscopy used to probe the electronic and magnetic excitations in strongly correlated solids. In the recent years, RIXS has been…
Since the initial exploration of soft gamma-ray sky in the 60's, high-energy celestial sources have been mainly characterized through imaging, spectroscopy and timing analysis. Despite tremendous progress in the field, the radiation…