Present and future of the OTELO project

OTELO is an emission-line object survey carried out with the red tunable filter of the instrument OSIRIS at the GTC, whose aim is to become the deepest emission-line object survey to date. With 100% of the data of the first pointing finally obtained in June 2014, we present here some aspects of the processing of the data and the very first results of the OTELO survey. We also explain the next steps to be followed in the near future.Comment: Oral contribution presented in the XI Scientific Meeting of the Spanish Astronomical Society held on September 8-12, in Teruel, Spain (7 pages, 2 figures, 1 table). To appear in Highlights of Spanish Astrophysics VIII, Proceedings of the XI Scientific Meeting of the Spanish Astronomical Society. Eds. A. J. Cenarro, F. Figueras, C. Hern\'andez-Monteagudo, J. Trujillo, L. Valdiviels

OTELO survey: optimal emission-line flux determination with OSIRIS/GTC

Emission-line galaxies are important targets for understanding the chemical evolution of galaxies in the universe. Deep, narrow-band imaging surveys allow to detect and study the flux and the equivalent widths (EW) of the emission line studied. The present work has been developed within the context of the OTELO project, an emission line survey using the Tunable Filters (TF) of OSIRIS, the first generation instrument on the GTC 10.4m telescope located in La Palma, Spain, that will observe through selected atmospheric windows relatively free of sky emission lines. With a total survey area of 0.1 square degrees distributed in different fields, reaching a 5 \sigma depth of 10^-18 erg/cm^2/s and detecting objects of EW < 0.3 A, OTELO will be the deepest emission line survey to date. As part of the OTELO preparatory activities, the objective of this study is to determine the best combination of sampling and full width at half maximum (FWHM) for the OSIRIS tunable filters for deblending H\alpha from [NII] lines by analyzing the flux errors obtained. We simulated the OTELO data by convolving a complete set of synthetic HII galaxies in EW with different widths of the OSIRIS TFs. We estimated relative flux errors of the recovered H\alpha and [NII]6583 lines. We found that, for the red TF, a FWHM of 12 A and a sampling of 5 A is an optimal combination that allow deblending H\alpha from the [NII]6583 line with a flux error lower than 20%. This combination will allow estimating SFRs and metallicities using the H\alpha flux and the N2 method, respectively.Comment: 16 pages, 9 figures. Some authors added. Accepted for publication in PAS

Radial turbine performance measurement under extreme off-design Conditions

[EN] During automotive urban driving conditions and future homologation cycles, automotive radial turbines experience transient conditions, whereby the same operate at very high blade speed ratios and, thus, at very low power outputs. Under those conditions, the turbine power output might not be enough to feed the mechanical power needs of the compressor. Typical fast one-dimensional full engine simulations rely on steady-state performance maps to characterize the turbocharger. Due to the restricting compressor braking power, extreme off-design measurements cannot be obtained in standard gas stands without using an external brake instead of the compressor or without using a motor attached to the turbocharger shaft. Such turbocharger assemblies cause shaft balancing issues inherent to the connection to a brake operating at high rotational speeds or need basic changes of the turbocharger geometry. This paper presents a novel approach for turbine performance map measurements at very low expansion ratio and very low mass flow without the aforementioned issues. The method uses the turbocharger compressor as a centrifugal turbine, providing mechanical power to the shaft and enabling turbine performance measurements from points of very high expansion ratio up to very low pressure ratio. It is even possible to measure at almost zero flow rate in the turbine when it consumes shaft power instead of producing it. This experimental procedure that can be applied to whatever turbocharger produces valuable information for the development and validation of turbine performance models aiming to extrapolate its behaviour at off-design conditions.The authors of this paper wish to thank M.A. Ortiz for his invaluable help during the experimental setup. The work has been partially supported by the Spanish Ministry of Economy and Competitiveness through grant number TRA2013-40853-R.Serrano, J.; Tiseira, AO.; García-Cuevas González, LM.; Inhestern, LB.; Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design Conditions. Energy. 125:72-84. https://doi.org/10.1016/j.energy.2017.02.118S728412

El turismo activo en la comunidad. Relación entre impactos percibidos por los residentes y apoyo al desarrollo del sector

The relationship between the tourism sector and sport has grown in importance, both academically and professionally. Residents also have an important role to play in harmonizing the development of the activity in the community, especially in those towns where tourism is the predominant sector. The objective of this study is to analyse which impacts associated with active tourism are perceived by residents and which are the best predictors of support for the development of this type of activity in the community. In addition, a descriptive analysis of the items corresponding to residents' perceptions of the impacts associated with active tourism has been carried out, as well as their support for its development in the area. Consequently, the importance of the assessment of these impacts by the bodies responsible for planning, organising and managing the sector is significant.La relación entre el sector turístico y el deporte ha crecido en importancia, tanto a nivel académico como profesional. Asimismo, los residentes tienen un importante papel a la hora de armonizar el desarrollo de la actividad en la comunidad, sobre todo en aquellas poblaciones donde la actividad turística es el sector predominante. El objetivo de este estudio es analizar qué impactos asociados al turismo activo son percibidos por los residentes y cuáles son los mejores predictores del apoyo al desarrollo de este tipo de actividad en la comunidad. Además, se ha realizado un análisis descriptivo de los ítems correspondientes a las percepciones de los residentes sobre los impactos asociados al turismo activo, así como su apoyo al desarrollo del mismo en la localidad. Resulta consecuente, la importancia en la evaluación de estos impactos por parte de los organismos encargados de la planificación, organización y gestión del sector

OTELO survey: Deep BVRI broad-band photometry of the Groth strip

Context. The Groth field is one of the sky regions that will be targeted by the OTELO (OSIRIS Tunable Filter Emission Line Object) survey in the optical 820 nm and 920 nm atmospheric windows. A complementary broad-band photometric catalogue of the field is essential for several purposes, in particular the inequivocal identification of sources, photometric redshift estimation, and population synthesis fitting.Aims. We aim to describe the OTELO survey and present deep BVRI imaging data of the Groth field. Galaxy number counts, colour distributions and galaxy clustering are analysed.Methods. BVRI deep images (?8 ks) were obtained with the Prime Focus Camera at the WHT (La Palma) and reduced with the IRAF package. The extraction and photometry of the sources was done with SExtractor software. We analysed the final catalogue to obtain galaxy number counts, as well as galaxy correlation functions as a function of I magnitude and V - I colour. It is also compared with estimations from mock catalogues of the Virgo-Millenium consortium.Results. We find excellent agreement between observed and mock data number counts. We also find evidence of galaxy clustering evolution and strong dependence of the angular correlation function on the V - I observed colour. Our data favour a flattening of the clustering amplitude with median apparent magnitude. The good general agreement between our clustering analysis and the estimates from the mock data is remarkableAcknowledgements. This work was supported by the Spanish Plan Nacional de Astronomía y Astrofísica under grants AYA2005–04149 and AYA2006–2358. We thank the referee for helpful comments that improved the clarity of this paper. The Millennium Simulation databases used in this paper and the web application providing online access to them were constructed as part of the activities of the German Astrophysical Virtual Observatory. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation

Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions

Turbine performance at extreme off-design conditions is growing in importance for properly computing turbocharged reciprocating internal combustion engines behaviour during urban driving conditions at current and future homologation cycles. In these cases, the turbine operates at very low flow rates and power outputs and at very high blade to jet speed ratios during transitory periods due to turbocharger wheel inertia and the high pulsation level of engine exhaust flow. This paper presents a physically based method that is able to extrapolate radial turbines reduced mass flow and adiabatic efficiency in blade speed ratio, turbine rotational speed and stator vanes position. The model uses a very narrow range of experimental data from turbine maps to fit the necessary coefficients. By using a special experimental turbocharger gas stand, experimental data have been obtained for extremely low turbine power outputs for the sake of model validation. Even if the data used for fitting only covers the turbine normal operation zone, the extrapolation model provides very good agreement with the experiments at very high blade speed ratio points; producing also good results when extrapolating in rotational speed and stator vanes position.The authors of this paper wish to thank M.A. Ortiz for his invaluable help during the experimental setup and to Arnau Blasco for his hard data fitting work. This work has been partially supported by the Spanish Ministry of Economy and Competitiveness through Grant No. TRA2013-40853-R.Serrano Cruz, JR.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Dombrovsky, A.; Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Conversion and Management. 128:281-293. https://doi.org/10.1016/j.enconman.2016.09.032S28129312

The central structure of Broad Absorption Line QSOs: observational characteristics in the cm-mm wavelength domain

Accounting for ~20% of the total QSO population, Broad Absorption Line QSOs are still an unsolved problem in the AGN context. They present wide troughs in the UV spectrum, due to material with velocities up to 0.2 c toward the observer. The two models proposed in literature try to explain them as a particular phase of the evolution of QSOs or as normal QSOs, but seen from a particular line of sight. We built a statistically complete sample of Radio-Loud BAL QSOs, and carried out an observing campaign to piece together the whole spectrum in the cm wavelength domain, and highlight all the possible differences with respect to a comparison sample of Radio-Loud non-BAL QSOs. VLBI observations at high angular resolution have been performed, to study the pc-scale morphology of these objects. Finally, we tried to detect a possible dust component with observations at mm-wavelengths. Results do not seem to indicate a young age for all BAL QSOs. Instead a variety of orientations and morphologies have been found, constraining the outflows foreseen by the orientation model to have different possible angles with respect to the jet axis

Effects of spin-elastic interactions in frustrated Heisenberg antiferromagnets

The Heisenberg antiferromagnet on a compressible triangular lattice in the spin- wave approximation is considered. It is shown that the interaction between quantum fluctuations and elastic degrees of freedom stabilizes the low symmetric L-phase with a collinear Neel magnetic ordering. Multi-stability in the dependence of the on-site magnetization on an unaxial pressure is found.Comment: Revtex, 4 pages, 2 eps figure

VLBA imaging of radio-loud BAL QSOs

Broad Absorption Line Quasars (BAL QSOs) have been found to be associated with extremely compact radio sources. These reduced dimensions can be either due to projection effects or these objects might actually be intrinsically small. Exploring these two hypotheses is important to understand the nature and origin of the BAL phenomenon because orientation effects are an important discriminant between the different models proposed to explain this phenomenon. In this work we present VLBA observations of 5 BAL QSOs and discuss their pc-scale morpholog