1. Search for UHE neutrinos – in coincidence with LIGO GW150914 event – with the Pierre Auger ObservatoryLili Yang, 2016, published scientific conference contribution abstract Abstract: 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.
Found in: ključnih besedah
Summary of found: ...gravitational waves, neutrinos, black hole physics...
Keywords: gravitational waves, neutrinos, black hole physics
Published: 06.12.2016; Views: 4384; Downloads: 0
 Fulltext (627,39 KB) |
2. SIFTING FOR SAPPHIRES: SYSTEMATIC SELECTION OF TIDAL DISRUPTION EVENTS IN iPTFTiara Hung, Suvi Gezari, Tanja Petrushevska, 2018, original scientific article Abstract: 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.
Found in: ključnih besedah
Summary of found: ...accretion, accretion disks – black hole physics – galaxies: nuclei – ultraviolet:...
Keywords: accretion, accretion disks – black hole physics – galaxies: nuclei – ultraviolet: general
Published: 02.03.2022; Views: 883; Downloads: 54
Fulltext (1,18 MB) |
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4. On the GeV Emission of the Type I BdHN GRB 130427ALaura 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, original scientific article Abstract: 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.
Found in: ključnih besedah
Summary of found: ...binary-driven hypernova (BdHN) is composed of Kerr black hole (BH) in a non-stationary state, embedded... ...black hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics...
Keywords: black hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena
Published: 20.07.2020; Views: 2089; Downloads: 0
Fulltext (1,09 MB) |
5. Studying TDEs in the era of LSSTKatja Bricman, A. Gomboc, 2019, published scientific conference contribution abstract Found in: ključnih besedah
Summary of found: ...disruption of stars by their host supermassive black hole (SMBH) can provide us with important... ...CA16104 Gravitational waves, black holes and fundamental physics (GWverse), supported by COST (European Cooperation in...
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: 04.01.2021; Views: 1837; Downloads: 0 |
6. The mass fallback rate of the debris in relativistic stellar tidal disruption eventsTaj Jankovič, 2022, published scientific conference contribution abstract Abstract: Highly energetic stellar tidal disruption events (TDEs) provide a way to study black hole characteristics and their environment. We simulate TDEs in a general relativistic and Newtonian description of a supermassive black hole's gravity. Stars, which are placed on parabolic orbits with different impact parameters, are constructed with the stellar evolution code MESA and therefore have realistic stellar density profiles. We focus our analysis on the mass fallback rate of the debris, which can trace the observed light curve of TDEs. I will present the dependence of the mass fallback rate of the debris on the impact parameter, stellar mass and age as well as the black hole's spin and the choice of the gravity's description.
Found in: ključnih besedah
Summary of found: ...events (TDEs) provide a way to study black hole characteristics and their environment. We simulate... ...black hole physics, hydrodynamics, relativistic processes...
Keywords: black hole physics, hydrodynamics, relativistic processes
Published: 21.10.2022; Views: 475; Downloads: 2
Fulltext (15,78 MB)
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