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High-definition Fourier Transform Infrared (FT-IR) Spectroscopic Imaging of Human Tissue Sections towards Improving Pathology
Published on: January 21, 2015
Summary
Star-forming galaxies show interstellar medium emission dominated by aromatic features in mid-infrared spectra. This emission, primarily from polycyclic aromatic hydrocarbons, can help determine redshifts for distant, obscured galaxies.
Area of Science:
- Astronomy and Astrophysics
- Cosmic Dust Studies
- Galactic Interstellar Medium
Background:
- Galactic emission in the mid-infrared is crucial for understanding star formation.
- Polycyclic Aromatic Hydrocarbons (PAHs) are key components of the interstellar medium.
- Previous studies have indicated the presence of aromatic features in galactic spectra.
Purpose of the Study:
- To analyze the mid-infrared spectral features of star-forming galaxies.
- To investigate the origin and contribution of different spectral components.
- To assess the potential of these features for redshift determination in obscured galaxies.
Main Methods:
- Utilized ISOPHOT instrument to obtain mid-infrared spectra (2.5-5 µm and 5.7-11.6 µm).
- Analyzed spectral dominance of aromatic features (6.2, 7.7, 8.6, 11.3 µm).
- Examined underlying continuum emission and its spectral shape (fnu~nu+0.65).
Main Results:
- Mid-infrared spectra are strongly dominated by aromatic features from polycyclic aromatic hydrocarbons.
- An underlying continuum, likely from non-stellar fluctuating grains, contributes significantly to luminosity.
- Feature fluxes show weak dependence on galaxy parameters, suggesting non-thermal equilibrium.
- The 10 µm dip is invariant, ruling out simple silicate absorption.
Conclusions:
- The observed spectral features are characteristic of the interstellar medium in most star-forming galaxies.
- These spectral signatures can be used to determine redshifts of highly obscured galaxies up to z=3 using SIRTF.
- The continuum emission is attributed to non-stellar fluctuating grains, distinct from aromatic features.
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