The Chandra Deep Field South as a test case for Global Multi Conjugate Adaptive Optics

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

et al. 2017

Global MCAO aims to exploit a very wide technical field of view to find AO-suitable NGSs, with the goal to increase the overall sky coverage. The concept foresees the use of numerical entities, called Virtual Deformable Mirrors, to deal with the nominally thin depth of focus reduction, due to the field of view size. These objects act together as a best fit of the atmospheric layers behavior, in a limited number of conjugation altitudes, so to become the starting point for a further optimization of the real deformable mirrors shapes for the correction of the -smaller-scientific field. We developed a simulator, which numerically combines, in a Layer-Oriented fashion, the measurements of a given number of wavefront sensors, each dedicated to one reference star, to optimize the performance in the NGSs directions.Here we describe some details of the numerical code employed in the simulator, along with the philosophy behind some of the algorithms involved, listing the main goals and assumptions. Several details, including, for instance, how the number and conjugation heights of the VDMs are chosen in the simulation code, are briefly given. Furthermore, we also discuss the possible approaches to define a merit function to optimize the best solution. Finally, after an overview of the remaining issues and limitations of the method, numerical results obtained studying the influence of C n 2 profiles on the reconstruction quality and the delivered SR in a number of fields in the sky are given.

Section: Discussionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

GMCAO simulation tool development

Viotto¹,

Portaluri²,

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

et al. 2017

“…The best performance are obtained with stars that are relatively close to the scientific FoV (Figure 4): stellar magnitudes of NGSs do not impact the performance, while mean off-axis position of NGSs plays a key role. In such a figure is also shown a comparison with a simulation made with a different atmospheric profile (the same used in [1]) to show the importance of choosing realistic parameters for the simulations in order to consistent results.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, by simulating K-band observations of 6000 high redshift galaxies in the Chandra Deep Field South region (a portion of the mock image is shown in Figure 1), we have demonstrated how a GMCAO-equipped ELT can carry out photometric surveys successfully [1]. Here we extended the analysis using 22 well-known deep field surveys to get a more robust statistics on the results, showing how GMCAO can correct homogeneously star-poor regions, otherwise impracticable without the use of laser guide stars.…”

Section: Introductionmentioning

confidence: 93%

Deep observations with an ELT in the Global Multi Conjugated Adaptive Optics perspective

Portaluri¹,

Viotto²,

et al. 2020

Preprint

Deep observations of the Universe, usually as a part of sky surveys, are one of the symbols of the modern astronomy because they can allow big collaborations, exploiting multiple facilities and shared knowledge. The new generation of extremely large telescopes will play a key role because of their angular resolution and their capability in collecting the light of faint sources. Our simulations combine technical, tomographic and observational information, and benefit of the Global-Multi Conjugate Adaptive Optics (GMCAO) approach, a well demonstrated method that exploits only natural guide stars to correct the scientific field of view from the atmospheric turbulence. By simulating K-band observations of 6000 high redshift galaxies in the Chandra Deep Field South area, we have shown how an ELT can carry out photometric surveys successfully, recovering morphological and structural parameters. We present here a wide statistics of the expected performance of a GMCAO-equipped ELT in 22 well-known surveys in terms of SR.

“…For a review of the concept and the implementation of an example of such a system, see [24]. [25] presented a scientific case in the area of applicability of the GMCAO technique, recovering the structural parameters of a sample of 6000 synthetic high-redshift galaxies observed in the Chandra Deep Field South region with a GMCAO-assisted extremely large telescope (ELT) and performing the source detection and twodimensional fitting analysis. These studies have shown that the GMCAO approach can produce robust results when studying the photometry of extragalactic fields and can provide a useful frame of reference for a number of science cases.…”

Section: Introductionmentioning

confidence: 99%

Prospects of Deep Field Surveys with Global-MCAO on an ELT

Portaluri¹,

Viotto²,

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

et al. 2017

Several astronomical surveys aimed at the investigation of the extragalactic components were carried out in order to map systematically the universe and its constituents. An excellent level of detail is needed, and it is possible only using space telescopes or with the application of adaptive optics (AO) techniques for ground-based observatories. By simulating K-band observations of 6000 high-redshift galaxies in the Chandra Deep Field South region, we have already shown how an extremely large telescope can carry out photometric surveys successfully using the Global-MCAO, a natural guide stars based technique that allows the development of extragalactic research, otherwise impracticable without using laser guide stars. As the outcome of the analysis represents an impact science case for the new instruments on upcoming ground-based telescopes, here we show how the investigation of other observed deep fields could profit from such a technique. Further to an overview of the surveys suitable for the proposed approach, we show preliminary estimations both on geometrical (FoV and height) and purely AO perspectives (richness and homogeneity of guide stars in the area) for planned giant telescopes.