1. 2FHLGabrijela Zaharijas, Collaboration Fermi LAT, M. Ackermann, 2016, original scientific article Abstract: We present a catalog of sources detected above 50 GeV by the Fermi-Large Area Telescope (LAT) in 80 months of data. The newly delivered Pass8 event-level analysis allows the detection and characterization of sources in the 50 GeV–2 TeV energy range. In this energy band, Fermi-LAT has detected 360 sources, which constitute the second catalog of hard Fermi-LAT sources (2FHL). The improved angular resolution enables the precise localization of point sources (∼1 7 radius at 68% C.L.) and the detection and characterization of spatially extended sources. We find that 86% of the sources can be associated with counterparts at other wavelengths, of which the majority (75%) are active galactic nuclei and the rest (11%) are Galactic sources. Only 25% of the 2FHL sources have been previously detected by Cherenkov telescopes, implying that the 2FHL provides a reservoir of candidates to be followed up at very high energies. This work closes the energy gap between the observations performed at GeV energies by Fermi-LATon orbit and the observations performed at higher energies by Cherenkov telescopes from the ground.
Found in: ključnih besedah
Keywords: catalogs – gamma-rays
Published: 25.02.2016; Views: 4305; Downloads: 0
 Fulltext (2,26 MB) |
2. FERMI-LAT OBSERVATIONS OF HIGH-ENERGY γ-RAY EMISSION TOWARD THE GALACTIC CENTERGabrijela Zaharijas, B. L. Winer, 2016, original scientific article Abstract: The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission toward the Galactic center (GC) in high-energy γ-rays. This paper describes the analysis of data taken during the first 62 months of the mission in the energy range 1–100 GeV from a 15° × 15° region about the direction of the GC. Specialized interstellar emission models (IEMs) are constructed to enable the separation of the γ-ray emissions produced by cosmic ray particles interacting with the interstellar gas and radiation fields in the Milky Way into that from the inner ∼1 kpc surrounding the GC, and that from the rest of the Galaxy. A catalog of point sources for the 15° × 15° region is self-consistently constructed using these IEMs: the First Fermi-LAT Inner Galaxy Point Source Catalog (1FIG). The spatial locations, fluxes, and spectral properties of the 1FIG sources are presented, and compared with γ-ray point sources over the same region taken from existing catalogs. After subtracting the interstellar emission and point-source contributions a residual is found. If templates that peak toward the GC are used to model the positive residual the agreement with the data improves, but none of the additional templates tried account for all of its spatial structure. The spectrum of the positive residual modeled with these templates has a strong dependence on the choice of IEM.
Found in: ključnih besedah
Summary of found: ...cosmic rays – Galaxy: center – gamma-rays: general – gamma-rays: ISM – radiation mechanisms:... ...toward the Galactic center (GC) in high-energy γ- rays. This paper describes the analysis of data...
Keywords: cosmic rays – Galaxy: center – gamma-rays: general – gamma-rays: ISM – radiation mechanisms: non-thermal
Published: 02.03.2016; Views: 4269; Downloads: 266
Fulltext (6,36 MB) |
3. Prospects On Testing Lorentz Invariance Violation With The Cherenkov Telescope Arraymarko zavrtanik, Danilo Zavrtanik, Gabrijela Zaharijas, Lili Yang, Serguei Vorobiov, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, M. K. Daniel, 2015, published scientific conference contribution Found in: ključnih besedah
Summary of found: ...(CTA),
Lorentz Invariance Violation (LIV),
Very High Energy (VHE) gamma-rays,
fundamental physics probes,
Active Galactic Nuclei (AGN),
Gamma Ray...
Keywords: Cherenkov Telescope Array (CTA), Lorentz Invariance Violation (LIV), Very High Energy (VHE) gamma-rays, fundamental physics probes, Active Galactic Nuclei (AGN), Gamma Ray Bursts (GRBs), pulsars
Published: 14.03.2016; Views: 3722; Downloads: 212
Fulltext (904,49 KB) |
4. Galactic Dark Matter signal and the Fermi-LAT measurement of the diffuse gamma-ray emissionGabrijela Zaharijas, published scientific conference contribution Abstract: 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.
Found in: ključnih besedah
Keywords: Dark matter, high-energy gamma rays
Published: 21.03.2016; Views: 3606; Downloads: 0
Fulltext (1,04 MB) |
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7. Constraints on the Galactic Dark Matter signal from the Fermi-LAT measurement of the diffuse gamma-ray emissionGabrijela Zaharijas, 2012, published scientific conference contribution Abstract: 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.
Found in: ključnih besedah
Summary of found: ...gamma rays, Galactic diffuse emission, dark matter serach...
Keywords: gamma rays, Galactic diffuse emission, dark matter serach
Published: 03.05.2016; Views: 3493; Downloads: 0
Fulltext (1,42 MB) |
8. Extragalactic gamma-ray signal from dark matter annihilationGabrijela Zaharijas, E. Sefusatti, Pasquale D. Serpico, D. Theurel, M. Gustafsson, 2014, original scientific article Found in: ključnih besedah
Summary of found: ...cosmology, dark matter, diffuse background, gamma- rays, ...
Keywords: cosmology, dark matter, diffuse background, gamma-rays
Published: 09.05.2017; Views: 3389; Downloads: 119
 Fulltext (0,00 KB) |
9. The spectrum and morphology of the Fermi bubblesGabrijela Zaharijas, M. Ackermann, Adrien Albert, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi, R. D. Blandford, 2014, original scientific article Found in: ključnih besedah
Summary of found: ...high energy astrophysics, gamma-rays, diffuse background, ...
Keywords: high energy astrophysics, gamma-rays, diffuse background
Published: 09.05.2017; Views: 3344; Downloads: 18
Fulltext (0,00 KB) |
10. Galactic Center gamma-ray "excess" from an active past of the Galactic Centre?Gabrijela Zaharijas, Pasquale D. Serpico, Jovana Petrović, 2014, original scientific article Found in: ključnih besedah
Summary of found: ...gamma rays, diffuse emission, Galactic center, ...
Keywords: gamma rays, diffuse emission, Galactic center
Published: 09.05.2017; Views: 2893; Downloads: 16
Fulltext (0,00 KB) |
