61. 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: 2368; Prenosov: 0
Gradivo ima več datotek! Več... |
62. Sensitivity of CTA to gamma-ray emission from the Perseus galaxy clusterJudit Pérez Romero, objavljeni znanstveni prispevek na konferenci Opis: In these proceedings we summarize the current status of the study of the sensitivity of the Cherenkov Telescope Array (CTA) to detect diffuse gamma-ray emission from the Perseus galaxy cluster. Gamma-ray emission is expected in galaxy clusters both from interactions of cosmic rays (CR) with the intra-cluster medium, or as a product of annihilation or decay of dark matter
(DM) particles in case they are weakly interactive massive particles (WIMPs). The observation of Perseus constitutes one of the Key Science Projects to be carried out by the CTA Consortium. In this contribution, we focus on the DM-induced component of the flux. OurDMmodelling includes the substructures we expect in the main halo which will boost the annihilation signal significantly. We adopt an ON/OFF observation strategy and simulate the expected gamma-ray signals. Finally we compute the expected CTA sensitivity using a likelihood maximization analysis including the most recent CTA instrument response functions. In absence of signal, we show that CTA will allow us to provide stringent and competitive constraints on TeV DM, especially for the case of
DM decay.
Ključne besede: dark matter, gamma-ray astronomy, galaxy clusters, cosmic rays and astroparticles
Objavljeno v RUNG: 27.01.2023; Ogledov: 2194; Prenosov: 18
 Povezava na celotno besedilo
Gradivo ima več datotek! Več... |
63. Spatial extension of dark subhalos as seen by Fermi-LAT and the implications for WIMP constraintsJavier Coronado-Blázquez, Miguel Sánchez-Conde, Judit Pérez Romero, Alejandra Aguirre-Santaella, 2022, izvirni znanstveni članek 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: 3103; Prenosov: 0
Gradivo ima več datotek! Več... |
64. Dark matter search in dwarf irregular galaxies with the Fermi Large Area TelescopeViviana Gammaldi, Judit Pérez Romero, Javier Coronado-Blázquez, Mattia di Mauro, Ekaterina Karukes, Miguel Sánchez-Conde, Paolo Salucci, 2021, izvirni znanstveni članek Opis: We analyze 11 years of Fermi-Large Area Telescope (LAT) data corresponding to the sky regions of seven dwarf irregular (dIrr) galaxies. DIrrs are dark matter (DM)-dominated systems, proposed as interesting targets for the indirect search of DM with gamma rays. The galaxies represent interesting cases with a strong disagreement between the density profiles (core versus cusp) inferred from observations and numerical simulations. In this work, we addressed the problem by considering two different DM profiles, based on both the fit to the rotation curve (in this case, a Burkert cored profile) and results from N-body cosmological simulations (i.e., Navarro-Frenk-White cuspy profile). We also include halo substructure in our analysis, which is expected to boost the DM signal by a factor of 10 in halos such as those of dIrrs. For each DM model and dIrr, we create a spatial template of the expected DM-induced gamma-ray signal to be used in the analysis of Fermi-LAT data. No significant emission is detected from any of the targets in our sample. Thus, we compute upper limits on the DM annihilation cross section versus mass parameter space.
Among the seven dIrrs, we find IC10 and NGC6822 to yield the most stringent individual constraints, independently of the adopted DM profile. We also produce combined DM limits for all objects in the sample, which turn out to be dominated by IC10 for all DM models and annihilation channels, i.e., b¯b, τ+τ−, and W+W−. The strongest constraints are obtained for b¯b and are at the level of <σv>∼7×10−26 cm3 s−1 at mχ ∼ 6 GeV. Though these limits are a factor of ∼3 higher than the thermal relic cross section at low weakly interacting massive particles masses, they are independent from and complementary to those obtained by means of other targets.
Ključne besede: Dark matter, gamma-ray astronomy, galaxies, astronomical masses and mass distributions
Objavljeno v RUNG: 26.01.2023; Ogledov: 2056; Prenosov: 0
Gradivo ima več datotek! Več... |
65. |
66. Multi-messenger studies with the Pierre Auger ObservatoryLukas Zehrer, Andrej Filipčič, Gašper Kukec Mezek, Jon Paul Lundquist, Samo Stanič, Marta Trini, Serguei Vorobiov, Marko Zavrtanik, Danilo Zavrtanik, 2021, objavljeni znanstveni prispevek na konferenci Opis: Over the past decade the multi-messenger astrophysics has emerged as a distinct discipline,
providing unique insights into the properties of high-energy phenomena in the Universe. The
Pierre Auger Observatory, located in Malargüe, Argentina, is the world’s largest cosmic ray
detector sensitive to photons, neutrinos, and hadrons at ultra-high energies. Using its data, stringent
limits on photon and neutrino fluxes at EeV energies have been obtained. The collaboration uses
the excellent angular resolution and the neutrino identification capabilities of the Observatory
for follow-up studies of events detected in gravitational waves or other messengers, through
cooperation with global multi-messenger networks. We present a science motivation together
with an overview of the multi-messenger capabilities and results of the Pierre Auger Observatory.
Ključne besede: high-energy cosmic phenomena, multi-messenger astrophysical studies, cosmic rays, gamma-rays, neutrinos, Pierre Auger Observatory
Objavljeno v RUNG: 06.05.2022; Ogledov: 2578; Prenosov: 0
Gradivo ima več datotek! Več... |
67. Identification of point sources in gamma rays using U-shaped convolutional neural networks and a data challengeBoris Panes, Christopher Eckner, Luc Hendriks, Sascha Caron, Klaas Dijkstra, Gudlaugur Johannesson, Roberto Ruiz de Austri, Gabrijela Zaharijas, 2021, izvirni znanstveni članek Ključne besede: gamma rays, astroparticle physics, data analysis
Objavljeno v RUNG: 17.02.2022; Ogledov: 3104; Prenosov: 9
Povezava na celotno besedilo
Gradivo ima več datotek! Več... |
68. Catalog of long-term transient sources in the first 10 yr of Fermi-LAT dataL. Baldini, J. Ballet, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, E. D. Bloom, Gabrijela Zaharijas, 2021, izvirni znanstveni članek Ključne besede: high energy astrophysics, active galactic nuclei, gamma-ray bursts, solar flares, solar gamma-ray emission
Objavljeno v RUNG: 17.02.2022; Ogledov: 2905; Prenosov: 43
Povezava na celotno besedilo
Gradivo ima več datotek! Več... |
69. First Fermi-LAT solar flare catalogM. Ajello, L. Baldini, D. Bastieri, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, R. Bonino, P. Bruel, Gabrijela Zaharijas, 2021, izvirni znanstveni članek Ključne besede: solar flares, solar gamma-ray emission, gamma-ray sources, gamma-ray telescopes, catalogs
Objavljeno v RUNG: 17.02.2022; Ogledov: 3564; Prenosov: 116
Povezava na celotno besedilo
Gradivo ima več datotek! Več... |
70. Gamma rays from fast black-hole windsM. Ajello, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, E. D. Bloom, Gabrijela Zaharijas, 2021, izvirni znanstveni članek Ključne besede: active galactic nuclei, galactic winds, gamma-rays
Objavljeno v RUNG: 17.02.2022; Ogledov: 2939; Prenosov: 113
Povezava na celotno besedilo
Gradivo ima več datotek! Več... |
