41. Cherenkov Telescope Array: the World's largest VHE gamma-ray observatoryRoberta Zanin, Saptashwa Bhattacharyya, Barbara MARČUN, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, objavljeni znanstveni prispevek na konferenci (vabljeno predavanje) Opis: Very-High Energy (VHE) gamma-ray astroparticle physics is a relatively young field, and obser-vations over the past decade have surprisingly revealed almost two hundred VHE emitters which appear to act as cosmic particle accelerators. These sources are an important component of the Universe, influencing the evolution of stars and galaxies. At the same time, they also act as a probe of physics in the most extreme environments known - such as in supernova explosions, and around or after the merging of black holes and neutron stars. However, the existing experiments have provided exciting glimpses, but often falling short of supplying the full answer. A deeper understanding of the TeV sky requires a significant improvement in sensitivity at TeV energies, a wider energy coverage from tens of GeV to hundreds of TeV and a much better angular and energy resolution with respect to the currently running facilities. The next generation gamma-ray observatory, the Cherenkov Telescope Array Observatory (CTAO), is the answer to this need. In this talk I will present this upcoming observatory from its design to the construction, and its potential science exploitation. CTAO will allow the entire astronomical community to explore a new discovery space that will likely lead to paradigm-changing breakthroughs. In particular, CTA has an unprecedented sensitivity to short (sub-minute) timescale phenomena, placing it as a key instrument in the future of multi-messenger and multi-wavelength time domain astronomy. I will conclude the talk presenting the first scientific results obtained by the LST-1, the prototype of one CTA telescope type - the Large Sized Telescope, that is currently under commission.
Ključne besede: Very-High Energy Gamma-rays, Cherenkov Telescope Array
Objavljeno v RUNG: 18.09.2023; Ogledov: 1928; Prenosov: 7
 Celotno besedilo (2,39 MB)
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42. Low-luminosity jetted AGN as particle multi-messenger sourcesAnita Reimer, Margot Boughelilba, Lukas Merten, Paolo Da Vela, Jon Paul Lundquist, Serguei Vorobiov, 2023, objavljeni povzetek znanstvenega prispevka na konferenci Opis: The detection of cosmic gamma rays, high-energy neutrinos and cosmic rays (CRs) signal the existence of environments in the Universe that allow particle acceleration to extremely high energies. These observable signatures from putative CR sources are the result of in-source acceleration of particles, their energy and time-dependent transport including interactions in an evolving environment and their escape from source, in addition to source-to-Earth propagation.
Low-luminosity AGN jets constitute the most abundant persistent jet source population in the local Universe. The dominant subset of these, Fanaroff-Riley 0 (FR0) galaxies, have recently been proposed as sources contributing to the ultra-high-energy cosmic ray (UHECR) flux observed on Earth. This presentation assesses the survival, workings and multi-messenger signatures of UHECRs in low-luminosity jet environments, with focus on FR0 galaxies. For this purpose we use our recently developed, fully time-dependent CR particle and photon propagation framework which takes into account all relevant secondary production and energy loss processes, allows for an evolving source environment and efficient treatment of transport non-linearities due to the produced particles/photons being fed back into the simulation chain.
Finally, we propagate UHE cosmic-ray nuclei and secondary cosmogenic photons and neutrinos from FR0 galaxies to Earth for several extragalactic magnetic field scenarios using the CRPropa3 framework, and confront the resulting energy spectra and composition on Earth with the current observational situation.
Ključne besede: multi-messenger astrophysics, ultra-high-energy cosmic rays, very-high-energy gamma-rays
Objavljeno v RUNG: 13.09.2023; Ogledov: 2433; Prenosov: 8
 Povezava na datoteko
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43. Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic CloudA. Acharyya, R. Adam, Saptashwa Bhattacharyya, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2023, izvirni znanstveni članek Opis: A deep survey of the Large Magellanic Cloud at ∼ 0.1−100 TeV photon energies with the Cherenkov Telescope Array is planned.
We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters,
mock populations of sources, and interstellar emission on galactic scales. We also assess the detectability of 30 Doradus and SN 1987A, and the constraints that can be derived on the nature of dark matter. The survey will allow for fine spectral studies of N 157B, N 132D, LMC P3, and 30 Doradus C, and half a dozen other sources should be revealed, mainly pulsar-powered
objects. The remnant from SN 1987A could be detected if it produces cosmic-ray nuclei with a flat power-law spectrum at high energies, or with a steeper index 2.3−2.4 pending a flux increase by a factor > 3−4 over ∼ 2015−2035. Large-scale interstellar emission remains mostly out of reach of the survey if its > 10 GeV spectrum has a soft photon index ∼ 2.7, but degree-scale 0.1 − 10 TeV pion-decay emission could be detected if the cosmic-ray spectrum hardens above >100 GeV. The 30 Doradus star-forming region is detectable if acceleration efficiency is on the order of 1 − 10% of the mechanical luminosity and diffusion is suppressed by two orders of magnitude within < 100 pc. Finally, the survey could probe the canonical velocity-averaged cross section for self-annihilation of weakly interacting massive particles for cuspy Navarro-Frenk-White profiles.
Ključne besede: very-high energy (VHE) gamma-rays, Cherenkov Telescope Array Observatory, Large Magellanic Cloud, pulsar wind nebulas, galaxiesstar-forming regions, cosmic rays, dark matter
Objavljeno v RUNG: 02.06.2023; Ogledov: 2965; Prenosov: 4
Celotno besedilo (3,66 MB) |
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45. Multi-messenger studies with the Pierre Auger ObservatoryLukas Zehrer, Andrej Filipčič, Gašper Kukec Mezek, Jon Paul Lundquist, Samo Stanič, Marta Trini, Serguei Vorobiov, Marko Zavrtanik, Danilo Zavrtanik, 2021, objavljeni znanstveni prispevek na konferenci Opis: Over the past decade the multi-messenger astrophysics has emerged as a distinct discipline,
providing unique insights into the properties of high-energy phenomena in the Universe. The
Pierre Auger Observatory, located in Malargüe, Argentina, is the world’s largest cosmic ray
detector sensitive to photons, neutrinos, and hadrons at ultra-high energies. Using its data, stringent
limits on photon and neutrino fluxes at EeV energies have been obtained. The collaboration uses
the excellent angular resolution and the neutrino identification capabilities of the Observatory
for follow-up studies of events detected in gravitational waves or other messengers, through
cooperation with global multi-messenger networks. We present a science motivation together
with an overview of the multi-messenger capabilities and results of the Pierre Auger Observatory.
Ključne besede: high-energy cosmic phenomena, multi-messenger astrophysical studies, cosmic rays, gamma-rays, neutrinos, Pierre Auger Observatory
Objavljeno v RUNG: 06.05.2022; Ogledov: 2569; Prenosov: 0
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46. Catalog of long-term transient sources in the first 10 yr of Fermi-LAT dataL. Baldini, J. Ballet, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, E. D. Bloom, Gabrijela Zaharijas, 2021, izvirni znanstveni članek Ključne besede: high energy astrophysics, active galactic nuclei, gamma-ray bursts, solar flares, solar gamma-ray emission
Objavljeno v RUNG: 17.02.2022; Ogledov: 2891; Prenosov: 42
Povezava na celotno besedilo
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48. On the GeV Emission of the Type I BdHN GRB 130427ARemo Ruffini, Rahim Moradi, Jorge Armando Rueda, Carlo Luciano Bianco, Christian Cherubini, Simonetta Filippi, Yen-Chen Chen, Mile Karlica, Narek Sahakyan, Yu Wang, She Sheng Xue, Laura Beccera, 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.
Ključne besede: black hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena
Objavljeno v RUNG: 20.07.2020; Ogledov: 4112; Prenosov: 0
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49. The bursts of high energy events observed by the telescope array surface detectorR.U. Abbasi, Jon Paul Lundquist, 2017, izvirni znanstveni članek Opis: The Telescope Array (TA) experiment is designed to detect air showers induced by ultra high energy cosmic rays. The TA ground Surface particle Detector (TASD) observed several short-time bursts of air shower like events. These bursts are not likely due to chance coincidence between single shower events. The expectation of chance coincidence is less than 10^-4 for five-year's observation. We checked the correlation between these bursts of events and lightning data, and found evidence for correlations in timing and position. Some features of the burst events are similar to those of a normal cosmic ray air shower, and some are not. On this paper, we report the observed bursts of air shower like events and their correlation with lightning.
Ključne besede: High energy radiation, Lightning, Terrestrial gamma-ray flash
Objavljeno v RUNG: 30.04.2020; Ogledov: 3948; Prenosov: 0
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50. Monte Carlo studies for the optimisation of the Cherenkov Telescope Array layoutA. Acharyya, Samo Stanič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2019, izvirni znanstveni članek Ključne besede: very-high energy gamma-ray astronomy, Cherenkov Telescope Array, array layout optimisation, Monte Carlo studies
Objavljeno v RUNG: 18.04.2019; Ogledov: 4186; Prenosov: 0
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