11. Detection methods for the Cherenkov Telescope Array at very-short exposure timesAmbra Di Piano, 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: The Cherenkov Telescope Array (CTA) will be the next generation ground-based observatory for very-high-energy (VHE) gamma-ray astronomy, with the deployment of tens of highly sensitive and fast-reacting Cherenkov telescopes. It will cover a wide energy range (20 GeV - 300 TeV) with unprecedented sensitivity. To maximize the scientific return, the observatory will be provided with an online software system that will perform the first analysis of scientific data in real-time. This study investigates the precision and accuracy of available science tools and analysis techniques for the short-term detection of gamma-ray sources, in terms of sky localization, detection significance and, if significant detection is achieved, a first estimation of the integral photon flux. The scope is to evaluate the feasibility of the algorithms’ implementation in the real-time analysis of CTA. In this contribution we present a general overview of the methods and some of the results for the test case of the short-term detection of a gamma-ray burst afterglow, as the VHE counterpart of a gravitational wave event.
Ključne besede: very-high-energy gamma-rays, Cherenkov Telescope Array, gamma-ray astronomy
Objavljeno v RUNG: 18.09.2023; Ogledov: 558; Prenosov: 6
 Celotno besedilo (1,08 MB)
Gradivo ima več datotek! Več... |
12. LensWatch. I. resolved HST observations and constraints on the strongly lensed type Ia supernova 2022qmx (ʺSN Zwickyʺ)Justin Pierel, N. Arendse, S. Ertl, X. Huang, L. A. Moustakas, S. Schuldt, A. J. Shajib, Y. Shu, Mateusz Bronikowski, Tanja Petrushevska, 2023, izvirni znanstveni članek Ključne besede: supernova, strong lensing, astronomy
Objavljeno v RUNG: 16.05.2023; Ogledov: 1066; Prenosov: 8
Celotno besedilo (3,48 MB)
Gradivo ima več datotek! Več... |
13. GRB minimum variability timescale with Insight-HXMT and Swift : implications for progenitor models, dissipation physics, and GRB classificationsA. E. Camisasca, Cristiano Guidorzi, Lorenzo Amati, F. Frontera, X. Y. Song, S. Xiao, S. L. Xiong, S. N. Zhang, Raffaella Margutti, Andreja Gomboc, 2023, izvirni znanstveni članek Ključne besede: astronomy, gamma ray burst, variability
Objavljeno v RUNG: 24.03.2023; Ogledov: 1083; Prenosov: 13
Celotno besedilo (3,64 MB)
Gradivo ima več datotek! Več... |
14. |
15. Sensitivity of CTA to gamma-ray emission from the Perseus galaxy clusterJudit Pérez Romero, objavljeni znanstveni prispevek na konferenci Opis: In these proceedings we summarize the current status of the study of the sensitivity of the Cherenkov Telescope Array (CTA) to detect diffuse gamma-ray emission from the Perseus galaxy cluster. Gamma-ray emission is expected in galaxy clusters both from interactions of cosmic rays (CR) with the intra-cluster medium, or as a product of annihilation or decay of dark matter
(DM) particles in case they are weakly interactive massive particles (WIMPs). The observation of Perseus constitutes one of the Key Science Projects to be carried out by the CTA Consortium. In this contribution, we focus on the DM-induced component of the flux. OurDMmodelling includes the substructures we expect in the main halo which will boost the annihilation signal significantly. We adopt an ON/OFF observation strategy and simulate the expected gamma-ray signals. Finally we compute the expected CTA sensitivity using a likelihood maximization analysis including the most recent CTA instrument response functions. In absence of signal, we show that CTA will allow us to provide stringent and competitive constraints on TeV DM, especially for the case of
DM decay.
Ključne besede: dark matter, gamma-ray astronomy, galaxy clusters, cosmic rays and astroparticles
Objavljeno v RUNG: 27.01.2023; Ogledov: 996; Prenosov: 15
 Povezava na celotno besedilo
Gradivo ima več datotek! Več... |
16. Spatial extension of dark subhalos as seen by Fermi-LAT and the implications for WIMP constraintsJavier Coronado-Blázquez, Miguel Sánchez-Conde, Judit Pérez Romero, Alejandra Aguirre-Santaella, 2022, izvirni znanstveni članek Opis: Spatial extension has been hailed as a “smoking gun” in the gamma-ray search of dark galactic subhalos, which would appear as unidentified sources for gamma-ray telescopes. In this work, we study the sensitivity of the Fermi-LAT to extended subhalos using simulated data based on a realistic sky model. We simulate spatial templates for a set of representative subhalos, whose parameters were derived from our previous work with N-body cosmological simulation data. We find that detecting an extended subhalo and finding an unequivocal signal of angular extension requires, respectively, a flux 2 to 10 times larger than in the case of a pointlike source. By studying a large grid of models, where parameters such as the WIMP mass, annihilation channel, or subhalo model are varied significantly, we obtain the response of the LAT as a function of the product of annihilation cross-section times the J-factor. Indeed, we show that spatial extension can be used as an additional “filter” to reject subhalos candidates among the pool of unidentified LAT sources, as well as a smoking gun for positive identification. For instance, typical angular extensions of a few tenths of a degree are expected for the considered scenarios. Finally, we also study the impact of the obtained LAT sensitivity to such extended subhalos on the achievable dark matter constraints, which are a few times less constraining than comparable point-source limits.
Ključne besede: dark matter, cosmic rays and astroparticles, gamma-ray astronomy, particle astrophysics, particle dark matter
Objavljeno v RUNG: 26.01.2023; Ogledov: 1241; Prenosov: 0
Gradivo ima več datotek! Več... |
17. Dark matter search in dwarf irregular galaxies with the Fermi Large Area TelescopeViviana Gammaldi, Judit Pérez Romero, Javier Coronado-Blázquez, Mattia di Mauro, Ekaterina Karukes, Miguel Sánchez-Conde, Paolo Salucci, 2021, izvirni znanstveni članek Opis: We analyze 11 years of Fermi-Large Area Telescope (LAT) data corresponding to the sky regions of seven dwarf irregular (dIrr) galaxies. DIrrs are dark matter (DM)-dominated systems, proposed as interesting targets for the indirect search of DM with gamma rays. The galaxies represent interesting cases with a strong disagreement between the density profiles (core versus cusp) inferred from observations and numerical simulations. In this work, we addressed the problem by considering two different DM profiles, based on both the fit to the rotation curve (in this case, a Burkert cored profile) and results from N-body cosmological simulations (i.e., Navarro-Frenk-White cuspy profile). We also include halo substructure in our analysis, which is expected to boost the DM signal by a factor of 10 in halos such as those of dIrrs. For each DM model and dIrr, we create a spatial template of the expected DM-induced gamma-ray signal to be used in the analysis of Fermi-LAT data. No significant emission is detected from any of the targets in our sample. Thus, we compute upper limits on the DM annihilation cross section versus mass parameter space.
Among the seven dIrrs, we find IC10 and NGC6822 to yield the most stringent individual constraints, independently of the adopted DM profile. We also produce combined DM limits for all objects in the sample, which turn out to be dominated by IC10 for all DM models and annihilation channels, i.e., b¯b, τ+τ−, and W+W−. The strongest constraints are obtained for b¯b and are at the level of <σv>∼7×10−26 cm3 s−1 at mχ ∼ 6 GeV. Though these limits are a factor of ∼3 higher than the thermal relic cross section at low weakly interacting massive particles masses, they are independent from and complementary to those obtained by means of other targets.
Ključne besede: Dark matter, gamma-ray astronomy, galaxies, astronomical masses and mass distributions
Objavljeno v RUNG: 26.01.2023; Ogledov: 956; Prenosov: 0
Gradivo ima več datotek! Več... |
18. The Palomar Transient Factory core-collapse supernova host-galaxy sample : Host- galaxy distribution functions and environment dependence of core-collapse supernovaeSteve Schulze, Ofer Yaron, Jesper Sollerman, Giorgos Leloudas, Amit Gal, Angus H. Wright, Ragnhild Lunnan, Avishay Gal-Yam, Eran O. Ofek, Tanja Petrushevska, 2021, izvirni znanstveni članek Ključne besede: supernovae, galaxies, core-collapse supernovae, astronomy
Objavljeno v RUNG: 23.08.2021; Ogledov: 1754; Prenosov: 118
Povezava na celotno besedilo
Gradivo ima več datotek! Več... |
19. |
20. Search for large-scale anisotropy on arrival directions of ultra-high-energy cosmic rays observed with the telescope array experimentR. U. Abbasi, Mitsuhiro Abe, T. Abu-Zayyad, M. Allen, R. Azuma, E. Barcikowski, J. W. Belz, Douglas R. Bergman, S. A. Blake, Jon Paul Lundquist, 2020, izvirni znanstveni članek Opis: Motivated by the detection of a significant dipole structure in the arrival directions of ultra-high-energy cosmic rays above 8 EeV reported by the Pierre Auger Observatory (Auger), we search for a large-scale anisotropy using data collected with the surface detector array of the Telescope Array Experiment (TA). With 11 yr of TA data, a dipole structure in a projection of the R.A. is fitted with an amplitude of 3.3% ± 1.9% and a phase of 131° ± 33°. The corresponding 99% confidence-level upper limit on the amplitude is 7.3%. At the current level of statistics, the fitted result is compatible with both an isotropic distribution and the dipole structure reported by Auger.
Ključne besede: cosmic rays, ultra-high-energy cosmic radiation, cosmic ray sources, cosmic ray showers, cosmic ray detectors, cosmic ray astronomy, extragalactic astronomy
Objavljeno v RUNG: 05.02.2021; Ogledov: 2369; Prenosov: 0
Gradivo ima več datotek! Več... |
