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The far-infrared spectroscopic surveyor (FIRSS)

The far-infrared spectroscopic surveyor (FIRSS)

The widely-appreciated importance of fine structure lines has been emphasized by the results from Herschel and new results emerging from ALMA. For Galactic stud- ies, a large-scale survey of [CII] was carried out at high spectral resolution with the HIFI instrument [34]. However, as eludicated above, this survey only sampled a few hundred points spaced approximately every degree in longitude, and did not result in images of any [CII]-emitting region. Only one giant molecular cloud, Orion, was even partially imaged [32, 81]. Indeed, only ∼0.06% was covered by HIFI hetero- dyne spectroscopy. GREAT on SOFIA has allowed limited observations of [CII] and [NII] and the upGREAT receiver having 14 mixers has improved on mapping speed and added the [OI] capability. Nevertheless, with only on the order of 100 hours per year available for any one instrument, and an estimated 20 years to cover the Galactic plane, it is clear that the required scientific objectives cannot be achieved on SOFIA. Similarly, for balloon based experiments such as STO2 (e.g. [123]) and GUSTO [5], given the flight durations (weeks), smaller apertures and limited channels (GUSTO will not observe CI), it will not be possible to carry out the wide area, multi-channel surveys required for the science objectives expressed in this proposal. Although there are future space borne facilities with impressive capabilities for far-infrared – sub- millimetre spectroscopy such as SPICA [100] and the Origins Space Telescope [8], both of these facilities are classed as observatories, dedicated to detailed spectro- scopic observations of a limited number of sources. FIRSS is the only mission that will provide velocity-resolved information for large areas of our Galaxy and nearby galaxies. The FIRSS concept is a surveyor mission and instead will provide the spec- troscopic equivalent to the wide-field to all-sky imaging surveys afforded by IRAS, AKARI and Herschel.
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Production of THz Radiation from Mid-and Far-Infrared Two-Color Femtosecond Pulses in Air

Production of THz Radiation from Mid-and Far-Infrared Two-Color Femtosecond Pulses in Air

Finally, we examine the role of many-body Coulomb ionization (MBI) [7] in THz generation. Under strong laser field irradiation, excited-state electrons from neighboring atoms are able to collide and thus increase the ionization rate. MBI becomes relevant for far-infrared pulses at early propagation distances, where multi-photon and tunnel ionizations remain minor players [see Fig. 1(d)]. With such plasma contribution, Fig. 1(e) show that THz emission starts at the very beginning of propagation, but saturates due to accumulated plasma defocusing actions.

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Review: far-infrared instrumentation and technological development for the next decade

Review: far-infrared instrumentation and technological development for the next decade

garnered worldwide interest due to its sensitivity in the mid- and far-infrared, enabled by the combination of the actively cooled telescope and the sensitive far-infrared detector arrays. Both ESA and JAXA have invested in a concurrent study, and an ESA–JAXA collaboration structure has gelled. ESA will pro- vide the 2.5-m telescope, science instrument assembly, satellite integration and testing, and the spacecraft bus. JAXA will pro- vide the passive and active cooling systems (supporting a tele- scope cooled to below 8 K), cryogenic payload integration, and launch vehicle. JAXA has indicated commitment to their portion of the collaboration, and the ESA selected SPICA as one of the three candidates for the Cosmic Visions M5 mission. The ESA phase-A study is underway now, and the downselect among the three missions will occur in 2021. Launch is envisioned for 2031. An example concept design of SPICA is shown in Fig. 11 . SPICA will have three instruments. JAXA’s SPICA MIRI will offer imaging and spectroscopy from 12 to 38 μm. It is designed to complement JWST-MIRI with wide-field mapping (broadband and spectroscopic), R ∼ 30;000 spectroscopy with
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Added value of far-infrared radiometry for remote sensing of ice clouds

Added value of far-infrared radiometry for remote sensing of ice clouds

Abstract Several cloud retrieval algorithms based on satellite observations in the infrared have been developed in the last decades. However, these observations only cover the midinfrared (MIR, 𝜆 < 15 μm) part of the spectrum, and none are available in the far-infrared (FIR, 𝜆≥15 μm). Using the optimal estimation method, we show that adding a few FIR channels to existing spaceborne radiometers would significantly improve their ability to retrieve ice cloud radiative properties. For clouds encountered in the polar regions and the upper troposphere, where the atmosphere is sufficiently transparent in the FIR, using FIR channels would reduce by more than 50% the uncertainties on retrieved values of optical thickness, effective particle diameter, and cloud top altitude. Notably, this would extend the range of applicability of current retrieval methods to the polar regions and to clouds with large optical thickness, where MIR algorithms perform poorly. The high performance of solar reflection-based algorithms would thus be reached in nighttime conditions. Since the sensitivity of ice cloud thermal emission to effective particle diameter is approximately 5 times larger in the FIR than in the MIR, using FIR observations is a promising venue for studying ice cloud microphysics and precipitation processes. This is highly relevant for cirrus clouds and convective towers. This is also essential to study precipitation in the driest regions of the atmosphere, where strong feedbacks are at play between clouds and water vapor. The deployment in the near future of a FIR spaceborne radiometer is technologically feasible and should be strongly supported.
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Predicting the global far-infrared SED of galaxies via machine learning techniques

Predicting the global far-infrared SED of galaxies via machine learning techniques

The predictor of Fig. A.1 did not use the redshift feature and was not K-corrected. We found that in this case, adding the redshift feature did not improve the results. However, when K-correcting, adding redshift as a feature notably improves the predictions (RMSE = 0.176 with redshift, RMSE = 0.201 with- out). The redshift is necessary for doing the K-correction, so it can as well be used as an additional feature. Still, K-correcting seems to slightly degrade the results. WISE 22 µm is an impor- tant feature to predict the far-infrared. For higher redshift galax- ies, this band probes a shorter wavelength (14.7 µm for z = 0.5). Recovering the rest-frame 22 µm band requires an extrapolation of the spectrum towards longer wavelengths – which is exactly the goal of this work. The UV-MIR best model fit provides this extrapolation, but it is not very accurate (see Sect. 4.1 ), and hence results in an uncertain estimation of the rest-frame 22 µm. Adding the redshift feature allows the neural network to rely less on the K-corrected 22 µm feature for higher redshift galaxies. While the long wavelength part of the input is being extrapolated, the observed GALEX FUV is essentially discarded at z = 0.5 (since the rest-frame FUV is measured by the observed NUV).
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Far infrared spectra of solid state aliphatic amino acids in different protonation states.

Far infrared spectra of solid state aliphatic amino acids in different protonation states.

Department of Structural Biology and Genomics, Biocomputing Group, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, CNRS UMR 7104, INSERM U964, 1 rue Laurent Fries, Illkirch, France 共Received 26 October 2009; accepted 16 February 2010; published online 19 March 2010兲 Far infrared spectra of zwitterionic, cationic, and anionic forms of aliphatic amino acids in solid state have been studied experimentally. Measurements were done on glycine, L-alanine, L-valine, L-leucine, and L-isoleucine powder samples and film samples obtained from dried solutions prepared at pH ranging from 1 to 13. Solid state density functional theory calculations were also performed, and detailed potential energy distributions were obtained from normal mode results. A good correspondence between experimental and simulated spectra was achieved and this allowed us to propose an almost complete band assignment for the far infrared spectra of zwitterionic forms. In the 700– 50 cm −1 range, three regions were identified, each corresponding to a characteristic set of normal modes. A first region between 700 and 450 cm −1 mainly contained the carboxylate bending, rocking, and wagging modes as well as the ammonium torsional mode. The 450– 250 cm −1 region was representative of backbone and sidechain skeletal bending modes. At last, the low wavenumber zone, below 250 cm −1 , was characteristic of carboxylate and skeletal torsional modes and of lattice
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A microbolometer-based far infrared radiometer to study thin ice clouds in the Arctic

A microbolometer-based far infrared radiometer to study thin ice clouds in the Arctic

With the intent to further investigate TICs’ formation and characteristics in the Arctic, a satellite project spon- sored by the Canadian Space Agency was initiated. The Thin Ice Clouds in Far InfraRed Experiment (TICFIRE) mission (Blanchet et al., 2011) aims to fill a gap in remote sensing ob- servation of the Earth in the F-IR range (e.g., Maestri et al., 2014), with a special focus on TICs and water vapor in the polar regions. The objective is to have a global picture of TICs and explore the impact of anthropogenic pollution on their physical properties (Grenier and Blanchet, 2010). This recent interest for the F-IR, largely fostered by technology developments, gave rise to other satellite projects such as REFIR (Radiation Explorer in the Far InfraRed) (Palchetti et al., 1999, 2006) and CLARREO (Climate Absolute Ra- diance and Refractory Observatory) (Taylor et al., 2010). While many recent developments in the F-IR have chosen the use of interferometers to get a hyperspectral picture of the Earth (e.g., Canas et al., 1997; Knuteson et al., 2004; Ro- chette et al., 2009; Bianchini and Palchetti, 2011), the TIC- FIRE detector will be an uncooled microbolometer-based imaging radiometer. This choice is consistent with the con- strained budget of the mission, with the emphasis put on ob-
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Broadband terahertz radiation from two-color mid- and far-infrared laser filaments in air

Broadband terahertz radiation from two-color mid- and far-infrared laser filaments in air

creased by a factor ∼ 3.5. Finally, it is compulsory to examine the many-body Coulomb ionization (MBI) effect on THz generation pro- posed by Schuh et al. [15, 16]. Under strong laser field ir- radiation, excited-state electrons from neighboring atoms are able to collide and thus increase the ionization rate. This effect is all the more relevant as the pump wave- length is large. It manifests at low laser intensities where multi-photon or tunnel ionizations vanish. Therefore, it should be taken into account for far-infrared optical fields. To model it, we use the fit proposed in [16] for a 10-µm pump wavelength interacting with argon atoms:
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Talc a far-infrared 20m space telescope and the ELICSIR consortium to reach TRL 3

Talc a far-infrared 20m space telescope and the ELICSIR consortium to reach TRL 3

[2] N. C. Anderson, Ferris wheels: an illustrated history, Bowling Green State University Popular Press, 1992. [3] G. Durand, M. Sauvage, A. Bonnet, L. Rodriguez, S. Ronayette, P. Chanial, L. Scola, V. R ́ev ́eret, H. Aussel, M. Carty, M. Durand, L. Durand, P. Tremblin, E. Pantin, M. Berthe, J. Martignac, F. Motte, M. Talvard, V. Minier, and P. Bultel, “TALC: a new deployable concept for a 20m far-infrared space telescope,” in Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 9143, p. 91431A, Aug. 2014. [4] C. Collette, Usure Ondulatoire en Transport Ferroviaire : Mécanismes et Réduction. PhD thesis, Université
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THz Emissions from Air-Plasmas Created by Mid-and Far-Infrared Two-Color Femtosecond Pulses

THz Emissions from Air-Plasmas Created by Mid-and Far-Infrared Two-Color Femtosecond Pulses

2 Univ. Bordeaux - CNRS - CEA, Centre Lasers Intenses et Applications, UMR 5107, 33405 Talence, France 3 Institut Lumi`ere Mati`ere, UMR 5306 Universit´e Lyon 1 - CNRS, Universit´e de Lyon, 69622 Villeurbanne, France alisee.nguyen@cea.fr Abstract: We study THz emission by two-color femtosecond filaments in air using mid- to far-infrared pump wavelengths. 3D numerical simulations show that 10.6-µm laser pulses can produce THz fields with unequaled mJ energies and GV/m amplitudes.

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Cosmological model dependence of the galaxy luminosity
          function: far-infrared results in the Lemaître-Tolman-Bondi model

Cosmological model dependence of the galaxy luminosity function: far-infrared results in the Lemaître-Tolman-Bondi model

We started from the far-infrared (FIR) LF which has been recently established by ( Gruppioni et al. 2013 ), using combined data obtained on the PACS ( Poglitsch et al. 2010 ), and SPIRE ( Gri ffin et al. 2010 ) instruments aboard the Herschel ( Pilbratt et al. 2010 ) space telescope, as part of two surveys, the PACS Evolutionary Probe (PEP; Lutz et al. 2011 ), and the Herschel Multi-tiered Extragalactic Survey (HerMES; Oliver et al. 2012 ). We used this sample because of its wide range of observations spanning from UV to the FIR and because it is the most com- plete one in terms of wavelength coverage. In future works we intend to investigate the e ffect on LF when changing the under- lying cosmology as a function of wavelength. The depth of the survey, or the relative depths at different wavelengths may also play a role.
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Conception of Thermal Far-Infrared Collective Thomson Scattering and Its Evolution to Gyrotron Scattering on JET/TEXTOR/ASDEX Upgrade

Conception of Thermal Far-Infrared Collective Thomson Scattering and Its Evolution to Gyrotron Scattering on JET/TEXTOR/ASDEX Upgrade

The author’s involvement in the development of thermal collective Thomson scattering for ion energy distribution measurements in plasmas is reviewed from early work with far infrared la[r]

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ESA Voyage 2050 White Paper Bringing high spatial resolution to the Far-infrared -A giant leap for astrophysics

ESA Voyage 2050 White Paper Bringing high spatial resolution to the Far-infrared -A giant leap for astrophysics

1 Introduction, science and mission heritage Many astronomical breakthroughs came with the advance of observing capabilities and the improvement of the achievable spatial resolution. The Hubble space telescope has been delivering diffraction-limited data with a spatial resolution of better than 0.1 arcsec in the Optical and UV for 25 years now. In the near-infrared (NIR) one has learned to overcome the disturbing effects of the turbulent atmosphere by means of adaptive optics, enabling observations with spatial resolutions of better than 0.1 arcsec when combined with 8–10 m class telescopes. Even better spatial resolution is achievable in the infrared when combining several telescopes in long-baseline interferometry with facilities like the VLTI or the Keck interferometer. In the radio regime, the adoption of interferometry has been a prime concept for decades. VLBI techniques achieve sub-milli-arcsec resolution up to frequencies of 86 GHz (and even to 230 GHz; see, e.g., Doeleman et al. 2008; Event Horizon Telescope Collaboration et al. 2019). Common interferometry has spread to ever higher frequencies (i.e. to the millimeter to sub-millimeter range), with arrays like NOEMA, SMA and especially ALMA as the current state of the art. Hence, we can access the sky at many wavelength regimes with high spatial resolution already. The Far-Infrared (FIR) is a noticeable exception. One commonly assigns the wavelength range from 30–300 µm (10–1 THz) to the FIR. In this range, the Earth atmosphere is very opaque in general. In particular, in the interval from 2–6 THz, the transmission never rises above 1–3 % even at the best observing sites from the ground, like Dome C in Antarctica (Schneider et al. 2009). Thus, high-flying airborne or space-borne telescopes are imperative to collect astronomical information in the FIR. Currently, the spatial resolution obtainable by the previous and by the currently planned missions is modest (cf. Fig. 1), and will not overcome the 1-arcsec barrier.
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Molecular Gas in a z~2.5 Triply-Imaged, sub-mJy Submillimetre Galaxy Typical of the Cosmic Far-Infrared Background

Molecular Gas in a z~2.5 Triply-Imaged, sub-mJy Submillimetre Galaxy Typical of the Cosmic Far-Infrared Background

In summary, several of the properties of SMM J16359 +6612 appear to resemble those of similar luminosity merging /interacting systems at low redshift, e.g. the dust spectral index, dust-to-gas ratio, presence of an obscured starburst in the overlap zone between the merging components, etc. However, the ratio of far-infrared luminosity to gas mass and the physical extent of the apparently high-density gas reservoirs in the progenitors are both an order of magnitude larger than for local systems. As SMM J16359 +6612 is an order of magnitude fainter at submm wavelengths than other distant SMGs studied in detail to date, and also less massive, it is not yet clear how many of these similarities and di fferences to low-redshift ULIRGs will carry over to the bulk of the SMG population. However, we stress that the properties of SMM J16359 +6612 may be more representative of the high-redshift population which produces a large fraction of the submm cosmic extragalactic background in the submm waveband, and hence are more relevant for understanding the evolutionary behaviour of the majority of the oldest stellar components in local galaxies: bulges. The fact that the properties of this system are more likely to resemble those expected for a merger of two typical Lyman-break galaxies suggests a link between these two populations (at least for sub-mJy SMGs). We also note that SMM J16359 +6612 has yet to be observed at the highest spatial resolution achievable with the IRAM array – these will provide a further factor of ten improvement in the resolution – probing the gas distribution within this rare example of the sub-mJy submm galaxy population at sub-kpc scales, which will fully characterize the nature of this system.
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Water in star-forming regions with Herschel (WISH): III. Far-infrared cooling lines in low-mass young stellar objects

Water in star-forming regions with Herschel (WISH): III. Far-infrared cooling lines in low-mass young stellar objects

The protostellar environment contains many physical compo- nents that can give rise to far-infrared line emission. As illus- trated in Figure 5 of van Dishoeck et al. (2011), these include (i) the warm quiescent inner part of the envelope passively heated by the luminosity of the source (the ‘hot core’); (ii) the en- trained outflow gas; (iii) UV-heated gas along the cavity walls; (iv) shocks along the outflow cavity walls where the wind from the young star directly hits the envelope; (v) bow shocks at the tip of the jet where it impacts the surrounding cloud; (vi) in- ternal working surfaces within the jet; and (vii) a disk embed- ded in the envelope. In the case of shocks, both C- and J-type shocks are possible. Spatially disentangling all of these compo- nents is not possible with the resolution of Herschel, but our data combined with velocity information from HIFI and physical- chemical models of the molecular excitation provide some in- sight into which components most likely dominate the emission (Visser et al. 2012, Herczeg et al. 2012).
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Airborne observations of far-infrared upwelling radiance in the Arctic

Airborne observations of far-infrared upwelling radiance in the Arctic

While most reported airborne FIR observations consist of constant altitude flights, vertical profiles of spectral radiance are very instructive to understand the vertical structure of the energy budget of the atmosphere (Mlynczak et al., 2011). For this reason, most measurements taken with the Far-InfraRed Radiometer (FIRR; Libois et al., 2016) during the campaign consisted of vertical profiles of upwelling radiance from the surface up to about 6 km. The FIRR was developed as a tech- nology demonstrator for the Thin Ice Clouds in Far-InfraRed Experiment (TICFIRE; Blanchet et al., 2011) satellite mis- sion, the primary focus of which is on the water cycle in the Arctic, and ice clouds in particular. Like cirrus at mid- latitudes (Cox et al., 2010; Maestri et al., 2014), ice clouds encountered in the Arctic significantly affect the atmosphere radiative budget in the FIR, especially because they can fill the whole troposphere (Grenier et al., 2009). In very dry con- ditions, they act as particularly efficient emitters that radia- tively cool the atmosphere (Blanchet et al., 2011). Unlike the tropics, such ice cloud layers occur at any altitude, from the ground to the stratosphere (polar stratospheric clouds). Their radiative effect depends on their physical properties (Maestri, 2003; Maestri et al., 2005) but is also very dependent on moisture (Cox et al., 2015), making the interactions between water vapour and Arctic clouds particularly complex.
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The Microwave and Far Infrared Spectra of Acetaldehyde-d1

The Microwave and Far Infrared Spectra of Acetaldehyde-d1

1. Introduction Because of its astrophysical interest and because it was used as a test case for the theoretical models developed to account for internal rotation of a methyl group, the non-rigid acetaldehyde molecule has been the subject of many high resolution investiga- tions. The microwave and far infrared spectra of the normal species have been studied in Refs. [1–7] and a satisfactory understanding of the rotation–torsion energy levels was achieved up to v t ¼ 4

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Terahertz spectroscopy : the renaissance of far infrared spectroscopy

Terahertz spectroscopy : the renaissance of far infrared spectroscopy

“submillimeter spectroscopy”, is also utilised by the molecular astrophysics community. Today, however, the majority of spectroscopists hav e adopted the increasingly fashionable term of “terahertz spectroscopy”. Still, regardless of which terminology is used, we are basically dealing with the same window in the electromagnetic spectrum that spans the range from 0.3 to 3 THz, or for those who prefer wavenumbers, from 10 to 100 cm −1 and for those who like wavelengths, from 1 to 0.1 mm. A recent query on the search engine Google turned up barely 754,000 entries for the new term of “terahertz spectroscopy”, versus 1,510,000 entries for the old term of “far infrared spectroscopy”, hence the idiom “renaissance” in the title of our article.
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Unveiling Far-Infrared Counterparts of Bright Submillimeter Galaxies Using PACS Imaging

Unveiling Far-Infrared Counterparts of Bright Submillimeter Galaxies Using PACS Imaging

We present a search for Herschel-PACS counterparts of dust-obscured, high-redshift objects previously selected at submillimeter and millimeter wavelengths in the Great Observatories Origins Deep Survey North field. We detect 22 of 56 submillimeter galaxies (39%) with a SNR of ≥ 3 at 100 µm down to 3.0 mJy, and/or at 160 µm down to 5.7 mJy. The fraction of SMGs seen at 160 µm is higher than that at 100 µm. About 50% of radio-identified SMGs are associated with PACS sources. We find a trend between the SCUBA/PACS flux ratio and redshift, suggesting that these flux ratios could be used as a coarse redshift indicator. PACS undetected submm/mm selected sources tend to lie at higher redshifts than the PACS detected ones. A total of 12 sources (21% of our SMG sample) remain unidentified and the fact that they are blank fields at Herschel-PACS and VLA 20 cm wavelength may imply higher redshifts for them than for the average SMG population (e.g., z > 3 − 4). The Herschel-PACS imaging of these dust-obscured starbursts at high-redshifts suggests that their far- infrared spectral energy distributions have significantly different shapes than template libraries of local infrared galaxies.
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Validation radiométrique du "Far Infrared Radiometer" et évaluation de sa sensibilité à l'état de l'atmosphère Arctique

Validation radiométrique du "Far Infrared Radiometer" et évaluation de sa sensibilité à l'état de l'atmosphère Arctique

Remote sensing of cirrus cloud microphysical properties using spectral measurements over the full range of their thermal emission. The Far Infrared FTS for the FORUM Mission[r]

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