A Mega Integral Field Spectrograph for the VLT

We describe MIFS, a second generation integral-field spectrograph for the VLT, operating in the visible wavelength range. It combines a 1^' × 1^' field of view with the improved spatial resolution provided by multi-conjugate adaptive optics and covers a large simultaneous spectral range (0.6-1.0 μm). A separate mode exploits the highest spatial resolution provided by adaptive optics. With this unique combination of capabilities, MIFS has a wide domain of application and a large discovery potential. The MIFS low-spatial resolution mode (sampled at 0^''.2) combined with the initial MCAO capabilities planned for the VLT will provide ultra-deep fields with a limiting magnitude for spectroscopy of R∼ 28. MIFS will improve the present day detection limit of Lyα emitters by a factor of 100, and will detect low-mass star-forming galaxies to z ∼ 7. The MIFS high-spatial resolution mode (3" x 3" field sampled at 0^''.01) is optimized for the next step in (MC)AO. It will probe, e.g., the relationship between supermassive central black holes and their host galaxy and the physics of winds from accretion disks in young stellar objects at unprecedented spatial resolution. MIFS will extend Europe's lead in integral-field spectroscopy. It capitalizes on new developments in adaptive optics, and is a key step towards instrumentation for OWL.