There are a variety of scientific goals that can uniquely be explored by SPICA. Here we list some representative goals:
One of the most important questions in astronomy is the history of star-formation in our universe. Most of the previous studies were based on optical observations, which traced ultraviolet radiation in the rest-frame of high-redshift galaxies and left large uncertainties due to dust extinction. Far-infrared observations, on the other hand, are free from these uncertainties and can reveal the star-formation history reliably even at high-redshift. The high spatial resolution of SPICA is essential to detect faint galaxies at high-redshift in the confusion-limited far-infrared sky.
Moreover, the mid- and far-infrared region is rich with many bright lines useful for the estimates of the redshift of each galaxy. In particular polycyclic aromatic hydrocarbons (PAH) features can be powerful tools, since these features can be measured even with lowresolution spectroscopic observations. SPICA covers most of the PAH features at any redshift, and will enable highsensitivity determination of the redshifts of galaxies at high z with high efficiency.
Active galactic nuclei (AGN) are one of the important energy release mechanisms in our universe and are believed to be the result of mass accretion on to massive black holes. Their origins are still uncertain, although massive black holes seem to be ubiquitous in galactic bulges.
The Infrared Space Observatory (ISO) demonstrated the effectiveness of spectroscopic observations in the mid-infrared to reveal the origin of the luminosity (AGN vs starbursts) of infrared luminous galaxies, but these observations were limited to the local universe. The high-sensitivity of SPICA will enable this type of observation even for highredshift galaxies and will reveal the formation process of AGN and its possible relations to starbursts.
Discoveries of "Vega-like stars" evoked much discussion on the formation process of planetary systems. The highresolution capability of SPICA in the mid-infrared will reveal the density and temperature profiles of the dusty disks of "Vega-like stars", which are essential to understand the formation process of planetary systems.
One more important capability of SPICA is that it is expected to detect extrasolar planets directly. We now have ~50 giant planet candidates in extrasolar systems discovered through "indirect" methods. SPICA will enable the first "direct" detection of extrasolar planets beyond ~2 AU around nearby (~5pc) stars. The nature of these extrasolar planets will be revealed by mid-infrared spectroscopy of planetary atmosphere also by SPICA. These observations will reveal a general picture of the formation process of planets.
The capability of the 2.5 m telescope of SPICA is a big jump from those of previous missions with smaller telescopes (< 1 m). Moreover, SPICA is a very efficient observatory with its wide field of view (6'). Hence, SPICA has a great potential to discover interesting objects serendipitously. Since SPICA can make both photometric and spectroscopic observations, we can make follow-up observations of "serendipitously found objects" with SPICA itself.
Please see the Documents and Publications page for recent scientific publications.
Please send any comments or questions to naylor(at)uleth.ca