English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Context: Broadband optical constants of astrophysical ice analogues in theinfrared (IR) and terahertz (THz) ranges are required for modeling the dustcontinuum emission and radiative transfer in dense and cold regions, wherethick icy mantles are formed on the surface of dust grains. Aims: In thispaper, the THz time-domain spectroscopy (TDS) and the Fourier-transform IRspectroscopy (FTIR) are combined to study optical constants of CO and CO$_2$ices in the broad THz-IR spectral range. Methods: The measured ices are grownat cryogenic temperatures by gas deposition on a cold Si window. A method toquantify the broadband THz-IR optical constants of ices is developed based onthe direct reconstruction of the complex refractive index of ices in the THzrange from the TDS data, and the use of the Kramers-Kronig relation in the IRrange for the reconstruction from the FTIR data. Uncertainties of theKramers-Kronig relation are eliminated by merging the THz and IR spectra. Thereconstructed THz-IR response is then analyzed using classical models ofcomplex dielectric permittivity. Results: The complex refractive index of COand CO$_2$ ices deposited at the temperature of $28$ K is obtained in the rangeof 0.3--12.0 THz. Based on the measured dielectric constants, opacities of theastrophysical dust with CO and CO$_2$ icy mantles are computed. Conclusions:The developed method can be used for a model-independent reconstruction ofoptical constants of various astrophysical ice analogs in a broad THz-IR range.Such data can provide important benchmarks to interpret the broadbandobservations from the existing and future ground-based facilities and spacetelescopes. The reported results will be useful to model sources that show adrastic molecular freeze-out, such as central regions of prestellar cores andmid-planes of protoplanetary disks, as well as CO and CO$_2$ snow lines indisks.

Broadband spectroscopy of astrophysical ice analogues: II. Optical constants of CO and CO$_2$ ices in the terahertz and infrared ranges