List of abstracts
2026

In this new era of high-energy spectro-polarimetry, our understanding of high-energy sources has the potential to be greatly improved. This is especially the case for Black Hole X-ray Binaries (BHXB), also known as Microquasars, for which many unresolved challenges remain. In particular acceleration mechanisms and how they relate to accretion-ejection processes. Combined with spectroscopy, polarization is a powerful tool to reveal the geometry of the system and the configuration of the magnetic fields. The persistent Microquasar Cygnus X-1 is particularly well suited for our analysis. In soft X-rays, the polarization is low and aligned with the general direction of the jet, while the polarization angle in the soft gamma-rays is found close to 70° away from the jet. We use a novel method to combine high-energy spectra and polarization of this bright source from 1 keV to 2 MeV in a single fit, including observations from IXPE, PoGO+, XL-Calibur, AstroSat, INTEGRAL/SPI and INTEGRAL/IBIS. Our study involves energy-dependent polarization models for both emission processes, in part inspired by similar studies on Blazars. Preliminary results already reveal new constraints about the non-thermal hard-tail origin (above 100 keV), in particular its high-energy spectral cut-off and the degree of order of the magnetic field.

Originally, the IBWS (INTEGRAL/BART) workshops focused on the work of High energy astrophysics group (at that dime dominated by young research fellows and students) in Astronomical Institute of the Academy of Sciences of the Czech Republic and relevant national and international collaborators from the field, with intensive student participation. During the early years, these activities were focussed on the ESA INTEGRAL satellite and on the related ground-based robotic telescopes, e.g. the small robotic BART telescope at the Ondrejov Observatory. Nowadays, the IBWS workshops promote regional collaboration in galactic and extragalactic high-energy astrophysics, both experimental as well as theoretical, with an emphasis on the interface between satellite projects and ground-based experiments (e.g. robotic telescopes). We continue our emphasis on wide participation and presentations of students and young research fellows.

Galaxy evolution over time remains unclear, with ongoing debate about how collisions affect star formation and metallicity. The role of the local environment shaped by the large-scale structure of the Universe in galaxy mergers may be significant, yet it has not been thoroughly examined. Using the IllustrisTNG cosmological simulation, we processed the catalog data and merger tree files of the TNG300-1 run. We calculated the average star formation rate (SFR) and stellar mass of galaxies over the redshift range 0 < z < 15 to trace the cosmic star formation history and galaxy growth. We investigated the environments of galaxy mergers with a focus on local density within the cosmic web, and found that interactions with gas-rich dwarf galaxies can trigger a resurgence in gas supply, highlighting the importance of gas dynamics in sustaining star formation. We compared our results with recent JWST observations and identified differences in the star formation rate density (SFRD) history between simulations and observations, providing new insights into early galaxy formation and evolution. See Koncz et. al. Universe 2025, 11(9), 286.

The origin of the Galactic 511 keV positron annihilation line has been a mystery for five decades. One proposed explanation is positron production in stellar flares, motivated by the detection of the 511 keV line in solar flares and by the association of this emission with old stellar populations. In this work, we explore this scenario using two complementary approaches. First, we build a theoretical model to estimate the quasi-persistent 511 keV emission from flaring stars. Starting from solar flare observations, we construct empirical scaling relations between flare energy and 511 keV luminosity and extend them to Galactic stellar populations using flare-frequency-energy distributions for different spectral types. In parallel, we analyze INTEGRAL/SPI data in the 511 keV band using combinations of known point sources and simple spatial templates, such as disk and bulge components modeled as two-dimensional Gaussians. We also test alternative descriptions in which no bulge template is assumed and the emission is instead described by a disk component together with a population of globular clusters, scaled by their masses and distances. This ongoing work aims to assess whether stellar flares can plausibly account for the observed Galactic 511 keV emission.

Many stellar high-energy sources are manifestations of one of the stages of binary star evolution. In this talk, I will discuss the astrophysical processes influencing binary star evolution such as mass transfer and the response of mass-losing and mass-accreting stars, formation of circumbinary medium, explosions, and violent events such as common envelope evolution, as well as their relation to end products such as gravitational wave sources. I will cover in greater detail two types of transient events: luminous red novae, which accompany stellar mergers and potentially hold the key to connecting many different evolutionary pathways , and classical novae, where recent GeV Fermi detections as well as ground, space, and interferometric observations suggest a much more complicated picture of mass ejection than previously thought.

Gamma rays provide a unique window on nuclear processes occurring throughout the Universe, directly tracing radioactive isotopes and matter antimatter annihilation. In this talk, I will review key results from gamma-ray line spectroscopy in space, focusing on observations from 22 years of the now completed ESA satellite mission INTEGRAL. Measurements of radioactive isotopes, such as 26Al and 60Fe, reveal ongoing nucleosynthesis in the Galaxy and connect stellar explosions to traces found on Earth, including signatures preserved in ocean crust sediments. In this context, the long-standing puzzle of the Galactic 511 keV positron annihilation emission is also discussed. NASA’s Compton Spectrometer and Imager (COSI) mission, scheduled for launch in 2027, is expected to significantly advance MeV measurements thanks to its increased sensitivity and imaging capabilities. I will introduce the Compton telescope concept and highlight open questions addressed by COSI, such as the role of massive stars and supernovae in Galactic feedback. Finally, I will show how analysis and imaging techniques developed for space-based gamma-ray astronomy are now being applied on Earth, enabling isotopic imaging of radioactive residues in nuclear facilities and related environments.

The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) is a space mission concept designed to perform repeated wide-area surveys of the sky, primarily to detect and characterize high-redshift gamma-ray bursts. As a consequence of its baseline observing strategy, THESEUS will also provide systematic, time-dependent coverage of large fractions of the sky in the soft X-ray and near-infrared domains, offering new opportunities for studies of Galactic sources beyond its core cosmological goals. We aim to assess the observability of nearby star-forming regions and young stellar objects (YSOs) within the baseline survey strategy of THESEUS. We investigate how the mission’s pointing concept and sky-coverage pattern translate into the temporal visibility of prominent nearby star-forming complexes and how this visibility is distributed over the mission lifetime.

We report on recent progress in the digitization of astronomical plate archives and the application of novel IT approaches, including machine learning methods, to these data. Astronomical photographic archives represent an extensive and largely untapped database of stellar, solar, and planetary observations, encompassing astrometric, photometric, and spectroscopic measurements accumulated over more than a century. These archives hold significant potential for a wide range of applications in modern astrophysics, including the study of long-term variability, detection of rare transient events, and identification of objects with peculiar spectra. We present results from visits to over 16 US institutions and numerous European, Mexican, and Chinese observatories, where plate samples were digitized using a transportable scanning device. We further describe the application of advanced computational techniques to digitized plates from the Sonneberg Observatory and the Henize Mt. Wilson Michigan Southern Sky Survey, demonstrating the feasibility of extracting new astrophysical findings from historical archival data.

The isotopes 26Al and 60Fe show short lifetimes (∼ 106 yr) with respect to the time scales of Galactic evolution and are therefore used as messengers of ongoing nucleosynthesis and star formation in the Milky Way. The production of both isotopes is commonly associated with massive stars. They are thought to be ejected in their supernovae, and in the case of 26Al partially in the wind phase of the star. Because of their similar origin and lifetimes , the ratio 60Fe/26Al of their γ-ray emission would be independent of the true location and distribution of their source, and yields a chance to test the outcome of stellar evolution models. The expected results of 60Fe/26Al for core-collapse supernovae, however, show discrepancies with measurements (Spyrou et al. 2024). This method only works, if 26Al and 60Fe have the same origin throughout the Galaxy. At the same time recent results from 26 Al measurements suggest a star formation rate (SFR) of ≳ 5 M⊙/yr (Siegert et al. 2023), which exceeds other literature values. Classical novae are also believed to produce 26 Al, which, if the contribution is large enough, would decrease the SFR from the correlation of 26 Al with massive stars. We aim to determine the 26 Al mass as a function of Galactocentric radius and compare it with two Galactic chemical evolution (GCE) models (Vasini et al. 2025; Martinet et al. 2022) to estimate the contribution of (very) massive stars and classical novae. We are using 20 yr of INTEGRAL/SPI observations of the decay gamma-ray line at 1. 809 MeV to test different assumptions on the radial structure of 26 Al. We present the total mass, the Galactic distribution of the 26Al, and the relative contribution of 26Al assuming different Galactic 3D models. We find significant contributions from classical novae which exceed prior studies for all tested models. A larger contribution of 26Al from classical novae directly decreases the effective 60Fe/26Al ratio affects the interpretation as a probe of massive-star nucleosynthesis and would lower the SFR from 26Al γ-ray measurements accordingly to 1-2 M⊙/yr

Since the typical lengths of the recurrence times Tc (cycle lengths) of outbursts in soft X-ray transients (SXTs) range from months to decades, X-ray monitors are needed to detect them and investigate their evolution. Evolution of Tc shows a complex curve with episodes of increase and decrease. Significant results can be obtained even when different monitors with various energy bands, available for the individual time segments (years or decades), are used (e.g., ASM/RXTE, MAXI/ISS, BAT/Swift). The character of the O-C curves of SXTs bears a striking similarity to that of dwarf novae observed in the optical band. It means that variations in Tc are large, but generally not chaotic, and long-term trends in the O-C curves can be resolved. Observing the variety of the X-ray evolution of dwarf novae is still limited by the low sensitivity of the current X-ray monitors.

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Accelerometers are devices that sense acceleration and transmit it as an electrical signal to measurement units. Recently, accelerometers have made an important contributionto several fields such as aerospace, space, health monitoring, and other industries.This study is dedicated to the mathematical modelling and development of a newly developed three-axis piezoelectric accelerometer for space applications based on LEO CubeSat missions. The modelling, development, and required simulations are carried out using COMSOL Multiphysics software. The main objective of this work is to develop an easily manufacturable, cost-effective, and sensitive three-axis piezoelectric accelerometer for attitude determination systems in low Earth orbit based space applications.

QUVIK is a Czech-led project of a small UV space telescope that has been selected and funded to be launched in year30/31. Masaryk University will be primarily responsible for developing and running a Science Operation Center that has 2 main tasks: defining most scientifically valuable observation plan (taking into account constraints of Low Earth Orbit and the power budget) and creating the most performing data processing pipeline (with a very limited baseline of on-board data handling). Our experience of operations of small telescopes on ground (mostly run in automatized regime) is the pincipal ingredience in this development. First steps taken in the process closely supervised by ESA support team will be presented.

Technology progress for small satellites allows self-organizing multi-satellite systems for observations. The satellite formation will be configured by miniature attitude and orbit control systems to optimize network properties. This potential is exploited in Earth observation regarding multi-perspective measurements. At the launch pad in California are currently multi-satellite missions from Würzburg, such as - TOM : 3 cooperating satellites to generate 3D surface images, - CuBy : 5 satellites with multi-spectral cameras for biomonitoring and geodesy applications. Transfer of such formation principles to support astronomical observations offer good potential for innovative distributed sensing methods and will be jointly further explored during this workshop.

We show that a Soft X-ray Imager (SXI) onboard the ESA-CAS satellite SMILE will be able to observe various types of mass accreting compact objects in the universe. We show that mainly neutron stars accreting matter from their companions in X-ray binaries are promising targets for evaluating the possibilities of SXI in astronomical research. We present the typical features of the long-term activity of various X-ray binaries in the SXI/SMILE field of view. We also show that binaries with steady-state thermonuclear reactions on board accreting white dwarfs in the Magellanic Clouds are promising targets for SXI observations. We discuss how SXI can contribute to this branch.