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109. Dark matter line searches with the Cherenkov Telescope ArrayS. Abe, Saptashwa Bhattacharyya, Christopher Eckner, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2024, original scientific article Abstract: Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating
or decaying dark matter particles that could relatively easily be distinguished from astrophysical
or instrumental backgrounds. We provide an updated assessment of the sensitivity of
the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic
centre region as well as of selected dwarf spheroidal galaxies. We find that current limits
and detection prospects for dark matter masses above 300 GeV will be significantly improved,
by up to an order of magnitude in the multi-TeV range.
This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing
on regions with large dark matter densities.
Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly
model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g. box-shaped spectra, that would likewise very clearly point to a particle dark matter origin.
Keywords: dark matter experiments, dark matter theory, gamma ray experiments, Cherenkov Telescope Array Observatory
Published in RUNG: 24.09.2024; Views: 370; Downloads: 5
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110. Impact of the magnetic horizon on the interpretation of the Pierre Auger Observatory spectrum and composition dataA. Abdul Halim, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2024, original scientific article Abstract: The flux of ultra-high energy cosmic rays reaching Earth above the ankle energy (5 EeV) can be described as a mixture of nuclei injected by extragalactic sources with very hard spectra and a low rigidity cutoff.
Extragalactic magnetic fields existing between the Earth and the closest sources can affect the observed CR spectrum by reducing the flux of low-rigidity particles reaching Earth. We perform a combined fit of the spectrum and distributions of depth of shower maximum measured with the Pierre Auger Observatory including the effect of this magnetic horizon in the propagation of UHECRs in the intergalactic space.
We find that, within a specific range of the various experimental and phenomenological systematics, the magnetic horizon effect can be relevant for turbulent magnetic field strengths in the local neighbourhood in which the closest sources lie
of order Brms ≃ (50–100) nG (20 Mpc/ds)( 100 kpc/Lcoh)1/2, with ds the typical intersource separation and Lcoh the magnetic field coherence length. When this is the case,
the inferred slope of the source spectrum becomes softer and can be closer to the expectations of diffusive shock acceleration, i.e., ∝ E-2.
An additional cosmic-ray population with higher source density and softer spectra, presumably also extragalactic and dominating the cosmic-ray flux at EeV energies, is also required to reproduce the overall spectrum and composition results for all energies down to 0.6 EeV.
Keywords: ultra high energy cosmic rays, UHECR propagation, magnetic horizon effect, Pierre Auger Observatory
Published in RUNG: 24.09.2024; Views: 346; Downloads: 1
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