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Opis: Spatial extension has been hailed as a “smoking gun” in the gamma-ray search of dark galactic subhalos, which would appear as unidentified sources for gamma-ray telescopes. In this work, we study the sensitivity of the Fermi-LAT to extended subhalos using simulated data based on a realistic sky model. We simulate spatial templates for a set of representative subhalos, whose parameters were derived from our previous work with N-body cosmological simulation data. We find that detecting an extended subhalo and finding an unequivocal signal of angular extension requires, respectively, a flux 2 to 10 times larger than in the case of a pointlike source. By studying a large grid of models, where parameters such as the WIMP mass, annihilation channel, or subhalo model are varied significantly, we obtain the response of the LAT as a function of the product of annihilation cross-section times the J-factor. Indeed, we show that spatial extension can be used as an additional “filter” to reject subhalos candidates among the pool of unidentified LAT sources, as well as a smoking gun for positive identification. For instance, typical angular extensions of a few tenths of a degree are expected for the considered scenarios. Finally, we also study the impact of the obtained LAT sensitivity to such extended subhalos on the achievable dark matter constraints, which are a few times less constraining than comparable point-source limits.
Ključne besede: dark matter, cosmic rays and astroparticles, gamma-ray astronomy, particle astrophysics, particle dark matter
Objavljeno v RUNG: 26.01.2023; Ogledov: 1237; Prenosov: 0
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Opis: The available classical diagnostic methods, due to many disadvantages, do not allow effective detection of pathogenic enteric viruses in environmental samples. Due to low concentrations of pathogenic viruses in the sea, it is important to develop an effective concentration procedure for their successful detection. In the first part of the doctoral thesis, we focused primarily on the development of a protocol for an effective concentration of pathogenic enteric viruses in coastal water samples. Monolithic chromatographic columns (BIAseparations) were used for the concentration of rotaviruses and noroviruses, prior to the detection with reverse transcription quantitative PCR in real time (RT-qPCR). We tested the efficiency of concentration using columns of various chemical properties and selected pathogenic enteric viruses (rotavirus and norovirus). Among them, hydrophobic interaction monolithic column (CIM® C4) was the most effective. CIM C4 was used to optimize the concentration step and tested in waters with different salinities. The presence of concentrated viruses was confirmed by RT-qPCR and transmission electron microscope. We have developed a protocol that enables rapid concentration of viruses in coastal waters of various salinities and can be used on-site. The presence of RoV and NoV was surveyed, using the developed concentration protocol, prior to one-step RT-qPCR molecular detection, in the inner part of the Bay of Koper, in mussel farming areas and a swimming area. Rotaviruses, noroviruses and fecal indicator bacteria were frequently detected in the inner part of the Bay of Koper. Rotaviruses and noroviruses were detected in the studied area, with higher rates close to the outfall of the wastewater treatment plant in the estuary of river Rižana and were also detected in the middle of the Bay of Koper and in areas used for recreation and mussel farming. The results show that water bodies, which are otherwise defined as suitable for bathing or mussel farming, based on the results of fecal indicator bacteria, still contain low concentrations of pathogenic enteric viruses. In addition to human pathogenic enteric viruses and faecal coliforms, changes in abundance of bacteria and virus particles were studied in relation to temperature, salinity, inorganic and organic nutrient concentrations in the organically polluted Rižana estuary. Preliminary results showed spatially and seasonally changes in bacterial and viral particles abundance, and bacterial composition spatially and seasonally. However, seasonality plays a greater role in bacterial dynamics.
Ključne besede: Concentration of viruses, Enteric viruses, Rotavirus, Norovirus, Feacal coliforms, Feacal contamination, qPCR, RT-qPCR, Monolithic columns, Sewage, Seasonal dynamics, Concentration, Coastal environment, Gulf of Trieste
Objavljeno v RUNG: 02.07.2018; Ogledov: 4810; Prenosov: 211
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