A Principal Component Analysis of the Diffuse Interstellar Bands
Abstract
We present a principal component (PC) analysis of 23 line-of-sight parameters (including the strengths of 16 diffuse interstellar bands, DIBs) for a well-chosen sample of single-cloud sightlines representing a broad range of environmental conditions. Our analysis indicates that the majority (∼93%) of the variations in the measurements can be captured by only four parameters The main driver (I.e., the first PC) is the amount of DIB-producing material in the line of sight, a quantity that is extremely well traced by the equivalent width of the λ5797 DIB. The second PC is the amount of UV radiation, which correlates well with the λ5797/λ5780 DIB strength ratio. The remaining two PCs are more difficult to interpret, but are likely related to the properties of dust in the line of sight (e.g., the gas-to-dust ratio). With our PCA results, the DIBs can then be used to estimate these line-of-sight parameters.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2017
- DOI:
- 10.3847/1538-4357/aa5b84
- arXiv:
- arXiv:1701.06180
- Bibcode:
- 2017ApJ...836..162E
- Keywords:
-
- ISM: lines and bands;
- ISM: molecules;
- methods: data analysis;
- methods: statistical;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 29 pages, 17 figures