List of abstracts in 2026

Laue lenses have long promised to extend focused observations into the soft gamma-ray domain; however, manufacturing challenges and limited efficiency have so far hampered their realization. At cosine, we use the Silicon Pore Optics technology developed for the NewAthena X-ray mirror to fabricate Silicon Laue Components (SiLCs). A SiLC consists of a stack of thin, wedged crystalline silicon plates that are bi-axially curved to provide both radial and azimuthal focusing, while achieving high diffraction efficiency within a bandpass tunable to specific applications. This scalable process offers full control of key parameters and enables the production of highly efficient Laue lens elements. We present the results of a two-year study funded by the European Space Agency that led to the fabrication of a demonstrator SiLC, subsequently characterized at 120 keV at the LARIX facility (University of Ferrara).

I will present an overview of recent and upcoming X-ray optics activities at the PANTER X-ray test facility of the High Energy Group at the Max Planck Institute for Extraterrestrial Physics in Neuried, southwest of Munich. This will cover tests of AXIS and NewAthena optics, reflectivity measurements of coatings and retesting of ABRIXAS and XMM-Newton flight spare mirrors.

I will give the conference Introduction and Historical Background, reviewing the history and recent state of the conference

I will give a concluding address for the AXRO 2026 conference

The New Advanced Telescope for High Energy Astrophysics (NewAthena) is planned to be launched in the late 2030s. This L-class mission endorsed by the European Space Agency features an unprecedentedly large x-ray mirror based on Silicon Pore Optics. The mirror will be a 2.6 m in diameter structure with an aperture segmented into more than 500 separate imaging elements arranged in a Wolter-Schwarzschild configuration with a focal length of 12 m. The half-energy width resolution target of the mirror is 9", with more than 1 m2 effective area at an energy of 1 keV. The coated reflective surface is designed to have an energy response up to 10 keV. The European Space Agency, cosine, and its partners have been developing the mirror technology, Silicon Pore Optics, to high maturity levels for the past 25 years. Demonstrating high maturity levels of the Silicon Pore Optics requires the manufacturing of hundreds of imaging elements within time and budget constraints while maintaining a high yield and satisfying scientific requirements. This endeavor requires bringing together scientific and technological developments at several facilities across a number of European countries. In this presentation we will detail the efforts in transferring the processes of manufacturing the imaging elements for three of the 13 mirror rows from research and development to pilot production. In addition, we report on the latest performance results of one state-of-the-art mirror module.

X-ray focusing telescopes are core equipment for space X-ray observation. To ensure observation accuracy, low-energy electrons entering the focusing mirror must be effectively deflected to reduce background noise. This paper addresses the development of an electron deflector for the focusing mirror, meeting deflection requirements while considering lightweight design and electromagnetic compatibility. Finite element analysis was used to build a full-physical simulation model of the electron deflector and focusing mirror lenses, analyzing magnetic flux density distribution, electron deflection trajectories, and the magnetic field's effect on the lenses. Results show that magnetic flux density decreases radially, with a maximum of 0.027 T between two spokes. When the radius exceeds 280 mm or longitudinal distance exceeds 60 mm, magnetic flux density is below 5×10⁻⁵ T (0.5 Gs), meeting electromagnetic compatibility requirements. For incidence angles ≤10°, deflection efficiency decreases with increasing electron energy and incidence angle, reaching 100% below 50 keV, meeting deflection design requirements. At a distance of 130 mm, the stress on the lenses is only ~10⁻³ N/m² and deformation ~10⁻⁵ nm, indicating no impact on optical performance. These results provide an important reference for the electron deflector development.

Gravitational wave observatories localize sources only in a small area of the sky that, also for future detectors, will be of ~10-100 deg². Current X-ray telescopes are incapable of quickly localizing the X-ray source in that area, because they either have a very small field of view – so incapable of scanning that area in a short period of time – or are wide-field monitors – but with inadequate sensitivity. This capability however will become increasingly important when the current gravitational wave experiments (LIGO and Virgo) will work at full sensitivity, or when the future experiments – Einstein Telescope and Cosmic Explorer observatories, and the space mission LISA – will come online in the next decade. With the goal of having a source localization accuracy of tens of arcsec over a ~10 square degrees field of view, together with hundreds of cm² effective area, we study how the Lobster eye optical design can be optimized for this objective. We also compare the advantages and drawbacks of this optical design in comparison to the Kirkpatrick-Baez design or to optimizing Wolter-I optics for the same objective.

The enhanced X-ray Timing and Polarimetry mission (eXTP) is a science mission designed to study the state of matter under extreme conditions of density, gravity and magnetism. The mission carries a unique and unprecedented suite of state-of-the-art scientific instruments enabling for the first time ever the simultaneous spectral-timing-polarimetry studies of cosmic sources in the energy range from 0.5-10 keV. Key elements of the payload are: the Spectroscopic Focusing Array (SFA), the Polarimetry Focusing Array (PFA). The SFA consists of 6 X-ray optics with a field-of-view (FoV) of 12 arcmin, the angular resolution targeted to be better than 30 arcsecond half-energy width on-axis. And the PFA consists of 3 X-ray optics with the angular resolution targeted to be 30 arcsec. The effective area for each optic is 820cm2 and 550cm2 at 2 keV and 6 keV respectively. The optics module is a gold layer coated Wolter-I telescope.Optical designs were carried out with 47 nested paraboloid and hyperboloid mirror shells, ranging from a diameter of 491mm in the outermost to 205 in the innermost. The focal length of the mirror system is 5.25m. Ray tracing simulations were performed to investigate the impact on the overall optical performance of eXTP telescope mirror, to estimate the contribution of the degradation of the mirror figure, surface roughness and the assembly accuracy. Through the simulations we identify the ranges of the acceptable tolerances.

Computing the effective area for focused rays and stray light in silicon pore optics (SPO) mirror modules is a complex issue, due to the multiple possible ways in which a reflected ray can be obstructed. An analysis of this kind is always possible via ray-tracing, but it is interesting to face the same problem from an analytical viewpoint also. To this specific end, we have developed SPONGE (Silicon Pore Optics NewAthena Geometric Estimator) a software tool that, under the approximation that the Wolter-I longitudinal profiles can be approximated by double cones, enables the computation of the effective area in double and single reflection, accounting for all possible self-baffling effect in the SPO mirror assembly of NewAthena. The results can be used as terms of comparison for ray-tracing codes such as SPORT which, just like SPONGE, is part of the SIMPOSIuM software suite being developed by INAF-Brera and DTU under ESA contract. In this presentation, we show the SPONGE program and its functionalities.

Results of optical tests of Schmidt lobster eye prototype module based on a new technology are presented. The technological concept offers precise assembly of optical mirrors, which is the key aspect to obtain sharp focal image. The prototype is designed for X-ray energies about 1keV. Dimensions and focal length of the prototype are chosen to allow boarding on CubeSat class Satellite. The module was tested using visible light, which is possible because glass plates coated with gold are used as mirrors. FWHM and field of view are measured and compared to calculated values.

In the Phase C study of the eXTP mission, we further optimized the optical design, reducing the number of mirror layers from 50 to 47, while adding 2 extra layers outside the ourmost shell. We developed the structural thermal model and the qualification model. Currently, the angular resolution of the small mirrors has reached the level of 20 arcseconds.

Aperiodic multilayers have important applications in hard X-rays astronomical observations due to their broadband responses. This report presents an optimization model of Pt/C power-law graded stack multilayers using the IMD software. The reflectivity expression of multilayers was derived from the reflection theory of X-ray multilayers and Fresnel recursion formulas. Then, the effects of maximum bi-layer thickness (dmax), ratio of high-density material thickness to bi-layer thickness (Γ), power-law index (c), number of bi-layers (N), grazing incidence angle (φ), interfacial roughness (σ), and photon energy (E) on the reflectivity were analyzed. The calculation results showed that the dmax, Γ and c control the shift of response range, absorption peak and Bragg peaks, respectively. And the decrease of N and increase of φ and σ can result in the reduction of reflectivity at different energies. Additionally, an optimized multilayer structure was proposed according to the extremum of merit function, which can achieve a broadband reflectivity of no less than 0.6 from 1 keV up to 80 keV. These results can provide important references for the response characteristic analysis and optimization design of multilayers.

Since more than one decade, highly reflective coatings for astronomical X-ray optics were developed at the “Aschaffenburg Competence Center for Astronomical and Space Instrumentation” (ACCASI). As part of a Bavarian-Czech cooperation between Aschaffenburg University and the Czech Technical University of Prague, also two mechanically identical X-ray telescopes were built. One telescope optic was equipped with conventional gold-coated mirrors, manufactured by the Czech project partners. The 34 X-ray mirrors of the second telescope use an innovative tri-layer coating system made of chromium and iridium, which was applied at the Aschaffenburg coating laboratory. Both telescopes are designed according to the bionic principle of a reflecting lobster eye. The optical system works using two successive reflections from mirror surfaces that are perpendicular to each other. This enables a large field of view with many square degrees in diameter, which, however, comes at the price of a reduced angular resolution. An extensive X-ray characterization of these telescopes was carried out at the PANTER test facility of MPE, which simulates parallel X-ray starlight incident on the telescopes. The telescopes have an angular resolution of about 4 arc minutes in X-rays and a focal length of about 2 meters. The development of X-ray mirror coatings as well as the design and testing of the X-ray telescope optics is presented within this poster contribution.

I will present the science case, design and expected performances of the X/Gamma-ray Imaging Spectrometer (XGIS), a GRB and transients monitor developed and studied for the THESEUS mission project, capable of covering an exceptionally wide energy band (2 keV - 10 MeV), with imaging capabilities and location accuracy <15 arcmin up to 150 keV over a Field of View of 2sr, a few hundreds eV energy resolution in the X-ray band (<30 keV) and few micro seconds time resolution over the whole energy band. Thanks to a design based on a modular approach, the XGIS can be easily re-scaled and adapted for fitting the available resources and specific scientific objectives of future high-energy astrophysics missions, and especially those aimed at fully exploiting GRBs and high-energy transients for multi-messenger astrophysics and fundamental physics.

The Follow-up X-ray Telescope (FXT) is a key payload onboard the Einstein Probe (EP), a Chinese-led international X-ray astronomy mission launched in January 2024. After nearly three years of in-orbit operation, FXT remains in excellent health, with stable and reliable performance across all subsystems. The telescope comprises two co-aligned Wolter-I mirror modules with a focal length of 1.6 m, delivering a combined on-axis effective area of ~600 cm2 at 1.5 keV over the 0.3–10 keV band, and is equipped with back-illuminated pnCCD detectors operated at approximately −90°C. In-orbit measurements confirm an energy resolution of ~92 eV FWHM at 1.25 keV, an angular resolution of ~22″ (HPD), and a source localisation accuracy of a few arcseconds. A defining advantage is FXT's exceptionally low instrumental particle background—only ~1/5 that of eROSITA—which underpins its outstanding sensitivity to low-surface-brightness diffuse X-ray emission. Three observing modes (full-frame, partial-window, and timing) provide flexible coverage from deep imaging to high-time-resolution studies. The first FXT source catalogue has been released, comprising more than 62,000 X-ray celestial sources. In addition, FXT data are now being made publicly available through a newly added portal—the National High Energy Physics Database—in parallel with the existing archives, further improving data access for the community. Significant progress has been made in galaxy cluster observations. These encompass not only luminous clusters such as A1795 and A478, whose extended emission has been mapped well beyond the cluster cores, but also the discovery and dedicated follow-up study of X-ray-faint clusters, extending cluster X-ray studies to markedly lower surface brightness. With its large field of view, low background, and rapid response capability, FXT is well positioned to continue delivering breakthroughs in time-domain and multi-messenger astrophysics, diffuse X-ray source studies, galaxy cluster cosmology, and solar-system X-ray astronomy.

In order to utilize the spectral capabilities of eROSITA, it is necessary to know how an incident X-ray spectrum is modified by the instrument. This modification involves two major effects: (i) energy-dependent sensitivity and spectral resolution, and (ii) charge splitting, charge transfer loss, and CCD column-specific amplification. Regarding (i), the corresponding information is contained in two quantities: the ARF (Ancillary Response File) and the RMF (Redistribution Matrix File). The ARF is a vector describing the sensitivity as a function of energy, whereas the RMF is a matrix representing the resulting pulse height distributions for these energies. In the ground calibration, we determined the RMF empirically by fitting mathematical functions to the pulse height distributions obtained at 29 monochromatic emission lines covering the energy range from 80 eV to 11 keV. In space, we adjusted the RMF together with the ARF by utilizing two astrophysical sources with sufficiently known spectra: the isolated neutron star RXJ1856-3754 and the supernova remnant 1E0102-7217. These adjustments allow us to reproduce the model spectra to an accuracy of about 5%. We find the energy resolution in the early phase of the mission to be essentially the same as on ground.

For more than a century, stratospheric balloon flights have proven to be an effective method to study cosmic radiation and its effects. The Aschaffenburg Stratospheric Balloon Experiment (“ASTRABAX”) enables research in the fields of materials science and the life sciences at altitudes of up to 35 km. In the three previous ASTRABAX balloon flights, active and passive radiation detectors mounted on a multimodal platform recorded the harsh radiation environment in the stratosphere - a combination of high-energy particles, gamma rays, and UV-C radiation. The gondola’s parameters, the required dosimetry range, and the the necessity for an autonomous operation of the equipment determined the selection and the suitability of these radiation detectors. Corresponding laboratory experiments supplemented the deployment of the different radiation detectors. In addition to measuring the radiation intensity and its spectrum, the effects of this radiation on the biopolymer poly-dopamine, as well as the dose-response relationship and repair mechanisms in human cells were studied. Conducting radiation experiments under the actual conditions of the stratosphere is highly relevant to radiobiological research, satellite-based experiments in low Earth orbit, and human space flights.

Observations in the high-energy domain are fundamental to understanding how matter is organised and behaves around black holes, as well as acceleration processes at shocks of all sizes, the origin of cosmic rays, and the non-thermal x-ray energy content of galaxy clusters. In addition, hard x-ray polarimetry is an important and unique diagnostic tool in the energy range where non-thermal processes dominate. Acceleration phenomena, non-thermal processes, and magnetic-field topology in all types of sources can be probed using this new and independent observable. The Polarimetric High-Energy Modular Telescope Observatory (PHEMTO) has been proposed as a candidate for the eighth ESA Medium-class mission, within the Voyage 2050 ESA Science Programme. PHEMTO is based on a Laue lens and multilayer optics, both focusing photons onto a silicon-based matrix and a fine-segmented CdTe/CZT spectrometer at a common focal distance of 20 m. PHEMTO is designed to provide fine spectroscopic and polarimetric performance over the broad 1–400 keV energy range. In this talk, we will review the science topics addressed by PHEMTO, the proposed technologies and their level of maturity, and the overall mission concept

This presentation describes recent upgrades to the X-ray beamline at ISAS/JAXA and their applications to the performance characterization of X-ray optics. The ISAS/JAXA X-ray beamline provides a distance of approximately 27 m between the X-ray source and the test optic. It has been used to characterize a variety of flight X-ray optical systems, including those developed for ASTRO-H. Recent upgrades have focused on expanding the beam size and improving the detector system to enhance measurement capabilities (Ishi et al., SPIE 2026, https://doi.org/10.1117/12.3104687). The distance between the test optic and the detector can be flexibly adjusted up to 9 m. The expanded beam now provides an illumination area of 14 cm × 14 cm, large enough to simultaneously illuminate the entire 3 × 3 array of LEO optics planned for HiZ-GUNDAM, a mission targeting launch in the 2030s. This capability allows multiple optical units to be characterized efficiently in a single measurement. In addition, a two-dimensional CMOS imager has been introduced, enabling high-resolution measurements over a 60 mm × 60 mm area with a pixel size of 10 µm. To demonstrate the capabilities of the upgraded beamline for larger optical systems, we have also performed measurements of the 45-cm-aperture X-ray telescope that we developed for the XL-Calibur balloon experiment. Although the telescope has a focal length of 12 m, we have developed a technique to characterize its vignetting, image position, and imaging performance with the detector positioned 6 m from the telescope. By optimizing the stage-scanning procedure and synchronizing the stage position with the detector data using timestamps, these measurements can be completed within a few hours (XL-Calibur Collaboration). This technique extends the measurement capabilities of the beamline to large-aperture, long-focal-length X-ray optics, despite its limited physical dimensions. We continue to improve the beamline and develop measurement techniques to meet two complementary requirements: rapid characterization of compact optical systems, such as the LEO optics for HiZ-GUNDAM, and detailed performance evaluation of large X-ray telescopes, such as the HXT for XL-Calibur.

eROSITA is the soft X-ray telescope on the SRG mission. It has been surveying the X-ray sky every six months from 2019 to 2022, providing a new and remarkably complete view of the high-energy Universe. Following DR1 in January 2024, which saw the release of data from the first all-sky survey, the results from the first three all-sky surveys (eRASS:3) were published in July of this year. These have expanded the known population of X-ray sources to nearly two million objects in the western galactic hemisphere. I will introduce the reduction and detection strategy and will give an overview of the kind and number of sources which where detected.

X-ray monitors are important instruments for observing the activity of X-ray sources over long timescales (even years). We present monitoring of the long-term X-ray activity of the example Aql X-1 (the X-ray binary with the neutron star accretor). Simultaneous monitoring of the same object with several monitors (e.g., ISS/MAXI (2-15 keV) and Swift/BAT (15-50 keV)) and smoothing the data with one-day means enables us to investigate activity across energy bands. Including on-Earth observations from the Zwicky Transient Facility (ZTF) enabled us to combine X-ray and optical data across a series of outbursts in Aql X-1. We show that the X-ray spectrum (especially its hardness) largely varies during some phases of the outbursts. Each outburst has a unique time evolution of X-ray and optical fluxes, so this monitoring can provide data to study the long-term activity of these objects.

The innermost regions of galactic nuclei host complex interactions between supermassive black holes, orbiting stars, compact companions, and accreting gas. Repeating eclipses and absorption events offer a promising way to probe these environments on spatial scales inaccessible to direct imaging. In the X-ray domain, we discuss the discovery of quasi-periodic outflows in the active galactic nucleus ASASSN-20qc, characterized by recurring absorption features separated by approximately 8.3 days. These events can be interpreted as signatures of an intermediate-mass black hole orbiting a supermassive primary and periodically perturbing its accretion flow. At millimeter wavelengths, we explore a complementary mechanism in which evolved stars orbiting within nuclear star clusters occult compact radio cores or photon-ring-like emission regions. Such transits can produce detectable flux decrements whose depths, durations, and recurrence times depend on the stellar population, orbital dynamics, and black hole mass. Together, these phenomena establish time-domain obscuration as a powerful tool for investigating galactic nuclei. We highlight how coordinated X-ray and millimeter monitoring can reveal otherwise hidden companions, constrain the structure of accretion flows, and provide new insights into stellar dynamics and black hole environments.