41. Gamma rays from fast black-hole windsM. Ajello, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, E. D. Bloom, Gabrijela Zaharijas, 2021, original scientific article Keywords: active galactic nuclei, galactic winds, gamma-rays
Published in RUNG: 17.02.2022; Views: 1723; Downloads: 111
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44. Localisation and classification of gamma ray sources using neural networksChris van den Oetelaar, Saptashwa Bhattacharyya, Boris Panes, Sascha Caron, Gabrijela Zaharijas, Roberto Ruiz de Austri, Guõlaugur Jóhannesson, 2021, published scientific conference contribution Abstract: With limited statistics and spatial resolution of current detectors, accurately localising and separating gamma-ray point sources from the dominating interstellar emission in the GeV energy range is challenging. Motivated by the challenges of the traditional methods used for the gamma-ray source detection, here we demonstrate the application of deep learning based algorithms to automatically detect and classify point sources, which can be applied directly to the binned Fermi-LAT data and potentially be generalised to other wavelengths. For the point source detection task, we use popular deep neural network structure U-NET, together with image segmentation, for precise localisation of sources, various clustering algorithms were tested on the segmented images. The training samples are based on the source properties of AGNs and PSRs from the latest Fermi-LAT source catalog, in addition to the background interstellar emission. Finally, we have created a more
complex but robust training data generation exploiting full detector potential, increasing spatial resolution at the highest energies.
Keywords: gamma-rays, deep learning, computer vision
Published in RUNG: 01.10.2021; Views: 1658; Downloads: 42
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45. Sensitivity of the Cherenkov Telescope Array for probing cosmology and fundamental physics with gamma-ray propagationH. Abdalla, H. Abe, Fabio Acero, A. Acharyya, R. Adam, Christopher Eckner, Samo Stanič, Serguei Vorobiov, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, original scientific article Abstract: The Cherenkov Telescope Array (CTA), the new-generation ground-based observatory for γ astronomy, provides unique capabilities to address significant open questions in astrophysics, cosmology, and fundamental physics. We study some of the salient areas of γ cosmology that can be explored as part of the Key Science Projects of CTA, through simulated observations of active galactic nuclei (AGN) and of their relativistic jets. Observations of AGN with CTA will enable a measurement of γ absorption on the extragalactic background light with a statistical uncertainty below 15% up to a redshift z=2 and to constrain or detect γ halos up to intergalactic-magnetic-field strengths of at least 0.3 pG . Extragalactic observations with CTA also show promising potential to probe physics beyond the Standard Model. The best limits on Lorentz invariance violation from γ astronomy will be improved by a factor of at least two to three. CTA will also probe the parameter space in which axion-like particles could constitute a significant fraction, if not all, of dark matter. We conclude on the synergies between CTA and other upcoming facilities that will foster the growth of γ cosmology.
Keywords: Cherenkov Telescope Array, active galactic nuclei, gamma-ray experiments, axions, extragalactic magnetic fields
Published in RUNG: 02.03.2021; Views: 2300; Downloads: 71
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48. Sensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centreA. Acharyya, R. Adam, C. Adams, I. Agudo, A. Aguirre-Santaella, Christopher Eckner, Samo Stanič, Serguei Vorobiov, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, original scientific article Keywords: dark matter, gamma ray, astrophysics
Published in RUNG: 26.02.2021; Views: 2406; Downloads: 141
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49. Skrivnosti prav posebnih zvezd, ki jim pravimo magnetarjiTomaž Zwitter, Nina Manfreda, Gabrijela Zaharijas, 2021, radio or television broadcast, podcast, interview, press conference Keywords: gama žarki, astrofizika, nevronske zvezde
Published in RUNG: 26.02.2021; Views: 2025; Downloads: 10
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