993 research outputs found
Simulating the WFXT sky
We investigate the scientific impact of the Wide Field X-ray Telescope
mission. We present simulated images and spectra of X-ray sources as observed
from the three surveys planned for the nominal 5-year WFXT lifetime. The goal
of these simulations is to provide WFXT images of the extragalactic sky in
different energy bands based on accurate description of AGN populations, normal
and star forming galaxies, groups and clusters of galaxies. The images are
realized using a detailed PSF model, instrumental and physical
backgrounds/foregrounds, accurate model of the effective area and the related
vignetting effect. Thanks to this comprehensive modelization of the WFXT
properties, the simulated images can be used to evaluate the flux limits for
detection of point and extended sources, the effect of source confusion at very
faint fluxes, and in general the efficiency of detection algorithms. We also
simulate the spectra of the detected sources, in order to address specific
science topics which are unique to WFXT. Among them, we focus on the
characterization of the Intra Cluster Medium (ICM) of high-z clusters, and in
particular on the measurement of the redshift from the ICM spectrum in order to
build a cosmological sample of galaxy clusters. The end-to-end simulation
procedure presented here, is a valuable tool in optimizing the mission design.
Therefore, these simulations can be used to reliably characterize the WFXT
discovery space and to verify the connection between mission requirements and
scientific goals. Thanks to this effort, we can conclude on firm basis that an
X-ray mission optimized for surveys like WFXT is necessary to bring X-ray
astronomy at the level of the optical, IR, submm and radio wavebands as
foreseen in the coming decade.Comment: "Proceedings of "The Wide Field X-ray Telescope Workshop", held in
Bologna, Italy, Nov. 25-26 2009. To appear in Memorie della Societa
Astronomica Italiana 2010 (arXiv:1010.5889)
IEA Wind 2013 Annual Report
Contribution to this annual report of the IEA Wind Implementing Agreement, Chapter 20 .Here the JRC, as representative of the Commission, exposes the achievements in wind R&D supported by the Commission programmes (FP7, IEE), after coordinating with our colleagues from ENER, RTD, the REU (JRC/IET) and EACI. Subchapter 2 of the European Commission/EWEA chapter is the Commission's responsibility whereas subchapters 1 and 3 are EWEA's responsibilityJRC.F.6 - Energy Technology Policy Outloo
FAVOR (FAst Variability Optical Registration) -- A Two-telescope Complex for Detection and Investigation of Short Optical Transients
An astronomical complex intended to detect optical transients (OTs) in a wide
field and follow them up with high time resolution investigation is described.Comment: 4 pages, 3 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
Simbol-X Hard X-ray Focusing Mirrors: Results Obtained During the Phase A Study
Simbol-X will push grazing incidence imaging up to 80 keV, providing a strong
improvement both in sensitivity and angular resolution compared to all
instruments that have operated so far above 10 keV. The superb hard X-ray
imaging capability will be guaranteed by a mirror module of 100 electroformed
Nickel shells with a multilayer reflecting coating. Here we will describe the
technogical development and solutions adopted for the fabrication of the mirror
module, that must guarantee an Half Energy Width (HEW) better than 20 arcsec
from 0.5 up to 30 keV and a goal of 40 arcsec at 60 keV. During the phase A,
terminated at the end of 2008, we have developed three engineering models with
two, two and three shells, respectively. The most critical aspects in the
development of the Simbol-X mirrors are i) the production of the 100 mandrels
with very good surface quality within the timeline of the mission; ii) the
replication of shells that must be very thin (a factor of 2 thinner than those
of XMM-Newton) and still have very good image quality up to 80 keV; iii) the
development of an integration process that allows us to integrate these very
thin mirrors maintaining their intrinsic good image quality. The Phase A study
has shown that we can fabricate the mandrels with the needed quality and that
we have developed a valid integration process. The shells that we have produced
so far have a quite good image quality, e.g. HEW <~30 arcsec at 30 keV, and
effective area. However, we still need to make some improvements to reach the
requirements. We will briefly present these results and discuss the possible
improvements that we will investigate during phase B.Comment: 6 pages, 3 figures, invited talk at the conference "2nd International
Simbol-X Symposium", Paris, 2-5 december, 200
ESPRESSO: The next European exoplanet hunter
The acronym ESPRESSO stems for Echelle SPectrograph for Rocky Exoplanets and
Stable Spectroscopic Observations; this instrument will be the next VLT high
resolution spectrograph. The spectrograph will be installed at the
Combined-Coud\'e Laboratory of the VLT and linked to the four 8.2 m Unit
Telescopes (UT) through four optical Coud\'e trains. ESPRESSO will combine
efficiency and extreme spectroscopic precision. ESPRESSO is foreseen to achieve
a gain of two magnitudes with respect to its predecessor HARPS, and to improve
the instrumental radial-velocity precision to reach the 10 cm/s level. It can
be operated either with a single UT or with up to four UTs, enabling an
additional gain in the latter mode. The incoherent combination of four
telescopes and the extreme precision requirements called for many innovative
design solutions while ensuring the technical heritage of the successful HARPS
experience. ESPRESSO will allow to explore new frontiers in most domains of
astrophysics that require precision and sensitivity. The main scientific
drivers are the search and characterization of rocky exoplanets in the
habitable zone of quiet, nearby G to M-dwarfs and the analysis of the
variability of fundamental physical constants. The project passed the final
design review in May 2013 and entered the manufacturing phase. ESPRESSO will be
installed at the Paranal Observatory in 2016 and its operation is planned to
start by the end of the same year.Comment: 12 pages, figures included, accepted for publication in Astron. Nach
Simultaneous Swift and REM monitoring of the blazar PKS0537-441 in 2005
The blazar PKS0537-441 has been observed by Swift between the end of 2004 and
November 2005. The BAT monitored it recurrently for a total of 2.7 Ms, and the
XRT and UVOT pointed it on seven occasions for a total of 67 ks, making it one
of the AGNs best monitored by Swift. The automatic optical and infrared
telescope REM has monitored simultaneously the source at all times. In
January-February 2005 PKS0537-441 has been detected at its brightest in optical
and X-rays: more than a factor of 2 brighter in X-rays and about a factor 60
brighter in the optical than observed in December 2004. The July 2005
observation recorded a fainter X-ray state. The simultaneous optical state,
monitored by both Swift UVOT and REM, is high, and in the VRI bands it is
comparable to what was recorded in early January 2005, before the outburst. In
November 2005, the source subsided both in X-rays and optical to a quiescent
state, having decreased by factors of ~4 and ~60 with respect to the
January-February 2005 outburst, respectively. Our monitoring shows an overall
well correlated optical and X-ray decay. On the shorter time scales (days or
hours), there is no obvious correlation between X-ray and optical variations,
but the former tend to be more pronounced, opposite to what is observed on
monthly time scales. The widely different amplitude of the long term
variability in optical and X-rays is very unusual and makes this observation a
unique case study for blazar activity. The spectral energy distributions are
interpreted in terms of the synchrotron and inverse Compton mechanisms within a
jet where the plasma radiates via internal shocks and the dissipation depends
on the distance of the emitting region from the central engine (abridged).Comment: 24 pages, 7 figures, 3 tables, in press in the Ap
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