Sensitive far-IR survey spectroscopy: BLISS for SPICA

摘要

We present a concept for BLISS, a sensitive far-IR-submillimeter spectrograph for SPICA. SPICA is a JAXA-ledmission featuring a 3.5-meter telescope actively cooled to below 5K, envisioned for launch in 2017. The low-background platform is especially compelling for moderate-resolution survey spectroscopy, for which BLISS isdesigned. The BLISS / SPICA combination will offer line sensitivities below 10~(-20)W m~(-2)in modest integra-tions, enabling rapid survey spectroscopy of galaxies out to redshift 5. The far-IR fine-structure and moleculartransitions which BLISS / SPICA will measure are immune to dust extinction, and will unambiguously revealthese galaxies' redshifts, stellar and AGN contents, gas properties, and heavy-element abundances. Taken to-gether, such spectra will reveal the history of galaxies from 1 GY after the Big Bang to the present day. BLISSis comprised of five sub-bands, each with two R ~ 700 grating spectrometer modules. The modules are con-figured with polarizing and dichroic splitters to provide complete instantaneous spectral coverage in two skypositions. To approach background-limited performance, BLISS detectors must have sensitivities at or below5 x 10~(-20)W Hz~(-1/2), and the format is 10 arrays of several hundred pixels each. It is anticipated that theserequirements can be met on SPICA's timescale with leg-isolated superconducting (TES) bolometers cooled witha 50 mK magnetic refrigerator.