178 research outputs found
The Microchannel X-ray Telescope for the Gamma-Ray Burst mission SVOM
We present the Microchannel X-ray Telescope, a new light and compact
focussing telescope that will be flying on the Sino-French SVOM mission
dedicated to Gamma-Ray Burst science. The MXT design is based on the coupling
of square pore micro-channel plates with a low noise pnCCD. MXT will provide an
effective area of about 50 cmsq, and its point spread function is expected to
be better than 3.7 arc min (FWHM) on axis. The estimated sensitivity is
adequate to detect all the afterglows of the SVOM GRBs, and to localize them to
better then 60 arc sec after five minutes of observation.Comment: 12 pages, 8 figures, to be published in SPIE Astronomical Telescopes
+ Instrumentation, Montreal, June 201
The Microchannel X-ray Telescope on Board the SVOM Satellite
We present the Micro-channel X-ray Telescope (MXT), a new narrow-field (about
1{\deg}) telescope that will be flying on the Sino-French SVOM mission
dedicated to Gamma-Ray Burst science, scheduled for launch in 2021. MXT is
based on square micro pore optics (MPOs), coupled with a low noise CCD. The
optics are based on a "Lobster Eye" design, while the CCD is a focal plane
detector similar to the type developed for the seven eROSITA telescopes. MXT is
a compact and light (<35 kg) telescope with a 1 m focal length, and it will
provide an effective area of about 45 cmsq on axis at 1 keV. The MXT PSF is
expected to be better than 4.2 arc min (FWHM) ensuring a localization accuracy
of the afterglows of the SVOM GRBs to better than 1 arc min (90\% c.l. with no
systematics) provided MXT data are collected within 5 minutes after the
trigger. The MXT sensitivity will be adequate to detect the afterglows for
almost all the SVOM GRBs as well as to perform observations of non-GRB
astrophysical objects. These performances are fully adapted to the SVOM science
goals, and prove that small and light telescopes can be used for future small
X-ray missions.Comment: 6 pages, 6 figures, proceedings of the conference "Swift: 10 years of
Discovery", Rome, December 2-5, 2014. To be published by Po
Rank-(n – 1) convexity and quasiconvexity for divergence free fields
The CAST experiment at CERN (European Organization of Nuclear Research)
searches for axions from the sun. The axion is a pseudoscalar particle that was
motivated by theory thirty years ago, with the intention to solve the strong CP
problem. Together with the neutralino, the axion is one of the most promising
dark matter candidates. The CAST experiment has been taking data during the
last two years, setting an upper limit on the coupling of axions to photons
more restrictive than from any other solar axion search in the mass range below
0.1 eV. In 2005 CAST will enter a new experimental phase extending the
sensitivity of the experiment to higher axion masses. The CAST experiment
strongly profits from technology developed for high energy physics and for
X-ray astronomy: A superconducting prototype LHC magnet is used to convert
potential axions to detectable X-rays in the 1-10 keV range via the inverse
Primakoff effect. The most sensitive detector system of CAST is a spin-off from
space technology, a Wolter I type X-ray optics in combination with a prototype
pn-CCD developed for ESA's XMM-Newton mission. As in other rare event searches,
background suppression and a thorough shielding concept is essential to improve
the sensitivity of the experiment to the best possible. In this context CAST
offers the opportunity to study the background of pn-CCDs and its long term
behavior in a terrestrial environment with possible implications for future
space applications. We will present a systematic study of the detector
background of the pn-CCD of CAST based on the data acquired since 2002
including preliminary results of our background simulations.Comment: 11 pages, 8 figures, to appear in Proc. SPIE 5898, UV, X-Ray, and
Gamma-Ray Space Instrumentation for Astronomy XI
eROSITA Science Book: Mapping the Structure of the Energetic Universe
eROSITA is the primary instrument on the Russian SRG mission. In the first
four years of scientific operation after its launch, foreseen for 2014, it will
perform a deep survey of the entire X-ray sky. In the soft X-ray band (0.5-2
keV), this will be about 20 times more sensitive than the ROSAT all sky survey,
while in the hard band (2-10 keV) it will provide the first ever true imaging
survey of the sky at those energies. Such a sensitive all-sky survey will
revolutionize our view of the high-energy sky, and calls for major efforts in
synergic, multi-wavelength wide area surveys in order to fully exploit the
scientific potential of the X-ray data. The design-driving science of eROSITA
is the detection of very large samples (~10^5 objects) of galaxy clusters out
to redshifts z>1, in order to study the large scale structure in the Universe,
test and characterize cosmological models including Dark Energy. eROSITA is
also expected to yield a sample of around 3 millions Active Galactic Nuclei,
including both obscured and un-obscured objects, providing a unique view of the
evolution of supermassive black holes within the emerging cosmic structure. The
survey will also provide new insights into a wide range of astrophysical
phenomena, including accreting binaries, active stars and diffuse emission
within the Galaxy, as well as solar system bodies that emit X-rays via the
charge exchange process. Finally, such a deep imaging survey at high spectral
resolution, with its scanning strategy sensitive to a range of variability
timescales from tens of seconds to years, will undoubtedly open up a vast
discovery space for the study of rare, unpredicted, or unpredictable
high-energy astrophysical phenomena. In this living document we present a
comprehensive description of the main scientific goals of the mission, with
strong emphasis on the early survey phases.Comment: 84 Pages, 52 Figures. Published online as MPE document. Edited by S.
Allen. G. Hasinger and K. Nandra. Few minor corrections (typos) and updated
reference
Feedback and feeding in the context of galaxy evolution with SPICA: direct characterization of molecular outflows and inflows
A far-infrared observatory such as the {\it SPace Infrared telescope for
Cosmology and Astrophysics} ({\it SPICA}), with its unprecedented spectroscopic
sensitivity, would unveil the role of feedback in galaxy evolution during the
last Gyr of the Universe (), through the use of far- and
mid-infrared molecular and ionic fine structure lines that trace outflowing and
infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni
line shapes and absorption blueshifted wings in molecular lines with high
dipolar moments, and through emission line wings of fine-structure lines of
ionized gas. We quantify the detectability of galaxy-scale massive molecular
and ionized outflows as a function of redshift in AGN-dominated,
starburst-dominated, and main-sequence galaxies, explore the detectability of
metal-rich inflows in the local Universe, and describe the most significant
synergies with other current and future observatories that will measure
feedback in galaxies via complementary tracers at other wavelengths.Comment: This paper belongs to the SPICA Special Issue on PASA. Accepted for
publication in PAS
The Scientific Performance of the Microchannel X-ray Telescope on board the SVOM Mission
The Microchannel X-ray Telescope (MXT) will be the first focusing X-ray
telescope based on a "Lobster-Eye" optical design to be flown on Sino-French
mission SVOM. SVOM will be dedicated to the study of Gamma-Ray Bursts and more
generally time-domain astrophysics. The MXT telescope is a compact (focal
length ~ 1.15 m) and light (< 42 kg) instrument, sensitive in the 0.2--10 keV
energy range. It is composed of an optical system, based on micro-pore optics
(MPOs) of 40 micron pore size, coupled to a low-noise pnCDD X-ray detector. In
this paper we describe the expected scientific performance of the MXT
telescope, based on the End-to-End calibration campaign performed in fall 2021,
before the integration of the SVOM payload on the satellite.Comment: 22 pages, 12 figures, accepted for publication in Experimental
Astronom
Improving XMM-Newton EPIC pn data at low energies: method and application to the Vela SNR
High quantum efficiency over a broad spectral range is one of the main
properties of the EPIC pn camera on-board XMM-Newton. The quantum efficiency
rises from ~75% at 0.2 keV to ~100% at 1 keV, stays close to 100% until 8 keV,
and is still ~90% at 10 keV. The EPIC pn camera is attached to an X-ray
telescope which has the highest collecting area currently available, in
particular at low energies (more than 1400 cm2 between 0.1 and 2.0 keV). Thus,
this instrument is very sensitive to the low-energy X-ray emission. However,
X-ray data at energies below ~0.2 keV are considerably affected by detector
effects, which become more and more important towards the lowest transmitted
energies. In addition to that, pixels which have received incorrect offsets
during the calculation of the offset map at the beginning of each observation,
show up as bright patches in low-energy images. Here we describe a method which
is not only capable of suppressing the contaminations found at low energies,
but which also improves the data quality throughout the whole EPIC pn spectral
range. This method is then applied to data from the Vela supernova remnant.Comment: Proc. SPIE Vol. 5488: Astronomical Telescopes and Instrumentation, UV
- Gamma-Ray Space Telescope Systems, Eds. Guenther Hasinger and Martin J.
Turner, 22-24 June 2004, Glasgow, Scotland United Kingdo
National Government Responses to Marine Stewardship Council (MSC) Fisheries Certification: Insights from Atlantic Canada
Over the last decade, the proliferation of social and environmental certification programmes has attracted the attention of a growing number of political scientists interested in new forms of ‘private’ transnational governance. However, we still lack analyses on the nature and extent of different state responses to and involvement in new private transnational governance arrangements in particular sectors and in different jurisdictions. This paper advances our understanding of the interactions between nation-state and private transnational modes of governance by analysing the role of national government authorities in Marine Stewardship Council (MSC) fisheries certification in Atlantic Canada, known more for the disastrous collapse of Northern cod stocks than good marine stewardship. Focusing on the 2008 certification of Northern shrimp (Pandalus borealis) fisheries off the Province of Newfoundland and Labrador, the analysis finds that the implementation and maintenance of MSC certification in this case depended on significant support from government authorities. The delicate legitimacy of both authorities face a period of uncertainty in this case since some certified shrimp stocks appear to be in decline and perhaps also migrating northward off Newfoundland and Labrador
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