4 research outputs found
MAGIC eyes to the extreme: testing the blazar emission models on EHBLs
Extreme high-energy peaked BL Lac objects (EHBLs) are blazars whose
synchrotron emission peaks at exceptionally high energies, above few keV, in
the hard X-ray regime. So far, only a handful of those objects has been
detected at very high energy (VHE, E > 100 GeV) gamma rays by Imaging
Atmospheric Cherenkov Telescopes. Very remarkably, VHE observations of some of
these blazars (like 1ES 0229+200) have provided evidence of a VHE gamma-ray
emission extending to several TeV, which is difficult to explain with standard,
one-zone synchrotron self-Compton models usually applied to BL Lac objects. The
MAGIC collaboration coordinated a multi-year, multi-wavelength observational
campaign on ten targets. The MAGIC telescopes detected VHE gamma rays from four
EHBLs. In this paper we focus on the source 1ES 1426+426 and its X-ray and VHE
gamma-ray properties. The results of different models (synchrotron
self-Compton, spine-layer, hadronic) reproducing the broadband spectral energy
distribution are also presented.Comment: Proceedings of the 36th International Cosmic Ray Conference
(ICRC2019), July 24th-August 1st, 2019. Madison, WI, U.S.
Dark matter constraints from observations of 25 Milky\ua0Way satellite galaxies with the Fermi Large Area Telescope
The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via \u3b3 rays. Here we report on \u3b3-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in \u3b3 rays, and we present \u3b3-ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical standard model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse \u3b3-ray background modeling, and assumed dark matter density profile
Prospects for Cherenkov Telescope Array Observations of the Young Supernova Remnant RX J1713.7 123946
We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7 123946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti)correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H i emission. We present a series of simulated images of RX J1713.7 123946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H i observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator