Prof Patrick Roche

Abstract:

Mid-infrared polarimetry remains an underexploited technique; where available it is limited in spectral coverage from the ground, and conspicuously absent from the Spitzer, JWST and Herschel instrument suites. The unique characteristics of SOFIA afford unprecedented spectral coverage and sensitivity in the mid-infrared waveband. We discuss the preliminary optical design for a 5-40 m spectro-polarimeter for use on SOFIA, the SOFIA Mid-InfraRed Polarimeter (SMIRPh). The design furthers the existing 5-40μm imaging and spectroscopic capabilities of SOFIA, and draws on experience gained through the University of Florida's mid-IR imagers, spectrometer and polarimeter designs of T-ReCS and CanariCam. We pay special attention to the challenges of obtaining polarimetric materials suitable at both these wavelengths and cryogenic temperatures. Finally, we (briefly) present an overview of science highlights that could be performed from a 5-40μm imaging- and spectro-polarimeter on SOFIA. Combined with the synergy between the possible future far-IR polarimeter, Hale, this instrument would provide the SOFIA community with unique and exciting science capabilities, leaving a unique scientific legacy.

Abstract:

The dusty molecular torus, cornerstone of the unified model of AGN, has been the subject of much observational and theoretical scrutiny in recent years, and much progress has been made with observations and models aiming to reveal, explain and predict its properties. ©2008: Instituto de Astronomía.

Abstract:

CanariCam is the facility mid-infrared (MIR) instrument for the Gran Telescopio Canarias (GTC), a 10.4m telescope at the Observatorio del Roque de los Muchachos on La Palma. One of the science drivers for Canari-Cam is the study of active galactic nuclei (AGN). We will exploit the instrument's high sensitivity in imaging,spectroscopy, and polarimetry modes to answer fundamental questions of AGN and their host galaxies. Dust in the nucleus of an active galaxy reprocesses the intrinsic radiation of the central engine to emerge in the MIR. Current work demonstrates that the hot dust immediately associated with the AGN, which blocks direct views of the AGN from some lines of sight, is con.ned to small (parsec) scales. Thus, high spatial resolution is essential to probe the "torus" of unified AGN models separate from the host galaxy. CanariCam provides a 0.08- pixel scal e for Nyquist sampling the diffraction-limited point spread function at 8μm, and narrow (0.2-) spectroscopy slits (with R=120-1300). New observations with the GTC/CanariCam will provide key constraints on the physical conditions in the clumpy torus, and we will sensitively determine AGN obscuration as a function of nuclear activity. We will therefore address the fueling process and its relationship to the torus, the interaction with the host galaxy, and dust chemistry. These data will be essential preparation for the next generation of telescopes that will observe the distant universe directly to explore galaxy and black hole formation and evolution, and the GTC/CanariCam system uniquely provides multiple modes to probe AGN.

Abstract:

Mid-infrared polarimetry remains an underexploited technique; where available it is limited in spectral coverage from the ground, and conspicuously absent from both the Spitzer and JWST instrument suites. The unique characteristics of SOFIA affords unprecedented spectral coverage and sensitivity in the mid-infrared waveband, offering new vistas in the exploration of astrophysical objects, including (a) galaxies and AGN, (b) star formation regions and (c) debris disks. Furthering the existing 5-40μm imaging and spectroscopic capabilities of SOFIA, and the University of Florida's mid-IR imagers, spectrometer and Polarimeter designs of T-ReCS and CanariCam, we present an overview of science highlights that could be performed from a ∼5-40μm imaging- and spectro-polarimeter on SOFIA. A secondary science driver is the inclusion of low- to moderate- resolution (total flux) spectroscopy at these wavelengths. Such an instrument concept would plug an unfilled area of both SOFIA and space-based instrumentation, providing SOFIA with unique and exciting science capabilities.