High-resolution Spectrograph for E-ELT

The importance of optical and near-IR high resolution spectroscopy for the E-ELT has been demonstrated by two phase A studies: CODEX and SIMPLE (completed in 2010). Following the successful completion of those studies, and the recommendations of the E-ELT Science Working Group and of the Scientific Technical Committee, ESO decided to include a High Resolution Spectrograph (tentatively named, E-ELT HIRES) in the E-ELT instrumentation roadmap.

Soon after conclusion of the respective phase A studies the CODEX and SIMPLE consortia merged into the HIRES initiative (http://www.hires-eelt.org) and started developing the concept of a high-resolution spectrograph capable of providing R~100.000 in the 0.37-2.5 μm wavelength range. With the start of construction for the E-ELT, the Initiative has decided to pursue the construction of HIRES and has changed its status into the HIRES Consortium (PI. A Marconi).

HIRES is conceived to be a very versatile instrument, capable of pursuing a range of outstanding, key science cases, most of which can only be achieved through high spectral resolution with the photon collecting area provided by the E-ELT. Among the most important are the characterization of exoplanet atmospheres with the ultimate goal to detect signature of life, the study of the Galactic disk and bulge and in neighboring dwarf galaxies with unprecedent SNR, the detection of elements synthesized by the first stars in the early Universe, the capability of obtaining a three-dimensional map of the distribution of metals in the IGM and to provide the most accurate constraints on a possible variation of the fundamental constants of nature, and in particular of the fine structure constant  and of the proton-to-electron mass ratio.

The overall concept is summarized in Figure 1. The light from the telescope is split, via dichroics, into N wavelength channels. Each wavelength channel includes several telescope optical interfaces that feeds, through groups of fibers, a dedicated spectrograph module. Each telescope-interface and fiber-bundle corresponds to an observing mode. Based on a preliminary analysis the consortium consider four spectrograph modules, but both the number of spectrograph and the representative wavelength may change due to dedicated trade off study during Phase-A (kick-off phase A March 22 2016).