List of abstracts
2020

7

High Energy Astrophysics (7)

record_voice_over Franco Giovannelli
The Impact of Space- and Ground-based Experiments on Our Knowledge of the Physics of the Universe in the Gravitational Wave Era

The advent of Space Experiments in the second half of the 20th century opened practically all the energy bands to be observed. This, together with ground-based experiments, allowed us to better understand the physics governing our Universe. The recent detection of gravitational waves (GWs) from space opened a new era of multimessenger astrophysics. With the new generation of GW detectors, new big and small space and ground-based experiments, our knowledge of the Universe will receive a strong impulse for a better understanding of the main pillars of the Bridge Between the Big Bang and Biology. In this talk I will discuss the main results obtained, without the pretence of completeness, and the outstanding problems that hopefully will be gradually closed in the coming decades.


record_voice_over Vladimir Karas
Effects of tidal disruption near an accreting supermassive black hole

Interaction between a plunging star and the environment of an accreting black hole can provide new routes of orbital migration of tidal disruption event (TDE) progenitors at late stages before the disruption. We discuss TDEs as an additional source of material to supply the accretion disc. In cores of active galactic nuclei, tidal disruption events can exhibit more varied signatures compared to a clean profile of light curves from TDE near a quiescent black hole. At the same time different modes of star-disc interaction influence the rate at which the embedded progenitors proceed down to the critical radius for TDE.


record_voice_over Debora Lančová
Puffy Accretion Disk: Properties and Observatioal Appereance

We obtained a new type of accretion disk as a result of simulations we performed using GRRMHD (General Relativistic Radiative Magnetohydrodynamical) code Koral. Our solution, which we named Puffy accretion disk, combines properties of a thin, slim and thick disk, has high-density core in the equatorial plane and optically thick corona. Most of the inflow occurs through a turbulent highly advective Keplerian region surrounding the core. The disk is radiation pressure dominated and thermally stable due to radial net flux of magnetic field. A significant part of the radiation from the disk is captured by the central black hole, so the disk is less luminous than a thin disk would be at the same accretion rate. The observed flux strongly depends on the inclination angle and the observed spectra have properties different from analytical models.


receipt Kateřina Klimovičová
Time-scale of twin-peak quasi-periodic oscillations and mass of accreting neutron stars

In more than a dozen of low-mass X-ray binarys, twin-peak quasi-periodic oscillations (QPOs) have been observed. We present a comparison among these sources. The comparison is Inspired by the expected proportionality between periods of orbital motion of an accretion material and mass of the central compact object. In our paper Török et al. (2019) we identify characteristic time-scales of QPOs associated with individual sources. It is believed that the time-scales can be determined by the relative mass of each compact object. We show that the characteristic time-scale of the millisecond pulsar XTE J1807.4-294 is longer than for most other low-mass X-ray binarys containing neutron star. We also discuss some possible explanation of exceptionality of this pulsar.


receipt Monika Matuszková
Oscillations of non-slender tori in the Hartle-Thorne geometry

We examine the influence of the quadrupole moment of slowly rotating neutron stars on oscillations of non-slender accretion tori. We focus on a perfect fluid, polytropic, constant specific angular momentum, non-selfgravitating torus for which we analytically obtain oscillating frequencies that were so far studied in approximative Kerr geometry. We apply known methods for calculation of radial and vertical axisymmetric and non-axisymmetric (m = -1) epicyclic modes of oscillating accretion tori in the Hartle-Thorne geometry with accuracy up the second order terms in the angular momentum of the neutron star and the first order in its quadrupole moment. Our results can be used to study properties of relativistic compact objects through the phenomenon known as the quasi-periodic oscillations.


receipt Zuzana Turoňová
Relativistic Iron Line Emission from Neutron Stars

In today’s X-ray satellite astronomy, the issue of efficiency of processing large amounts of observational data needs to be addressed as well as their rapid comparison with theoretical models. Therefore, the main motivation of our work was to create very fast code. We focused on developing an analytical approximation to construct relativistic projection of the surface of spherically symmetric neutron stars in the Schwarzschild spacetime. Based on the analytical expression of the transfer function, a numerical code LSDmini was developed for modeling the relativistic projection of neutron star’s surface and relativistic spectral profiles of the iron Kα lines. We analyzed the influence of gravitational lensing and gravitational and Doppler shifts on the resulting spectral profiles as well as the dependence of spectral profiles on the angular radius of the radiating surface of the neutron star.


receipt Gabriela Urbancová
Epicyclic oscillations in the Hartle-Thorne external geometry

The external Hartle-Thorne geometry, which describes the spacetime outside a slowly rotating compact star, is characterised by the gravitational mass M, angular momentum J, and quadrupole moment Q of the star and gives a convenient description, which, for the rotation frequencies of more than 95% of known pulsars, is sufficiently accurate for most purposes. Our investigation is motivated by X-ray observations of binary systems containing a rotating neutron star that is accreting matter from its binary companion. We use realistic equations of state for the stellar matter and proceed in a self-consistent way, following the Hartle-Thorne approach in calculating both the corresponding values of Q, M, and J for the stellar model and the properties of the surrounding spacetime. Our results are then applied to a range of geodetical models for QPOs.


Gamma-Ray Bursts & Robotic Telescopes (1)

record_voice_over Attila Meszaros
Spatial distribution of the gamma-ray bursts: Impact on the global properties of the Universe

The gamma-ray bursts (GRBs) are at cosmological distances, and do not vanish at the plane of Milky Way. Hence, they may well serve for the observational testing of the Cosmological Principle requiring an isotropic and homogeneous distribution of any cosmological sources at the observable part of the Universe. In this contribution the author\'s, his collaborators\' and also other\'s published articles are surveyed from this topic. Both the redshift distribution and the angular sky positions are discussed. Briefly also other cosmological observations (cf. fast-radio sources, dipole anisotropy of the cosmic microwave background radiation) are surveyed, too. Finally, the surprising conclusions concerning the Cosmological Principle and the global properties of the Universe are provided.


Small satellites & Instrumental session (8)

record_voice_over Enrico Bozzo
The ESA M5 mission candidate THESEUS

THESEUS is a mission concept proposed in response to the ESA call for medium-size mission (M5) within the Cosmic Vision Programme and selected by ESA on 2018 May 7 to enter an assessment phase study. The mission is designed to vastly increase the discovery space of the high energy transient phenomena over the entirety of cosmic history. Its primary scientific goals will address the Early Universe ESA Cosmic Vision themes “How did the Universe originate and what is made of?” (4.1, 4.2 and 4.3) and will also impact on “The gravitational wave Universe” (3.2) and “The hot and energetic Universe” themes. This is achieved via a unique payload providing an unprecedented combination of: 1) wide and deep sky monitoring in a broad energy band (0.3keV - 20 MeV); 2) focusing capabilities in the soft X-ray band providing large grasp and high angular resolution; and 3) on board near-IR capabilities for immediate transient identification and redshift determination. In this talk we will review the status of the mission current assessment phase being carried out in collaboration with ESA as part of the M5 competition.


record_voice_over Rene Hudec
ESA SMILE and Czech Participation: X-ray Astrophysics as Secondary Science

The Solar wind Magnetosphere Ionosphere Link Explorer, or SMILE, is a joint mission between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). SMILE aims to build a more complete understanding of the Sun-Earth connection by measuring the solar wind and its dynamic interaction with the magnetosphere. SMILE will gather remote-sensing (X-ray) measurements of Earth\'s magnetospheric cusps, magnetopause, and bow shock, while also providing simultaneous auroral imaging (UV) of Earth, and coordinated in situ measurements (plasma and magnetic). These data will complement and build on the localized data provided by existing ground- and space-based observatories, including ESA\'s Cluster and Swarm missions, and NASA\'s Magnetospheric Multiscale Mission (MMS). The SXI – Soft X-ray Imager represents the main onboard telescope. The SXI is a wide-field lobster-eye telescope using wide-field X-ray optics to spectrally map the location, shape, and motion of Earth\'s magnetospheric boundaries, including the bow shock, magnetopause, and cusps, by observing emission from the solar wind charge exchange (SWCX) process. The SXI is equipped with two large X-ray-sensitive CCD detectors covering the 0.2 keV to 2.5 keV energy band and provides a large field of view (FOV) of 15.5° × 26.5°. This large FOV offers the possibility to study not only the X-ray emission from the magnetosphere, but also celestial X-ray sources passing through the FOV. We will discuss the SMILE SXI importance for X-ray astrophysics in general and will present selected examples of celestial X-ray sources to be observed and monitored in particular.


record_voice_over Rene Hudec
Astronomy and Astrophysics with Cubesatellites

The recent progress in cube satellite technology and engineering along with instrumental miniaturization allows astronomical and astrophysical applications to be considered based on these nanosatellites. This includes not only single minisatellites but also tandem flights and satellite fleets. Albeit recently most of the cube satellites orbit our Earth, one can also consider these nanosatellites to investigate a more distant universe e.g. Moon and other planetary system bodies including comets and asteroids. I will present and discuss the recent status of astronomical and astrophysical applications with emphasis on X-ray and UV astronomy along with some related applications including planetary system bodies surface X-ray fluorescence analyses, meteor UV spectroscopy, and observations of meteoroid impacts on the Moon surface.


record_voice_over Michael Mann
Power Quality at Observatories: Measurement, Analysis and Evaluation

Within the context of the Project SLOBATCO in 2018, the requirement of a full-scale Power Quality measurement campaign was substantiated to analyse the electric power grid supplying observatories. In 2020, time-synchronized measurements were performed at the power grid of Skalnaté Pleso stellar observatory, Lomnicky Peak solar observatory and the Astronomical Institute of the Slovak Academy of Sciences at Tatranská Lomnica, Slovakia. The measurement and analysis of high-resolution voltage and current signals at 5 measurement points allows for a detailed assessment of the electric grid. This contribution summarizes the first results and puts the outcomes of the campaign in perspective with current power quality standards and additional requirements.


record_voice_over Klaus Schilling
Small Satellite Formations: Innovative Sensor Networks in Space

Internet of Things raises challenging demands for connecting sensors and actuators via communication links, as well as for networked control. Those techniques enable also networks of small satellites in low Earth orbits (LEO) for Earth, as well as for astronomical observations. The University Würzburg’s Experimental satellite (UWE) program used a step by step approach to develop and test in orbit the crucial technologies for formation flying at minimum mass. Key technologies related to communication, attitude and orbit determination and control, were successfully demonstrated in orbit. Advanced formation missions like NetSat, TOM, CloudCT, and future application perspectives in astronomy will be addressed.


receipt Rene Hudec
Digitization and astrophysical application of astronomical photographic plate collections in Austria

We will report and discuss the preliminary results of a small collaborative Czech Austrian project on Digitization and astrophysical application of astronomical photographic plate collections in Austria. The key was the visit and inspection of two important archives of astronomical photographic plates in Austria, at the University Observatory in Vienna, and at the Kuffner Observatory in Vienna. The technical and scientific value of both archives was assessed, with emphasis on the use of these databases in modern astrophysics. At the University Observatory, approximately 10,000 archival photographic plates were identified, which were evaluated in particular with regard to their archiving status, suitability for digitization and scientific significance. The inspection itself contained 9600 records, about half of superior quality, of which 1000 were digitized. Relevant metadata and observation logs and protocols were also studied and digitized. The plates were found well stored, suitable for digitization and with appropriate metadata. At the Kuffner Observatory, about 600 perfectly archived astrophotographic glass negatives were acquired using a long-focal astrometric telescope. The collection has a strong historical subtext as it contains historically valuable experiments by Professor Schwarzschild dating back almost 100 years ago to prove the Schwarzschild effect discovered and named after him.


receipt Rene Hudec
Lunar CubeSat mission

The application areas of cube satellites are rapidly growing including placing the minisatellites also outside Earth orbits, based on recent progress in nanosatellite technologies. We present and evaluate the design of a small and cost-effective CubeSat mission to be placed on lunar orbit. Its scientific payload will monitor lunar meteoroid impacts by detecting their optical flashes. We discuss past and recent ground-based and satellite-based projects focussing on monitoring of these events and discuss important aspects of the proposed mission and various alternatives for their solutions. Several spacecraft orbits around Moon and their usefulness for lunar impact observation are studied. In addition, we discuss the environmental risks and challenges, which such spacecraft needs to face, mainly thermal management and radiation tolerance. In addition to that, we propose the design of an optical camera suitable to detect meteoroid impacts on the lunar surface.


receipt Ondrej Nentvich
Ray-tracing simulation program for Lobster-eye optics in Python



record_voice_over - Talks (9) receipt - Posters (7)