1. A Search for Ultra-high-energy Neutrinos from TXS 0506+056 Using the Pierre Auger ObservatoryMarko Zavrtanik, Lukas Zehrer, Danilo Zavrtanik, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, A. Aab, 2020, original scientific article Found in: ključnih besedah
Summary of found: ...TXS 0506+056, the Pierre Auger Observatory, high-energy astrophysics, neutrino astronomy, blazars, transient sources, active galaxies...
Keywords: ultra-high energy neutrinos, blazar TXS 0506+056, the Pierre Auger Observatory, high-energy astrophysics, neutrino astronomy, blazars, transient sources, active galaxies
Published: 20.10.2020; Views: 2308; Downloads: 0
 Fulltext (696,03 KB) |
2. The spectrum and morphology of the Fermi bubblesGabrijela Zaharijas, M. Ackermann, Adrien Albert, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi, R. D. Blandford, 2014, original scientific article Found in: ključnih besedah
Summary of found: ...high energy astrophysics, gamma-rays, diffuse background, ...
Keywords: high energy astrophysics, gamma-rays, diffuse background
Published: 09.05.2017; Views: 3453; Downloads: 18
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3. SUMMER SCHOOL AT FYSIKUMTanja Petrushevska, other performed works Abstract: This summer, for two weeks, 120 high school students (out of 750 applicants) had the opportunity to taste how research is done at Stockholm University. The students worked in small groups under the supervision of doctoral students in chemistry, physics, biology and geology. At the Physics department, the two PhD students Tanja Petrushevska and Seméli Papadogiannakis offered a project that involved supernovae and their host galaxies.
Found in: ključnih besedah
Keywords: summer school for high school students in astrophysics
Published: 06.02.2018; Views: 2512; Downloads: 0
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4. PM SPECIAL – ALLDELES NY UPPTÄCKT INOM SUPERNOVOR OCH GRAVITATIONSLINSNINGKatarina Bendtz, Tanja Petrushevska, other performed works Abstract: I dagarna offentliggjordes att astrofysikerna på (iPTF) Intermediate Palomar Transient Factory detekterat en supernova typ 1a som vars ljus just nu böjs av en galax. Fenomenet kallas ”gravitational lensing” och är en effekt av att rumtiden kröks av massiva objekt, som vi diskuterade i Professor Magenta avsnitt om maskhål. Tanja Petrushevska är doktorand på Stockholms universitet och medlem av iPTF. Hon och de andra i iPTF skriver just nu på artikeln om upptäckten som hon berättar mer om i detta PM special!
Found in: ključnih besedah
Summary of found: ...interview, astrophysics outreach...
Keywords: interview, astrophysics outreach
Published: 06.02.2018; Views: 2567; Downloads: 0
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6. Multi-Messenger Physics With the Pierre Auger ObservatoryKarl-Heinz Kampert, Andrej Filipčič, Gašper Kukec Mezek, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, original scientific article Found in: ključnih besedah
Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays, photons, neutrinos, protons, multi-messenger physics and astrophysics
Published: 06.05.2019; Views: 2572; Downloads: 104
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7. Evidence for Declination Dependence of Ultrahigh Energy Cosmic Ray Spectrum in the Northern HemisphereJ. P. Lundquist, R.U. Abbasi, 2018, other component parts Abstract: The energy of the ultrahigh energy spectral cutoff was measured, integrating over the northern hemisphere sky, by the Telescope Array (TA) collaboration, to be 10^19.78±0.06 eV, in agreement with the High Resolution Fly's Eye (HiRes) experiment, whereas the Pierre Auger experiment, integrating over the southern hemisphere sky, measured the cutoff to be at 10^19.62±0.02 eV. An 11% energy scale difference between the TA and Auger does not account for this difference. However, in comparing the spectra of the Telescope Array and Pierre Auger experiments in the band of declination common to both experiments ( −15.7∘<δ<24.8∘ ) we have found agreement in the energy of the spectral cutoff. While the Auger result is essentially unchanged, the TA cutoff energy has changed to 10^19.59±0.06 eV. In this paper we argue that this is an astrophysical effect.
Found in: ključnih besedah
Summary of found: ... Astrophysics, High Energy Astrophysical Phenomena, UHECR, Cosmic Rays,...
Keywords: Astrophysics, High Energy Astrophysical Phenomena, UHECR, Cosmic Rays, Anisotropy, Energy Spectrum
Published: 27.04.2020; Views: 2237; Downloads: 77
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8. Magnetic Fields and Afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A, and GRB 190114CJorge Armando Rueda, Remo Ruffini, Mile Karlica, Rahim Moradi, Yu Wang, 2020, original scientific article Abstract: GRB 190114C is the first binary-driven hypernova (BdHN) fully observed from initial supernova (SN) appearance to the final emergence of the optical SN signal. It offers an unprecedented testing ground for the BdHN theory, which is here determined and further extended to additional gamma-ray bursts (GRBs). BdHNe comprise two subclasses of long GRBs, with progenitors a binary system composed of a carbon–oxygen star (COcore) and a neutron star (NS) companion. The COcore explodes as an SN, leaving at its center a newborn NS (νNS). The SN ejecta hypercritically accretes on both the νNS and the NS companion. BdHNe I are very tight binaries, where the accretion leads the companion NS to gravitationally collapse into a black hole (BH). In BdHN II, the accretion rate onto the NS is lower, so there is no BH formation. We observe the same afterglow structure for GRB 190114C and other selected examples of BdHNe I (GRB 130427A, GRB 160509A, GRB 160625B) and for BdHN II (GRB 180728A). In all cases, the afterglows are explained via the synchrotron emission powered by the νNS, and their magnetic field structures and their spin are determined. For BdHNe I, we discuss the properties of the magnetic field embedding the newborn BH, which was inherited from the collapsed NS and amplified during the gravitational collapse process, and surrounded by the SN ejecta.
Found in: ključnih besedah
Summary of found: ... Astrophysics - High Energy Astrophysical Phenomena, Astrophysics -...
Keywords: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology
Published: 20.07.2020; Views: 1910; Downloads: 0
Fulltext (1,37 MB) |
9. 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: ...physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena...
Keywords: black hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena
Published: 20.07.2020; Views: 2080; Downloads: 0
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10. Electromagnetic emission of white dwarf binary mergersJorge Armando Rueda, Remo Ruffini, Yu Wang, Carlo Luciano Bianco, J.M. Blanco-Iglesias, Mile Karlica, P. Lorén-Aguilar, Rahim Moradi, Narek Sahakyan, 2019, original scientific article Abstract: It has been recently proposed that the ejected matter from white dwarf (WD) binary mergers can produce transient, optical and infrared emission similar to the "kilonovae" of neutron star (NS) binary mergers. To confirm this we calculate the electromagnetic emission from WD-WD mergers and compare with kilonova observations. We simulate WD-WD mergers leading to a massive, fast rotating, highly magnetized WD with an adapted version of the smoothed-particle-hydrodynamics (SPH) code Phantom. We thus obtain initial conditions for the ejecta such as escape velocity, mass and initial position and distribution. The subsequent thermal and dynamical evolution of the ejecta is obtained by integrating the energy-conservation equation accounting for expansion cooling and a heating source given by the fallback accretion onto the newly-formed WD and its magneto-dipole radiation. We show that magnetospheric processes in the merger can lead to a prompt, short gamma-ray emission of up to ≈ 1046 erg in a timescale of 0.1-1 s. The bulk of the ejecta initially expands non-relativistically with velocity 0.01 c and then it accelerates to 0.1 c due to the injection of fallback accretion energy. The ejecta become transparent at optical wavelengths around ~ 7 days post-merger with a luminosity 1041-1042 erg s-1. The X-ray emission from the fallback accretion becomes visible around ~ 150-200 day post-merger with a luminosity of 1039 erg s-1. We also predict the post-merger time at which the central WD should appear as a pulsar depending on the value of the magnetic field and rotation period.
Found in: ključnih besedah
Summary of found: ... Astrophysics - High Energy Astrophysical Phenomena...
Keywords: Astrophysics - High Energy Astrophysical Phenomena
Published: 20.07.2020; Views: 1916; Downloads: 0
Fulltext (8,22 MB) |
