Technical challenges and solutions:

1. SIGNALS AC-BIAS DETECTORS MIXER LC FILTERS SUM SQUID DOWN SHIFT + FILTER DEMUX + SIGNAL PROCESSING LNA PHASE SHIFT UP SHIFT SUB-GROUP P.R. Roelfsema, F.P. Helmich (SRON NetherlandsInstituteforSpace Research, Groningen, The Netherlands), B.S. Swinyard (UCL, London, UK), J. Goicoechea (CAB-CSIC/Inta, Madrid, Spain) onbehalf of the SPICA-SAFARI consortium GalaxyEvolutionwithSAFARI We present the science capabilities for a far-IR instrument to be flown on the Japanese SPICA satellite. The development is being undertaken by a consortium of European, Canadian and Japanese institutes, SPICA is a Mission of Opportunity in ESA’s Cosmic Vision Program with an expected launch in FY 2018. SAFARI – SpicA FAR-infrared Instrument – is an imaging spectrometer with both spectral and photometric capabilities covering the ~34-210mm waveband. While SAFARI is a highly versatile instrument we highlight some of the science questions that will be addressed in the field of galaxy evolution and cosmology. SuzannaMadden put logo & name here SPICA – the nextfar-IRmission The formation and evolution of galaxies: SPICA observations will provide a unique insight into the basic questions about how galaxies form and evolve such as: What drives the evolution of the massive, dusty distant galaxy population, and what feedback/interplay exists between the physical processes of mass accretion and star formation? How and when do the normal, quiescent galaxies such as our own form, and how do they relate to (Ultra) Luminous Infrared Galaxies (ULIRGs)? How do galaxy evolution, star formation rate and AGN activity vary with environment and cosmological epoch? Substantial progress in this area can only be made by making the transition from large-area photometric to large-area spectroscopic surveys in the mid to far infrared, which will be possible with SPICA. This is because the mid and far infrared region plays host to a unique suite of diagnostic lines to trace the accretion and star formation, and to probe the physical and chemical conditions in different regimes from AGN to star-forming regions. While the Herschel-PACS spectrometer will detect the brightest far infrared objects at z ∼ 1, SPICA will be able to carry out blind spectroscopic surveys out to z ∼ 3. This will lead to the first statistically unbiased determination of the co-evolution of star formation and masaccretion with cosmic time. Spectroscopic surveys will provide direct and unbiased information on the evolution of the large scale structure in the Universe from z ∼ 3 and the unprecedented possibility to investigate the impact of environment on galaxy formation and evolution as a function of redshift. The high sensitivity of SPICA will enable photometric surveys beyond z ∼ 4 that will resolve more than 90% of the Cosmic Infrared Background (in comparison with 50% that Herschel will achieve). SPICA will also observe Milky Way type galaxies in the far infrared out to z ∼ 1, where the cosmic star formation rate peaks. For the first time, we will be able to piece together the story of the evolution of our own galaxy and answer the question of whether we are in a “special place” in the cosmos. • Access to a keywaveband • Opening astrophysical research to λ’s blocked by the atmosphere but the emission peak of exo-zodiacal dust and cool bodies. • A successor to Spitzer and Herschel • Herschel: passively cooled (~80 K), sensitivity limited. • Spitzer: poor angular resolution due to modest mirror size. • Complementary to optical telescopes • Unique spectroscopic toolkit in many astrophysical environments: oxygen, ammonia, water ice and vapor, deuterated reservoirs: HD and a plethora of atomic and ionic fine structure lines. • Emission from dusty disks & cool bodies as well as obscured phenomena • SPICA (< 5 K)→“Cooled Herschel”: • Much lower background → deep spectroscopy possible • Imaging instead of point-source observations • No cryogenics → Long lived mission Herschel PACS and SPIRE spectroscopyonlensedgalaxies at high z (Sturm et al. 2010; Ivison et al 2010) SAFARI has access to a broad range of diagnosticatomic, ionic and molecularlines and willbeable to do these observationsroutinely • SAFARI Instrument concept: • Imaging Fourier Transform Spectrometer FTS • Wavelength coverage of ~34-210mm (using 3-detector arrays, Fl/2 sampling) • Range not covered by JWST or ALMA! • Field of view of 2’ x 2’ • Spectroscopy R up to ~2,000 at 100 μm • Photometry(R~3) • Sensitivity: • Unresolved lines 5s-1hr: few x 10-19 W/m2 • Photometry5s-1hr : <50mJy • Filter options for photometry under study SPIRE – Hermes consortium PACS – PEP consortium Technical challenges and solutions: Detectors: The required sensitivity, dynamic range and array formats are all challenging for the currently available technology. TES detectors arrays with lithographic LC filters , squids and frequency multiplexed read-out are chosen for SAFARI. The optical coupling is done with horn arrays Cooler technology: a hybrid sorption cooler/ADR is under development for the low temperatures the detectors are operated on (50 -150 mK) Broadband beam splitters and filters: ~3 octave bandwidth required. Cryo-mechanisms: The Fourier Transform Spectrometer mechanism and the filter wheels are being qualified now 500 m