Fabio Zandanel - GRAPPA Institute, University of Amsterdam

Fabio Zandanel
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Name
Fabio Zandanel
Affiliation
GRAPPA Institute, University of Amsterdam
City
Amsterdam
Country
Netherlands

Pubs By Year

Pub Categories

 
High Energy Astrophysical Phenomena (18)
 
Cosmology and Nongalactic Astrophysics (14)
 
High Energy Physics - Phenomenology (6)
 
Astrophysics (1)

Publications Authored By Fabio Zandanel

Dwarf spheroidals are low-luminosity satellite galaxies of the Milky Way highly dominated by dark matter. Therefore, they are prime targets to search for signals from dark matter annihilation using gamma-ray observations. We analyse about 7 years of PASS8 Fermi data for seven classical dwarf galaxies, including Draco, adopting both the widely used Navarro-Frenk-White (NFW) profile and observationally motivated axisymmetric density profiles. Read More

The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. Read More

Mounting evidence suggests that the TeV-PeV neutrino flux detected by the IceCube telescope has mainly an extragalactic origin. If such neutrinos are primarily produced by a single class of astrophysical sources via hadronuclear ($pp$) interactions, a similar flux of gamma-ray photons is expected. For the first time, we employ tomographic constraints to pinpoint the origin of the IceCube neutrino events by analyzing recent measurements of the cross correlation between the distribution of GeV gamma rays, detected by the Fermi satellite, and several galaxy catalogs in different redshift ranges. Read More

2015Sep
Affiliations: 1GRAPPA Institute, University of Amsterdam, 2GRAPPA Institute, University of Amsterdam, 3APC, Univ. Paris Diderot, 4GRAPPA Institute, University of Amsterdam

Cosmic-ray (CR) protons can accumulate for cosmological times in clusters of galaxies. Their hadronic interactions with protons of the intra-cluster medium (ICM) generate secondary electrons, gamma-rays and high-energy neutrinos. In light of the high-energy neutrino events recently discovered by the IceCube observatory, we estimate the contribution from galaxy clusters to the diffuse gamma-ray and neutrino backgrounds. Read More

Galaxy clusters are the largest and most massive gravitationally bound structures known in the Universe. Cosmic-Ray (CR) hadrons accelerated at structure formation shocks and injected by galaxies, are confined in galaxy clusters where they accumulate for cosmological times. The presence of diffuse synchrotron radio emission in several clusters proves the existence of high-energy electrons, and magnetic fields. Read More

We investigate for the first time the potential of angular auto- and cross-correlation power spectra in identifying sterile neutrino dark matter in the cosmic X-ray background. We take as reference the performance of the soon-to-be-launched eROSITA satellite. The main astrophysical background sources against sterile neutrino decays are active galactic nuclei, galaxies powered by X-ray binaries, and clusters of galaxies. Read More

We investigate the prospects of indirect and direct dark matter searches within the minimal supersymmetric standard model with nine parameters (MSSM-9). These nine parameters include three gaugino masses, Higgs, slepton and squark masses, all treated independently. We perform a Bayesian Monte Carlo scan of the parameter space taking into consideration all available particle physics constraints such as the Higgs mass of 126 GeV, upper limits on the scattering cross-section from direct-detection experiments, and assuming that the MSSM-9 provides all the dark matter abundance through thermal freeze-out mechanism. Read More

The intra-cluster medium of several galaxy clusters hosts large-scale regions of diffuse synchrotron radio emission, known as radio halos and relics, which demonstrate the presence of magnetic fields and relativistic electrons in clusters. These relativistic electrons should also emit X-rays through inverse-Compton scattering off of cosmic microwave background photons. The detection of such a non-thermal X-ray component, together with the radio measurement, would permit to clearly separate the magnetic field from the relativistic electron distribution as the inverse-Compton emission is independent from the magnetic field in the cluster. Read More

2014Oct
Affiliations: 1GRAPPA Institute, University of Amsterdam, 2GRAPPA Institute, University of Amsterdam, 3APC, Univ. Paris Diderot, 4GRAPPA Institute, University of Amsterdam

Cosmic-ray protons accumulate for cosmological times in clusters of galaxies as their typical radiative and diffusive escape times are longer than the Hubble time. Their hadronic interactions with protons of the intra-cluster medium generate secondary electrons, gamma-rays and neutrinos. We here estimate the contribution from clusters to the diffuse gamma-ray and neutrino backgrounds. Read More

2013Dec
Affiliations: 1GRAPPA Institute, University of Amsterdam, Netherlands, 2GRAPPA Institute, University of Amsterdam, Netherlands

We analyze 5-year (63 months) data of the Large Area Telescope on board Fermi satellite from the Coma galaxy cluster in the energy range between 100 MeV and 100 GeV. The likelihood analyses are performed with several templates motivated by models predicting gamma-ray emission due to structure formation processes. We find no excess emission and derive the most stringent constraints to date on the Coma cluster above 100 MeV, and on the tested scenarios in general. Read More

2013Nov
Affiliations: 1Instituto de Astrofisica de Andalucia, 2Heidelberg Institute for Theoretical Studies, Heidelberg, Germany, 3Campus of International Excellence UAM+CSIC, Madrid, Spain

Cosmological hydrodynamical simulations of galaxy clusters are still challenged to produce a model for the intracluster medium that matches all aspects of current X-ray and Sunyaev-Zel'dovich observations. To facilitate such comparisons with future simulations and to enable realistic cluster population studies for modeling e.g. Read More

2013Nov
Affiliations: 1Instituto de Astrofisica de Andalucia, 2Heidelberg Institute for Theoretical Studies, Heidelberg, Germany, 3Campus of International Excellence UAM+CSIC, Madrid, Spain

The underlying physics of giant and mini radio halos in galaxy clusters is still an open question. We find that mini halos (such as in Perseus and Ophiuchus) can be explained by radio-emitting electrons that are generated in hadronic cosmic ray (CR) interactions with protons of the intracluster medium. By contrast, the hadronic model either fails to explain the extended emission of giant radio halos (as in Coma at low frequencies) or would require a flat CR profile, which can be realized through outward streaming and diffusion of CRs (in Coma and A2163 at 1. Read More

The nearby active galaxy IC 310 (z=0.019), located in the Perseus cluster of galaxies is a bright and variable multi-wavelength emitter from the radio regime up to very high gamma-ray energies above 100 GeV. Very recently, a blazar-like compact radio jet has been found by parsec-scale VLBI imaging. Read More

In order to detect the gamma-ray emission from cosmic ray (CR) interactions with the intra-cluster medium, the ground-based imaging Cherenkov telescope MAGIC conducted the deepest-to-date observational campaign targeting a galaxy cluster at very high-energies (> 100 GeV) and observed the Perseus cluster for a total of 85 hr during 2009-2011. The observations constrain the average CR-to-thermal pressure ratio to be 1-2% and the maximum CR acceleration efficiency at structure formation shocks to be <50%. Alternatively, this may argue for non-negligible CR transport processes such as CR streaming and diffusion into the outer cluster regions. Read More

2012Jul
Affiliations: 1Instituto de Astrofisica de Andalucia, 2Heidelberg Institute for Theoretical Studies, Heidelberg, Germany, 3Campus of International Excellence UAM+CSIC, Madrid, Spain

The underlying physics of giant radio halos and mini halos in galaxy clusters is still an open question, which becomes more pressing with the growing number of detections. In this paper, we explore the possibility that radio-emitting electrons are generated in hadronic cosmic ray (CR) proton interactions with ambient thermal protons of the intra-cluster medium. Our CR model derives from cosmological hydrodynamical simulations of cluster formation and additionally accounts for CR transport in the form of CR streaming and diffusion. Read More

The Fermi-LAT collaboration has recently reported the detection of angular power above the photon noise level in the diffuse gamma-ray background between 1 and 50 GeV. Such signal can be used to constrain a possible contribution from Dark-Matter-induced photons. We estimate the intensity and features of the angular power spectrum (APS) of this potential Dark Matter (DM) signal, for both decaying and annihilating DM candidates, by constructing template all-sky gamma-ray maps for the emission produced in the galactic halo and its substructures, as well as in extragalactic (sub)halos. Read More

The MAGIC telescopes performed a deep observation of the central region of the Perseus galaxy cluster in stereoscopic mode between October 2009 and February 2011. The nearly 85 hr of collected data (after quality selection) represent the deepest observation of a cluster of galaxies at very high energies (VHE, E > 100 GeV) ever. The survey resulted in the detection of VHE gamma-ray emissions from its central galaxy NGC 1275 and from the radio galaxy IC 310. Read More

The MAGIC Cherenkov telescopes observed the Perseus cluster sky region in stereo mode for nearly 90 hr from October 2009 to February 2011. This campaign led to the discovery of very high energy Gamma-ray emission from the central radio galaxy NGC 1275 and the head-tail radio galaxy IC 310. Here we report the results on the most recent discovery of NGC 1275 which was detected at low energies in the 2010/2011 data. Read More

We present high resolution 240 and 607 MHz GMRT radio observations, complemented with 74 MHz archival VLA radio observations of the Ophiuchus cluster of galaxies, whose radio mini-halo has been recently detected at 1400 MHz. We also present archival Chandra and XMM-Newton data of the Ophiuchus cluster. Our observations do not show significant radio emission from the mini-halo, hence we present upper limits to the integrated, diffuse non-thermal radio emission of the core of the Ophiuchus cluster. Read More