Dark matter searches in dwarf spheroidal galaxies with the Cherenkov Telescope ArrayFrancesco Gabriele Saturni
, Saptashwa BHATTACHARYYA
, Judit PÉREZ ROMERO
, Samo STANIČ
, Veronika VODEB
, Serguei Vorobiov
, Danilo ZAVRTANIK
, Marko ZAVRTANIK
, Miha ŽIVEC
, 2023, objavljeni znanstveni prispevek na konferenci
Opis: Dark matter (DM) is one of the major components in the Universe. However, at present its existence is still only inferred through indirect astronomical observations. DM particles can annihilate or decay, producing final-state Standard Model pairs that subsequently annihilate into high-energy �-rays. The dwarf spheroidal galaxies (dSphs) in the Milky Way DM halo have long been considered optimal targets to search for annihilating DM signatures in GeV-to-TeV �-ray spectra due to their high DM densities (hence high astrophysical factors), as well as the expected absence of intrinsic �-ray emission of astrophysical origin. For such targets, it is important to compute the amount of DM in their halos in a consistent way to optimize the �-ray data analysis. Such estimates directly affect the observability of DM signals in dSphs, as well as the DM constraints that can be derived in case of null detection. In this contribution, we present the results on the sensitivity of the Cherenkov Telescope Array (CTA) for DM annihilation and decay searches using planned observations of the Milky Way dSphs. We select the most promising targets among all presently known dwarf satellites, providing new determinations of their expected DM signal. This study shows an improvement of approximately an order of magnitude in sensitivity compared to current searches in similar targets. We also discuss the results in terms of cuspy and cored DM models, and investigate the sensitivity obtained by the combination of observations from different dSphs. Finally, we explore the optimal strategies for CTA observations of dSphs.
Ključne besede: Cherenkov Telescope Array, CTA, Dark matter, Standard Model, dwarf spheroidal galaxies
Objavljeno v RUNG: 26.09.2023; Ogledov: 22; Prenosov: 0
Celotno besedilo (4,11 MB)
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Classification of gamma-ray targets for velocity-dependent and subhalo-boosted dark-matter annihilationThomas Lacroix
, Gaetán Facchinetti
, Judit Pérez-Romero
, Martin Stref
, Julien Lavalle
, David Maurin
, Miguel Sánchez-Conde
, izvirni znanstveni članek
Opis: Gamma-ray observations have long been used to constrain the properties of dark matter (DM), with a strong focus on weakly interacting massive particles annihilating through velocity-independent processes. However, in the absence of clear-cut observational evidence for the simplest candidates, the interest of the community in more complex DM scenarios involving a velocity-dependent cross-section has been growing steadily over the past few years. We present the first systematic study of velocity-dependent DM annihilation (in particular p-wave annihilation and Sommerfeld enhancement) in a variety of astrophysical objects, not only including the well-studied Milky Way dwarf satellite galaxies, but nearby dwarf irregular galaxies and local galaxy clusters as well. Particular attention is given to the interplay between velocity dependence and DM halo substructure. Uncertainties related to halo mass, phase-space and substructure modelling are also discussed in this velocity-dependent context. We show that, for s-wave annihilation, extremely large subhalo boost factors are to be expected, up to 10^11 in clusters and up to 10^6–10^7 in dwarf galaxies where subhalos are usually assumed not to play an important role. Boost factors for p-wave annihilation are smaller but can still reach 10^3 in clusters. The angular extension of the DM signal is also significantly impacted, with e.g. the cluster typical emission radius increasing by a factor of order 10 in the s-wave case. We also compute the signal contrast of the objects in our sample with respect to annihilation happening in the Milky Way halo. Overall, we find that the hierarchy between the brightest considered targets depends on the specific details of the assumed particle-physics model.
Ključne besede: dark matter theory, dwarf galaxies, galaxy clusters, gamma-ray theory
Objavljeno v RUNG: 27.01.2023; Ogledov: 605; Prenosov: 0
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