31. On velocity-dependent dark matter annihilations in dwarf satellitesMihael Petač, Piero Ullio, Mauro Valli, 2018, original scientific article Abstract: Milky Way dwarf spheroidal satellites are a prime target for Dark Matter (DM) indirect searches. There have been recent reassessments of the expected DM gamma-ray signals in case of long-range interactions, commonly known as Sommerfeld enhancement. Since details of the underlying DM phase-space distribution function become critical, there are potentially large uncertainties in the final result. We provide here a first attempt towards a comprehensive investigation of these systematics, addressing the impact on the expected DM flux from Milky Way dwarfs via Bayesian inference on the available stellar kinematic datasets. After reconsidering the study case of ergodic systems, we investigate for the first time scenarios where DM particle orbits may have a radial or tangential bias. We consider both cuspy and cored parametric DM density profiles, together with the case of a non-parametric halo modelling directly connected to line-of-sight observable quantities. The main findings of our work highlight the relevance of the assumed phase-space distribution: Referring to a generalized J-factor, namely the line-of-sight convolution of the spatial part in case of velocity-dependent annihilation rate, an enhancement (suppression) with respect to the limit of isotropic phase-space distributions is obtained for the case of tangentially (radially) biased DM particle orbits. We provide new estimates for J-factors for the eight brightest Milky Way dwarfs also in the limit of velocity-independent DM annihilation, in good agreement with previous results in literature, and derive data-driven lower-bounds based on the non-parametric modelling of the halo density. The outcome of our broad study stands out as a representative of the state-of-the-art in the field, and falls within the interest of current and future experimental collaborations involved in DM indirect detection programs.
Keywords: dark matter, indirect detection, dwarf satellites, sommerfeld enhancement, gamma-rays
Published in RUNG: 01.10.2021; Views: 1693; Downloads: 43 (1 vote)
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35. 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: 2511; Downloads: 141
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38. Real-time characterization and source apportionment of fine particulate matter in the Delhi megacity area during late winterVipul Lalchandan, Varun Kumar, Anna Tobler, M.T. Navaneeth, Suneeti Mishra, J. G. Slowik, Deepika Bhattu, Pragati Rai, Rangu Satish, Dilip Ganguly, Tiwari Tiwari, Neeraj Rastogi, Tiwari Sashi, Griša Močnik, André S. H. Prévôt, Sachchida Tripathi, 2021, original scientific article Abstract: National Capital Region (NCR) encompassing New Delhi is one of the most polluted urban metropolitan areas in the world.
Real-time chemical characterization of fine particulate matter (PM1 and PM2.5) was carried out using three aerosol mass
spectrometers, two aethalometers, and one single particle soot photometer (SP2) at two sites in Delhi (urban) and one site located
~40 km downwind of Delhi, during January-March, 2018. The campaign mean PM2.5 (NR-PM2.5 + BC) concentrations at the two
urban sites were 153.8±109.4 μg.m-3 and 127.8±83.2 μg.m-3, respectively, whereas PM1 (NR-PM1 + BC) was 72.3 ± 44.0 μg.m-3
at the downwind site. PM2.5 particles were composed mostly of organics (43-44)% followed by chloride (14-17)%, ammonium
(9-11)%, nitrate (9%), sulfate (8-10)%, and black carbon (11-16)%, whereas PM1 particles were composed of 47% organics,
13% sulfate as well as ammonium, 11% nitrate as well as chloride, and 5% black carbon. Organic aerosol (OA) source
apportionment was done using positive matrix factorization (PMF), solved using an advanced multi-linear engine (ME-2) model.
Highly mass-resolved OA mass spectra at one urban and downwind site were factorized into three primary organic aerosol
(POA) factors including one traffic-related and two solid-fuel combustion (SFC), and three oxidized OA (OOA) factors.
Whereas unit mass resolution OA at the other urban site was factorized into two POA factors related to traffic and SFC, and one
OOA factor. OOA constituted a majority of the total OA mass (45-55)% with maximum contribution during afternoon hours
~(70-80)%. Significant differences in the absolute OOA concentration between the two urban sites indicated the influence of local emissions on the oxidized OA formation. Similar PM chemical composition, diurnal and temporal variations at the three
sites suggest similar type of sources affecting the particulate pollution in Delhi and adjoining cities, but variability in mass concentration suggest more local influence than regional.
Keywords: source apportionment, air pollution, particulate matter, Delhi
Published in RUNG: 25.01.2021; Views: 3452; Downloads: 0
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