354 research outputs found
Active galactic nuclei synapses: X-ray versus optical classifications using artificial neural networks
(Abridged) Many classes of active galactic nuclei (AGN) have been defined
entirely throughout optical wavelengths while the X-ray spectra have been very
useful to investigate their inner regions. However, optical and X-ray results
show many discrepancies that have not been fully understood yet. The aim of
this paper is to study the "synapses" between the X-ray and optical
classifications.
For the first time, the new EFLUXER task allowed us to analyse broad band
X-ray spectra of emission line nuclei (ELN) without any prior spectral fitting
using artificial neural networks (ANNs). Our sample comprises 162 XMM-Newton/pn
spectra of 90 local ELN in the Palomar sample. It includes starbursts (SB),
transition objects (T2), LINERs (L1.8 and L2), and Seyferts (S1, S1.8, and S2).
The ANNs are 90% efficient at classifying the trained classes S1, S1.8, and
SB. The S1 and S1.8 classes show a wide range of S1- and S1.8-like components.
We suggest that this is related to a large degree of obscuration at X-rays. The
S1, S1.8, S2, L1.8, L2/T2/SB-AGN (SB with indications of AGN), and SB classes
have similar average X-ray spectra within each class, but these average spectra
can be distinguished from class to class. The S2 (L1.8) class is linked to the
S1.8 (S1) class with larger SB-like component than the S1.8 (S1) class. The L2,
T2, and SB-AGN classes conform a class in the X-rays similar to the S2 class
albeit with larger fractions of SB-like component. This SB-like component is
the contribution of the star-formation in the host galaxy, which is large when
the AGN is weak. An AGN-like component seems to be present in the vast majority
of the ELN, attending to the non-negligible fraction of S1-like or S1.8-like
component. This trained ANN could be used to infer optical properties from
X-ray spectra in surveys like eRosita.Comment: 15 pages, 7 figures, accepted for publication in A&A. Appendix B only
in the full version of the paper here:
https://dl.dropboxusercontent.com/u/3484086/AGNSynapsis_OGM_online.pd
Software di riduzione dati della Camera Infrarossa CAINDR. User Manual
User Manual- Software per la riduzioni dei dati infrarossi della camera CAINDR, situata nel Telescopio Carlos Sanchez (TCS) all'Osservatorio del Teide (Tenerife, Spagna
Fotometria e calibrazione infrarossi. User Manual
Manuale dove si descrivono le procedure di calibrazione e fotometria infraross
Upholding the unified model for Active Galactic Nuclei: VLT/FORS2 spectropolarimetry of Seyfert 2 galaxies
The origin of the unification model for Active Galactic Nuclei (AGN) was the detection of broad hydrogen recombination lines in the optical polarized spectrum of the Seyfert 2 galaxy (Sy2) NGC 1068. Since then, a search for the hidden broad-line region (HBLR) of nearby Sy2s started, but polarized broad lines have only been detected in ?30â40% of the nearby Sy2s observed to date. Here we present new VLT/FORS2 optical spectropolarimetry of a sample of 15 Sy2s, including Compton-thin and Compton-thick sources. The sample includes six galaxies without previously published spectropolarimetry, some of them normally treated as non-hidden BLR (NHBLR) objects in the literature, four classified as NHBLR, and five as HBLR based on previous data. We report ?4? detections of a HBLR in 11 of these galaxies (73% of the sample) and a tentative detection in NGC 5793, which is Compton-thick according to the analysis of X-ray data performed here. Our results confirm that at least some NHBLRs are misclassified, bringing previous publications reporting differences between HBLR and NHBLR objects into question. We detect broad H? and H? components in polarized light for 10 targets, and just broad H? for NGC 5793 and NGC 6300, with line widths ranging between 2100 and 9600 km s?1. High bolometric luminosities and low column densities are associated with higher polarization degrees, but not necessarily with the detection of the scattered broad components
Permutation entropy and irreversibility in gait kinematic time series from patients with mild cognitive decline and early alzheimerâs dementia
Gait is a basic cognitive purposeful action that has been shown to be altered in late stages
of neurodegenerative dementias. Nevertheless, alterations are less clear in mild forms of dementia,
and the potential use of gait analysis as a biomarker of initial cognitive decline has hitherto mostly
been neglected. Herein, we report the results of a study of gait kinematic time series for two groups of
patients (mild cognitive impairment and mild Alzheimerâs disease) and a group of matched control
subjects. Two metrics based on permutation patterns are considered, respectively measuring the
complexity and irreversibility of the time series. Results indicate that kinematic disorganisation is
present in early phases of cognitive impairment; in addition, they depict a rich scenario, in which
some joint movements display an increased complexity and irreversibility, while others a marked
decrease. Beyond their potential use as biomarkers, complexity and irreversibility metrics can open a
new door to the understanding of the role of the nervous system in gait, as well as its adaptation and
compensatory mechanismsThis research was funded through the Premio del Ilustre Colegio Profesional de Fisioterapeutas de la
Comunidad De Madrid, prize number ICPFM-IX-201
The Structure of IR Luminous Galaxies at 100 Microns
We have observed twenty two galaxies at 100 microns with the Kuiper Airborne
Observatory in order to determine the size of their FIR emitting regions. Most
of these galaxies are luminous far-infrared sources, with L_FIR > 10^11 L_sun.
This data constitutes the highest spatial resolution ever achieved on luminous
galaxies in the far infrared. Our data includes direct measurements of the
spatial structure of the sources, in which we look for departures from point
source profiles. Additionally, comparison of our small beam 100 micron fluxes
with the large beam IRAS fluxes shows how much flux falls beyond our detectors
but within the IRAS beam. Several sources with point- like cores show evidence
for such a net flux deficit. We clearly resolved six of these galaxies at 100
microns and have some evidence for extension in seven others. Those galaxies
which we have resolved can have little of their 100 micron flux directly
emitted by a point-like active galactic nucleus (AGN). Dust heated to ~40 K by
recent bursts of non-nuclear star formation provides the best explanation for
their extreme FIR luminosity. In a few cases, heating of an extended region by
a compact central source is also a plausible option. Assuming the FIR emission
we see is from dust, we also use the sizes we derive to find the dust
temperatures and optical depths at 100 microns which we translate into an
effective visual extinction through the galaxy. Our work shows that studies of
the far infrared structure of luminous infrared galaxies is clearly within the
capabilities of new generation far infrared instrumentation, such as SOFIA and
SIRTF.Comment: 8 tables, 23 figure
The soft X-ray and narrow-line emission of Mrk573 on kiloparcec scales
We present a study of the circumnuclear region of the nearby Seyfert galaxy
Mrk573 using Chandra, XMM-Newton and HST data. The X-ray morphology shows a
biconical region extending up to 12 arcsecs (4 kpc) in projection from the
nucleus. A strong correlation between the X-rays and the highly ionized gas
seen in the [O III] image is reported. Moreover, we have studied the line
intensities detected with the RGS/XMM-Newton and used them to fit the low
resolution EPIC/XMM-Newton and ACIS/Chandra spectra. The RGS spectrum is
dominated by emission lines of C VI, O VII, O VIII, Fe XVII, and Ne IX, among
others. A good fit is obtained using these emission lines found in the RGS
spectrum as a template for Chandra spectra of the nucleus and extended
emission. The photoionization model Cloudy provides a reasonable fit for both
the nuclear region and the cone-like structures. For the nucleus the emission
is modelled using two phases: a high ionization [log(U)=1.23] and a low
ionization [log(U)=0.13]. For the high ionization phase the transmitted and
reflected component are in a ratio 1:2, whereas for the low ionization the
reflected component dominates. For the extended emission, we successfully
reproduced the emission with two phases. The first phase shows a higher
ionization parameter for the NW (log(U)=0.9) than for the SE cone (log(U)=0.3).
The second phase shows a low ionization parameter (log(U)=-3) and is rather
uniform for NW and SE cones. In addition, the nuclear optical/infrared SED has
been modeled by a clumpy torus model. The torus bolometric luminosity agrees
with the AGN luminosity inferred from the observed hard X-ray spectrum. The
optical depth along the line of sight derived from the SED fit indicates a high
neutral column density in agreement with the classification of the nucleus as a
Compton-thick AGN.Comment: 15 pages, 14 figures, final version of the paper submitted to Ap
Economic risk assessment of drought impacts on irrigated agriculture
[EN] In this paper, we present an innovative framework for an economic risk analysis of drought impacts on irrigated agriculture. It consists on the integration of three components: stochastic time series modelling for prediction of inflows and future reservoir storages at the beginning of the irrigation season; statistical regression for the evaluation of water deliveries based on projected inflows and storages; and econometric modelling for economic assessment of the production value of agriculture based on irrigation water deliveries and crop prices. Therefore, the effect of the price volatility can be isolated from the losses due to water scarcity in the assessment of the drought impacts. Monte Carlo simulations are applied to generate probability functions of inflows, which are translated into probabilities of storages, deliveries, and finally, production value of agriculture. The framework also allows the assessment of the value of mitigation measures as reduction of economic losses during droughts.
The approach was applied to the Jucar river basin, a complex system affected by multiannual severe droughts, with irrigated agriculture as the main consumptive demand. Probability distributions of deliveries and production value were obtained for each irrigation season. In the majority of the irrigation districts, drought causes a significant economic impact. The increase of crop prices can partially offset the losses from the reduction of production due to water scarcity in some districts. Emergency wells contribute to mitigating the droughts' impacts on the Jucar river system. (C) 2017 Elsevier B.V. All rights reserved.This study has been supported by the IMPADAPT project (CGL2013-48424-C2-1-R) with Spanish MINECO (Ministerio de Economia y Competitividad) and European FEDER funds; the European Union's Horizon 2020 research and innovation programme under the IMPREX project (GA 641.811) and the FP7 project ENHANCE (FP7, 308438).Lopez-Nicolas, A.; Pulido-Velazquez, M.; Macian-Sorribes, H. (2017). Economic risk assessment of drought impacts on irrigated agriculture. Journal of Hydrology. 550:580-589. https://doi.org/10.1016/j.jhydrol.2017.05.004S58058955
Near Infrared Spectroscopic Monitoring of EXor variables: First Results
We present low resolution (R approximately 250) spectroscopy in the near-IR
(0.8 to 2.5um) of the EXor variables. These are the initial results (obtained
during the period 2007-2008) from a long term photometric and spectroscopic
program aimed to study the variability in the accretion processes of pre-Main
Sequence (PMS) stars, by correlating the continuum fluctuations with the
spectroscopical properties. Eight sources have been observed in different
epochs, for a total of 25 acquired spectra. EXor spectra show a wide variety of
emission features dominated by HI recombination (Paschen and Brackett series).
We have investigated whether line and continuum variability could be due to a
variable extinction, but such hypothesis is applicable only to the peculiar
source PV Cep. By comparing the observed spectra with a wind model, mass loss
rates in the range (2-10)x10^(-8) M_sun} yr^(-1) are derived, along with other
wind parameters. Consistent results are also obtained by assuming that HI lines
are due to accretion. CO overtone is also detected in the majority of the
sources both in absorption and in emission. It appears to come from regions
more compact than winds, likely the stellar photosphere (when in absorption)
and the circumstellar disk (when in emission). NaI and CaI IR lines behave as
the CO does, thus they are thought to arise in the same locations. For some
targets multiple spectra correspond to different activity stages of the source.
Those exhibiting the largest continuum variation at 2um (DeltaK > 1 mag)
present a significant line flux fading during the continuum declining phases.
In particular, CO absorption (emission) appears associated to inactive (active)
stages, respectively.Comment: To be published in Ap
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