714 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
The far-IR spectrum of Sagittarius B2 region: Extended molecular absorption, photodissociation and photoionization
We present large scale 9'x 27'(25 pc x 70 pc) far-IR observations around Sgr
B2 using the Long-wavelength spectrometer (LWS) on board the Infrared Space
Observatory (ISO). The spectra are dominated by the strong continuum emission
of dust, the widespread molecular absorption of light hydrides (OH, CH and H2O)
and the fine structure lines of [NII], [NIII], [OIII], [CII] and [OI]. The
molecular richness in the outer layers of Sgr B2 is probed by the ISO-LWS
Fabry-Perot (35 km s^-1) detections towards Sgr B2(M), where more that 70 lines
from 15 molecular and atomic species are observed at high signal to noise
ratio.Comment: 46 pages, 10 figures, 5 tables, accepted in ApJ part I. (Figs. 1, 2,
3, 9 and 10 have been bitmapped to low resolution
A 5.5-year robotic optical monitoring of Q0957+561: substructure in a non-local cD galaxy
New light curves of the gravitationally lensed double quasar Q0957+561 in the
gr bands during 2008-2010 include densely sampled, sharp intrinsic fluctuations
with unprecedentedly high signal-to-noise ratio. These relatively violent flux
variations allow us to very accurately measure the g-band and r-band time
delays between the two quasar images A and B. Using correlation functions, we
obtain that the two time delays are inconsistent with each other at the 2sigma
level, with the r-band delay exceeding the 417-day delay in the g band by about
3 days. We also studied the long-term evolution of the delay-corrected flux
ratio B/A from our homogeneous two-band monitoring with the Liverpool Robotic
Telescope between 2005 and 2010. This ratio B/A slightly increases in periods
of violent activity, which seems to be correlated with the flux level in these
periods. The presence of the previously reported dense cloud within the cD
lensing galaxy, along the line of sight to the A image, could account for the
observed time delay and flux ratio anomalies.Comment: 8 pages, 6 figures, 4 tables, to appear in Astronomy and Astrophysic
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
Optimal management of a mega pumped hydro storage system under stochastic hourly electricity prices in the Iberian Peninsula
Concern for the environment led in some developed countries to planning future energy use that combines greater electrification with increasing use of Renewable Energy (RE) in the electricity generation mix. These scenarios can affect Security of Supply (SoS) because the intermittence of RE, its stochastic nature as an electricity generation sources and the demand's behaviour. It is necessary to increase storage capacity, among other measures. This paper analyses the effects of an optimal management strategy based on prices for Pumped Hydro Storage plants (PHES) using a daily mean reverting jump diffusion stochastic model of electricity prices in a risk neutral world including daily seasonality. Results show that a) income with this strategy under uncertainty may be insufficient compared to investment costs; b) the strategy does not usually provide proper guarantees as regards SoS at times of high demand for electricity; c) the technical characteristics of PHES such as the maximum upper & lower reservoir volume are highly significant. The effect of a minimum reservoir capacity at times of high demand is also analysed. PHES profitability can be improved under a Generating Company (GENCO) strategy coordinated with a wind farm and if the avoided CO2 emissions are taken into account. © 2022 Elsevier LtdThis 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 RTI 2018-093352-B-I00
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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