Erlangen Center for Astroparticle Physics

Erlangen, Germany

Erlangen Center for Astroparticle Physics

Erlangen, Germany
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Katsuta J.,Hiroshima University | Uchiyama Y.,Rikkyo University | Funk S.,Erlangen Center for Astroparticle Physics
Astrophysical Journal | Year: 2017

We report a study of extended γ-ray emission with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope, which is likely to be the second case of a γ-ray detection from a star-forming region (SFR) in our Galaxy. The LAT source is located in the G25 region, 1.°7 × 2.°1 around (l, b) = (25.°0, 0.°0). The γ-ray emission is found to be composed of two extended sources and one pointlike source. The extended sources have similar sizes of about 1.°4 × 0.°6. An ∼0.°4 diameter subregion of one has a photon index of Γ = 1.53 0.15, and is spatially coincident with HESS J1837-069, likely a pulsar wind nebula. The other parts of the extended sources have a photon index of Γ = 2.1 0.2 without significant spectral curvature. Given their spatial and spectral properties, they have no clear associations with sources at other wavelengths. Their γ-ray properties are similar to those of the Cygnus cocoon SFR, the only firmly established γ-ray detection of an SFR in the Galaxy. Indeed, we find bubble-like structures of atomic and molecular gas in G25, which may be created by a putative OB association/cluster. The γ-ray emitting regions appear confined in the bubble-like structure; similar properties are also found in the Cygnus cocoon. In addition, using observations with the XMM-Newton, we find a candidate young massive OB association/cluster G25.18+0.26 in the G25 region. We propose that the extended γ-ray emission in G25 is associated with an SFR driven by G25.18+0.26. Based on this scenario, we discuss possible acceleration processes in the SFR and compare them with the Cygnus cocoon. © 2017. The American Astronomical Society. All rights reserved.

Principe G.,Erlangen Center for Astroparticle Physics | Malyshev D.,Erlangen Center for Astroparticle Physics
AIP Conference Proceedings | Year: 2017

One of the largest uncertainties in the Point Source (PS) studies, at Fermi-LAT energies [1], is the uncertainty in the diffuse background. In general there are two approaches for PS analysis: background-dependent methods, that include modeling of the diffuse background, and background-independent methods. In this work we study PGWave [2], which is one of the background-independent methods, based on wavelet filtering to find significant clusters of gamma rays. PGWave is already used in the Fermi-LAT catalog pipeline for finding candidate sources. We test PGWave, not only for source detection, but especially to estimate the flux without the need of a background model. We use Monte Carlo (MC) simulation to study the accuracy of PS detection and estimation of the flux. We present preliminary results of these MC studies. © 2017 Author(s).

Malyshev D.,Erlangen Center for Astroparticle Physics
EPJ Web of Conferences | Year: 2017

The Fermi bubbles are one of the most remarkable features in the gamma-ray sky revealed by the Fermi Large Area Telescope (LAT). The nature of the gamma-ray emission and the origin of the bubbles are still open questions. In this note, we will review some basic features of leptonic and hadronic modes of gamma-ray production. At the moment, gamma rays are our best method to study the bubbles, but in order to resolve the origin of the bubbles multi-wavelength and multi-messenger observations will be crucial. © The Authors, published by EDP Sciences, 2017.

Schnabel J.,Erlangen Center for Astroparticle Physics
Physics Procedia | Year: 2015

The ANTARES neutrino telescope, situated off the French coast at about 2.5 km depth in the Mediterranean Sea, is optimized to detect charged leptons induced by neutrinos in the TeV range. Since its full deployment in 2008, modelling and reconstruction of neutrino-induced event signatures have been introduced and developed to obtain a high degree of accuracy. In this work, muon track directional and energy reconstruction have been applied to four years of ANTARES data in the search for a diffuse flux of astrophysical neutrinos from the charged-current interactions of νμ. Reaching a sensitivity which well surpasses the sensitivity of previous ANTARES analyses, a best upper limit of Φν+ν,90%C.L. E2 = 5.1 × 10-8 GeV sr-1 s-1 cm-2 can be set. © 2015 Published by Elsevier B.V.

Motz H.,Erlangen Center for Astroparticle Physics
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

Deep-sea neutrino telescopes consist of an array of photomultipliers to detect Cherenkov light emitted by neutrino-induced muons and particle showers in the surrounding sea water, allowing for reconstruction of the neutrino direction from position and timing of the Cherenkov photons. Since the photomultipliers are in most cases mounted on flexible structures, e.g. lines, and move with the sea current, a positioning system is required to determine the precise location of each sensor. The positioning system of the ANTARES neutrino telescope is based on acoustic triangulation using hydrophones mounted along the lines in combination with tiltmeters and compasses and provides centimetre precision alignment. For the future KM3NeT detector an Optical Module with integrated Piezo sensors for position calibration is proposed as a cost-effective solution. The performance of this system is tested with several sensors of the AMADEUS project, which is integrated in ANTARES to study the background for acoustic detection of highest energy neutrinos. © 2010 Elsevier B.V. All rights reserved.

Lahmann R.,Erlangen Center for Astroparticle Physics
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

Arrays of acoustic receivers are an integral part of present and potential future Cherenkov neutrino telescopes in the deep sea. They measure the positions of individual detector elements which vary with time as an effect of undersea currents. At the same time, the acoustic receivers can be employed for marine science purposes, in particular for monitoring the ambient noise environment and the signals emitted by the fauna of the sea. And last but not least, they can be used for studies towards acoustic detection of ultra-high-energy neutrinos. Measuring acoustic pressure pulses in huge underwater acoustic arrays with an instrumented volume of the order of 100 km3 is a promising approach for the detection of cosmic neutrinos with energies exceeding 1 EeV. Pressure signals are produced by the particle cascades that evolve when neutrinos interact with nuclei in water, and can be detected over large distances in the kilometre range. In this article, the status of acoustic detection will be reviewed and plans for the future - most notably in the context of KM3NeT - will be discussed. The connection between neutrino detection, position calibration and marine science will be illustrated. © 2013 Elsevier B.V. All rights reserved.

Kraus C.,Laurentian University | Singer A.,University of Munster | Singer A.,German Electron Synchrotron | Valerius K.,University of Munster | And 2 more authors.
European Physical Journal C | Year: 2013

The recent analysis of the normalization of reactor antineutrino data, the calibration data of solar neutrino experiments using gallium targets, and the results from the neutrino oscillation experiment MiniBooNE suggest the existence of a fourth light neutrino mass state with a mass of O (eV), which contributes to the electron neutrino with a sizable mixing angle. Since we know from measurements of the width of the Z0 resonance that there are only three active neutrinos, a fourth neutrino should be sterile (i. e., interact only via gravity). The corresponding fourth neutrino mass state should be visible as an additional kink in β-decay spectra. In this work the phase II data of the Mainz Neutrino Mass Experiment have been analyzed searching for a possible contribution of a fourth light neutrino mass state. No signature of such a fourth mass state has been found and limits on the mass and the mixing of this fourth mass state are derived. © 2013 The Author(s).

Kalekin O.,Erlangen Center for Astroparticle Physics
Nuclear Physics B - Proceedings Supplements | Year: 2012

The KM3NeT consortium has completed a Technical Design Report (TDR) for a proposed multi-cubic-kilometer sized underwater neutrino telescope that will be deployed in the Mediterranean Sea. The basic unit of an underwater neutrino telescope is the Optical Module (OM), a pyrex glass sphere capable of withstanding the great pressure of the deep sea (up to 5 km water depth) where the telescope will be deployed. The glass spheres house photomultipliers (PMTs), either a single large PMT or many smaller ones, which register the Cherenkov light arising from the secondaries of neutrino interactions. The front-end electronics, installed off-shore, will be based on an ASIC implementing a time-over-threshold signal processing. For the readout scheme, the preferred solution is a fully optical fibre-based approach with point-to-point connections between OMs and shore. All signals above an adjustable noise-rejection threshold will be transferred to shore. © 2012 Elsevier B.V.

Herold B.,Erlangen Center for Astroparticle Physics | Kalekin O.,Erlangen Center for Astroparticle Physics
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

KM3NeT is a future neutrino telescope in the Mediterranean Sea with at least 1 km3 of instrumented volume. During the current design stage, 3-, 8- and 10-in. photomultiplier tubes from Hamamatsu and ET Enterprises have been investigated as candidates for the telescope's optical modules. The most important parameters of these photomultiplier tubes, such as the time resolution, the absolute quantum efficiency of the photocathode, the inhomogeneity of the overall efficiency over the photocathode and the resulting effective photocathode area, have been measured in a test bench at the Erlangen Centre for Astroparticle Physics. These results are presented. © 2010 Elsevier B.V. All rights reserved.

Kalekin O.,Erlangen Center for Astroparticle Physics
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

KM3NeT is a future deep-sea research infrastructure hosting a neutrino telescope with a volume of at least one cubic kilometer to be constructed in the Mediterranean Sea. The experiment aims to detect high-energy cosmic neutrinos using a 3D array of optical modules to collect the Cherenkov light induced by charged particles in the water. Upward going muons and showers produced in neutrino interactions with the surrounding matter will allow the search and study of possible sources of extra-terrestrial neutrinos. The design of optical modules makes an important impact on the performance and cost of the KM3NeT project. Several different optical module configurations are under consideration; based on glass pressure spheres containing: a large (10 in.) hemispherical photomultiplier tube (with a multi-anode version as an option); 2531 3 in. photomultiplier tubes, or a crystal scintillator-based hybrid device (X-HPD). The features and advantages of each optical module design are discussed. © 2010 Elsevier B.V. All rights reserved.

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