CRIRES-VLT high-resolution spectro-astrometry as a tool in the search of small structures at the cores of Planetary Nebulae

The onset of the asymmetry in planetary nebulae (PNe) occurs during the short transition between the end of the asymptotic giant branch (AGB) phase and the beginning of the PN phase. Sources in this transition phase are compact and emit intensely in infrared wavelengths, making high spatial resolution observations in the infrared mandatory to investigate the shaping process of PNe. Interferometric VLTI IR observations have revealed compelling evidence of disks at the cores of PNe, but the limited sensitivity, strong observational constraints, and limited spatial coverage place severe limits on the universal use of this technique. Inspired by the successful detection of proto-planetary disks using spectro-astrometric observations, we apply here for the first time this technique to search for sub-arcsecond structures in PNe. Our exploratory study using CRIRES (CRyogenic high-resolution Infra-Red Echelle Spectrograph) commissioning data of the proto-PN IRAS 17516-2525 and the young PN SwSt 1 has revealed small-sized structures after the spectro-astrometric analysis of the two sources. In IRAS 17516-2525, the spectro-astrometric signal has a size of only 12 mas, as detected in the Brackett-gamma line, whereas the structures found in SwSt 1 have sizes of 230 mas in the [Fe III] line and 130 mas in the Brackett-gamma line. The spectroscopic observations required to perform spectro-astrometry of sources in the transition towards the PN phase are less time consuming and much more sensitive than VLTI IR observations. The results presented here open a new window in the search of the small-sized collimating agents that shape the complex morphologies of extremely axisymmetric PNe.Comment: 6 pages, 4 figure

VISIR-VLT Images of the Water Maser Emitting Planetary Nebula K 3-35

K3-35 is an extremely young bipolar planetary nebula that contains a precessing bipolar jet and a small (radius 80 AU) water maser equatorial ring. We have obtained VISIR- VLT images of K 3-35 in the PAH1 ({\lambda}=8.6 {\mu}m), [S iv] ({\lambda}=10.6 {\mu}m), and SiC ({\lambda}=11.85 {\mu}m) filters to analize the mid-IR morphology and the temperature structure of its dust emission. The images show the innermost nebular regions undetected at optical wavelegths and the precessing bipolar jets. The temperature map shows variations in the temperature in the equatorial zone and in regions associated to its jets.Comment: 2 pages, 2 figures, 283 IAU Symp. Planetary Nebulae an Eye to the Futur

Mechanisms for photon sorting based on slit-groove arrays

Mechanisms for one-dimensional photon sorting are theoretically studied in the framework of a coupled-mode method. The considered system is a nanopatterned structure composed of two different pixels drilled on the surface of a thin gold layer. Each pixel consists of a slit-groove array designed to squeeze a large fraction of the incident light into the central slit. The Double-Pixel is optimized to resolve two different frequencies in the near infrared. This system shows high transmission efficiencies and a small crosstalk. It is found that the response of the system strongly depends on the effective area shared by overlapping pixels. According to such degree of overlap, photon sorting can be achieved within three different regimes, which are discussed in detail. Optimal photon-sorting efficiencies are obtained for a moderate number of grooves that overlap with grooves of the neighbor pixel. These results could be applied to both optical and infrared detectors.The authors gratefully acknowledge financial support by European Projects EC FP7-ICT PLAISIR Project Ref. 247991, the Spanish Ministry of Science and Innovation project MAT2011-28581-C02-02, and the CUD project Ref. 2013-13.Peer Reviewe

Redescription of the Mexican scorpion \u3cem\u3eCentruroides hoffmanni\u3c/em\u3e Armas, 1996 (Scorpiones: Buthidae)

The Mexican scorpion Centruroides hoffmanni Armas, 1996 is redescribed, based on adults of both sexes. It is readily diagnosed by its medium size, dark brown two-banded tergites and brown marbling on carapace, appendages and metasoma, pectinal tooth counts, the shape of the female basal plate of the pectines, development of metasomal carinae, and shape of the telson and subaculear tubercle. The geographical distribution of this species ranges from southeastern Oaxaca to southwestern Chiapas, Mexico. It was originally compared with Centruroides thorelli (Kraepelin, 1891), but actually it seems to be closely related to C. infamatus (C. L. Koch, 1845) and C. baergi Hoffmann, 1932

Enhanced acoustical transmission and beaming effect through a single aperture

6 páginas, 5 figuras.-- PACS number(s): 78.66.Bz, 42.25.Bs, 41.20.Jb, 73.20.MfIn this paper we explore from a fundamental theoretical point of view, transmission phenomena of acoustic waves transferred through a single subwavelength slit milled into a sound-hard plate that is textured by surface corrugations. It is shown that the enhanced acoustical transmission unambiguously is linked to the excitation of acoustic surface waves and Fabry-Perot modes within the aperture. With the former resonant condition, we give a prescription on how these surface waves are induced and connected to the formation of a collimated sound beam in the far field.This work was financially supported by the Spanish Ministry of Science and Innovation under Projects No. MAT2008-06609-C02 and No. CSD2007-046-Nanolight.es. J.C. gratefully acknowledges financial support from the Carlsberg Foundation under Contract No. QUANTONICS 2009-01-0167.Peer reviewe

Observation of enhanced transmission for s-polarized light through a subwavelength slit

6 páginas, 4 figuras.-- et al.Enhanced optical transmission (EOT) through a single aperture is usually achieved by exciting surface plasmon polaritons with periodic grooves. Surface plasmon polaritons are only excited by p-polarized incident light, i.e. with the electric field perpendicular to the direction of the grooves. The present study experimentally investigates EOT for s-polarized light. A subwavelength slit surrounded on each side by periodic grooves has been fabricated in a gold film and covered by a thin dielectric layer. The excitation of s-polarized dielectric waveguide modes inside the dielectric film strongly increases the s-polarized transmission. A 25 fold increase is measured as compared to the case without the dielectric film. Transmission measurements are compared with a coupled mode method and show good qualitative agreement. Adding a waveguide can improve light transmission through subwavelength apertures, as both s and p-polarization can be efficiently transmitted.This work was funded by the European Community, project no. IST-FP6- 034506 'PLEAS'. AYN acknowledges MICINN for a Juan de la Cierva Grant.Peer reviewe

Form invariance symmetry generates a large set of FRW cosmologies

We show that Einstein's field equations for spatially flat Friedmann-Robertson-Walker (FRW) space times have a form invariance symmetry (FIS) realized by the form invariance transformations (FIT) which are indeed generated by an invertible function of the source energy density. These transformations act on the Hubble expansion rate, the energy density, and pressure of the cosmic fluid; likewise such transformations are endowed with a Lie group structure. Each representation of this group is associated with a particular fluid and consequently a determined cosmology, so that, the FIS defines a set of equivalent cosmological models. We focus our seek in the FIT generated by a linear function because it provides a natural framework to express the duality and also produces a large sets of cosmologies, starting from a seed one, in several contexts as for instance in the cases of a perfect fluid source and a scalar field driven by a potential depending linearly on the scalar field kinetic energy density.Comment: 11 pages, 3 figures. Accepted for publication in Modern Physics Letters A (2012

Weak and strong coupling regimes in plasmonic QED

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).We present a quantum theory for the interaction of a two-level emitter with surface plasmon polaritons confined in single-mode waveguide resonators. Based on the Green's function approach, we develop the conditions for the weak and strong coupling regimes by taking into account the sources of dissipation and decoherence: radiative and nonradiative decays, internal loss processes in the emitter, as well as propagation and leakage losses of the plasmons in the resonator. The theory is supported by numerical calculations for several quantum emitters, GaAs and CdSe quantum dots, and nitrogen vacancy (NV) centers together with different types of resonators constructed of hybrid, cylindrical, or wedge waveguides. We further study the role of temperature and resonator length. Assuming realistic leakage rates, we find the existence of an optimal length at which strong coupling is possible. Our calculations show that the strong coupling regime in plasmonic resonators is accessible within current technology when working at very low temperatures (≲4 K). In the weak coupling regime, our theory accounts for recent experimental results. By further optimization we find highly enhanced spontaneous emission with Purcell factors over 1000 at room temperature for NV centers. We finally discuss more applications for quantum nonlinear optics and plasmon-plasmon interactions. © 2013 American Physical Society.This work was supported by Spanish MICINN Projects No. FIS2011-25167, No. MAT2011-28581-C02, and No. CSD2007-046-Nanolight.es. F.J.G.-V. acknowledges financial support by the European Research Council, Grant No. 290981 (PLASMONANOQUANTA).Peer Reviewe