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121.
Sensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centre
Christopher Eckner, 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

Opis: High-energy gamma rays are promising tools to constrain or reveal the nature of dark matter, in particular Weakly Interacting Massive Particles. Being well into its pre-construction phase, the Cherenkov Telescope Array (CTA) will soon probe the sky in the 20 GeV - 300 TeV energy range. Thanks to its improved energy and angular resolutions as well as significantly larger e˙ective area when compared to the current generation of Cherenkov telescopes, CTA is expected to probe heavier dark matter, with unprecedented sensitivity, reaching the thermal annihilation cross-section at 1 TeV. This talk will summarise the planned dark matter search strategies with CTA, focusing on the signal from the Galactic centre. As observed with the Fermi LAT at lower energies, this region is rather complex and CTA will be the first ground-based observatory sensitive to the large scale di˙use astrophysical emission from that region. We report on the collaboration e˙ort to study the impact of such extended astrophysical backgrounds on the dark matter search, based on Fermi-LAT data in order to guide our observational strategies, taking into account various sources of systematic uncertainty.
Ključne besede: high-energy gamma rays, Cherenkov Telescope Array, dark matter, galactic centre
Objavljeno v RUNG: 18.09.2023; Ogledov: 468; Prenosov: 7
.pdf Celotno besedilo (2,47 MB)
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122.
Cherenkov Telescope Array: the World's largest VHE gamma-ray observatory
Roberta 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: 402; Prenosov: 6
.pdf Celotno besedilo (2,39 MB)
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123.
Bright blazar flares with CTA
M. Cerruti, Saptashwa Bhattacharyya, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The TeV extragalactic sky is dominated by blazars, radio-loud active galactic nuclei with a relativistic jet pointing towards the Earth. Blazars show variability that can be quite exceptional both in terms of flux (orders of magnitude of brightening) and time (down to the minute timescale). This bright flaring activity contains key information on the physics of particle acceleration and photon production in the emitting region, as well as the structure and physical properties of the jet itself. The TeV band is accessed from the ground by Cherenkov telescopes that image the pair cascade triggered by the interaction of the gamma ray with the Earth’s atmosphere. The Cherenkov Telescope Array (CTA) represents the upcoming generation of imaging atmospheric Cherenkov telescopes, with a significantly higher sensitivity and larger energy coverage with respect to current instruments. It will thus provide us with unprecedented statistics on blazar light-curves and spectra. In this contribution we present the results from realistic simulations of CTA observations of bright blazar flares, taking as input state-of-the-art numerical simulations of blazar emission models and including all relevant observational constraints.
Ključne besede: active galactic nuclei, radio-loud AGN, blazars
Objavljeno v RUNG: 15.09.2023; Ogledov: 582; Prenosov: 5
.pdf Celotno besedilo (1,82 MB)
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124.
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, objavljeni znanstveni prispevek na konferenci

Opis: 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.
Ključne besede: gravitational waves, binary neutron star merger, short gamma-ray bursts
Objavljeno v RUNG: 15.09.2023; Ogledov: 665; Prenosov: 4
.pdf Celotno besedilo (1,66 MB)
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125.
Ov to the rescue
Petra Mišmaš, Marko Simonović, 2023, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: Slovenian, morphology, deverbal nouns, nominalizations, verbs, affix, suffixation, multifunctionality
Objavljeno v RUNG: 29.08.2023; Ogledov: 637; Prenosov: 2
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126.
Constraining the sources of ultra-high-energy cosmic rays across and above the ankle with the spectrum and composition data measured at the Pierre Auger Observatory
A. Abdul Halim, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, izvirni znanstveni članek

Opis: In this work we present the interpretation of the energy spectrum and mass composition data as measured by the Pierre Auger Collaboration above 6 × 10[sup]17 eV. We use an astrophysical model with two extragalactic source populations to model the hardening of the cosmic-ray flux at around 5 × 10[sup]18 eV (the so-called "ankle" feature) as a transition between these two components. We find our data to be well reproduced if sources above the ankle emit a mixed composition with a hard spectrum and a low rigidity cutoff. The component below the ankle is required to have a very soft spectrum and a mix of protons and intermediate-mass nuclei. The origin of this intermediate-mass component is not well constrained and it could originate from either Galactic or extragalactic sources. To the aim of evaluating our capability to constrain astrophysical models, we discuss the impact on the fit results of the main experimental systematic uncertainties and of the assumptions about quantities affecting the air shower development as well as the propagation and redshift distribution of injected ultra-high-energy cosmic rays (UHECRs).
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, extensive air showers, UHECR propagation, UHECR energy spectrum, UHECR mass composition
Objavljeno v RUNG: 18.08.2023; Ogledov: 625; Prenosov: 8
.pdf Celotno besedilo (2,39 MB)
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127.
Search for photons above ▫$10^19$▫ eV with the surface detector of the Pierre Auger Observatory
P. Abreu, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2023, izvirni znanstveni članek

Opis: We use the surface detector of the Pierre Auger Observatory to search for air showers initiated by photons with an energy above 10[sup]19 eV. Photons in the zenith angle range from 30 deg. to 60 deg. can be identified in the overwhelming background of showers initiated by charged cosmic rays through the broader time structure of the signals induced in the water-Cherenkov detectors of the array and the steeper lateral distribution of shower particles reaching ground. Applying the search method to data collected between January 2004 and June 2020, upper limits at 95% CL are set to an E[sup]-2 diffuse flux of ultra-high energy photons above 10[sup]19 eV, 2 × 10[sup]19 eV and 4 × 10[sup]19 eV amounting to 2.11 × 10[sup]-3, 3.12 × 10[sup]-4 and 1.72 × 10[sup]-4 km-2 sr-1 yr-1, respectively. While the sensitivity of the present search around 2 × 10[sup]19 eV approaches expectations of cosmogenic photon fluxes in the case of a pure-proton composition, it is one order of magnitude above those from more realistic mixed-composition models. The inferred limits have also implications for the search of super-heavy dark matter that are discussed and illustrated.
Ključne besede: ultra-high-energy cosmic rays, UHE photons, Pierre Auger Observatory, extensive air showers, water Cherenkov detectors
Objavljeno v RUNG: 18.08.2023; Ogledov: 612; Prenosov: 8
.pdf Celotno besedilo (2,46 MB)
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Marko Jakše: Brez gospodarja / Senza padrone / Without a Master : 59. beneški bienale, mednarodna umetnostna razstava, 23. 4.–27. 11. 2022
Narvika Bovcon, Ana Korenini, Borut Kovačec, Jaka Železnikar, Marko Jakše, 2022, programska oprema

Opis: Spletna razstava - interaktivni generator videov iz širšega izbora slik Marka Jakšeta. Paviljon Republike Slovenije na 59. mednarodni umetnostni razstavi – La Biennale di Venezia, Tese all'Isolotto, Arzenali, Benetke, 23. april–27. november 2022. Marko Jakše: Brez gospodarja. Komisar: Aleš Vaupotič. Kustos: Robert Simonišek. Spletišče: Ana Korenini, Borut Kovačec (VIKIDA), Narvika Bovcon, Jaka Železnikar. Producenta: Moderna galerija, Ljubljana, in Kulturno izobraževalno društvo KIBLA. Razstavo in katalog je podprlo Ministrstvo za kulturo Republike Slovenije.
Ključne besede: 59. beneški bienale, Marko Jakše, Paviljon Republike Slovenije, slikarstvom, spletna razstava, interaktivni generator videov
Objavljeno v RUNG: 19.07.2023; Ogledov: 653; Prenosov: 8
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