236 research outputs found
Gravitational lens system SDSS J1339+1310: microlensing factory and time delay
We spectroscopically re-observed the gravitational lens system SDSS
J1339+1310 using OSIRIS on the GTC. We also monitored the -band variability
of the two quasar images (A and B) with the LT over 143 epochs in the period
20092016. These new data in both the wavelength and time domains have
confirmed that the system is an unusual microlensing factory. The
C emission line is remarkably microlensed, since the
microlensing magnification of B relative to that for A, ,
reaches a value of 1.4 ( 0.4 mag) for its core. Moreover, the B image
shows a red wing enhancement of C flux (relative to A),
and = 2 (0.75 mag) for the C broad-line
emission. Regarding the nuclear continuum, we find a chromatic behaviour of
, which roughly varies from 5 (1.75 mag) at 7000 \AA\ to
6 (1.95 mag) at 4000 \AA. We also detect significant microlensing
variability in the band, and this includes a number of microlensing events
on timescales of 50100 d. Fortunately, the presence of an intrinsic 0.7 mag
dip in the light curves of A and B, permitted us to measure the time delay
between both quasar images. This delay is = 47
d (1 confidence interval; A is leading), in good agreement with
predictions of lens models.Comment: Accepted to A&A; 19 pages, 2 appendices, 3 long tables (Tables 1-3).
Tables 1-2 and an updated version of Table 3 are available at
http://grupos.unican.es/glendama/q1339.ht
A Survey of Electronic Literature Collections
In their article A Survey of Electronic Literature Collections Luis Pablo and MarÃa Goicoechea describe characteristics and functions of collections of electronic literature and analyze descriptors used and the way information can be accessed. Based on their observations, Pablo and Goicoechea advocate a database structure which is flexible and can produce a dynamic archiving model as texts are registered and collected so that tags form a close set for the texts in the collection and this set can expand as new texts make new tags necessary. Further, the organization of tags into ever more complex taxonomies seems inevitable, since this provides an accurate description of knowledge accumulation with respect to the field\u27s richness. They postulate that the study of tagging practices applied to digital works provides us with guidelines not only to describe texts of electronic literature, but also to demonstrate the wide variety of forms which a literary text can embody
New database for a sample of optically bright lensed quasars in the northern hemisphere
In the framework of the Gravitational LENses and DArk MAtter (GLENDAMA)
project, we present a database of nine gravitationally lensed quasars (GLQs)
that have two or four images brighter than = 20 mag and are located in the
northern hemisphere. This new database consists of a rich variety of follow-up
observations included in the GLENDAMA global archive, which is publicly
available online and contains 6557 processed astronomical frames of the nine
lens systems over the period 19992016. In addition to the GLQs, our archive
also incorporates binary quasars, accretion-dominated radio-loud quasars, and
other objects, where about 50% of the non-GLQs were observed as part of a
campaign to identify GLQ candidates. Most observations of GLQs correspond to an
ongoing long-term macro-programme with 210 m telescopes at the Roque de los
Muchachos Observatory, and these data provide information on the distribution
of dark matter at all scales. We outline some previous results from the
database, and we additionally obtain new results for several GLQs that update
the potential of the tool for astrophysical studies.Comment: Accepted to A&A; 32 pages. Tables 4-6, 8-11 and 13-16 are only
available in electronic form at the CDS and
https://grupos.unican.es/glendama/LQLM_results.ht
The Evolution of OSI Network Management by Integrated the Expert Knowledge
The management of modern telecommunications networks must satisfy
ever-increasing operational demands. Operation and quality service requirements
imposed by the users are also an important aspect to consider. In
this paper we have carried out a study for the improvement of intelligent administration
techniques in telecommunications networks. This task is achieved
by integrating knowledge base of expert system within the management information
used to manage a network. For this purpose, an extension of OSI management
framework specifications language has been added and investigated
in this study. A new property named RULE has also been added, which gathers
important aspects of the facts and the knowledge base of the embedded
expert system. Networks can be managed easily by using this proposed integration
Review and analysis of energy storage systems by hydro-pumping to support a mix of electricity generation with a high percentage of renewables
In some countries the planning of the electricity generation mix for the future includes a considerable increase in Renewable Energy (RE) to reduce the emissions caused by the use of fossil fuels. This trend can be reinforced if the installed power capacity of nuclear and coal plants is considerably decreased. On the other hand future electricity demand seems to increase due to population growth and greater domestic electrification, especially if transport electrification is tackled. The combination of these factors may result in an ever greater decline in Security of Supply (SoS), mainly due to the stochastic nature of electricity supply and demand behaviour. To achieve an acceptable level of SoS when introducing renewable energy into the grid it is necessary to increase storage capacity and tackle other measures such as demand management. Many energy storage technologies can be found, and Pumped Hydro Energy Storage (PHES) is recognised as the most mature, though other technologies such as batteries are also available.
In this paper, we first review PHES and its ability to support intermittent generation from energy plants, such as wind and solar, preventing energy losses and storing energy for use at times of high demand; second we analyse the performance of PHES in Spain over five years (2014-2018); our conclusion confirms that adequate SoS cannot be guaranteed with PHES management of the kind observed in the past.This research is supported by the Basque Government through the BERC 2018-2021 programme and by the Spanish Ministry of Economy and Competitiveness (MINECO) through BC3 MarÃa de Maeztu excellence accreditation MDM-2017-0714.Further support is provided by the project MINECO RTI2018-093352-B-I0
Time-domain studies of gravitationally lensed quasars (GLQs)
We present the overview and current results of an ongoing optical/NIR
monitoring of seven GLQs with the 2-m Liverpool Robotic Telescope. The
photometric data over the first seven years of this programme (2005-2011) are
leading to high-quality light curves, which in turn are being used as key tools
for different standard and novel studies. While brightness records of
non-lensed distant quasars may contain unrecognized extrinsic variations, one
can disentangle intrinsic from extrinsic signal in certain GLQs. Thus, some
GLQs in our sample allow us to assess their extrinsic and intrinsic variations,
as well as to discuss the origin of both kinds of fluctuations. We also
demonstrate the usefulness of GLQ time-domain data to obtain successful
reverberation maps of inner regions of accretion disks around distant
supermassive black holes, and to estimate redshifts of distant lensing
galaxies.Comment: 3 pages, 1 figure, 1 table, New Horizons in Time Domain Astronomy,
Proceedings IAU Symposium 285, R.E.M. Griffin, R.J. Hanisch and R. Seaman,
eds. (2012
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