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Thomas Günther Bretz

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Related publications (25)

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MAGIC observations of the February 2014 flare of 1ES 1011+496 and ensuing constraint of the EBL density

Thomas Günther Bretz

Context. During February-March 2014, the MAGIC telescopes observed the high-frequency peaked BL Lac 1ES 1011 + 496 (z = 0.212) in flaring state at very-high energy (VHE, E > 100 GeV). The flux reached a level of more than ten times higher than any previous ...

Edp Sciences S A2016

Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009

Thomas Günther Bretz

Aims. We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, MAGIC, VERITAS, Whipple 10 m, and Fer ...

Edp Sciences S A2017

Searches for dark matter annihilation signatures in the Segue 1 satellite galaxy with the MAGIC-I telescope

Thomas Günther Bretz

We report the results of the observation of the nearly satellite galaxy Segue 1 performed by the MAGIC-I ground-based gamma-ray telescope between November 2008 and March 2009 for a total of 43.2 hours. No significant gamma-ray emission was found above the ...

2011

Deep observation of the NGC1275 region with MAGIC: search of diffuse gamma-ray emission from cosmic rays in the Perseus cluster

Thomas Günther Bretz

Clusters of galaxies are expected to be reservoirs of cosmic rays (CRs) that should produce diffuse gamma-ray emission due to their hadronic interactions with the intra-cluster medium. The nearby Perseus cool-core cluster, identified as the most promising ...

Edp Sciences S A2016

MULTIWAVELENGTH STUDY OF QUIESCENT STATES OF Mrk 421 WITH UNPRECEDENTED HARD X-RAY COVERAGE PROVIDED BY NuSTAR IN 2013

Xin Chen, Thomas Günther Bretz

We present coordinated multiwavelength observations of the bright, nearby BL Lacertae object Mrk 421 taken in 2013 January-March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations and instruments, providing data from r ...

Iop Publishing Ltd2016

Observations of Sagittarius A* during the pericenter passage of the G2 object with MAGIC

Thomas Günther Bretz

Context. We present the results of a multi-year monitoring campaign of the Galactic center (GC) with the MAGIC telescopes. These observations were primarily motivated by reports that a putative gas cloud (G2) would be passing in close proximity to the supe ...

Edp Sciences S A2017

The simultaneous low state spectral energy distribution of 1ES 2344+514 from radio to very high energies

Thomas Günther Bretz

Context. BL Lacertae objects are variable at all energy bands on time scales down to minutes. To construct and interpret their spectral energy distribution (SED), simultaneous broad-band observations are mandatory. Up to now, the number of objects studied ...

Edp Sciences S A2013

FIRST NuSTAR OBSERVATIONS OF MRK 501 WITHIN A RADIO TO TeV MULTI-INSTRUMENT CAMPAIGN

Xin Chen, Thomas Günther Bretz

We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 2013 April 1 and August 10, including the first detailed characterization of the synchrotron peak with Swift and NuSTAR. During the campaign, the nearby BL La ...

Iop Publishing Ltd2015

Very-high-energy gamma-ray observations of the Type Ia Supernova SN 2014J with the MAGIC telescopes

Thomas Günther Bretz

Context. In this work we present data from observations with the MAGIC telescopes of SN 2014J detected on January 21 2014, the closest Type Ia supernova since Imaging Air Cherenkov Telescopes started to operate. Aims. We aim to probe the possibility of ver ...

Edp Sciences S A2017

Multiwavelength observations of a VHE gamma-ray flare from PKS 1510-089 in 2015

Thomas Günther Bretz

Context. PKS 1510 089 is one of only a few flat spectrum radio quasars detected in the very-high-energy (VHE, > 100 GeV) gamma-ray band. Aims. We study the broadband spectral and temporal properties of the PKS 1510 089 emission during a high gamma-ray stat ...

Edp Sciences S A2017

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

Christophe Bauer, Francisco Sanchez, Mathieu Ribordy, Etienne Antoine Julien Moulin, Thomas Günther Bretz, Steve Couturier

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmol ...

2011

Long-Term Monitoring Of Bright Blazars With A Dedicated Cherenkov Telescope

Mathieu Ribordy, Thomas Günther Bretz

Flaring activity of Active Galactic Nuclei (AGN) in VHE gamma-ray astronomy is observed on timescales from minutes to years and can be explained either by the interaction of relativistic jets with the surrounding material or by imprints of the central engi ...

2009

Teraelectronvolt pulsed emission from the Crab Pulsar detected by MAGIC

Thomas Günther Bretz

Aims. We investigate the extension of the very high-energy spectral tail of the Crab Pulsar at energies above 400 GeV. Methods. We analyzed similar to 320 h of good-quality Crab data obtained with the MAGIC telescope from February 2007 to April 2014. Resul ...

Edp Sciences S A2016

MAGIC detection of very high energy gamma-ray emission from the low-luminosity blazar 1ES 1741+196

Thomas Günther Bretz

We present the first detection of the nearby (z = 0.084) low-luminosity BL Lac object 1ES 1741+196 in the very high energy (E > 100 GeV) band. This object lies in a triplet of interacting galaxies. Early predictions had suggested 1ES 1741+196 to be, along ...

Oxford Univ Press2017

Design and operation of FACT - the first G-APD Cherenkov telescope

Mathieu Ribordy, Camille Haller, Thomas Günther Bretz

The First G-APD Cherenkov Telescope (FACT) is designed to detect cosmic gamma-rays with energies from several hundred GeV up to about 10 TeV using the Imaging Atmospheric Cherenkov Technique. In contrast to former or existing telescopes, the camera of the ...

Iop Publishing Ltd2013

Multiwavelength observations of Mrk 501 in 2008

Xin Chen, Thomas Günther Bretz

Context. Blazars are variable sources on various timescales over a broad energy range spanning from radio to very high energy (>100 GeV, hereafter VHE). Mrk 501 is one of the brightest blazars at TeV energies and has been extensively studied since its firs ...

Edp Sciences S A2015

First multi-wavelength campaign on the gamma-ray-loud active galaxy IC 310

Thomas Günther Bretz, Udo Bach

Context. The extragalactic very-high-energy gamma-ray sky is rich in blazars. These are jetted active galactic nuclei that are viewed at a small angle to the line-of-sight. Only a handful of objects viewed at a larger angle are so far known to emit above 1 ...

Edp Sciences S A2017

G-APDs in Cherenkov astronomy: The FACT camera

Mathieu Ribordy, Thomas Günther Bretz

Geiger-mode avalanche photodiodes (G-APD, SiPM) are a much discussed alternative to photomultiplier tubes in Cherenkov astronomy. The First G-APD Cherenkov Telescope (FACT) collaboration builds a camera based on a hexagonal array of 1440 G-APDs and has now ...

Elsevier Science Bv2012

Design constraints on Cherenkov telescopes with Davies-Cotton reflectors

Mathieu Ribordy, Thomas Günther Bretz

This paper discusses the construction of high-performance ground-based gamma-ray Cherenkov telescopes with a Davies-Cotton reflector. For the design of such telescopes, usually physics constrains the field-of-view, while the photo-sensor size is defined by ...

Elsevier2013

Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies

Thomas Günther Bretz

We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 ob ...

Iop Publishing Ltd2016