1 research outputs found
A simple non-parametric method for resolving merged doublet lines:Insights into complex kinematics and outflows
Doublet line emission and absorption is common in astronomical sources (e.g.
[OIII], [OII], NaD, MgII). In many cases, complex kinematics in the emitting
source can cause the doublet lines to merge, making characterisation of the
source kinematics challenging. Here, we present a non-parametric method for
resolving merged doublet emission when the line ratio and wavelength difference
is known. The method takes as input only the line ratio and wavelength
difference, using these quantities to resolve the components of the doublet
without resorting to fitting (e.g. using multiple Gaussians) or making any
assumptions about the components' line profiles (save that they are the same
for both components). The method is simple, fast and robust. It is also ideal
for visualisation. We show that the method recovers line profiles of merged
emission lines in simulated data. We also show, using simulated data and
mathematical analysis, that the method does not significantly increase noise
levels in the extracted lines, and is robust to background contamination. We
demonstrate the strength of the method by applying it to strongly merged [OIII]
5007/4959~{\AA} in Active Galactic Nuclei (AGN). A python implementation of the
method is provided in the Appendix.Comment: Accepted for publication in MNRAS (changes from v1: comparison of
method to fitting procedures and additional tests of method added