Misc,
The influence of magnetic fields on absorption and emission spectroscopy
(2016)cite arxiv:1610.00106Comment: 19 pages, 13 Figures, ApJ submitted.
Abstract
Spectroscopic observations play essential roles in astrophysics. They are
crucial for determining important physical parameters, providing information
about the composition of various objects in the universe, as well as depicting
motions in the universe. However, spectroscopic studies often do not consider
the influence of magnetic fields. In this paper, we explore the influence of
magnetic fields on the spectroscopic observations arising from Ground State
Alignment (GSA). Synthetic spectra are generated to show the measurable changes
of the spectra due to GSA. The influences of atomic alignment on absorption
from DLAs, emission from H\,ii Regions, submillimeter fine-structure
lines from star forming regions are presented as examples to illustrate the
effect in diffuse gas. Furthermore, we demonstrate the influence of atomic
alignment on physical parameters derived from spectral line ratios, such as the
alpha-to-iron ratio(X/Fe), interstellar temperature, and ionization rate.
Results in our paper show that due to GSA, magnetic fields will affect the
spectra of diffuse gas with high signal-to-noise(S/N) ratio under the condition
that photon-excitation is much more efficient than thermal collision.
