Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where V. Marandon is active.

Publication


Featured researches published by V. Marandon.


Astroparticle Physics | 2014

Impact of aerosols and adverse atmospheric conditions on the data quality for spectral analysis of the H.E.S.S. telescopes

J. Hahn; R. de los Reyes; K. Bernlöhr; P. P. Krüger; Y. T. E. Lo; P. M. Chadwick; M. K. Daniel; C. Deil; H. Gast; K. Kosack; V. Marandon

The Earth’s atmosphere is an integral part of the detector in ground-based imaging atmospheric Cherenkov telescope (IACT) experiments and has to be taken into account in the calibration. Atmospheric and hardware-related deviations from simulated conditions can result in the mis-reconstruction of primary particle energies and therefore of source spectra. During the eight years of observations with the High Energy Stereoscopic System (H.E.S.S.) in Namibia, the overall yield in Cherenkov photons has varied strongly with time due to gradual hardware aging, together with adjustments of the hardware components, and natural, as well as anthropogenic, variations of the atmospheric transparency. Here we present robust data selection criteria that minimize these effects over the full data set of the H.E.S.S. experiment and introduce the Cherenkov transparency coefficient as a new atmospheric monitoring quantity. The influence of atmospheric transparency, as quantified by this coefficient, on energy reconstruction and spectral parameters is examined and its correlation with the aerosol optical depth (AOD) of independent MISR satellite measurements and local measurements of atmospheric clarity is investigated.


arXiv: High Energy Astrophysical Phenomena | 2011

Exploring the Galaxy at TeV energies: Latest results from the H.E.S.S. Galactic Plane Survey

H. Gast; Francois Brun; S. Carrigan; R. C. G. Chaves; C. Deil; Arache Djannati-Atai; Y. A. Gallant; V. Marandon; M. de Naurois; R. de los Reyes

The High Energy Stereoscopic System (H.E.S.S.) is an array of four imaging atmospheric-Cherenkov telescopes located in Namibia and designed to detect extensive air showers initiated by gamma-rays in the very-high-energy domain. It is an ideal instrument for surveying the Galactic plane in search of new sources, thanks to its location in the Southern Hemisphere, its excellent sensitivity, and its large field-of-view. The efforts of the H.E.S.S. Galactic Plane Survey, the first comprehensive survey of the inner Galaxy at TeV energies, have contributed to the discovery of an unexpectedly large and diverse population of over 60 sources of VHE gamma rays within its current range of l=250 to 65 degrees in longitude and |b|<=3.5 degrees in latitude. The population of VHE gamma-ray emitters is dominated by the pulsar wind nebula and supernova remnant source classes, although nearly a third remain unidentified or confused. The sensitivity of H.E.S.S. to sources in the inner Galaxy has improved significantly over the past two years, from continued survey observations, dedicated follow-up observations of interesting source candidates, and from the development of advanced methods for discrimination of gamma-ray-induced showers from the dominant background of hadron-induced showers. The latest maps of the Galaxy at TeV energies will be presented, and a few remarkable new sources will be highlighted.


arXiv: High Energy Astrophysical Phenomena | 2016

Observations of the Crab Nebula with H.E.S.S. Phase II

M. Holler; D. Berge; C. van Eldik; J.-P. Lenain; V. Marandon; T. Murach; M. de Naurois; R. D. Parsons; Heike Prokoph; D. Zaborov

The High Energy Stereoscopic System (H.E.S.S.) phase I instrument was an array of four 100m2 mirror area Imaging Atmospheric Cherenkov Telescopes (IACTs) that has very successfully mapped the sky at photon energies above ∼ 100GeV. Recently, a 600m2 telescope was added to the centre of the existing array, which can be operated either in standalone mode or jointly with the four smaller telescopes. The large telescope lowers the energy threshold for gamma-ray observations to several tens of GeV, making the array sensitive at energies where the Fermi-LAT instrument runs out of statistics. At the same time, the new telescope makes the H.E.S.S. phase II instrument. This is the first hybrid IACT array, as it operates telescopes of different size (and hence different trigger rates) and different field of view. In this contribution we present results of H.E.S.S. phase II observations of the Crab Nebula, compare them to earlier observations, and evaluate the performance of the new instrument with Monte Carlo simulations.


arXiv: High Energy Astrophysical Phenomena | 2017

Discovery of new TeV supernova remnant shells in the Galactic plane with H.E.S.S.

D. Gottschall; M. Capasso; C. Deil; A. Djannati-Ataï; A. Donath; P. Eger; V. Marandon; N. Maxted; G. Pühlhofer; M. Renaud; Manami Sasaki; R. Terrier; J. Vink

Supernova remnants (SNRs) are prime candidates for efficient particle acceleration up to the knee in the cosmic ray particle spectrum. In this work we present a new method for a systematic search for new TeV-emitting SNR shells in 2864 hours of H.E.S.S. phase I data used for the H.E.S.S. Galactic Plane Survey. This new method, which correctly identifies the known shell morphologies of the TeV SNRs covered by the survey, HESS J1731-347, RX 1713.7-3946, RCW 86, and Vela Junior, reveals also the existence of three new SNR candidates. All three candidates were extensively studied regarding their morphological, spectral, and multi-wavelength (MWL) properties. HESS J1534-571 was associated with the radio SNR candidate G323.7-1.0, and thus is classified as an SNR. HESS J1912+101 and HESS J1614-518, on the other hand, do not have radio or X-ray counterparts that would permit to identify them firmly as SNRs, and therefore they remain SNR candidates, discovered first at TeV energies as such. Further MWL follow up o...


Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017) | 2017

Observations of the Pulsar Wind Nebula HESS J1825–137 with H.E.S.S. II

Alison Mitchell; S. Caroff; R. D. Parsons; J. Hahn; V. Marandon; J. A. Hinton

We present a new and deep analysis of the pulsar wind nebula (PWN) HESS\,J1825--137 with a comprehensive data set of almost 400 hours taken with the H.E.S.S. array between 2004 and 2016. The large amount of data, and the inclusion of low-threshold H.E.S.S. II data allows us to include a wide energy range of more than 2.5 orders of magnitude, ranging from 150 GeV up to 70 TeV. We exploit this rich data set to study the morphology and the spectral distributions of various subregions of this largely extended source in more detail. We find that HESS\,J1825--137 is not only the brightest source in that region above 32 TeV, but is also one of the most luminous of all firmly identified pulsar wind nebulae in the Milky Way.


arXiv: Instrumentation and Methods for Astrophysics | 2016

A major electronics upgrade for the H.E.S.S. Cherenkov telescopes 1-4

G. Giavitto; Terry Ashton; A. Balzer; D. Berge; Francois Brun; Thomas Chaminade; E. Delagnes; G. Fontaine; Matthias Füßling; B. Giebels; J. F. Glicenstein; Tobias Gräber; J. A. Hinton; Albert Jahnke; S. Klepser; Marko Kossatz; Axel Kretzschmann; Valentin Lefranc; Holger Leich; Hartmut Lüdecke; Pascal Manigot; V. Marandon; E. Moulin; M. de; P. Nayman; Marek Penno; D. Ross; D. Salek; Markus Schade; Thomas Schwab

The High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in the Khomas Highland in Namibia. It consists of four 12-m telescopes (CT1-4), which started operations in 2003, and a 28-m diameter one (CT5), which was brought online in 2012. It is the only IACT system featuring telescopes of different sizes, which provides sensitivity for gamma rays across a very wide energy range, from ~30 GeV up to ~100 TeV. Since the camera electronics of CT1-4 are much older than the one of CT5, an upgrade is being carried out; first deployment was in 2015, full operation is planned for 2016. The goals of this upgrade are threefold: reducing the dead time of the cameras, improving the overall performance of the array and reducing the system failure rate related to aging. Upon completion, the upgrade will assure the continuous operation of H.E.S.S. at its full sensitivity until and possibly beyond the advent of CTA. In the design of the new components, several CTA concepts and technologies were used and are thus being evaluated in the field: The upgraded read-out electronics is based on the NECTAR readout chips; the new camera front- and back-end control subsystems are based on an FPGA and an embedded ARM computer; the communication between subsystems is based on standard Ethernet technologies. These hardware solutions offer good performance, robustness and flexibility. The design of the new cameras is reported here.


arXiv: High Energy Astrophysical Phenomena | 2016

Study of the VHE diffuse emission in the central 200 pc of our Galaxy with H.E.S.S

A. Lemiere; R. Terrier; L. Jouvin; V. Marandon; B. Khelifi

The very high energy emission from the Galactic Center Ridge was revealed by the High Energy Stereoscopic System (H.E.S.S.) in 2006, after subtraction of the point sources HESS J1745-290, possibly associated with Sgr A


arXiv: High Energy Astrophysical Phenomena | 2011

Very-high-energy gamma radiation from supernova remnants as seen with H.E.S.S

A. Bochow; S. Carrigan; H. Gast; V. Marandon; M. Renaud; W. Hofmann

^\star


arXiv: Instrumentation and Methods for Astrophysics | 2018

Performance of the upgraded H.E.S.S. cameras

G. Giavitto; S. Bonnefoy; Terry Ashton; Michael Backes; A. Balzer; D. Berge; Francois Brun; Thomas Chaminade; E. Delagnes; G. Fontaine; Matthias Fuessling; B. Giebels; Jean-Francois Glicenstein; Tobias Gräber; J. A. Hinton; Albert Jahnke; S. Klepser; Marko Kossatz; Axel Kretzschmann; V. Lefranc; Holger Leich; Jean-Philippe Lenain; Hartmut Lüdecke; I. Lypova; Pascal Manigot; V. Marandon; E. Moulin; Mathieu de Naurois; P. Nayman; S. Ohm

, and HESS J1747


arXiv: High Energy Astrophysical Phenomena | 2017

The TeV supernova remnant shell HESS J1731-347 and its surroundings

M. Capasso; B. Condon; M. Coffaro; Y. Cui; D. Gottschall; D. Klochkov; V. Marandon; N. Maxted; G. Puehlhofer; G. Rowell

-

Collaboration


Dive into the V. Marandon's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Terry Ashton

University of Leicester

View shared research outputs
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge