223 research outputs found
The INTEGRAL/SPI response and the Crab observations
The Crab region was observed several times by INTEGRAL for calibration
purposes. This paper aims at underlining the systematic interactions between
(i) observations of this reference source, (ii) in-flight calibration of the
instrumental response and (iii) the development and validation of the analysis
tools of the SPI spectrometer. It first describes the way the response is
produced and how studies of the Crab spectrum lead to improvements and
corrections in the initial response. Then, we present the tools which were
developed to extract spectra from the SPI observation data and finally a Crab
spectrum obtained with one of these methods, to show the agreement with
previous experiments. We conclude with the work still ahead to understand
residual uncertainties in the response.Comment: 4 pages, 4 figures, Proc. of the 5th INTEGRAL Workshop (Feb. 16-20
2004), to be published by ES
INTEGRAL broadband spectroscopy of Vela X-1
The wind-accreting X-ray binary pulsar and cyclotron line source Vela X-1 has
been observed extensively during INTEGRAL Core Program observations of the Vela
region in June-July and November-December 2003. In the latter set of
observations the source showed intense flaring -- see also Staubert et al.
(2004), these proceedings.
We present early results on time averaged and time resolved spectra, of both
epochs of observations. A cyclotron line feature at ~53 keV is clearly detected
in the INTEGRAL spectra and its broad shape is resolved in SPI spectra. The
remaining issues in the calibration of the instruments do not allow to resolve
the question of the disputed line feature at 20-25 keV.
During the first main flare the average luminosity increases by a factor of
\~10, but the spectral shape remains very similar, except for a moderate
softening.Comment: Accepted for proceedings of 5th INTEGRAL Worksho
Fault-controlled and stratabound dolostones in the Late Aptian-earliest Albian Benassal Formation (Maestrat Basin, E Spain) : petrology and geochemistry constrains
This study was developed under the ExxonMobil FC2 Alliance (Fundamental Controls on Flow in Carbonates). The authors wish to thank ExxonMobil Production Company and ExxonMobil Upstream Research Company for providing funding. The views in this article by Sherry L. Stafford are her own and not necessarily those of ExxonMobil. This research was supported by the Sedimentary Geology Research Group of the Generalitat de Catalunya (2014SGR251). We would like to thank Andrea Ceriani and Paola Ronchi for their critical and valuable reviews, and Associated Editor Piero Gianolla for the editorial work.Peer reviewedPostprin
LâObservation du Comportement du Nouveau-Ne: Une Source Pertinente dâInformations Medicales
Lâobservation du comportement du nouveau-nĂ© est une source importante dâinformations dâordre mĂ©dical. Trois domaines bĂ©nĂ©ficient des donnĂ©es de lâobservation : 1) lâanalyse du dĂ©veloppement grĂące Ă lâutilisation de lâAssessment of Preterm Infant Behavior (Ă©valuation du comportement de lâenfant prĂ©maturĂ©) ; 2) lâĂ©valuation de la douleur dominĂ©e par lâanalyse de lâexpression faciale grĂące Ă des Ă©chelles validĂ©es, telle que le Neonatal Facial Coding System (systĂšme nĂ©onatal de codage facial) ; 3) la recherche de lĂ©sions cĂ©rĂ©brales par le Quality Assessment of General Movements (Ă©valuation de la qualitĂ© des mouvements gĂ©nĂ©raux). Lâobservation comportementale fondĂ©e sur des outils validĂ©s par la recherche clinique constitue un complĂ©ment utile des donnĂ©es de lâimagerie en pĂ©riode nĂ©onatale.
The neonatal behavioral observation is an important source of medical informations in three domains: 1) assessment of development which can be done with the Assessment of Preterm Infant Behavior, 2) assessment of pain with the analysis of facial expression using validated pain scales such as the Neonatal Facial Coding System, 3) assessement of brain injuries with the Quality Assessment of General Movements. Such a behavioral observation of the newborn using validated tools is a useful complement of the neuro-imaging techniques
Influence of the Earth on the background and the sensitivity of the GRM and ECLAIRs instruments aboard the Chinese-French mission SVOM
SVOM (Space-based multi-band astronomical Variable Object Monitor) is a
future Chinese-French satellite mission which is dedicated to Gamma-Ray Burst
(GRB) studies. Its anti-solar pointing strategy makes the Earth cross the field
of view of its payload every orbit. In this paper, we present the variations of
the gamma-ray background of the two high energy instruments aboard SVOM, the
Gamma-Ray Monitor (GRM) and ECLAIRs, as a function of the Earth position. We
conclude with an estimate of the Earth influence on their sensitivity and their
GRB detection capability.Comment: 24 pages, 15 figures, accepted for publication in Experimental
Astronom
The INTEGRAL spectrometer SPI: performance of point-source data analysis
The performance of the SPI point-source data analysis system is assessed using a combination of simulations and of observations gathered during the first year of INTEGRAL operations. External error estimates are derived by comparing source positions and fluxes obtained from independent analyses. When the source detection significance provided by the spiros imaging reconstruction program increases from âŒ10 to âŒ100, the errors decrease as the inverse of the detection significance, with values from âŒ10 to âŒ1 arcmin in positions, and from âŒ10 to âŒ1 per cent in relative flux. These errors are dominated by Poisson counting noise. Our error estimates are consistent with those provided by the spiros program. With higher detection significance, the accuracy is ultimately limited to âŒ0.5 arcmin in position and âŒ1 per cent in relative flux by other types of errors. In these cases, spiros underestimates the true errors as it only takes into account the Poisson counting noise. At the low signal-to-noise ratio end, spiros is also too optimistic, and the number of spurious detections is significantly higher than would be expected from statistical noise fluctuations only. The analysis results do not depend significantly on the target off-axis angle, or on the number of pointings considered, provided that this number is larger than âŒ15. Realistic source confusion tests are carried out by adding simulated data to the observation of the Crab nebula and pulsar. Reliable flux values can be obtained for sources separated by angles as small as 0.5 deg if their positions are known and kept fixed in the data deconvolution process. However, when spiros is searching for best source positions, if two sources are separated by less than âŒ2 deg, it may only find a single spurious source located between the real ones (with a flux equal to the sum of the fluxes). Finally, users of the spiros program can find a number of important recommendations in the conclusio
Annihilation emission from young supernova remnants
A promising source of the positrons that contribute through annihilation to
the diffuse Galactic 511keV emission is the beta-decay of unstable nuclei like
56Ni and 44Ti synthesised by massive stars and supernovae. Although a large
fraction of these positrons annihilate in the ejecta of SNe/SNRs, no
point-source of annihilation radiation appears in the INTEGRAL/SPI map of the
511keV emission. We exploit the absence of detectable annihilation emission
from young local SNe/SNRs to derive constraints on the transport of MeV
positrons inside SN/SNR ejecta and their escape into the CSM/ISM, both aspects
being crucial to the understanding of the observed Galactic 511keV emission. We
simulated 511keV lightcurves resulting from the annihilation of the decay
positrons of 56Ni and 44Ti in SNe/SNRs and their surroundings using a simple
model. We computed specific 511keV lightcurves for Cas A, Tycho, Kepler,
SN1006, G1.9+0.3 and SN1987A, and compared these to the upper-limits derived
from INTEGRAL/SPI observations. The predicted 511keV signals from positrons
annihilating in the ejecta are below the sensitivity of the SPI instrument by
several orders of magnitude, but the predicted 511keV signals for positrons
escaping the ejecta and annihilating in the surrounding medium allowed to
derive upper-limits on the positron escape fraction of ~13% for Cas A, ~12% for
Tycho, ~30% for Kepler and ~33% for SN1006. The transport of ~MeV positrons
inside SNe/SNRs cannot be constrained from current observations of the 511keV
emission from these objects, but the limits obtained on their escape fraction
are consistent with a nucleosynthesis origin of the positrons that give rise to
the diffuse Galactic 511keV emission.Comment: 15 pages, 11 figures, accepted for publication in A&
NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array
NectarCAM is a camera proposed for the medium-sized telescopes of the
Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV
to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the
heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog
to Digital converter. The camera will be equipped with 265 7-photomultiplier
modules, covering a field of view of 8 degrees. Each module includes the
photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and
Ethernet transceiver. The recorded events last between a few nanoseconds and
tens of nanoseconds. The camera trigger will be flexible so as to minimize the
read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data
rate of more than 4 kHz with less than 5\% dead time. The camera concept, the
design and tests of the various subcomponents and results of thermal and
electrical prototypes are presented. The design includes the mechanical
structure, cooling of the electronics, read-out, clock distribution, slow
control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
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