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21.
Galactic Dark Matter signal and the Fermi-LAT measurement of the diffuse gamma-ray emission
Gabrijela Zaharijas, objavljeni znanstveni prispevek na konferenci

Opis: We study diffuse gamma-ray emission at intermediate Galactic latitudes measured by the Fermi LAT with the aim of searching for a signal from dark matter annihilation or decay. In the absence of a robust dark matter signal, constraints are presented. We present and improve upon conservative dark matter limits obtained with no modeling of the foreground astrophysical diffuse emission. We do so, by taking into account uncertainties in several parameters which characterize conventional astrophysical emission and using a profile likelihood formalism. The resulting limits impact the range of particle masses over which dark matter thermal production in the early Universe is possible, and challenge the interpretation of the PAMELA/Fermi-LAT cosmic ray anomalies as annihilation of dark matter.
Najdeno v: ključnih besedah
Ključne besede: Dark matter, high-energy gamma rays
Objavljeno: 21.03.2016; Ogledov: 3327; Prenosov: 0
.pdf Polno besedilo (1,04 MB)

22.
Azimuthal asymmetry in the risetime of the surface detector signals of the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, A. Aab, 2016, izvirni znanstveni članek

Opis: The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, (secθ)max, sensitive to the mass composition of cosmic rays above 3×1018  eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modeling that must be resolved before the mass composition can be inferred from (secθ)max.
Najdeno v: ključnih besedah
Povzetek najdenega: ...sensitive to the mass composition of cosmic rays above 3×1018  eV. By comparing measurements with predictions...
Ključne besede: ultra-high energy cosmic rays (UHECR), UHECR mass composition, Pierre Auger Observatory, extensive air showers, Auger Surface Detector signals risetime, azimuthal symmetry
Objavljeno: 15.04.2016; Ogledov: 4153; Prenosov: 0
.pdf Polno besedilo (698,19 KB)

23.
Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations With the Fermi Large Area Telescope
Gabrijela Zaharijas, 2016, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...dark matter, gamma rays theory, gamma rays experiment...
Ključne besede: dark matter, gammarays theory, gamma rays experiment
Objavljeno: 26.04.2016; Ogledov: 3789; Prenosov: 0
.pdf Polno besedilo (801,77 KB)

24.
Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data
Gabrijela Zaharijas, 2016, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...gamma rays experiment, gamma rays theory, Galactic diffuse emission...
Ključne besede: gamma rays experiment, gamma rays theory, Galactic diffuse emission
Objavljeno: 26.04.2016; Ogledov: 3331; Prenosov: 0
.pdf Polno besedilo (4,59 MB)

25.
Constraints on the Galactic Dark Matter signal from the Fermi-LAT measurement of the diffuse gamma-ray emission
Gabrijela Zaharijas, 2012, objavljeni znanstveni prispevek na konferenci

Opis: We study diffuse gamma-ray emission at intermediate Galactic latitudes measured by the Fermi Large Area Telescope with the aim of searching for a signal from dark matter annihilation or decay. In the absence of a robust dark matter signal, constraints are presented. We set both, conservative dark matter limits requiring that the dark matter signal does not exceed the observed diffuse gamma-ray emission and limits derived based on modeling the foreground astrophysical diffuse emission. Uncertainties in several parameters which characterize conventional astrophysical emission are taken into account using a profile likelihood formalism. The resulting limits impact the range of particle masses over which dark matter thermal production in the early Universe is possible, and challenge the interpretation of the PAMELA/Fermi-LAT cosmic ray anomalies as annihilation of dark matter.
Najdeno v: ključnih besedah
Povzetek najdenega: ...gamma rays, Galactic diffuse emission, dark matter serach...
Ključne besede: gamma rays, Galactic diffuse emission, dark matter serach
Objavljeno: 03.05.2016; Ogledov: 3155; Prenosov: 0
.pdf Polno besedilo (1,42 MB)

26.
Extragalactic gamma-ray signal from dark matter annihilation
Gabrijela Zaharijas, E. Sefusatti, Pasquale D. Serpico, D. Theurel, M. Gustafsson, 2014, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...cosmology, dark matter, diffuse background, gamma- rays, ...
Ključne besede: cosmology, dark matter, diffuse background, gamma-rays
Objavljeno: 09.05.2017; Ogledov: 3035; Prenosov: 105
URL Polno besedilo (0,00 KB)

27.
The spectrum and morphology of the Fermi bubbles
Gabrijela Zaharijas, M. Ackermann, Adrien Albert, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi, R. D. Blandford, 2014, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...high energy astrophysics, gamma- rays, diffuse background, ...
Ključne besede: high energy astrophysics, gamma-rays, diffuse background
Objavljeno: 09.05.2017; Ogledov: 2989; Prenosov: 15
URL Polno besedilo (0,00 KB)

28.
Ultra high energy neutrinos
Lili Yang, Cecilia Lunardini, Eray Sabancilar, 2013, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...ultra high energy, cosmic rays, cosmological neutrinos, cosmic ray theory, ...
Ključne besede: ultra high energy, cosmic rays, cosmological neutrinos, cosmic ray theory
Objavljeno: 09.05.2017; Ogledov: 2781; Prenosov: 17
URL Polno besedilo (0,00 KB)

29.
Galactic Center gamma-ray "excess" from an active past of the Galactic Centre?
Gabrijela Zaharijas, Pasquale D. Serpico, Jovana Petrović, 2014, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...gamma rays, diffuse emission, Galactic center, ...
Ključne besede: gamma rays, diffuse emission, Galactic center
Objavljeno: 09.05.2017; Ogledov: 2600; Prenosov: 13
URL Polno besedilo (0,00 KB)

30.
Sensitivity projections for dark matter searches with the Fermi large area telescope
Gabrijela Zaharijas, Collaboration Fermi LAT, 2016, izvirni znanstveni članek

Opis: The nature of dark matter is a longstanding enigma of physics; it may consist of particles beyond the Standard Model that are still elusive to experiments. Among indirect searchtechniques, which look for stable products from the annihilation or decay of dark matter particles, or from axions coupling to high-energy photons, observations of the γ -ray sky have come to prominence over the last few years, because of the excellent sensitivity of the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope mission. The LAT energy range from 20 meV to above 300 GeV is particularly well suited for searching for products of the interactions of dark matter particles. In this report we describe methods used to search for evidence of dark matter with the LAT, and review the status of searches performed with up to six years of LAT data. We also discuss the factors that determine the sensitivities of these searches, including the magnitudes of the signals and the relevant backgrounds, considering both statistical and systematic uncertainties. We project the expected sensitivities of each search method for 10 and 15 years of LAT data taking. In particular, we find that the sensitivity of searches targeting dwarf galaxies, which provide the best limits currently, will improve faster than the square root of observing time. Current LAT limits for dwarf galaxies using six years of data reach the thermal relic level for masses up to 120 GeV for the bb ̄ annihilation channel for reasonable dark matter density profiles. With projected discoveries of additional dwarfs, these limits could extend to about 250 GeV. With as much as 15 years of LAT data these searches would be sensitive to dark matter annihilations at the thermal relic cross section for masses to greater than 400 GeV (200 GeV) in the bb ̄(τ+τ−) annihilation channels.
Najdeno v: ključnih besedah
Ključne besede: dark matter, gamma rays
Objavljeno: 20.06.2016; Ogledov: 3486; Prenosov: 0
.pdf Polno besedilo (4,66 MB)

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