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1.
Detection of gravitational waves
Gregor Mrak, 2016, diplomsko delo

Opis: This report mainly focuses on the first two detections of gravitational waves (GW). At the beginning of the thesis the historical background of GW explorations is discussed by pointing out some arguments and researchers that were essential for the progress. Continuing with the derivation based on the theory of general relativity, in order to express where certain properties derive. In the main part of the report, the subject of interest becomes Laser interferometer gravitational-wave observatory (LIGO), beginning with the problems occurring on the way to detection, describing different noise sources one by one. After pointing out the problems, solutions are discussed, namely the technological advances made to lower the background noise as much as possible. The chapter (4) points out different parts of the detector which are implemented to produce a clearer signal. As only physical noise reduction methods are not enough, digital signal processing algorithms are mentioned as well which are used to analyze the data. Subsequently the required theoretical knowledge is given, so the main part ends with the analysis of actual data taken from LIGO’s public release for both GW150914 and GW151226 events (first and second official detections). In the conclusion of the report a brief descriptions of various detectors besides Ligo are given and some insight of the future detectors that are planned to be built.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Gravitational waves, Ligo, Binary black hole merger, gravitational wave interferometry...
Ključne besede: Gravitational waves, Ligo, Binary black hole merger, gravitational wave interferometry
Objavljeno: 27.09.2016; Ogledov: 5523; Prenosov: 271
.pdf Polno besedilo (3,27 MB)

2.
Search for UHE neutrinos – in coincidence with LIGO GW150914 event – with the Pierre Auger Observatory
Lili Yang, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: The first gravitational wave transient GW150914 was observed by Advanced LIGO on September 14th, 2015 at 09:50:45 Universal Time. In addition to follow-up electromagnetic observations, the detection of neutrinos will probe deeply and more on the nature of astrophysical sources, especially in the ultra-high energy regime. Neutrinos in the EeV energy range were searched in data collected at the surface detector of the Pierre Auger Observatory within ± 500 s and 1 day after the GW150914 event. No neutrino candidates were found. Based on this non-observation, we derive the first and only one neutrino fluence upper limit at EeV energies for this event at 90% CL, and report constraints on existence of accretion disk around mergers.
Najdeno v: ključnih besedah
Povzetek najdenega: ...gravitational waves, neutrinos, black hole physics...
Ključne besede: gravitational waves, neutrinos, black hole physics
Objavljeno: 06.12.2016; Ogledov: 3743; Prenosov: 0
.pdf Polno besedilo (627,39 KB)

3.
SIFTING FOR SAPPHIRES: SYSTEMATIC SELECTION OF TIDAL DISRUPTION EVENTS IN iPTF
Tiara Hung, Suvi Gezari, Tanja Petrushevska, 2018, izvirni znanstveni članek

Opis: We present results from a systematic selection of tidal disruption events (TDEs) in a wide area (4800 deg2 ) g + R band experiment by the Intermediate Palomar Transient Factory (iPTF) with a rolling cadence of 1 and 3 days. We use photometric selection criteria to down select from a total of 493 nuclear transients detected during the experiment to a sample of 26 blue (g − r < 0 mag) nuclear transients in red host galaxies. Using Swift follow-up UV and X-ray imaging, and ground-based optical spectroscopy, we classify 14 Type Ia supernovae (SNe Ia), 9 highly variable active galactic nuclei (AGNs), 2 confirmed TDEs, and 1 potential core-collapse supernova. From our study, we measure a TDE per galaxy rate of 1.7 +2.85 −1.27 ×10−4 gal−1 yr−1 (90% CL in Poisson statistics) using a galaxy number density estimated from the SDSS luminosity function. We find that it is possible to filter out AGNs by employing a more stringent transient color cut (g − r < −0.2 mag). The UV is an important discriminator for filtering out SN contamination, since in the optical, SNe Ia can appear as blue as TDEs in their early phases. However, the contamination from SN Ia drops significantly with a more stringent spatial offset cut, suggesting higher precision in astrometry is essential for separating TDEs from SNe Ia in the optical. Our most stringent optical photometric selection criteria yields a contamination rate of 4.5:1, allowing for a manageable number of TDE candidates for complete spectroscopic follow-up and real-time classification in the ZTF era.
Najdeno v: ključnih besedah
Povzetek najdenega: ...accretion, accretion disks – black hole physics – galaxies: nuclei – ultraviolet:...
Ključne besede: accretion, accretion disks – black hole physics – galaxies: nuclei – ultraviolet: general
Objavljeno: 02.03.2022; Ogledov: 427; Prenosov: 21
.pdf Polno besedilo (1,18 MB)

4.
Search for Gamma-Ray Emission from Local Primordial Black Holes with the Fermi Large Area Telescope
Gabrijela Zaharijas, 2018, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...astroparticle physics, black hole physics, methods: data analysis...
Ključne besede: astroparticle physics, black hole physics, methods: data analysis
Objavljeno: 23.08.2018; Ogledov: 2479; Prenosov: 0
.pdf Polno besedilo (788,37 KB)

5.
On the GeV Emission of the Type I BdHN GRB 130427A
Laura Beccera, She Sheng Xue, Yu Wang, Narek Sahakyan, Mile Karlica, Yen-Chen Chen, Simonetta Filippi, Christian Cherubini, Carlo Luciano Bianco, Jorge Armando Rueda, Rahim Moradi, Remo Ruffini, 2019, izvirni znanstveni članek

Opis: We propose that the inner engine of a type I binary-driven hypernova (BdHN) is composed of Kerr black hole (BH) in a non-stationary state, embedded in a uniform magnetic field B_0 aligned with the BH rotation axis and surrounded by an ionized plasma of extremely low density of 10^−14 g cm−3. Using GRB 130427A as a prototype, we show that this inner engine acts in a sequence of elementary impulses. Electrons accelerate to ultrarelativistic energy near the BH horizon, propagating along the polar axis, θ = 0, where they can reach energies of ~10^18 eV, partially contributing to ultrahigh-energy cosmic rays. When propagating with $\theta \ne 0$ through the magnetic field B_0, they produce GeV and TeV radiation through synchroton emission. The mass of BH, M = 2.31M ⊙, its spin, α = 0.47, and the value of magnetic field B_0 = 3.48 × 10^10 G, are determined self consistently to fulfill the energetic and the transparency requirement. The repetition time of each elementary impulse of energy ${ \mathcal E }\sim {10}^{37}$ erg is ~10^−14 s at the beginning of the process, then slowly increases with time evolution. In principle, this "inner engine" can operate in a gamma-ray burst (GRB) for thousands of years. By scaling the BH mass and the magnetic field, the same inner engine can describe active galactic nuclei.
Najdeno v: ključnih besedah
Povzetek najdenega: ...binary-driven hypernova (BdHN) is composed of Kerr black hole (BH) in a non-stationary state, embedded...
Ključne besede: black hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena
Objavljeno: 20.07.2020; Ogledov: 1610; Prenosov: 0
.pdf Polno besedilo (1,09 MB)

6.
Follow-up searches for ultra-high energy neutrinos from transient astrophysical sources with the Pierre Auger Observatory
Lukas Zehrer, Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, Michael Schimp, 2019, objavljeni znanstveni prispevek na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...Pierre Auger Observatory, transient astrophysical sources, binary black hole mergers, gravitational wave events, blazar TXS...
Ključne besede: Pierre Auger Observatory, transient astrophysical sources, binary black hole mergers, gravitational wave events, blazar TXS 0506+056, follow-up search for counterpart ultra-high energy neutrinos
Objavljeno: 21.12.2020; Ogledov: 1377; Prenosov: 45
.pdf Polno besedilo (366,82 KB)

7.
Studying TDEs in the era of LSST
Katja Bricman, A. Gomboc, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...disruption of stars by their host supermassive black hole (SMBH) can provide us with important...
Ključne besede: 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).
Objavljeno: 04.01.2021; Ogledov: 1401; Prenosov: 0

8.
Bound debris in stellar TDEs
Aurora Clerici, A. Gomboc, Taj Jankovič, 2020

Najdeno v: ključnih besedah
Povzetek najdenega: ...tidal disruption, black hole, astronomy, astrophyiscs, hydrodynamics...
Ključne besede: tidal disruption, black hole, astronomy, astrophyiscs, hydrodynamics
Objavljeno: 29.07.2021; Ogledov: 954; Prenosov: 0
.pdf Polno besedilo (5,29 MB)

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