Stray-light issues for background-limited far-infrared telescope operation

Abstract Space Infrared Telescope for Cosmology and Astrophysics (SPICA), the cryogenic infrared space telescope recently pre-selected for a ‘Phase A’ concept study as one of the three remaining candidates for European Space Agency (ESA's) fifth medium class (M5) mission, is foreseen to include a far-infrared polarimetric imager [SPICA-POL, now called B-fields with BOlometers and Polarizers (B-BOP)], which would offer a unique opportunity to resolve major issues in our understanding of the nearby, cold magnetised Universe. This paper presents an overview of the main science drivers for B-BOP, including high dynamic range polarimetric imaging of the cold interstellar medium (ISM) in both our Milky Way and nearby galaxies. Thanks to a cooled telescope, B-BOP will deliver wide-field 100–350 $\mu$ m images of linearly polarised dust emission in Stokes Q and U with a resolution, signal-to-noise ratio, and both intensity and spatial dynamic ranges comparable to those achieved by Herschel images of the cold ISM in total intensity (Stokes I). The B-BOP 200 $\mu$ m images will also have a factor $\sim $ 30 higher resolution than Planck polarisation data. This will make B-BOP a unique tool for characterising the statistical properties of the magnetised ISM and probing the role of magnetic fields in the formation and evolution of the interstellar web of dusty molecular filaments giving birth to most stars in our Galaxy. B-BOP will also be a powerful instrument for studying the magnetism of nearby galaxies and testing Galactic dynamo models, constraining the physics of dust grain alignment, informing the problem of the interaction of cosmic rays with molecular clouds, tracing magnetic fields in the inner layers of protoplanetary disks, and monitoring accretion bursts in embedded protostars.

Download Full-text

A liquid-helium-cooled far-infrared grating spectrometer for a balloon-borne infrared telescope

Publications of the Astronomical Society of the Pacific ◽

10.1086/132071 ◽

1987 ◽

Vol 99 ◽

pp. 1022

Author(s):

Hideki Takami ◽

Toshinori Maihara ◽

Kohei Mizutani ◽

Norihisa Hiromoto ◽

Hiroshi Shibai

Keyword(s):

Liquid Helium ◽

Far Infrared ◽

Grating Spectrometer ◽

Infrared Telescope

Download Full-text

Ultra-low-noise transition edge sensors for far infrared wavelengths: optical design, measurement and stray light control

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX ◽

10.1117/12.2313611 ◽

2018 ◽

Cited By ~ 2

Author(s):

Emily A. Williams ◽

Stafford Withington ◽

David J. Goldie ◽

Christopher N. Thomas ◽

Jiajun Chen ◽

...

Keyword(s):

Optical Design ◽

Far Infrared ◽

Transition Edge Sensors ◽

Low Noise ◽

Stray Light ◽

Light Control ◽

Transition Edge ◽

Infrared Wavelengths ◽

Ultra Low Noise

Download Full-text

Stray light issues for background-limited infrared telescope operation

10.1117/12.48788 ◽

1991 ◽

Author(s):

Marija Scholl ◽

James W. Scholl

Keyword(s):

Stray Light ◽

Infrared Telescope

Download Full-text

Feedback and Feeding in the Context of Galaxy Evolution with SPICA: Direct Characterisation of Molecular Outflows and Inflows

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2017.46 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 9

Author(s):

E. González-Alfonso ◽

L. Armus ◽

F. J. Carrera ◽

V. Charmandaris ◽

A. Efstathiou ◽

...

Keyword(s):

Fine Structure ◽

Galaxy Evolution ◽

Far Infrared ◽

Molecular Outflows ◽

Line Shapes ◽

Infrared Telescope ◽

Molecular Lines ◽

The Universe ◽

Fine Structure Lines

AbstractA far-infrared observatory such as the SPace Infrared telescope for Cosmology and Astrophysics, with its unprecedented spectroscopic sensitivity, would unveil the role of feedback in galaxy evolution during the last ~10 Gyr of the Universe (z = 1.5–2), through the use of far- and mid-infrared molecular and ionic fine structure lines that trace outflowing and infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni line shapes and absorption blueshifted wings in molecular lines with high dipolar moments, and through emission line wings of fine-structure lines of ionised gas. We quantify the detectability of galaxy-scale massive molecular and ionised outflows as a function of redshift in AGN-dominated, starburst-dominated, and main-sequence galaxies, explore the detectability of metal-rich inflows in the local Universe, and describe the most significant synergies with other current and future observatories that will measure feedback in galaxies via complementary tracers at other wavelengths.

Download Full-text

Circumstellar ammonia in oxygen-rich evolved stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731873 ◽

2018 ◽

Vol 612 ◽

pp. A48 ◽

Cited By ~ 10

Author(s):

K. T. Wong ◽

K. M. Menten ◽

T. Kamiński ◽

F. Wyrowski ◽

J. H. Lacy ◽

...

Keyword(s):

Vibrational State ◽

Ambient Medium ◽

Far Infrared ◽

Rotational Transition ◽

Echelle Spectrograph ◽

Vibrationally Excited ◽

Excited Vibrational State ◽

Very Large Array ◽

Evolved Stars ◽

Infrared Telescope

Context. The circumstellar ammonia (NH3) chemistry in evolved stars is poorly understood. Previous observations and modelling showed that NH3 abundance in oxygen-rich stars is several orders of magnitude above that predicted by equilibrium chemistry.Aims. We would like to characterise the spatial distribution and excitation of NH3 in the oxygen-rich circumstellar envelopes (CSEs) of four diverse targets: IK Tau, VY CMa, OH 231.8+4.2, and IRC +10420. Methods. We observed NH3 emission from the ground state in the inversion transitions near 1.3 cm with the Very Large Array (VLA) and submillimetre rotational transitions with the Heterodyne Instrument for the Far-Infrared (HIFI) aboard Herschel Space Observatory from all four targets. For IK Tau and VY CMa, we observed NH3 rovibrational absorption lines in the ν2 band near 10.5 μm with the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF). We also attempted to search for the rotational transition within the excited vibrational state (v2 = 1) near 2 mm with the IRAM 30m Telescope. Non-LTE radiative transfer modelling, including radiative pumping to the vibrational state, was carried out to derive the radial distribution of NH3 in the CSEs of these targets. Results. We detected NH3 inversion and rotational emission in all four targets. IK Tau and VY CMa show blueshifted absorption in the rovibrational spectra. We did not detect vibrationally excited rotational transition from IK Tau. Spatially resolved VLA images of IK Tau and IRC +10420 show clumpy emission structures; unresolved images of VY CMa and OH 231.8+4.2 indicate that the spatial-kinematic distribution of NH3 is similar to that of assorted molecules, such as SO and SO2, that exhibit localised and clumpy emission. Our modelling shows that the NH3 abundance relative to molecular hydrogen is generally of the order of 10−7, which is a few times lower than previous estimates that were made without considering radiative pumping and is at least ten times higher than that in the carbon-rich CSE of IRC +10216. NH3 in OH 231.8+4.2 and IRC +10420 is found to emit in gas denser than the ambient medium. Incidentally, we also derived a new period of IK Tau from its V-band light curve. Conclusions. NH3 is again detected in very high abundance in evolved stars, especially the oxygen-rich ones. Its emission mainly arises from localised spatial-kinematic structures that are probably denser than the ambient gas. Circumstellar shocks in the accelerated wind may contribute to the production of NH3. Future mid-infrared spectroscopy and radio imaging studies are necessary to constrain the radii and physical conditions of the formation regions of NH3.

Download Full-text