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The explanation of the coronal heating problem potentially lies in the existence of nanoflares, numerous small-scale heating events occuring across the whole solar disk. In this paper, we present the first imaging spectroscopy X-ray…

(Abridged) We present a systematic fit of a model of resonant cyclotron scattering (RCS) to the X-ray data of ten magnetars, including canonical and transient anomalous X-ray pulsars (AXPs), and soft gamma repeaters (SGRs). In this…

Astrophysics · Physics 2009-11-13 Nanda Rea , Silvia Zane , Roberto Turolla , Maxim Lyutikov , Diego Gotz

Recently a distinctive class of hard X ray (HXR) sources located in the corona was found, which implies that the collisionally thick target model (CTTM) applies even to the corona. We investigated whether this idea can independently be…

Solar and Stellar Astrophysics · Physics 2015-06-15 Jeongwoo Lee , Daye Lim , G. S. Choe , Kap-Sung Kim , Minhwan Jang

Context: Solar flare hard X-rays (HXRs) are thought to be produced by nonthermal coronal electrons stopping in the chromosphere, or remaining trapped in the corona. The collisional thick target model (CTTM) predicts that sources produced by…

Solar and Stellar Astrophysics · Physics 2015-06-15 A. O'Flannagain , P. Gallagher , J. Brown , R. Milligan , G. Holman

We compute the hard X-ray spectra from a hot plasma pervaded by small cold dense clouds. The main cooling mechanism of the plasma is Compton cooling by the soft thermal emission from the clouds. We compute numerically the equilibrium…

Astrophysics · Physics 2009-11-07 Julien Malzac , Annalisa Celotti

Small-scale transient phenomena in the quiet Sun are believed to play an important role in coronal heating and solar wind generation. One of them named as "X-ray jet" is the subject of our study. We indent to investigate the dynamics,…

Solar and Stellar Astrophysics · Physics 2015-05-19 M. S. Madjarska

This paper investigates a quiescent (non-flaring) active region observed on July 13, 2010 in EUV, SXR, and HXRs to search for a hot component that is speculated to be a key signature of coronal heating. We use a combination of RHESSI…

Solar and Stellar Astrophysics · Physics 2019-05-15 Shin-nosuke Ishikawa , Sam Krucker

The Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter (SolO) provides a unique opportunity to systematically perform stereoscopic X-ray observations of solar flares with current and upcoming X-ray missions at Earth.…

X-rays are a valuable diagnostic tool for the study of high energy accelerated electrons. Bremsstrahlung X-rays produced by, and directly related to, high energy electrons accelerated during a flare, provide a powerful diagnostic tool for…

Solar and Stellar Astrophysics · Physics 2015-03-09 Natasha L. S. Jeffrey

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…

Astrophysics · Physics 2010-09-17 I. G. Hannah , S. Krucker , H. S. Hudson , S. Christe , R. P. Lin

X-ray polarimetry offers a unique window into neutron star physics and can provide answers to questions that cannot otherwise be probed. The up-and-coming REDSoX sounding rocket mission will be the first experiment equipped with a detector…

High Energy Astrophysical Phenomena · Physics 2025-05-29 Ruth M. E. Kelly , Herman L. Marshall , Silvia Zane , Nabil Brice , Swati Ravi , Roberto Turolla , Roberto Taverna , Denis González-Caniulef

Over the next year, a new era of observations of compact objects in X-ray polarization will commence. Among the key targets for the upcoming Imaging X-ray Polarimetry Explorer mission, will be the magnetars 4U 0142+61 and 1RXS…

High Energy Astrophysical Phenomena · Physics 2022-06-22 Ilaria Caiazzo , Denis González-Caniulef , Jeremy Heyl , Rodrigo Fernández

The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray imager that observes the solar corona with unprecedentedly high angular resolution (consistent with its 1" pixel size). XRT has nine X-ray analysis filters with different…

Solar active regions contain a broad range of temperatures, with the thermal plasma distribution often observed to peak in the few millions of kelvin. Differential emission measure (DEM) analysis can allow instruments with diverse…

We investigate the thermal properties of a solar flare by the observations of soft X-ray Telescope (XRT) on board Hinode and the Atmospheric Image Assembly on board the Solar Dynamics Observatory (SDO/AIA). Our analysis reveals a tenuous…

Solar and Stellar Astrophysics · Physics 2025-10-22 Xiaoyan Xie , Anna Chen , Crisel Suarez , Katharine K. Reeves , Soumya Roy , Christopher S. Moore , Nishu Karna , Joy Velasquez

Recently CMOS (complementary metal-oxide semiconductor) sensors have progressed to a point where they may offer improved performance in imaging x-ray detection compared to the CCDs often used in x-ray satellites. We demonstrate x-ray…

Instrumentation and Detectors · Physics 2020-12-23 Steve Tammes , Tyler Roth , Philip Kaaret , Casey DeRoo , Abdallah Elmaleh , Jessica L McChesney , Fanny Rodolakis

Solar flares are associated with intense soft X-ray emission generated by the hot flaring plasma. Kink unstable twisted flux-ropes provide a source of magnetic energy which can be released impulsively and account for the flare plasma…

Solar and Stellar Astrophysics · Physics 2015-03-25 R. F. Pinto , N. Vilmer , A. S. Brun

Understanding the initiation of solar flares and coronal mass ejections (CMEs) is essential for improving forecasts of extreme space weather. Soft X-ray (SXR) and Extreme Ultraviolet (EUV) observations provide critical diagnostics of the…

The soft X-ray emissions of solar flares come mainly from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy,…

Solar and Stellar Astrophysics · Physics 2015-06-03 Paulo J. A. Simões , Hugh S. Hudson , Lyndsay Fletcher