Article
Astronomy & Astrophysics
Hannah Collier, Laura A. A. Hayes, Andrea F. F. Battaglia, Louise K. K. Harra, Sam Krucker
Summary: The aim of this work is to develop a method to systematically detect and characterise fast-time variations in the non-thermal hard X-ray time profiles of solar flares using high-resolution data from Solar Orbiter's STIX. The HXR time profiles were smoothed using Gaussian Process regression, and then fitted with a linear combination of Gaussians to decompose the time profile and derive key characteristics such as periodicity, full width at half maximum, time evolution, and amplitude.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
T. Mrozek, R. Falewicz, S. Kolomanski, M. Litwicka
Summary: This study investigates the deposition process of non-thermal electron beams in a solar flare through numerical simulation and analysis of observed data. The results provide estimates of the evaporated mass and contribute to a better understanding of the precipitation process of non-thermal electron beams.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Jonas Saqri, Astrid M. Veronig, Alexander Warmuth, Ewan C. M. Dickson, Andrea Francesco Battaglia, Tatiana Podladchikova, Hualin Xiao, Marina Battaglia, Gordon J. Hurford, Sam Krucker
Summary: This study used the Spectrometer/Telescope for Imaging X-rays (STIX) instrument to observe the energy release and transport in solar flares. By analyzing data from multiple instruments, the study found that two microflare events are consistent with the standard chromospheric evaporation flare scenario and that accelerated electrons can account for the required thermal energy.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Andrea Francesco Battaglia, Jonas Saqri, Paolo Massa, Emma Perracchione, Ewan C. M. Dickson, Hualin Xiao, Astrid M. Veronig, Alexander Warmuth, Marina Battaglia, Gordon J. Hurford, Aline Meuris, Olivier Limousin, Laszlo Etesi, Shane A. Maloney, Richard A. Schwartz, Matej Kuhar, Frederic Schuller, Valliappan Senthamizh Pavai, Sophie Musset, Daniel F. Ryan, Lucia Kleint, Michele Piana, Anna Maria Massone, Federico Benvenuto, Janusz Sylwester, Michalina Litwicka, Marek Steslicki, Tomasz Mrozek, Nicole Vilmer, Frantisek Farnik, Jana Kasparova, Gottfried Mann, Peter T. Gallagher, Brian R. Dennis, Andre Csillaghy, Arnold O. Benz, Sam Krucker
Summary: STIX successfully observed solar microflares during its commissioning phase, revealing differences in temporal and spectral evolution compared to Earth-orbiting observatories. Future diagnostic efforts should focus on multi-wavelength studies to accurately describe the energetics of solar flares.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Andrea Francesco Battaglia, Wen Wang, Jonas Saqri, Tatiana Podladchikova, Astrid M. Veronig, Hannah Collier, Ewan C. M. Dickson, Olena Podladchikova, Christian Monstein, Alexander Warmuth, Frederic Schuller, Louise Harra, Saem Krucker
Summary: This study investigates the electron acceleration and energy release sites, as well as the mechanism by which accelerated electrons access interplanetary space, in the case of the SOL2021-02-18T18:05 event. By utilizing observations from Solar Orbiter, STEREO-A, and Earth, the researchers found that the onset of electron acceleration coincides with the coronal jet and radio type III bursts. They also discovered nonthermal hard X-ray emission and a curved trajectory of the ejected plasma during the microflare.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Douglas Felix da Silva, Li Hui, Paulo J. A. Simoes, Adriana Valio, Joaquim E. R. Costa, Hugh S. Hudson, Lyndsay Fletcher, Laura A. Hayes, Iain G. Hannah
Summary: Understanding the physical processes that trigger solar flares is crucial for forecasting space weather and mitigating the impacts on our technological infrastructure. Recent research has revealed that the hot-onset phenomenon is common in solar flares, with 75% of flares exhibiting an onset temperature above 8.6 MK.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Manon Jarry, Alexis P. Rouillard, Illya Plotnikov, Athanasios Kouloumvakos, Alexander Warmuth
Summary: This study analyzes the geometrical and kinematic properties of coronal and interplanetary shock waves produced by CMEs. The results show the evolution of the shock wave's shape, expansion speeds, and their correlation with the underlying flare activity. These findings contribute to improving space weather forecasting and understanding the eruption process of CMEs.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Muriel Zoe Stiefel, Andrea Francesco Battaglia, Krzysztof Barczynski, Hannah Collier, Anna Volpara, Paolo Massa, Conrad Schwanitz, Sofia Tynelius, Louise Harra, Saem Krucker
Summary: In this study, a multiwavelength analysis of a GOES M1.8 flare was presented. Four nonthermal hard X-ray sources were observed, two located outside the flare loop and two at the loop ends. It was found that the outer sources are anchor points of an erupting filament and the hard X-ray emission is due to flare-accelerated electrons injected into the filament.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Prabir K. Mitra, Astrid M. Veronig, Bhuwan Joshi
Summary: This study investigates an M-class circular ribbon flare that occurred near a quasi-separatrix layer (QSL) and reveals the complex magnetic configuration involved. The flare originated from a region with negative magnetic patches surrounded by positive-polarity regions on three sides. A QSL structure was found near the flaring region, and RHESSI X-ray sources were identified from its footpoints. The analysis suggests that the activation of a flux rope within the fan-like lines, triggered by activities near the QSL, led to the circular ribbon flare.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Fang-Kun Peng, Fa-Yin Wang, Xin-Wen Shu, Shu-Jin Hou
Summary: This study focuses on the frequency distribution, duration, and flux characteristics of solar GeV flares, finding consistent behavior with the SOC model, suggesting that magnetic reconnection may dominate the energy-release process and particle acceleration for solar flares at GeV energies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Kristopher Cooper, Iain G. Hannah, Brian W. Grefenstette, Lindsay Glesener, Sam Krucker, Hugh S. Hudson, Stephen M. White, David M. Smith, Jessie Duncan
Summary: The study investigates the X-ray properties and radio properties of 10 microflares on AR12721, and examines their energy and temperature. Direct evidence of accelerated electrons in the form of non-thermal X-ray emission was found in one microflare. Additionally, the study highlights the matches between X-ray time profiles and fainter sources in the extreme-ultraviolet band, and observes evidence of photospheric magnetic flux cancellation/emergence at the footpoints of eight microflares.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Navin Chandra Joshi, Bhuwan Joshi, Prabir K. Mitra
Summary: In this study, a complex M-class solar eruptive flare with three sets of flare ribbons and 3D null-point magnetic topology in the source active region NOAA 12242 was reported. The event progressed through stages of circular ribbon appearance, flux rope construction and eruption, and enhancement in parallel ribbon brightness, showing interactions between different reconnection processes. The analyses suggest the roles of torus instability and breakout model in triggering the eruptive flare, showcasing the dynamic evolution of the flux rope in a null-point topology.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Anna Volpara, Paolo Massa, Emma Perracchione, Andrea Francesco Battaglia, Sara Garbarino, Federico Benvenuto, Sam Krucker, Michele Piana, Anna Maria Massone
Summary: This study compares the difficulty of solving the problem of forward fitting visibilities measured by STIX on Solar Orbiter with previous hard X-ray solar imaging missions, and seeks an effective optimization scheme. By comparing experimental and synthetic data, it is found that particle swarm optimization performs the best in terms of stability and computational effectiveness. The standard optimization based on local search is not effective enough for STIX, and more sophisticated global search optimization schemes are needed.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Hugh S. Hudson, Paulo J. A. Simoes, Lyndsay Fletcher, Laura A. Hayes, Iain G. Hannah
Summary: Research has found that there is a period of increased plasma temperature before a solar flare, known as the "hot onset," which occurs before the increase in soft X-ray emissions and is typically located in footpoint and low-lying loop regions rather than coronal structures. This phenomenon challenges standard modeling techniques, as the hot X-ray onsets appear before evidence of collisional heating by non-thermal electrons.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Jonas Saqri, Astrid M. Veronig, Ewan C. M. Dickson, Tatiana Podladchikova, Alexander Warmuth, Hualin Xiao, Dale E. Gary, Andrea Francesco Battaglia, Saem Krucker
Summary: In this study, observations from different perspectives are combined to analyze a long duration eruptive C7 class flare that occurred on April 17, 2021. The dynamics and thermal properties of the flare-related plasma flows, as well as the kinematic evolution of the associated CME, are studied. The results provide valuable insights into the dynamics and energy release mechanisms of eruptive flares. Rating: 9 out of 10.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Physics, Multidisciplinary
Aleksander Stanislavsky, Aleksander Weron
Summary: In this paper, we demonstrate the connection between tempered subdiffusion and confinement through the conjugate property of Bernstein functions. The transformation of diffusive motion into pure jumps in a confined environment, accompanied by multiple-trapping events with infinite mean sojourn time, explains the tendency of anomalous diffusion towards confinement. This model has broad applicability in problems of transport in random media, including live cells, relaxation in heterogeneous substances, and jump-diffusion. The relation of our approach to diffusive diffusivity is also explained.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Physics, Multidisciplinary
Joanna Janczura, Michal Balcerek, Krzysztof Burnecki, Adal Sabri, Matthias Weiss, Diego Krapf
Summary: The diffusion of nanoparticles in the cytoplasm of live cells shows a dichotomous switching between two distinct mobility states, with an overall subdiffusive mode of motion similar to fractional Brownian motion. The heterogeneity in experimental data is mainly due to variations in transport coefficients, rather than locally varying anomaly exponents. This approach demonstrates that diffusion heterogeneities can be accurately extracted and quantified from short trajectories obtained through single-particle tracking in complex media.
NEW JOURNAL OF PHYSICS
(2021)
Article
Astronomy & Astrophysics
Aleksander A. Stanislavsky, Igor N. Bubnov, Artem A. Koval, Serge N. Yerin
Summary: The interpretation of solar radio bursts observed by Parker Solar Probe during the encounter phase is important for understanding the emission mechanism in the solar corona. Ground-based observations with advanced antennas can help overcome the lower time-frequency resolution of the PSP receiver. In this study, observations were made of solar bursts generated by active region 12765, and radio events behind the solar limb of the PSP spacecraft were detected using special conditions in the solar corona.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Mathematics, Interdisciplinary Applications
Joanna Janczura, Krzysztof Burnecki, Monika Muszkieta, Aleksander Stanislavsky, Aleksander Weron
Summary: In this paper, a new approach based on fractional Levy stable motion (FLSM) is proposed for the analysis of experimental data and applied to the Golding-Cox mRNA dataset. The study utilizes non-Gaussian alpha-stable distributions and estimates the memory parameter to classify trajectories along the x and y coordinates. The results show that most trajectories exhibit subdiffusion, some follow Levy diffusion, but none demonstrate superdiffusion. The presence of non-Gaussian alpha-stable distribution is also justified through goodness-of-fit tests.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Physics, Multidisciplinary
Aleksander A. Stanislaysky, Aleksander Weron
Summary: Stochastic resetting with home returns is a common phenomenon in life and nature. By studying the problem without home returns and the solution to the home return problem, we have developed a theoretical framework for search with home returns in the case of subdiffusion. This model provides a more realistic description of restart by considering random walks with random stops.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Physics, Multidisciplinary
Farzad Sabzikar, Jinu Kabala, Krzysztof Burnecki
Summary: The autoregressive tempered fractionally integrated moving average (ARTFIMA) process is obtained by applying the tempered fractional difference operator to non-Gaussian stable noise. The tempering parameter enhances the stability of the ARTFIMA process compared to the classical autoregressive fractionally integrated moving average, resulting in semi-long range dependence and transient anomalous behavior. The article investigates the dependence structure of ARTFIMA with stable noise and develops Whittle estimators. The stable Yaglom noise is introduced as a continuous version of the ARTFIMA model with stable noise, and the usefulness of the ARTFIMA process is illustrated using a trajectory from the Golding and Cox experiment.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Astronomy & Astrophysics
Lev A. Stanislavsky, Igor N. Bubnov, Aleksander A. Konovalenko, Aleksander A. Stanislavsky, Serge N. Yerin
Summary: This study presents measurements of the continuum spectrum of Cassiopeia A using the GURT, revealing the absorption properties and radiation characteristics of the SNR. The results are consistent with other studies and confirm the accuracy of the theoretical model.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Geochemistry & Geophysics
Aleksander A. Stanislavsky, Igor N. Bubnov, Artem A. Koval, Lev A. Stanislavsky, Serge N. Yerin, Andriy Zalizovski, Volodymyr M. Lisachenko, Oleksander O. Konovalenko, Mykola M. Kalinichenko
Summary: Researchers detected solar radio bursts and observed the ionospheric cutoff using a new active antenna. The experiment serves as a prototype for a future radio array on the farside of the Moon and provides new opportunities to study the F2-layer critical frequency of the ionosphere.
JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS
(2023)
Article
Astronomy & Astrophysics
Artem Koval, Aleksander Stanislavsky, Marian Karlicky, Bing Wang, Serge Yerin, Aleksander Konovalenko, Miroslav Barta
Summary: On July 25, 2014, a type II burst was observed using radio telescopes UTR-2 and GURT. The burst exhibited various spectral features, including fundamental and harmonic components, band splitting, a herringbone structure, and a spectral break. The herringbone pattern was analyzed to study electron density turbulence in the solar corona. It was also noted that the second type II burst consisted of three drifting lanes, which coincided with the spectral break in the first burst. This suggests that the CME/shock-streamer interaction played a role in the occurrence of the type II burst.
ASTROPHYSICAL JOURNAL
(2023)
Article
Physics, Fluids & Plasmas
Yann Lanoiselee, Aleksander Stanislavsky, Davide Calebiro, Aleksander Weron
Summary: In this article, we investigated the trapped motion of a molecule undergoing diffusivity fluctuations inside a harmonic potential. We examined two possible interpretations for the diffusivity fluctuations - temperature or friction fluctuations - and found that they exhibit significantly different statistical properties inside the harmonic potential. By calculating the characteristic function and analyzing the limit behavior, we computed the mean-squared displacement and the normalized excess kurtosis. The results showed that, in the long-time limit, the probability density function (PDF) always converges to a Gaussian distribution for friction fluctuations, while for temperature fluctuations, the stationary PDF can exhibit either a Gaussian distribution or a generalized Laplace (Bessel) distribution depending on the ratio between diffusivity and positional correlation times.
Article
Business, Finance
Krzysztof Burnecki, Marek A. Teuerle, Aleksandra Wilkowska
Summary: This article introduces a diffusion-type approximation of ruin probability for a two-dimensional risk process and discusses it in both finite and infinite time. By applying the weak convergence of stochastic processes, we obtain simple ruin probability approximations for the insurer-reinsurer model.