11. 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: 1164; Prenosov: 0
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12. The ‘Physiognomic Fallacy:’ An Archaeology of the Photographic Identity DocumentPolonyi Eszter, prispevek na konferenci brez natisa Opis: In an era of allegedly total surveillance (Goh, Galloway), possession of a biometric identity document can still result in being denied one’s identity or being mistaken for someone else. States have been outsourcing the processes of civic management and local governance to artificial intelligence corporations with increasing intensity since the pandemic despite awareness of systematic errors committed by facial recognition software, a “coded” bias (Kantayya, Buolamwini) that risks the further effacing an already marginalized population of non-white and non-gender conforming subjects. The project this paper is based on returns to the time it first became standard practice to validate state-issued ID documents using facial analysis in Europe of the 1920s and 1930s. While at this time images derived from human heads in photographic albums, personality tests and facial atlases purportedly aimed to record personality and character, they nonetheless often instructed their readers to locate these in parts of images that remain disconnected from the head, such as hands and feet, hair, clothing or in the subject’s immediate environment. Drawing on the concept of conjectural knowledge (Ginzburg), embodiment or tact (Balazs) and the optical unconscious (Benjamin), the project seeks to locate the “physiognomic fallacy” (Gray) in early attempts at humanizing machine vision.
Ključne besede: History of art, critical theory, surveillance studies
Objavljeno v RUNG: 13.01.2023; Ogledov: 907; Prenosov: 0
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14. Semihypergroup-Based Graph for Modeling International Spread of COVID-n in Social SystemsNarjes Firouzkouhi, Reza Ameri, Abbas Amini, Hashem Bordbar, 2022, izvirni znanstveni članek Opis: Graph theoretic techniques have been widely applied to model many types of links in social systems. Also, algebraic hypercompositional structure theory has demonstrated its systematic
application in some problems. Influenced by these mathematical notions, a novel semihypergroup based graph (SBG) of G = hH, Ei is constructed through the fundamental relation gn on H, where semihypergroup H is appointed as the set of vertices and E is addressed as the set of edges on SBG. Indeed, two arbitrary vertices x and y are adjacent if xgny. The connectivity of graph G is characterized by xg y, whereby the connected components SBG of G would be exactly the elements of the fundamental group H/g . Based on SBG, some fundamental characteristics of the graph such as complete, regular, Eulerian, isomorphism, and Cartesian products are discussed along with illustrative examples to clarify the relevance between semihypergroup H and its corresponding graph. Furthermore, the notions of geometric space, block, polygonal, and connected components are introduced in terms of the developed SBG. To formulate the links among individuals/countries in
the wake of the COVID (coronavirus disease) pandemic, a theoretical SBG methodology is presented to analyze and simplify such social systems. Finally, the developed SBG is used to model the trend diffusion of the viral disease COVID-n in social systems (i.e., countries and individuals).
Ključne besede: graph theory, hypergroup, fundamental relation, social systems, geometric space
Objavljeno v RUNG: 23.11.2022; Ogledov: 978; Prenosov: 0
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