Repository of University of Nova Gorica

Search the repository
A+ | A- | Help | SLO | ENG

Query: search in
search in
search in
search in
* old and bologna study programme


1 - 10 / 24
First pagePrevious page123Next pageLast page
Follow-up Search for UHE Photons from Gravitational Wave Sources with the Pierre Auger Observatory
P. Ruehl, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, published scientific conference contribution

Abstract: Multimessenger astronomy has become increasingly important during the past decade. Some astronomical objects have already been successfully observed in the light of multiple messenger signals, allowing for a much deeper understanding of their physical properties. The Pierre Auger Observatory has taken part in multimessenger astronomy with an exhaustive exploration of the ultra-high-energy sky. In this contribution, for the first time, a search for UHE photons from the sources of gravitational waves is presented. Interactions with the cosmic background radiation fields are expected to attenuate any possible flux of ultra-high-energy photons from distant sources and a non-negligible background of air shower events with hadronic origin makes an unambiguous identification of primary photons a challenging task. In the analysis presented here, a selection strategy is applied to both GW sources and air shower events aiming to provide maximum sensitivity to a possible photon signal. At the same time, a window is kept open for hypothetical new-physics processes, which might allow for much larger interaction lengths of photons in the extragalactic medium. Preliminary results on the UHE photon fluence from a selection of GW sources, including the binary neutron star merger GW170817 are presented.
Keywords: Pierre Auger Observatory, indirect detection, fluorescence detection, ultra-high energy, photons, cosmic rays, anisotropy, gravitational waves, multimessenger
Published in RUNG: 29.09.2023; Views: 820; Downloads: 6
.pdf Full text (940,08 KB)
This document has many files! More...

Searching for very-high-energy electromagnetic counterparts to gravitational-wave events with the Cherenkov Telescope Array
Barbara Patricelli, Saptashwa Bhattacharyya, Barbara MARČUN, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, published scientific conference contribution

Abstract: The detection of electromagnetic (EM) emission following the gravitational wave (GW) event GW170817 opened the era of multi-messenger astronomy with GWs and provided the first direct evidence that at least a fraction of binary neutron star (BNS) mergers are progenitors of short Gamma-Ray Bursts (GRBs). GRBs are also expected to emit very-high energy (VHE, > 100 GeV) photons, as proven by the recent MAGIC and H.E.S.S. observations. One of the challenges for future multi-messenger observations will be the detection of such VHE emission from GRBs in association with GWs. In the next years, the Cherenkov Telescope Array (CTA) will be a key instrument for the EM follow-up of GW events in the VHE range, owing to its unprecedented sensitivity, rapid response, and capability to monitor a large sky area via scan-mode operation. We present the CTA GW follow-up program, with a focus on the searches for short GRBs possibly associated with BNS mergers. We investigate the possible observational strategies and we outline the prospects for the detection of VHE EM counterparts to transient GW events.
Keywords: Cherenkov Telescope Array, very-high energy photons, gravitational waves, gravitational wave counterparts
Published in RUNG: 19.09.2023; Views: 1047; Downloads: 6
.pdf Full text (1,52 MB)
This document has many files! More...

Chasing gravitational waves with the Cherenkov Telescope Array
J. G. Green, Saptashwa Bhattacharyya, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2023, published scientific conference contribution

Abstract: The detection of gravitational waves (GWs) from a binary neutron star (BNS) merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this GW event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100 GeV) photons which have yet to be detected in coincidence with a GW signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. Achieving such a feat will require a comprehensive real-time strategy capable of coordinating searches over potentially very large regions of the sky. This work will evaluate and provide estimations on the number of GW-CTA events determined from simulated BNS systems and short GRBs, considering both on and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA.
Keywords: gravitational waves, binary neutron star merger, short gamma-ray bursts
Published in RUNG: 15.09.2023; Views: 980; Downloads: 4
.pdf Full text (1,66 MB)
This document has many files! More...

Business-information system for smart homes based on Z-Wave technology : diploma thesis
David Manchevski, 2021, undergraduate thesis

Abstract: The goal of this thesis is to show how to create a system, that can be implemented in today’s market of smart home modules. This will be done by introducing how the Z-Wave technology works, how it can be implemented in the user’s home. Furthermore, the functionalities of the Z-Wave technology will be presented together with the Z-Wave modules and their everyday uses. In addition, the business-information system can put on display how a smart home company operates, how the data is distributed between the departments of said smart home company. The business-information system is shown with the help of a data flow diagrams, entity relationship diagrams and a database of the data that is stored inside the particular database. This system will be used by a user interested in the buying the smart home technology products, partners, Z-wave certifiers, reclamation department.
Keywords: Z-Waves, smart homes, business-information systems, entity-relationship, processes, data flows, data stores, modules, diploma thesis
Published in RUNG: 24.01.2022; Views: 2308; Downloads: 79
URL Link to full text
This document has many files! More...

Gravity wave instability structures and turbulence from more than 1.5 years of OH[ast] airglow imager observations in Slovenia
René Sedlak, Patrick Hannawald, Carsten Schmidt, Sabine Wüst, Michael Bittner, Samo Stanič, 2021, original scientific article

Abstract: We analyzed 286 nights of data from the OH* airglow imager FAIM 3 (Fast Airglow IMager) acquired at Otlica Observatory, Slovenia, between 26 October 2017 and 6 June 2019. Measurements were performed with a spatial resolution of 24 m per pixel and a temporal resolution of 2.8 s. Multiple turbulence episodes were observed and the energy dissipation rate in the upper mesosphere/lower thermosphere region was estimated from image sequences in 25 cases. Values range around 0.08 and 9.03 W/kg and would lead to an approximated localized maximum heating of 0.03–3.02 K per turbulence event.
Keywords: upper mesosphere, lower thermosphere, remote sensing, gravity waves, turbulence, Bora episodes
Published in RUNG: 25.10.2021; Views: 1993; Downloads: 0
This document has many files! More...

Space-time ripples
Taj Jankovič, 2017, professional article

Abstract: Recent first direct detection of gravitational waves opened a new window on the universe. Gravitational waves arise from small perturbations of space-time and from their characteristics it is possible to determine properties of astrophysical objects from which they originate. In this seminar Einstein equation is introduced to describe gravitational waves and ascertain their properties. Furthermore, possible astrophysical sources are presented, as well as the first directly and indirectly detected event.
Keywords: gravitation, gravitational waves, theory of relativity, astrophysics
Published in RUNG: 29.07.2021; Views: 1965; Downloads: 0

Studying TDEs in the era of LSST
Katja Bricman, Andreja Gomboc, 2019, published scientific conference contribution abstract

Keywords: The observing strategy with continuous scanning and large sky coverage of the upcoming ground-based Large Synoptic Survey Telescope (LSST) will make it a perfect tool in search of rare transients, such as Tidal Disruption Events (TDEs). Bright optical flares resulting from tidal disruption of stars by their host supermassive black hole (SMBH) can provide us with important information about the mass of the SMBH involved in the disruption and thus enable the study of quiescent SMBHs, which represent a large majority of SMBHs found in centres of galaxies. These types of transients are extremely rare, with only about few tens of candidates discovered so far. It is expected that the LSST will provide a large sample of new TDE light curves. Here we present simulations of TDE observations using an end-to-end LSST simulation framework. Based on the analysis of simulated light curves we estimate the number of TDEs with good quality light curves the LSST is expected to discover in 10 years of observations. In addition, we investigate whether TDEs observed by the LSST could be used to probe the SMBH mass distribution in the universe. The participation at this conference is supported by the Action CA16104 Gravitational waves, black holes and fundamental physics (GWverse), supported by COST (European Cooperation in Science and Technology).
Published in RUNG: 04.01.2021; Views: 2833; Downloads: 0

Orographic gravity waves in OH-airglow imaging systems
Sabine Wuest, Jonas Till, René Sedlak, Patrick Hannawald, Carsten Schmidt, Samo Stanič, Michael Bittner, 2020, published scientific conference contribution abstract

Abstract: Atmospheric dynamics is strongly influenced by waves on different scales. Airflow over mountains can lead to all kinds of atmospheric waves, planetary and gravity waves as well as infrasound. Under certain circumstances these waves can propagate through the atmosphere and lead to a re- distribution of energy. In the case of gravity waves, a stably stratified atmosphere is a mandatory requirement for their generation and vertical propagation. Additionally, the vertical propagation depends on the horizontal wind field. In the Alpine and pre-Alpine region, we currently operate five OH-airglow imaging systems, which allow the investigation of orographic gravity waves. Depending on tropo-, strato- and mesospheric wind and temperature, it is checked which wavelengths can propagate into the fields of view of our instruments. This is done for a whole year in order to take into account annual and semi- annual cycles in wind and temperature. Concerning the generation of gravity waves, we put our focus on our OH-airglow imager (FAIM) deployed at Otlica (45.9°N, 13.9°E), Slovenia. Here, we also have additional measurements of an OH-airglow spectrometer (GRIPS). In case studies, we investigate whether strong wind events (Bora) lead to strong gravity waves activity or enhanced potential energy density.
Keywords: Orographic gravity waves, Bora, Otlica, Slovenia, OH-airglow imaging
Published in RUNG: 08.10.2020; Views: 2634; Downloads: 0
This document has many files! More...

Lidar Observations of Mountain Waves During Bora Episodes
Longlong Wang, Marija Bervida, Samo Stanič, Klemen Bergant, William Eichinger, Benedikt Strajnar, 2020, published scientific conference contribution

Abstract: Airflows over mountain barriers in the Alpine region may give rise to strong, gusty downslope winds, called Bora. Oscillations, caused by the flow over an orographic barrier, lead to formation of mountain waves. These waves can only rarely be observed visually and can, in general, not be reliably reproduced by numerical models. Using aerosols as tracers for airmass motion, mountain waves were experimentally observed during Bora outbreak in the Vipava valley, Slovenia, on 24-25 January 2019 by two lidar systems: a vertical scanning lidar positioned just below the peak of the lee side of the mountain range and a fixed direction lidar at valley floor, which were set up to retrieve two-dimensional structure of the airflow over the orographic barrier into the valley. Based on the lidar data, we determined the thickness of airmass layer exhibiting downslope motion, observed hydraulic jump phenomena that gave rise to mountain waves and characterized their properties.
Keywords: Bora, mountain waves, lidar observations
Published in RUNG: 08.07.2020; Views: 2942; Downloads: 0
This document has many files! More...

Search done in 0.06 sec.
Back to top