Recent Talks

The inflow of accretion in active galactic nuclei (AGN) and subsequent outflow are ultimately related to the feedback processes that link galaxy and black hole growth. New capabilities, especially JWST and ALMA, probe the scales where feedback is initiated. They reveal the multi-phase AGN environment that produces emission and obscures the activity of the central engine. Even nearby samples show evolution, distinguishing a phase of building up the AGN from one where outflow dominates and dusty winds can appear. Numerical radiative transfer models that aim to account for the resulting observations must be augmented to include a wider range of physical properties in these environments.

The atmosphere has a turbulent which produces aberrations on the wavefront of what otherwise would be a point source of laser light in the case of free-space optical communications, as well as it is the case for starlight when a telescope is pointed at a distant star. This problem is of special relevance in the arise of extremely large telescopes, as a bigger aperture encompasses the collection of more patches of an already turbulent atmosphere. Therefore, innovative adaptive optic techniques must be applied in order to exploit the outstanding resolution that can be achieved only at the diffraction limit of telescopes such as GTC, TMT, or ELT.

In this talk we present results incoming from applying Spatial Light Modulators (SLM) as the core element both for sensing and correcting the wavefront distortions. Instead of the common approach, which involves the use of Deformable Mirrors (DM), we make use of liquid-crystal-on-silicon (LCOS) SLM's, which can digitally modify the refractive index of each of the nearly half a million pixels it possess. In the sensing aspect we implement the novel Diffractive Wavefront Sensor (DWS) that can produce a wavefront directly from the image obtained after placing a diffractive element in the focal plane. Experimental results indicate robustness against obscurations and diffraction (caused by segmented mirrors and structures ubiquitous in large telescopes), and a spatial resolution orders of magnitude higher that the well known Shack-Hartman sensor.

En esta charla se mostrará el trabajo de los compañeros del IAC que fueron a Borobia para ver, fotografiar y retransmitir el eclipse, a parte de dar charlas y colaborar en las actividades realizadas por el observatorio de Borobia. ¿Qué tal ha sido la experiencia del primer eclipse total de este singular grupito?

LiteBIRD is the next-generation CMB space mission designed to produce full-sky polarization maps with unprecedented sensitivity. Spain contributes to the scientific exploitation, to the data-processing centres that will support operations and analysis to the mission, and to the technological development of the payload through the Temperature Monitoring and Compensation System (TMCS). The TMCS is responsible for monitoring the instrument’s thermal environment, with particular focus on the sub-kelvin cryogenic stage that sets the operating temperature of the Transition Edge Sensor (TES) detectors. This stage operates near 100 mK, where the scientific requirements impose thermal stability at the level of a few micro-kelvin—or even fractions of a micro-kelvin—over the relevant time scales (<0.1uHz - 5Hz). Achieving such performance, while potentially compensating for temperature fluctuations induced by cosmic-ray impacts and sky-background variations on the focal plane, constitutes a major technical challenge. The ongoing prototyping activities are therefore centred on identifying the critical functions of the TMCS electronics, developing dedicated electronic designs for each of them, and validating their feasibility through targeted tests. A first complete readout chain has been implemented to characterise components, evaluate noise and stability performance, verify subsystem functionality, and determine the architectural refinements required for the next design iteration. This presentation will summarise the thermal and stability requirements of the LiteBIRD instrument, describe the architecture and expected performance of the TMCS readout electronics, and present the results obtained during the current validation campaign. Finally, the status and needs of the room-temperature and sub-kelvin test benches, as well as the key development activities planned for the coming months, will be outlined.

Oscillations of solar-like stars are thought to be stochastically excited, and following Lighthill, the primary excitation mechanism is often assumed to be quadrupolar turbulent Reynolds stresses, though other models for excitation have been proposed. Recently, techniques have been developed to measure the near field wavefronts emitted by individual solar acoustic sources. These techniques have been successfully applied to radiative magnetohydrodynamic simulations of the upper solar convection zone and lower solar atmosphere, and direct waveform fitting has been used to invert for the source properties. Efforts to extend these measurements to high spatial resolution, high temporal cadence solar observations are underway. In this talk we will summarize what the global p-mode spectrum suggests about the stochastic excitation of the solar acoustic oscillations, describe what we have learned about the excitation of acoustic waves recently from the numerical simulations, and outline an observational path to similar success with the real Sun.

Una de las principales limitaciones tanto del sistema LGS como de sus componentes es evitar las frecuencias propias que pudieran afectar al espejo primario de GTC, empeorando sus prestaciones. El objetivo de la presente charla es presentar los estudios analíticos, FEMs y resultados experimentales para las frecuencias propias del Banco Óptico del Sistema de Transferencia de la Estrella Guía Láser para GTC. Se hará hincapié en la cualificación de modelos de elementos finitos, así como una demostración práctica de las complicaciones que presenta el estudio dinámico de los sistemas.

The European Solar Telescope (EST) has completed the Preliminary Design Review (PDR) of its Single Conjugate Adaptive Optics (SCAO) system and real-time controller. We present an overview of the expected SCAO performance based on the consolidated preliminary design, including simulations of a dual-branch configuration at 500nm and 680nm. The results, obtained with the new open-source Solar Adaptive Optics Simulator (SAOS) and validated against DASP, also evaluate key error sources specific to solar observations. We summarise the performance of the proposed real-time controller, the Durham Adaptive Optics (DAO) platform, and the successful demonstration tests conducted with SAOS.

A lo largo del último año, el programa de la óptica adaptativa de GTC (GTCAO) ha experimentado un enorme avance. Los equipos de GRANTECAN y del IAC han estado trabajando juntos en GTC para mejorar la calidad óptica del telescopio, poner a punto el sistema de GTCAO e integrar el primer instrumento de alta resolución espacial, la cámara infrarroja GRANCAIN. Este enorme esfuerzo ha dado resultados y el pasado mes de abril se consiguieron las primeras imágenes de GTC, en banda K, en el límite de difracción, alcanzando un Strehl Ratio por encima del 60%.

En la presentación se resume el trabajo realizado en el cofaseo del telescopio con la imprescindible colaboración del equipo de Keck y TMT, el trabajo de integración y pruebas de GRANCAIN, y los resultados en cielo con GTCAO.