SAFARI new and improved: extending the capabilities of SPICA's imaging spectrometer

Abstract

The Japanese SPace Infrared telescope for Cosmology and Astrophysics, SPICA, aims to provide astronomers with a truly new window on the universe. With a large -3 meter class-cold -6K-telescope, the mission provides a unique low background environment optimally suited for highly sensitive instruments limited only by the cosmic background itself. SAFARI, the SpicA FAR infrared Instrument SAFARI, is a Fourier Transform imaging spectrometer designed to fully exploit this extremely low far infrared background environment.The SAFARI consortium, comprised of European and Canadian institutes, has established an instrument reference design based on a Mach-Zehnder interferometer stage with outputs directed to three extremely sensitive Transition Edge Sensor arrays covering the 35 to 210 μm domain. The baseline instrument provides R > 1000 spectroscopic imaging capabilities over a 2' by 2' field of view. A number of modifications to the instrument to extend its capabilities are under investigation. With the reference design SAFARI's sensitivity for many objects is limited not only by the detector NEP but also by the level of broad band background radiation -the zodiacal light for the shorter wavelengths and satellite baffle structures for the longer wavelengths. Options to reduce this background are dedicated masks or dispersive elements which can be inserted in the optics as required. The resulting increase in sensitivity can directly enhance the prime science goals of SAFARI; with the expected enhanced sensitivity astronomers would be in a better position to study thousands of galaxies out to redshift 3 and even many hundreds out to redshifts of 5 or 6. Possibilities to increase the wavelength resolution, at least for the shorter wavelength bands, are investigated as this would significantly enhance SAFARI's capabilities to study star and planet formation in our own galaxy.

Cosmic X-ray surveys of distant active galaxies

“…The primary aim of SPICA (e.g., Nakagawa et al 2014;Roelfsema et al 2014) is faint medium-resolution spectroscopy over the broad 20-210 µm band pass, which will allow for the first extensive studies of the MIR-FIR emission lines of distant systems to provide accurate measurements of the star-formation properties and the interstellar medium of distant X-ray AGNs; however, SPICA will also provide deep broadband MIR-FIR photometry to sensitivity levels slightly below those of Spitzer and Herschel , allowing for deep MIR-FIR observations beyond the X-ray survey regions with existing Spitzer-Herschel coverage. Future MIR-FIR space-borne observatories such as SPICA are key to drive forward our understanding of the role that distant AGNs play in the formation and evolution of galaxies.…”

Tracing black hole accretion with SED decomposition and IR lines: from local galaxies to the high-zUniverse

“…Complementary to JWST, SPICA (Nakagawa et al 2012), to be proposed for the ESA 5th Medium missions call (due launch in 2028-2030), will observe the Universe at mid-/far-IR, from 10 to 37 µm with the SMI camera and spectrograph (Kataza et al 2015) and continuously from 34 to 230 µm with the SAFARI grating spectrograph (Roelfsema et al 2014). The SPICA 2.5-m diameter mirror, cooled down to < ∼ 8 K, will allow us to reach unprecedented sensitivities over an unexplored wavelength range, bridging the gap between JWST and ALMA.…”

The next-generation infrared astronomy mission SPICA under the new framework

“…SAFARI has continuous spectroscopic capability from 34-210 μm with three bands, and natural-background limited operation is expected. Table 3 shows main features of SAFARI, and Roelfsema et al 6 discusses its details. …”