Mid-Infrared Research Papers - Academia.edu (original) (raw)

2025

discriminate among possible hot components in symbiotic systems. Obviously, the data required to apply this method are continuum magnitudes in the UV spectral range. Since the symbiotic star AS 338 is presently bright enough to make its continuum accessible to the IUE low-dispersion mode, I have applied for observing time with the IUE satellite, to make use of this opportunity. In addition, the observers of the Sterken group (The Messenger, 33, 10) are going to monitor the optical brightness variations of AS 338, using one of ESO's photometrie telescopes. Although my story ends here, it is not at all finished. A hint in favour of the accretion event model is given by the polarimetrie observations. But, for the time being, we have to wait for the ultraviolet observations to derive, as I hope, the nature of the hot component in my pet symbiotic system.

2025, Astronomy & Astrophysics

HeH+ was the first heteronuclear molecule to form in the metal-free Universe after the Big Bang. The molecule gained significant attention following its first circumstellar detection in the young and dense planetary nebula NGC 7027. We target some hydride ions associated with the noble gases (HeH+, ArH+, and NeH+) to investigate their formation in harsh environments like the nova outburst region. We use a photoionization modeling (based on previously published best-fit physical parameters) of the moderately fast ONe type nova, QU Vulpeculae 1984, and the CO type novae, RS Ophiuchi and V1716 Scorpii. Our steady-state modeling reveals a convincing amount of HeH+, especially in the dense clump of RS Ophiuchi and V1716 Scorpii. The calculated upper limit on the surface brightness of HeH+ transitions suggests that the James Webb Space Telescope (JWST) could detect some of them, particularly in sources like RS Ophiuchi and V1716 Scorpii, which have similar physical and chemical conditions...

2025, The Astrophysical Journal Supplement Series

We have compiled a catalog of optically-selected quasars with simultaneous observations in UV/optical and X-ray bands by the Swift Gamma Ray Burst Explorer. Objects in this catalog are identified by matching the Swift pointings with the Sloan Digital Sky Survey Data Release 5 quasar catalog. The final catalog contains 843 objects, among which 637 have both UVOT and XRT observations and 354 of which are detected by both instruments. The overall X-ray detection rate is ∼ 60% which rises to ∼ 85% among sources with at least 10 ks of XRT exposure time. We construct the time-averaged spectral energy distribution for each of the 354 quasars using UVOT photometric measurements and XRT spectra. From model fits to these SEDs, we find that the big blue bump contributes about ∼ 0.3 dex to the quasar luminosity. We re-visit the α ox -L 2500 Å relation by selecting a clean sample with only type 1 radio-quiet quasars; the dispersion of this relation is reduced by at least 15% compared to studies that use non-simultaneous UV/optical and X-ray data. We only found a weak correlation between L bol /L Edd and α UV . We do not find significant correlations between α x and α ox , α ox and α UV , and α x and log L(0.3-10 keV). The correlations between α UV and α x , α ox and α x , α ox and α UV , L bol /L Edd and α x , and L bol /L Edd and α ox are stronger amongst low-redshift quasars, indicating that these correlations are likely driven by the changes of SED shape with accretion state.

2025, Bulletin of the American Physical Society

It is widely accepted that quasar radiation is emitted from a thick torus shaped accretion disk surrounding a black hole. However, the Chandra X-ray Observatory wide field panorama released on March 12, 2007, indicates many quasars do not... more

2025, The European Physical Journal Applied Physics

The tunable operation of an all solid-state diode pumped Raman laser on a Yb:KYW crystal is demonstrated. The possibility of a simultaneous tunable operation for laser generation in the 1029-1032 nm range and Stokes generation in the 1136-1139 nm range is shown. A slope efficiency of 12% and a maximum average power of 14.5 mW were achieved for the Stokes output.

2025, The Astrophysical Journal

The processing of energetic photons on bare silicate grains was simulated experimentally on silicate films submitted to soft X-rays of energies up to 1.25 keV. The silicate material was prepared by means of a microwave assisted solgel technique. Its chemical composition reflects the Mg 2 SiO 4 stoichiometry with residual impurities due to the synthesis method. The experiments were performed using the spherical grating monochromator beamline at the National Synchrotron Radiation Research Center in Taiwan. We found that soft X-ray irradiation induces structural changes that can be interpreted as an amorphization of the processed silicate material. The present results may have relevant implications in the evolution of silicate materials in X-ray irradiated protoplanetary disks.

2025

We present low-resolution ultraviolet spectra of 14 low redshift (zem . 0.8) quasars observed with HST/STIS as part of a Snap project to understand the relationship between quasar outflows and luminosity. By design, all observations cover the C IV emission line. Nine of the quasars are from the Hamburg-ESO catalog, three are from the Palomar-Green catalog, and one is from the Parkes catalog. The sample contains a few interesting quasars including two broad absorption line (BAL) quasars (HE 01433535, HE0436-2614), one quasar with a mini-BAL (HE 1105-0746), and one quasar with associated narrow absorption (HE 0409-5004). These BAL quasars are among the brightest known (though not the most luminous) since they lie at zem < 0.8. We compare the properties of these BAL quasars to the zem < 0.5 Palomar-Green and zem > 1.4 Large Bright Quasar samples. By design, our objects sample luminosities in between these two surveys, and our four absorbed objects are consistent with the v ∼ L...

2025, Animals

Knowing the body weight (BW) of a cow at a specific moment or measuring its changes through time is of interest for management purposes. The current work aimed to validate the feasibility of predicting BW using the day in milk, parity, milk yield, and milk mid-infrared (MIR) spectrum from a multiple-country dataset and reduce the number of predictors to limit the risk of over-fitting and potentially improve its accuracy. The BW modeling procedure involved feature selections and herd-independent validation in identifying the most interesting subsets of predictors and then external validation of the models. From 1849 records collected in 9 herds from 360 Holstein cows, the best performing models achieved a root mean square error (RMSE) for the herd-independent validation between 52 ± 2.34 kg to 56 ± 3.16 kg, including from 5 to 62 predictors. Among these models, three performed remarkably well in external validation using an independent dataset (N = 4067), resulting in RMSE ranging fr...

2025, Applied Spectroscopy

Raman spectroscopy was used to study the NaCl aqueous solutions around the solid-liquid phase transition. Special attention was devoted to the modification induced by the salt on the OH stretching band of water. Investigations were carried out in the temperature range between-21 and 10 °C, for concentrations from 0 to 200 g/L. We demonstrated that micro-Raman spectroscopy can be used as a marker, allowing the determination of the salt concentration of an aqueous solution with an error close to ±5%.

2025, Zeitschrift für Naturforschung

Benzoic acid in dilute solution of n-heptane and of CC1 4 is studied via high-pressure hightemperature IR spectroscopy on the C = 0 and O-H stretching fundamentals. Lambert-Beer's law is shown to be valid for the C = 0 modes of the acid monomer and of the hydrogen-bonded cyclic dimer, which enables the quantitative measurement of the dimerization equilibrium to a maximum pressure of 2 kbar and up to 175 °C. At identical pressure and temperature the dimerization equilibrium constant is larger in n-heptane than in CC1 4 . From the monomer-cyclic dimer equilibrium constants the pressure dependence of the dimerization enthalpy is determined and compared with direct information on both species as derived from their O-H fundamental mode absorption. Toward lower temperature the dimerization volume is decreasingly negative and, in CC1 4 solution, AV even changes sign around 40 °C. Increasing pressure thus favours the dissociation of the hydrogen-bonded dimer into benzoic acid monomer molecules at ambient temperature.

2025, Journal of Lightwave Technology

The noise power spectral density of a detector is essential for determining the frequency of operation and readout architecture that yields an optimal signal-to-noise ratio. In this work, we characterize a waveguide-integrated PbTe mid-infrared detector and report on its noise spectrum, highlighting the presence of a current-dependent 1/f term dominating at low frequency and/or high bias over the Johnson component typical of a photoconductor. This behaviour, together with the substantially flat frequency response in the range between 1 kHz to 1 MHz, guide towards a lock-in readout strategy, that allows one to operate in the region of minimum noise without penalties in the detection performance. Practical guidelines to optimize the readout resolution are provided and the limit of detection of a gas sensing system exploiting PbTe photoconductors is derived, as an example of how a careful co-design of sensors and electronics can dramatically improve the detection performance.

2025, … and Systems X

ORAC-DR is a flexible and extensible data reduction pipeline suitable for both on-line and off-line use. Since its development it has been in use on-line at UKIRT for data from the infrared cameras UFTI and IRCAM and at JCMT for data from the sub-millimetre bolometer array SCUBA. We have now added a suite of on-line reduction recipes that produces publication quality (or nearly so) data from the CGS4 near-infrared spectrometer and the MICHELLE mid-infrared Echelle spectrometer. As an example, this paper briefly describes some pipeline features for one of the more commonly used observing modes.

2025, The Astrophysical Journal

We highlight a representative sample of active galactic nuclei selected independent of orientation. The defining characteristic of the selection is sophisticated matching between the 0.1 < z < 0.6 Sloan Digital Sky Survey quasars from the Seventh Data Release to the Westerbork Northern Sky Survey at 325 MHz and the subsequent application of a total radio luminosity cut. The resulting sample is complete down to the limiting luminosity and unbiased by orientation. Compared to orientation samples in the literature this approach yields less bias with redshift, relatively more lobe-dominated sources including those with radio lobes and no visible core, and a distribution of radio core dominance that is consistent with expectations from a uniform distribution of inclinations with solid angle. We measure properties of the optical spectra, and use the sample to investigate the orientation dependence of the velocity width of the broad Hβ emission line. We recover the known orientation dependence, but the sharp envelope of previous studies where only edge-on sources display the broadest lines, is absent. Scatter in this diagram is not attributable solely to black hole mass, Eddington ratio, or contamination in the sample from compact steep spectrum sources. A physical framework for quasar beaming and a disk-like broad-line region can describe the representative sample when it is expanded to include additional parameters, in particular jet properties and the broad-line region velocity field. These points serve to illustrate the critical role of sample selection in the interpretation of observable properties as indicators of physical parameters of quasar central engines.

2025, Journal of Raman Spectroscopy

A complete study of the decayed gilded decorations of the stalactite vaults in the Hall of the Kings in the Alhambra complex (Granada, Spain) has been carried out for the first time. Preliminary investigations were carried out in situ using a portable Raman spectrometer and enabled the identification of tin (II) oxide in the black areas nearby the golden flakes. This suggested the presence of an altered tin foil. Then, a comprehensive characterization of these decorations was achieved through the use of complementary nondestructive techniques working on microsamples. Two main metallic structures were identified by means of scanning electron microscopy coupled to energy dispersive X-ray spectroscopy: (1) a thin (1-2 μm) gold leaf (probably original), and (2) redecorations with a laminated structure formed by a gold leaf placed over a thicker (10-15 μm) tin foil. Synchrotron Fourier-transform infrared microspectroscopy revealed the use of proteinaceous glue to fix the gold leaf directly on the plasterwork, whereas in the case of the laminated structures, either glue or a natural resin was found. Raman microspectroscopy provided insight into the main decay processes affecting the gildings: the detachment of the metals due to the alteration of the organic materials employed as adhesives (forming calcium oxalates) and the oxidation of the tin foil. In addition, two technologies of false gilding have been encountered. One was based on a tin foil tinted to look like gold by means of a varnish (composed of a drying oil and a natural resin), and the second was made up with a tin-copper alloy (bronze) that appears severely degraded to copper oxalate and tin (II) oxide, as revealed by Raman microspectroscopy.

2025, Proceedings of the 72nd International Symposium on Molecular Spectroscopy

The thermal lens technique is applied to vibrational overtone spectroscopy of solutions of naphthalene in n-hexane. The pump and probe thermal lens technique is found to be very sensitive for detecting samples of low composition (ppm) in transparent solvents. In this experiment two different probe lasers: one at 488 nm and another 568 nm were used. The C-H fifth vibrational overtone spectrum of benzene is detected at room temperature for different concentrations. A plot of normalized integrated intensity as a function of concentration of naphthalene in solution reveals a non-linear behavior at low concentrations when using the 488 nm probe and a linear behavior over the entire range of concentrations when using the 568 nm probe. The non-linearity cannot be explained assuming solvent enhancement at low concentrations. A two color absorption model that includes the simultaneous absorption of the pump and probe lasers could explain the enhanced magnitude and the non-linear behavior of the thermal lens signal. Other possible mechanisms will also be discussed.

2025, Proceedings of the 2021 International Symposium on Molecular Spectroscopy

2025, Applied spectroscopy

The thermal lens technique is applied to vibrational overtone spectroscopy of solutions of naphthalene (CH) in liquid hexane. The C-H fifth vibrational (Δν = 6) overtone spectrum of CHis detected at room temperature for mole fractions from 0.08 to 19 × 10using n-CHas solvent. By detecting the absorption band in a 19 ppm (parts per million) solution, the peak absorption of the signal is approximately (2.2 ± 0.3) × 10cm. A plot of normalized integrated intensity as a function of the mole fraction of naphthalene in solution reveals a dependence of the magnitude of the signal with the probe laser wavelength. If the wavelength of the probe laser is 568 nm, the thermal lens signal (TLS) is linear as a function of the mole fraction of the solution. When the wavelength of the probe laser is 488 nm, the TLS is nonlinear as a function of the concentration. Three different models of nonlinear absorption are discussed. A two-color absorption model that includes the simultaneous absorption of th...

2025, Applied Optics

The complex index of refraction of aqueous methanesulfonic acid ͑MSA͒ at room temperature and at concentrations of 1-70 wt. % is presented. The complex index of refraction is obtained in the entire wave-number region from the mid infrared to the ultraviolet-visible regions. An analysis of the infrared spectra reveals a single absorption band, which makes it possible to identify MSA in aqueous H 2 SO 4 . The surface tension of 1-99-wt. % aqueous MSA from room temperature to ϳ263 K, depending on the concentration of MSA, is reported. A polynomial parameterization of the surface tension in terms of acid weight fraction and temperature is presented.

2025

Optical measurements of atmospheric minor constituents are performed using spectrometers working in the UV-visible, infrared and microwave spectral ranges. In particular recently the satellite ENVISAT has been launched with three spectrometers on board, SCIAMACHY and GOMOS working in the UV-visible spectral region and MIPAS working in the thermal infrared. In the future, the combined use of Nadir-viewing UV-visible and thermal infrared spectrometers (onboard remote-sensing satellites such as OMI and TES onboard EOS-AURA, or GOME-2 and IASI onboard MetOP) will provide an important improvement of vertical trace gas concentration profiles. The analysis and interpretation of the atmospheric spectra require good knowledge of the molecular parameters of the species of interest as well as of the interfering species. This is true not only in the spectral domain used to retrieve the species (thermal infrared for MIPAS for example) but also in the other spectral domains used by other instruments: Meaningful comparisons of profiles retrieved by various instruments using different spectral domains require indeed that the spectral parameters are consistent in these spectral domains. To illustrate these points we will concentrate on two molecules namely ozone and formaldehyde. In the mid-infrared range, the 10 µm ozone band is very strong and is the most widely used to derive concentration profiles. In the UV region, the Huggins and/or Hartley bands are currently used for spectroscopic remote-sensing of ozone. In this paper we will present two sets of results: -First a careful comparison of four sets of ozone line intensities measured independently in the 10 µm region has been achieved. From them new and more accurate transition moment constants for the ν 1 and ν 3 bands of 16 O 3 were derived and used to generate new line positions and intensities. These new spectroscopic parameters allowed one to simulate atmospheric spectra better than the previous spectroscopic parameters showing that on a relative basis the new spectral parameters are of better quality (

2025, arXiv (Cornell University)

We discuss spectral energy distributions, photometric redshifts, redshift distributions, luminosity functions, source-counts and the far infrared to optical luminosity ratio for sources in the SWIRE Legacy Survey. The spectral energy distributions of selected SWIRE sources are modelled in terms of a simple set of galaxy and quasar templates in the optical and near infrared, and with a set of dust emission templates (cirrus, M82 starburst, Arp 220 starburst, and AGN dust torus) in the mid infrared. The optical data, together with the IRAC 3.6 and 4.5 µm data, have been used to determine photometric redshifts. For galaxies with known spectroscopic redshifts there is a notable improvement in the photometric redshift when the IRAC data are used, with a reduction in the rms scatter from 10 % in (1+z) to 5 %. While further spectroscopic data are needed to confirm this result, the prospect of determining good photometric redshifts for the 2 million extragalactic objects in SWIRE is excellent. The distribution of the different infrared sed types in the L ir /L opt versus L ir plane, where L ir and L opt are the infrared and optical bolometric luminosities, is discussed. Source-counts at 24, 70 and 160 µm are discussed, and luminosity functions at 3.6 and 24 µm are presented.

2025, The Astrophysical Journal

We present the broadband SEDs of the largest available highly complete (72%) spectroscopic sample of MIRselected galaxies and AGNs at intermediate redshift. The sample contains 203 extragalactic sources from the 15 m ELAIS-SWIRE survey, all with measured spectroscopic redshift. Most of these sources have full multiwavelength coverage from the FUV (GALEX ) to the FIR (Spitzer) and lie in the redshift range 0:1 < z < 1:3. This large sample allows us for the first time to characterize the spectral properties of sources responsible for the strong evolution observed in the MIR. Based on SED-fitting, we have classified the MIR sources, identifying AGN signatures in about 50% of them. This fraction is significantly higher than that derived from optical spectroscopy ($29%) and is due in particular to the identification of AGN activity in objects spectroscopically classified as galaxies (the spectroscopic classification may be somewhat unreliable because of host galaxy dilution in the optical). It is likely that in most of our objects, the AGN is either obscured or low luminosity, and thus dominates the energetic output only in the MIR, showing up just in the range where the host galaxy SED has a minimum. The fraction of AGNs strongly depends on flux density, with that derived through the SED-fitting about 20% at S 15m $ 0:5Y1 mJy and gradually increasing to 100% at S 15m > 10 mJy, while that obtained from optical spectroscopy is never >30%, even at higher flux densities. Our results will be very useful for updating all models aimed at interpreting the deep IR survey data and in particular for constraining the nature and role of dust-obscured systems in the intermediate/ high-redshift universe.

2025, The Astrophysical Journal

We present mid-infrared spectra of thirty two high redshift ultraluminous infrared galaxies, selected via the stellar photospheric feature at rest-frame 1.6µm, and an observed-frame 24µm flux of >500µJy. Nearly all the sample reside in a redshift range of z = 1.71 ± 0.15, and have rest-frame 1-1000µm luminosities of 10 12.9 -10 13.8 L ⊙ . Most of the spectra exhibit prominent polycyclic aromatic hydrocarbon emission features, and weak silicate absorption, consistent with a starburst origin for the IR emission. Our selection method appears

2025, Astronomy & Astrophysics

Context. Spitzer's wide-field surveys and followup capabilities have allowed a new breakthrough in mid-IR spectroscopy up to redshifts ≥2, especially for 24 μm detected sources. Aims. We want to study the mid-infrared properties and the starburst and AGN contributions, of 24 μm sources at z ∼ 2, through analysis of mid-infrared spectra combined with millimeter, radio, and infrared photometry. Mid-infrared spectroscopy allows us to recover accurate redshifts. Methods. A complete sample of 16 Spitzer-selected sources (ULIRGs) believed to be starbursts at z ∼ 2 ("5.8 μm-peakers") was selected in the (0.5 deg 2 ) J1064+56 SWIRE Lockman Hole field ("Lockman-North"). These sources have S 24 μm > 0.5 mJy, a stellar emission peak redshifted to 5.8 μm, and r Vega > 23. The entire sample was observed with the low resolution units of the Spitzer/IRS infrared spectrograph. These sources have 1.2 mm observations with IRAM 30 m/MAMBO and very deep 20 cm observations from the VLA. Nine of our sources also benefit from 350 μm observation and detection from CSO/SHARC-II. All these data were jointly analyzed. Results. The entire sample shows good quality IRS spectra dominated by strong PAH features. The main PAH features at 6.2, 7.7, 8.6, and 11.3 μm have high S /N average luminosities of 2.90 ± 0.31, 10.38 ± 1.09, 3.62 ± 0.27, and 2.29 ± 0.26 × 10 10 L , respectively. Thanks to their PAH spectra, we derived accurate redshifts spanning from 1.750 to 2.284. The average of these redshifts is 2.017 ± 0.038. This result confirms that the selection criteria of "5.8 μm-peakers" associated with a strong detection at 24 μm are reliable to select sources at z ∼ 2. We have analyzed the different correlations between PAH emission and infrared, millimeter, and radio emissions. Practically all our sources are strongly dominated by starburst emission, with only one source showing an important AGN contribution. We have also defined two subsamples based on the equivalent width at 7.7 μm to investigate AGN contributions. Conclusions. Our sample contains strong starbursts and represents a particularly 24 μm-bright class of SMGs. The very good correlation between PAH and far-IR luminosities is now confirmed in high-z starburst ULIRGs. These sources show a small AGN contribution to the mid-IR, around ∼20% or less in most cases.

2025, Monthly Notices of the Royal Astronomical Society

Heavily obscured active galactic nuclei (AGNs) play an important role in contributing to the cosmic X-ray background (CXRB). However, the AGNs found in deep X-ray surveys are often too weak to allow direct measurement of the column density of obscuring matter. One method adopted in recent years to identify heavily obscured, Compton-thick AGNs under such circumstances is to use the observed mid-infrared-to-X-ray luminosity ratio as a proxy for the column density. This is based on the supposition that the amount of energy lost by the illuminating X-ray continuum to the obscuring matter and reprocessed into infrared emission is directly related to the column density and that the proxy is not sensitive to other physical parameters of the system (aside from contamination by dust emission from, for example, starforming regions). Using Monte Carlo simulations, we find that the energy losses experienced by the illuminating X-ray continuum in the obscuring matter are far more sensitive to the shape of the X-ray continuum and to the covering factor of the X-ray reprocessor than they are to the column density of the material. Specifically we find that it is possible for the infrared to X-ray luminosity ratio for a Compton-thin source to be just as large as that for a Comptonthick source even without any contamination from dust. Since the intrinsic X-ray continuum and covering factor of the reprocessor are poorly constrained from deep X-ray survey data, we conclude that the mid-infrared-to-X-ray luminosity ratio is not a reliable proxy for the column density of obscuring matter in AGNs even when there is no other contribution to the mid-infrared luminosity aside from X-ray reprocessing. This conclusion is independent of the geometry of the obscuring matter.

2025, Monthly Notices of the Royal Astronomical Society

2025

Two magnesium chlorate hydrates, Mg(ClO 3 ) 2 ×6(H 2 O) (1) and Mg(ClO 3 ) 2 ×2(H 2 O) (2), have been synthesized by slow evaporation from water and ethanol, respectively. The structures were determined by single-crystal X-ray diffraction at 150 K due to the dehydration-rehydration at room temperature leading to multiple phase transitions. Both compounds crystallized in the monoclinic space group P2 1 /c (SG 14) with respective unit cell parameters of a = 6.3899( ), b = 6.5139(3), c = 13.8963(6)Å, β = 100.319(5)°, V = 569.05(5) Å 3 , Z = 2, R= 0.0210 and a = 6.3707( ), b = 5.4092(3), c = 9.8208(6) Å, β = 97.338(6)°, V = 335.66(4) Å 3 , Z = 2, R = 0.0201. The structure solution shows an octahedral coordination of the Mg 2+ for both compounds 1 and 2. In the case of Mg(ClO 3 ) 2 ×6(H 2 O) the coordination is achieved by the water molecules, while for Mg(ClO 3 ) 2 ×2(H 2 O) the coordination involves two water molecules and is complemented by four oxygen atoms from the chlorate moiety.

2025, Advanced materials (Deerfield Beach, Fla.)

High-performance photodetectors operating over a broad wavelength range from ultraviolet, visible, to infrared are of scientific and technological importance for a wide range of applications. Here, a photodetector based on van der Waals heterostructures of graphene and its fluorine-functionalized derivative is presented. It consistently shows broadband photoresponse from the ultraviolet (255 nm) to the mid-infrared (4.3 µm) wavelengths, with three orders of magnitude enhanced responsivity compared to pristine graphene photodetectors. The broadband photodetection is attributed to the synergistic effects of the spatial nonuniform collective quantum confinement of sp(2) domains, and the trapping of photoexcited charge carriers in the localized states in sp(3) domains. Tunable photoresponse is achieved by controlling the nature of sp(3) sites and the size and fraction of sp(3) /sp(2) domains. In addition, the photoresponse due to the different photoexcited-charge-carrier trapping times ...

2025, … de Astronomía y …

El experimento Cámara (CIRCE) es un instrumento visitador para el infrarrojo cercano para el Gran Telescopio de Canarias (GTC) de 10.4-m. Además de su funcionamiento como un formador de imágenes de 1-2.5 micrones, CIRCE tendrá la capacidad para obtener imágenes de banda angosta, espectroscopía de grisma de baja y moderada resolución, y polarimetría. El diseño óptico asférico totalmente reflectivo de CIRCE ofrece un excelente rendimiento y calidad de imagen. Presentamos un análisis del diseño óptico, revisión del desarrollo del software y el progreso del diseño opto-y crio-mecánico y de la manufactura.

2025, Revista Mexicana De Astronomia Y Astrofisica

2025

The 2.5m Isaac Newton Telescope (INT) is currently being used to carry out a series of wide field imaging programs under the generic title of the ING Wide Field Survey (WFS) project (McMahon et al., 2000; http://www.ing.iac.es/Astronomy/science/wfs/). The largest of the survey programs is the Wide Angle Survey which aims to observe 100 deg2 in a filter set analogous to that used by the Sloan Digital Sky Survey. The strategy for finding a z=5 quasar is to search for point sources which are absent in u' and g' images (due to the Lyman series limit), with a large r'- i' colour (suppression of the r' band by the Lyman-a forest) and fairly neutral i'-z' colour (very cool stars and brown dwarfs can generally be distinguished from quasars on the basis of a much redder i'-z' colour).

2025, IEE proceedings

Self-assembled Sb-based quantum dots (QDs) were grown by metal-organic vapour phase epitaxy and assessed by means of atomic force microscopy, transmission electron microscopy and photoluminescence. Two series of InSb QDs in a GaSb matrix were grown at 490 ± 10 °C and luminesced in the mid-infrared at about 1.7 µm. Reductions in the III / V ratio and growth rate as used for the second series resulted in a change of the morphology of the InSb islands from hillocks without facets and a low level of order to dumbbell shaped islands with distinct facets and a higher level of order. Self-assembled GaSb islands were grown on GaAs at 550 °C and assessed for comparison purposes by means of AFM.

2025, IEE Proceedings - Optoelectronics

2025, Memorie Della Societa Astronomica Italiana

This review describes the properties of several components in the central kpc of active galactic nuclei (AGN) and points to old, as well as recently found relationships between dust gas and luminous starbursts in those regions. The spectroscopic properties of the broad line gas are becoming the main source for obtaining black hole mass, accretion rate and metalicity with important implications to AGN evolution. The central torus is the focus of numerous mid-infrared spectroscopic studies suggesting, in some cases, a two component origin for the spectrum: the torus itself and an additional contribution from a dusty narrow line region gas. Finally, luminous starburst regions seem to be associated with luminous AGN resulting in a significant L(starburst)-L(AGN) correlation over four orders of magnitude in luminosity. Such starbursts are not likely to be located in the central kpc. The correlation is difficult to explain and is a new important source for estimating AGN and starburst duty cycles at all redshifts.

2025, The Astrophysical Journal

We present Spitzer rest-frame mid-infrared spectroscopy of twelve z∼2 mmbright type 1 QSOs, selected from unlensed and lensed QSO samples and covering a range of AGN optical luminosities L 5100 = 10 45 to 10 47 erg s -1 . On top of the... more

2025, The Astrophysical Journal

We queried the Spitzer archive for high-resolution observations with the Infrared Spectrograph of optically selected active galactic nuclei (AGNs) for the purpose of identifying sources with resolved fine-structure lines that would enable studies of the narrow-line region (NLR) at mid-infrared wavelengths. By combining 298 Spitzer spectra with 6 Infrared Space Observatory spectra, we present kinematic information of the NLR for 81, z 0.3 AGNs. We used the [Ne v], [O iv], [Ne iii], and [S iv] lines, whose fluxes correlate well with each other, to probe gas photoionized by the AGN. We found that the widths of the lines are, on average, increasing with the ionization potential of the species that emit them. No correlation of the line width with the critical density of the corresponding transition was found. The velocity dispersion of the gas, σ , is systematically higher than that of the stars, σ * , in the AGN host galaxy, and it scales with the mass of the central black hole, M BH . Further correlations between the line widths and luminosities L, and between L and M BH , are suggestive of a three-dimensional plane connecting log(M BH ) to a linear combination of log(σ ) and log(L). Such a plane can be understood within the context of gas motions that are driven by AGN feedback mechanisms, or virialized gas motions with a power-law dependence of the NLR radius on the AGN luminosity. The M BH estimates obtained for 35 type 2 AGNs from this plane are consistent with those obtained from the M BH -σ * relation.

2025, The Astrophysical Journal

This paper addresses the origin of the silicate emission observed in PG QSOs, based on observations with the Spitzer Space Telescope. Scenarios based on the unified model suggest that silicate emission in AGN arises mainly from the illuminated faces of the clouds in the torus at temperatures near sublimation. However, detections of silicate emission in Type 2 QSOs, and the estimated cool dust temperatures, argue for a more extended emission region. To investigate this issue we present the mid-infrared spectra of 23 QSOs. These spectra, and especially the silicate emission features at ∼ 10 and ∼ 18 µm, can be fitted using dusty narrow line region (NLR) models and a combination of black bodies. The bolometric luminosities of the QSOs allow us to derive the radial distances and covering factors for the silicate-emitting dust. The inferred radii are 100-200 times larger than the dust sublimation radius, much larger than the expected dimensions of the inner torus. Our QSO mid-IR spectra are consistent with the bulk of the silicate dust emission arising from the dust in the innermost parts of the NLR.

2025, Analytical Chemistry

A novel method is presented that is capable of collecting time-resolved vibrational spectroscopic information with sub-100-µs temporal resolution. Unlike previous step scan FT-IR approaches, the phenomena under study do not necessarily need to be repeatable. The methodology described herein is based on the planar array infrared (PA-IR) technique, which utilizes a spectrograph for wavelength dispersion and a mid-infrared focal plane array (FPA) detector for simultaneous detection of multiple wavelengths. Unlike previous PA-IR approaches, a rolling mode FPA is employed. This unique data readout mode, where data are read out of the array two rows at a time, is exploited to generate increased temporal resolution. The capabilities of this technique are demonstrated using the example of the electric field-induced Freedericksz transition of a nematic liquid crystal. It is shown that the orientational dynamics of a single transition can be tracked over a spectral range of 154 cm -1 with a temporal resolution of 99.17 µs while requiring a total experimental time of less than 1 s.

2025, Nucleation and Atmospheric Aerosols

We presentastatistical analysis of 248 luminous infrared galaxies (LIRGs)w hich compriset he GreatO bservatories All-skyL IRGS urvey( GOALS) observedw ith theI nfraredS pectrograph( IRS) on-board Spitzer in ther est-framew avelengthr ange between 5a nd 38 µm. The GOALSs amplee nables ad irect measuremento ft he relative contributions of star-formationa nd activeg alactic nuclei( AGN) to thet otal infrared (IR) emission from al arge,s tatistically complete sampleofLIRGs in thelocal Universe. Severaldiagnosticseffectiveati solatingt he AGNc ontributiontot he Mid-infrared (MIR)e mission using[ NeV],[ OIV] and[ NeII] gase mission lines,t he 6.2 µmP AH equivalent width( EQW) andt he shapeo ft he MIR continuum arec ompared. The[ NeV] linew hich indicates thep resence of an AGNi sd etected in 22% of allLIRGs.T he 6.2 µmP AH EQW, [NeV]/L IR ,[ NeV]/[NeII] and [OIV]/[NeII] ratios, andthe ratiosof6.2 µmP AH fluxtothe integrated continuum fluxbetween 5.3 and5.8 µmsuggest values of around 10% forthe fractionalA GN contributiontot he totalIRl uminosity of LIRGs.T he median of thesee stimates suggestst hatf or local LIRGs thef ractionalA GN contributiont ot he totalI Rl uminosity is ∼ 12%.A GN dominatedL IRGs have higherg lobala nd nuclear IR luminosities, warmer MIR colors andare interactingmorethanstarburst (SB) dominated LIRGs.H owever therea re no obvious linear correlations between thesep roperties, suggestingthat none of thesepropertiesalone can determinethe activity ande volutionofanindividualLIRG. As tudy of theI RACc olorso fL IRGs confirmst hatm ethods of finding AGNo nt he basiso f theirMIR colors areeffectiveatchoosingA GN but50% to 40% of AGNdominatedLIRGs arenot selected as such with thesemethods.

2025, Physica C: Superconductivity

The infrared photo-induced spectra of the isotope-substituted stoichiometric La 2 CuO 4 samples were studied at T = 20 K. It was found that the mid-infrared photo-induced absorption spectra of the La 2 Cu 18 O 4 and La 2 Cu 16 O 4 do not show any difference within experimental error. It is shown that this observation is consistent with the polaron hopping theory predictions and cannot be used to rule out the polaronic origin of the charge carriers in cuprates.

2025, Indian Journal of Natural Sciences

Slot-coupled waveguide junctions often produce desired polarized radiated fields. The array of such junctions can be used to generate specified radiation patterns if they are optimally designed. This depends on several parameters; however, an attempt is made to investigate the influence of power loss in matched terminations on designing an array of such junctions. A cascade of junctions is replaced by its equivalent circuit, where each junction represents a shunt element of admittance. When the second port of the feed guide is connected to a matched termination, 5 to 15% power is dissipated in the termination, as no termination is ideal. The terminations assume power loss for a typical Taylor amplitude distribution. The desired conductance values of each junction are numerically computed. From such data, slot parameters are evaluated in the present work. The results show that power loss in termination significantly affects the design of slotted junctions.

2025, Arxiv preprint astro-ph/ …

We report TIMMI2 diffraction-limited mid-IR images of the multipolar PPN IRAS 16594-4656. By using the Lucy-Richardson deconvolution algorithm we recover a two-peaked morphology in the innermost region at 8.6 µm and 11.5 µm. We interpret the observed mid-IR structure as the detection of the two limb-brightened peaks indicating the presence of a dusty toroidal structure in IRAS 16594-4656. We find that the supposed biconical openings of the dust torus are in good agreement with one of the bipolar outflows identified in the HST optical images.

2025

The knowledge of the properties of supernovae (SNe) at optical wavelengths has experienced enormous progress in the current decade. In contrast, comparatively little is known about the SN behaviour in the near-infrared (NIR) window. Such a knowledge would give us relevant clues to key questions related to the nature of SN progenitors and to the interaction with SN environments. Hence,

2025, The Astrophysical Journal

TIMMI2 diffraction-limited mid-infrared images of a multipolar protoplanetary nebula IRAS 16594-4656 and a young [WC] elliptical planetary nebula IRAS 07027-7934 are presented. Their dust shells are for the first time resolved (only marginally in the case of IRAS 07027-7934) by applying the Lucy-Richardson deconvolution algorithm to the data, taken under exceptionally good seeing conditions (≤0.5 ′′ ). IRAS 16594-4656 exhibits a two-peaked morphology at 8.6, 11.5 and 11.7 µm which is mainly attributed to emission from PAHs. Our observations suggest that the central star is surrounded by a toroidal structure observed edge-on with a radius of 0.4 ′′ (∼640 AU at an assumed distance of 1.6 kpc) with its polar axis at P.A.∼80 • , coincident with the orientation defined by only one of the bipolar outflows identified in the HST optical images. We suggest that the material expelled from the central source is currently being collimated in this direction and that the multiple outflow formation has not been coeval. IRAS 07027-7934 shows a bright, marginally extended emission (FWHM=0.3 ′′ ) in the mid-infrared with a slightly elongated shape along the N-S direction, consistent with the morphology detected by HST in the near-infrared. The mid-infrared emission is interpreted as the result of the combined contribution of small, highly ionized PAHs and relatively hot dust continuum. We propose that IRAS 07027-7934 may have recently experienced a thermal pulse (likely at the end of the AGB) which has produced a radical change in the chemistry of its central star.

2025, Monthly Notices of the Royal Astronomical Society

We exploit very deep mid-infrared (MIR) and X-ray observations by Spitzer and Chandra in the GOODS-North field to identify signs of hidden [either starburst or active galactic nucleus (AGN)] activity in spheroidal galaxies between z 0.3 and 1. Our reference is a complete sample of 168 morphologically classified spheroidal (elliptical/lenticular) galaxies with z AB < 22.5 selected from GOODS Advanced Camera for Surveys imaging. Of these 19 have 24-μm detections in the GOODS catalogue, half of which have an X-ray counterpart in the 2-Ms Chandra catalogue (six detected in the 2-10 keV X-rays hard band), while about 25 per cent have 1.4-GHz fluxes larger than 40 μJy. Traces of hidden activity in the spheroidal population are also searched for in the deep X-ray images and 14 additional galaxies are detected in X-rays only. The nature of the observed MIR emissions is investigated by modelling their spectral energy distributions based on the available multiwavelength photometry, including X-ray, ultraviolet, optical, near-infrared, MIR and radio fluxes, and optical spectroscopy. The amount of dust derived from the infrared emission observed by Spitzer appears in excess of that expected by mass loss from evolved stars. When the available independent diagnostics are compared, in general, they provide consistent classifications about the nature of the activity in our spheroidal population. Given that, in principle, none of these diagnostics alone can be considered as conclusive, only trough a panchromatic comparison of them, we can reach an accurate comprehension of the underlying physical processes. In particular, our multiwavelength analysis of the X-ray and MIR properties leads us to conclude that at least eight of the 19 24-μm bright sources should hide an obscured AGN, while the X-ray undetected sources are more likely dominated by star formation. We conclude that ∼30 objects (∼20 per cent) of the original flux-limited sample of 168 spheroidal galaxies in the GOODS-North are detected during phases of prominent activity, of both stellar and quasar origin. Due to the short expected lifetimes of the infrared and X-ray emissions, this fraction might imply a significant level of activity in this class of galaxies during the relatively recent cosmic epochs -z ∼ 0.3-1 -under investigation.

2025, Monthly Notices of the Royal Astronomical Society

The radio counterparts to the 15-µm sources in the European Large Area ISO Survey southern fields are identified in 1.4-GHz maps down to ∼80 µJy. The radio-mid-infrared correlation is investigated and derived for the first time at these flux densities for a sample of this size. Our results show that radio and mid-infrared (MIR) luminosities correlate almost as well as radio and far-infrared (FIR), at least up to z 0.6. Using the derived relation and its spread together with the observed 15-µm counts, we have estimated the expected contribution of the 15-µm extragalactic populations to the radio source counts and the role of MIR starburst galaxies in the well-known 1.4-GHz source excess observed at sub-mJy levels. Our analysis demonstrates that IR emitting starburst galaxies do not contribute significantly to the 1.4-GHz counts for strong sources, but start to become a significant fraction of the radio source population at flux densities 0.5-0.8 mJy. They are expected to be responsible for more than 60 per cent of the observed radio counts at 0.05 mJy. These results are in agreement with the existing results on optical identifications of faint radio sources.

2025

We present the estimate of the evolution of type 1 AGNs in the hard (2-10 keV) X-rays drawn from the HELLAS survey, and in the IR (15 µm) obtained from the ELAIS survey. We find that the local luminosity function (LF) of AGN1 in the 2-10 keV is fairly well represented by a double-power-law-function. There is evidence for significant cosmological evolution according to a pure luminosity evolution model L X (z)∝(1 + z) k , with k=2.12 +0.13 -0.14 and k=2.19 +0.13 -0.14 in a (Ω m ,Ω Λ )=(1.0,0.0) and in a (Ω m ,Ω Λ )=(0.3,0.7) cosmology respectively. In a (Ω m ,Ω Λ )=(1.0,0.0) Universe the data show an excess of faint high redshift type 1 AGN which is well modeled by a luminosity dependent density evolution, similarly to what observed in the soft X-rays. In the IR band, with a (Ω m ,Ω Λ )=(1.0,0.0) cosmology, the evolution is similar to what observed at other wavebands, the LF is a double-power-law-function with a bright slope 2.9 and a faint slope 1.1, following a pure luminosity evolution model with k=3.00 +0.16 -0.20 .

2025, Icarus

We have analyzed data recorded by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft during the Titan flybys T0-T10 (July 2004-January 2006). The spectra characterize various regions on Titan from 70 • S to 70 • N with a variety of emission angles. We study the molecular signatures observed in the mid-infrared CIRS detector arrays (FP3 and FP4, covering roughly the 600-1500 cm -1 spectral range with apodized resolutions of 2.54 or 0.53 cm -1 ). The composite spectrum shows several molecular signatures: hydrocarbons, nitriles and CO 2 . A firm detection of benzene (C 6 H 6 ) is provided by CIRS at levels of about 3.5 × 10 -9 around 70 • N. We have used temperature profiles retrieved from the inversion of the emission observed in the methane ν 4 band at 1304 cm -1 and a line-by-line radiative transfer code to infer the abundances of the trace constituents and some of their isotopes in Titan's stratosphere. No longitudinal variations were found for these gases. Little or no change is observed generally in their abundances from the south to the equator. On the other hand, meridional variations retrieved for these trace constituents from the equator to the North ranged from almost zero (no or very little meridional variations) for C 2 H 2 , C 2 H 6 , C 3 H 8 , C 2 H 4 and CO 2 to a significant enhancement at high northern (early winter) latitudes for HCN, HC 3 N, C 4 H 2 , C 3 H 4 and C 6 H 6 . For the more important increases in the northern latitudes, the transition occurs roughly between 30 and 50 degrees north latitude, depending on the molecule. Note however that the very high-northern latitude results from tours TB-T10 bear large uncertainties due to few available data and problems with latitude smearing effects. The observed variations are consistent with some, but not all, of the predictions from dynamical-photochemical models. Constraints are set on the vertical distribution of C 2 H 2 , found to be compatible with 2-D equatorial predictions by global circulation models. The D/H ratio in the methane on Titan has been determined from the CH 3 D band at 1156 cm -1 and found to be 1.17 +0.23 -0.28 × 10 -4 . Implications of this deuterium enrichment, with respect to the protosolar abundance on the origin of Titan, are discussed. We compare our results with values retrieved by Voyager IRIS observations taken in 1980, as well as with more recent (1997) disk-averaged Infrared Space Observatory (ISO) results and with the latest Cassini-Huygens inferences from other instruments in an attempt to better comprehend the physical phenomena on Titan.