AO4ELT 2

Science Requirements for EAGLE (E-ELT)

Jean-gabriel CUBY — 2011-07-05T12:14:19Z

Submitted by J.-G. Cuby

Authors

C. Evans, M. Puech, N. Welikala, S. Morris, J.-G. Cuby et al.

Affiliations

UK ATC, GEPI-Observatoire de Paris, LAM, Durham University, LAM

Abstract

EAGLE is a Phase A study of a multi-IFU, near-IR spectrometer for the European Extremely Large Telescope (E-ELT). The design employs wide-field adaptive optics to deliver excellent image quality across a large (40 arcmin2) field. We summarise the functional and performance requirements that flow-down from the science case and provide illustrative performances from simulated observations.

Testing the limits of AO: near diffraction limited astronomy in the red optical

Matthias TECZA — 2011-05-17T13:55:27Z

Submitted by M. Tecza

Authors

M. Tecza

Affiliations

University of Oxford

Abstract

In this presentation I explore selected science cases that benefit from the increased spatial resolution and sensitivity delivered by advanced, e.g. tomographic and multi conjugate, adaptive optics assisted observations at ELTs. In particular I will show that near diffraction-limited spatial resolution can be achieved at red optical wavelengths, even in the low Strehl ( 5%) regime. A typical AO-PSF has a diffraction limited core sumperimposed on the seeing halo. At 8m telescopes, the AO PSF for a 5% Strehl ratio would have a very low intensity diffraction limited core on top of the seeing halo, however, at an ELT because of the 4-5 times higher angular resolution, the diffraction limited core stands more prominently atop the shallow seeing halo as the halo flux per resolution element is smaller by a factor of 16-25. I focus on prominent example science cases that use the Calcium triplet and thus exploit this gain in spatial resolution in the red-optical: stellar populations in dense environments or crowded fields; and the case of intermediate mass black holes in nuclear and globular stellar clusters as well as (super-) massive black holes in galaxies. Additionally, kinematic studies of intermediate to high-redshift galaxies benefit from the increased spatial resolution in the red-optical. I will show that well measured AO-PSFs are a necessary ingredient for the successful analysis and interpretation of diffraction limited data

The extragalactic heritage of the Layer-Oriented MAD at VLT.

Renato FALOMO — 2009-02-28T23:00:00Z

Submitted by Renato FALOMO

Authors

R. Falomo, R. Ragazzoni, et al.

Affiliations

INAF - OAPD

Abstract

The layer-oriented wavefront sensor onboard MAD, capable to catch up to 8 stars on the pins of pyramids in a 2 arcmin Field of View has been tested at the VLT in a unique dedicated run lasting 6 consecutive nights. As this kind of MCAO observations is focused onto a field with many relatively faint reference stars our main focus was onto extragalactic targets that are plagued by the problem of limited sky coverage.

While we achieved demonstrative science onto a very crowded field using a globular cluster, allowing to assess firmly the compensation stability over the FoV,we succeeded into securing scientific data for a number of extragalctic sources from the local Universe up to Z = 3. In particular we devised stellar population study in a dwarf galaxy, morphology of the jets in nearby AGN and the properties of the environment for high redshift quasars.

The scientific outcome of the observation run, consisting into 6 published refereed papers and two forthcoming, is briefly reported along with some lessons learned.

Science Driven AO Performance Metrics

Richard DAVIES — 2009-02-28T23:00:00Z

Submitted by Richard DAVIES

Authors

R. Davies

Affiliations

MPE

Abstract

The design study for MICADO, the E-ELT AO imaging camera, has shown that the commonly used performance metrics of Strehl ratio and encircled energy are unsatisfactory for astronomers. The reasons are simple. Strehl ratio that can be achieved is tied to sky coverage; and to an astronomer, observing a specific object or field is usually more important than achieving a high strehl ratio. On the other hand, encircled energy is too vague: it provides no information about resolution and is often given within a diameter that is too large to be scientifically useful. I propose an alternative metric, consisting of 2 parts, that should be of practical use to both astronomers and AO system designers. Making use of the characteristic core+halo profile of the partially corrected PSF, it comprises the fraction of flux within the core and the diameter of the core. From the astronomer's perspective, the first part is akin to strehl ratio (for perfect tip-tilt correction), while the second part allows one to widen the sky coverage at the expense of resolution. For AO designers, it enables one to separate the performance requirements of the high order and tip-tilt correction.

NFIRAOS High-Contrast Exoplanet Imaging Capabilities

Christian MAROIS — 2009-02-28T23:00:00Z

Submitted by Christian MAROIS

Authors

Christian Marois, Jean-Pierre Veran

Affiliations

NRC-HIA

Abstract

The TMT offers great potential to find and study nearby planetary systems, possibly imaging down to super-Earth size planets or still accreting distant planets in very young star forming regions. Since no first generation dedicated exoplanet finding instruments have been selected, initial direct exoplanet imaging will have to rely on the NFIRAOS facility AO system. I will present end-to-end Fresnel NFIRAOS simulations using its current optical design to evaluate its multi-wavelength high-contrast imaging capabilities. Long exposures have been simulated using the expected AO-delivered phase screens and the estimated speckle lifetime. It is shown that NFIRAOS will offer contrasts comparable to GPI (an optimized NIR planet-finding instrument that will soon be installed on the Gemini South 8-m telescope). Without coronograph and higher order correction, NFIRAOS will not be able to achieve high contrast at very small IWA, which are potentially accessible with a 30-meter telescope. However, TMT, with its larger aperture and better angular resolution, will acquire higher SNR planet spectra and will achieve an astrometric accuracy three times smaller than GPI, resulting in better atmospheric characterization and faster orbital parameters determination.