The mid/far infrared hosts a wealth of spectral information that allows direct determination of the physical state of matter in a large variety of astronomical objects, unhindered by foreground obscuration. Accessing this domain is essential for astronomers to much better grasp the fundamental physical processes underlying the evolution of many types of celestial objects, ranging from protoplanetary systems in our own Milky Way to 10-12 billion year old galaxies at the high noon of galaxy formation in our universe. The joint ESA/JAXA SPICA mission will give such access to the astronomical community at large, by providing an observatory with unprecedented mid- to far-Infrared spectroscopic, polarimetric and imaging capabilities. SAFARI, developed by a large international SRON-led consortium, is a core instrument on SPICA, providing unprecedented sensitivity for far infrared spectroscopy. SPICA also hosts the mid infrared imager/spectrometer SMI and the imaging polarimeter B-BOP.
SAFARI and SMI provide sensitive spectroscopy at spectral resolving power ranging from R~50 through 11000 in the 17-230 μm domain as well as R~28.000 spectroscopy between 12 and 18 μm. SAFARI utilizes state-of-the-art Transition Edge Sensors - a development area spearheaded by SRON’s physicists - yielding an unprecedented sensitivity of ~5×10−20 W/m2 (5σ/1hr) in the 35-230 μm domain - at least two orders of magnitude improvement over what has been attained to date. SAFARI will be able to probe the universe far deeper than possible with any of its predecessors. With the 10’x12’ Field of View SMI imager SPICA will very efficiently do sensitive large area 30-37 μm broad band mapping, recording R~100 low resolution spectra in parallel for all sources in the field. B-BOP will provide accurate polarimetric imaging at 70, 220 and 350 μm. With this exceptional leap in performance, new domains in infrared astronomy will become accessible, allowing us, e.g. to definitively unravel galaxy evolution and metal production over cosmic time, to study dust formation and evolution from very early epochs onwards, and to trace the gas, dust and ice evolution in planet forming systems, gauging the building blocks of our universe.
As a general observatory SPICA with SAFARI will address a large range of science topics pertaining to the evolution of celestial objects. A key science goal for SAFARI is to follow the evolution of galaxies through their most active periods in cosmic time from about 10 billion years ago to what they look like today. Astronomers will be able to do just that by detecting molecular as well as a range of atomic forbidden lines out to redshift z~3 even for average mass galaxies. The observed line strengths provide direct measures for the physical conditions for these objects, which subsequently can be correlated with environmental conditions, age, size etc., tracing these correlations over cosmic time. Additionally, we will observe cosmic dust out to very early epochs, at redshifts of z~7-8, thus providing insight into dust formation also in the very early phases of the universe. A third major goal is the study of planet forming systems, for which we expect to e.g. determine the molecular content and trace the snow line for a large range of disk masses, and thus to better understand the evolution of such systems, including our own solar system.
The SAFARI instrument is a joint development of a large consortium with partners from across Europe, Canada, the United States and Taiwan. The SAFARI consortium and the SPICA scientific collaboration are currently led by SRON, giving the Netherlands a very prominent position in the SPICA project. Together with SPICA, SAFARI will fill the information gap in the wavelength domain between the other great observatories, complementing e.g. the James Webb Space telescope and the ALMA radio observatory – only with SPICA/SAFARI we will be able to complete the view on the star-formation history of our universe.