Mapping low and high density clouds in astrophysical nebulae by imaging forbidden line emission

TL;DR

This paper introduces a novel imaging method that transforms emission line images into maps of high and low-density clouds in nebulae, enhancing the analysis of astrophysical gaseous regions.

Contribution

The paper presents a new technique using forbidden line ratios and a transformation matrix to map density variations in nebulae from spectroscopic images.

Findings

Successfully applied the method to galactic nuclei data.

Enabled mapping of low and high-density clouds.

Provides new insights into nebular structure.

Abstract

Emission line ratios have been essential for determining physical parameters such as gas temperature and density in astrophysical gaseous nebulae. With the advent of panoramic spectroscopic devices, images of regions with emission lines related to these physical parameters can, in principle, also be produced. We show that, with observations from modern instruments, it is possible to transform images taken from density sensitive forbidden lines into images of emission from high and low-density clouds by applying a transformation matrix. In order to achieve this, images of the pairs of density sensitive lines as well as the adjacent continuum have to be observed and combined. We have computed the critical densities for a series of pairs of lines in the infrared, optical, ultraviolet and X-rays bands, and calculated the pair line intensity ratios in the high and low-density limit using a 4 and 5 level atom approximation. In order to illustrate the method we applied it to GMOS-IFU data of two galactic nuclei. We conclude that this method provides new information of astrophysical interest, especially for mapping low and high-density clouds; for this reason we call it "the ld/hd imaging method".