CODEX: the high-resolution visual spectrograph for the E-ELT

A number of outstanding scientific problems require a high resolution, visual spectrograph at the E-ELT. Measuring the dynamics of the universe, finding earth-like planets with radial velocity techniques, determining the chemical evolution of the intergalactic medium and if physical constants varied in the past, all require a superior capability of measuring exceedingly small Doppler shifts. We have started a Phase A study for CODEX at the E-ELT. We present here the scientific cases, the requirements, the basic technical choices and trade offs, as well as a couple of design under evaluation. We aim at a super stable instrument, capable of obtaining a radial velocity precision of 2 cm/sec over several decades. It will be located at the coude focus. The design will make use of anamorphosis, pupil slicing, slanted VPH gratings and a novel calibration system based on laser frequency combs. Several CODEX-related R&D activities are running, and, in addition, a Call for Proposal for a precursor at the VLT has been issued.

[1]  Antonio Manescau,et al.  ESPRESSO: a high resolution spectrograph for the combined coude focus of the VLT , 2009 .

[2]  R. Holzwarth,et al.  High‐precision wavelength calibration of astronomical spectrographs with laser frequency combs , 2007, astro-ph/0703622.

[3]  D. Queloz,et al.  Cosmic dynamics in the era of Extremely Large Telescopes , 2008, 0802.1532.

[4]  M. T. Murphy,et al.  Revisiting VLT/UVES constraints on a varying fine-structure constant , 2008 .

[5]  D. Queloz,et al.  CODEX: measuring the acceleration of the universe and beyond , 2005, Proceedings of the International Astronomical Union.

[6]  Allan Sandage,et al.  The Change of Redshift and Apparent Luminosity of Galaxies due to the Deceleration of Selected Expanding Universes. , 1962 .

[7]  P. Petitjean,et al.  Indication of a cosmological variation of the proton-electron mass ratio based on laboratory measurement and reanalysis of H2 spectra. , 2006, Physical review letters.

[8]  Francesca Primas,et al.  Submitted to ApJ Preprint typeset using L ATEX style emulateapj v. 6/22/04 LITHIUM ISOTOPIC ABUNDANCES IN METAL-POOR HALO , 2005 .

[9]  Jean-Luis Lizon,et al.  Setting New Standards with HARPS , 2003 .

[10]  James A. Arns,et al.  Slanted fringe volume phase holographic gratings in astronomical instrumentation , 2008, Astronomical Telescopes + Instrumentation.

[11]  Bernard Delabre,et al.  New design approaches for a very high resolution spectrograph for the combined focus of the VLT , 2008, Astronomical Telescopes + Instrumentation.

[12]  Martino Romaniello,et al.  Precision Spectroscopy in Astrophysics , 2008 .