23 research outputs found
Very-High Energy Gamma Astrophysics
High-energy photons are a powerful probe for astrophysics and for fundamental
physics under extreme conditions. During the recent years, our knowledge of the
most violent phenomena in the Universe has impressively progressed thanks to
the advent of new detectors for high-energy gamma-rays. Observation of
gamma-rays gives an exciting view of the high-energy universe thanks to
satellite-based telescopes (AGILE, GLAST) and to ground-based detectors like
the Cherenkov telescopes (H.E.S.S. and MAGIC in particular), which recently
discovered more than 60 new very-high-energy sources. The progress achieved
with the last generation of Cherenkov telescopes is comparable to the one drawn
by EGRET with respect to the previous gamma-ray satellite detectors. This
article reviews the present status of high-energy gamma astrophysics, with
emphasis on the recent results and on the experimental developments.Comment: 60 pages, 52 figures, (on line abstract replacement
Detection of distant AGN by MAGIC: the transparency of the Universe to high-energy photons
The recent detection of blazar 3C279 by MAGIC has confirmed previous
indications by H.E.S.S. that the Universe is more transparent to
very-high-energy gamma rays than previously thought. We show that this fact can
be reconciled with standard blazar emission models provided photon oscillations
into a veri light Axion-Like Particle occur in extragalactic magnetic fields. A
quantitative estimate of this effect explains the observed spectrum of 3C279.
Our prediction can be tested in the near future by the satellite-borne GLAST
detector as well as by the ground-based Imaging Atmospheric Cherenkov
Telescpoes H.E.S.S., MAGIC, CANGAROO III, VERITAS and by the Extensive Air
Shower arrays ARGO-YBJ and MILAGRO.Comment: 4 pages, 1 figure, Proceeding of the Conference "4th Patras Workshop
on Axions, WIMPs and WISPs
Have Cherenkov telescopes detected a new light boson?
Recent observations by H.E.S.S. and MAGIC strongly suggest that the Universe
is more transparent to very-high-energy gamma rays than previously thought. We
show that this fact can be reconciled with standard blazar emission models
provided that photon oscillations into a very light Axion-Like Particle occur
in extragalactic magnetic fields. A quantitative estimate of this effect indeed
explains the observed data and in particular the spectrum of blazar 3C279.Comment: 3 pages, 1 figure, Proceeding of the "Eleventh International Workshop
on Topics in Astroparticle and Underground Physics" (TAUP), Roma, Italy, 1 -
5 July 2009 (to be published in the Proceedings
Evidence for a New Light Boson from Cosmological Gamma-Ray Propagation?
An anomalously large transparency of the Universe to gamma rays has recently
been discovered by the Imaging Atmospheric Cherenkov Telescopes (IACTs)
H.E.S.S. and MAGIC. We show that observations can be reconciled with standard
blazar emission models provided photon oscillations into a very light
Axion-Like Particle occur in extragalactic magnetic fields. A quantitative
estimate of this effect is successfully applied to the blazar 3C279. Our
prediction can be tested with the satellite-borne Fermi/LAT detector as well as
with the ground-based IACTs H.E.S.S., MAGIC, CANGAROOIII, VERITAS and the
Extensive Air Shower arrays ARGO-YBJ andMILAGRO. Our result also offers an
important observational test for models of dark energy wherein quintessence is
coupled to the photon through an effective dimension-five operator.Comment: 11 pages, 2 figures, Proceeding of the Conference "Frontiers of
Fundamental and Computational Physics", AIP Conference Proceedings 1018
(2008
Management of the science ground segment for the Euclid mission
Euclid is an ESA mission aimed at understanding the nature of dark energy and dark matter by using simultaneously two probes (weak lensing and baryon acoustic oscillations). The mission will observe galaxies and clusters of galaxies out to z~2, in a wide extra-galactic survey covering 15000 deg2, plus a deep survey covering an area of 40 deg\ub2. The payload is composed of two instruments, an imager in the visible domain (VIS) and an imager-spectrometer (NISP) covering the near-infrared. The launch is planned in Q4 of 2020. The elements of the Euclid Science Ground Segment (SGS) are the Science Operations Centre (SOC) operated by ESA and nine Science Data Centres (SDCs) in charge of data processing, provided by the Euclid Consortium (EC), formed by over 110 institutes spread in 15 countries. SOC and the EC started several years ago a tight collaboration in order to design and develop a single, cost-efficient and truly integrated SGS. The distributed nature, the size of the data set, and the needed accuracy of the results are the main challenges expected in the design and implementation of the SGS. In particular, the huge volume of data (not only Euclid data but also ground based data) to be processed in the SDCs will require distributed storage to avoid data migration across SDCs. This paper describes the management challenges that the Euclid SGS is facing while dealing with such complexity. The main aspect is related to the organisation of a geographically distributed software development team. In principle algorithms and code is developed in a large number of institutes, while data is actually processed at fewer centers (the national SDCs) where the operational computational infrastructures are maintained. The software produced for data handling, processing and analysis is built within a common development environment defined by the SGS System Team, common to SOC and ECSGS, which has already been active for several years. The code is built incrementally through different levels of maturity, going from prototypes (developed mainly by scientists) to production code (engineered and tested at the SDCs). A number of incremental challenges (infrastructure, data processing and integrated) have been included in the Euclid SGS test plan to verify the correctness and accuracy of the developed systems
A new light boson from MAGIC observations?
Recent detection of blazar 3C279 by MAGIC has confirmed previous indications
by H.E.S.S. that the Universe is more transparent to very-high-energy gamma
rays than currently thought. This circumstance can be reconciled with
observations of nearby blazars provided that photon oscillations into a very
light Axion-Like Particle occur in extragalactic magnetic fields. The emerging
"DARMA scenario" can be tested in the near future by the satellite-borne Fermi
LAT detector as well as by the ground-based Imaging Atmospheric Cherenkov
Telescopes H.E.S.S., MAGIC, CANGAROO III, VERITAS and by the Extensive Air
Shower arrays ARGO-YBJ and MILAGRO.Comment: 4 pages, 1 figure, Proceeding of the "Neutrino Oscillation Workshop",
Conca Specchiulla, Otranto, Italy, 6-12 September 200
Axion-Like Particles, Cosmic Magnetic Fields and Gamma-Ray Astrophysics
Axion-Like Particles (ALPs) are predicted by many extensions of the Standard
Model and give rise to characteristic dimming and polarization effects in a
light beam travelling in a magnetic field. In this Letter, we demonstrate that
photon-ALP mixing in cosmic magnetic fields produces an observable distortion
in the energy spectra of distant gamma-ray sources (like AGN) for ranges of the
ALP parameters allowed by all available constraints. The resulting effect is
expected to show up in the energy band 100 MeV - 100 GeV, and so it can be
serched with the upcoming GLAST mission.Comment: 17 pages, 6 figures; accepted for publication in Physics Letters B.
Revised versio
ECSGS Management Plan
Version 0.9 reviewed by ESA at the Euclid SGS Preliminary Requirements Review (2013)
Version 1.9 reviewed by ESA at the Euclid SGS System Requirements Review (2015)The ECSGS Management Plan is focused on the following topics: ECSGS organisation, responsibilities, reporting; ECSGS costing, manpower, effort tracking; ECSGS logistic (when relevant); organisation of individual OUs and SDCs under ECSGS coordination. Sections 9 and 10 contain global and local organisation details, and the names of responsible staff. The management principles expressed in this document are a coherent extension of those described in the ECSGS Science Implementation Plan. The document is compliant with the ECSS standards, as tailored for the Euclid SGS