Related papers: The WHaD diagram: Classifying the ionizing source …
Optical emission-line diagnostic diagrams, such as the classical BPT, are widely used to identify ionisation mechanisms in galaxies but often suffer from degeneracies, especially when multiple sources coexist. We critically evaluate the…
Buried active galactic nuclei and obscured young stellar clusters pose significant challenges to traditional optical diagnostic diagrams. Therefore, developing new tools to trace the excitation sources across the spectrum is a necessary…
Current methods of identifying the ionizing source of nebular emission in galaxies are well defined for the era of single fiber spectroscopy, but still struggle to differentiate the complex and overlapping ionization sources in some…
Two-dimensional (2D) line ratio diagnostic diagrams have become a key tool in understanding the excitation mechanisms of galaxies. The curves used to separate the different regions - HII-like or else excited by an active galactic nucleus…
Optical emission lines are used to categorize galaxies into three groups according to their dominant central radiation source: active galactic nuclei, star formation, or low-ionization (nuclear) emission regions [LI(N)ERs] that may trace…
We compute synthetic optical and ultraviolet (UV) emission-line properties of galaxies in a full cosmological framework by coupling, in post-processing, new-generation nebular-emission models with high-resolution, cosmological zoom-in…
We propose a new diagram, the Kinematic-Excitation diagram (KEx diagram), which uses the [OIII]/H\beta\ line ratio and the [OIII]5007 emission line width (\sigma_{[OIII]}) to diagnose the ionization source and physical properties of the…
Understanding galaxy classification depends on our interpretation of their spectra. To date, the hydrogen Balmer lines remain the most consistent way to classify galaxies, but at 'intermediate' redshifts ($1.5 < z < 2.5$), galaxies are hard…
We review the use of emission-lines for understanding galaxy evolution, focusing on excitation source, metallicity, ionization parameter, ISM pressure and electron density. We show that the UV, optical and infrared contain complementary…
Optical diagnostic diagrams are powerful tools to separate different ionizing sources in galaxies. However, the model-constraining power of the most widely-used diagrams is very limited and challenging to visualize. In addition, there have…
Once thought to be devoid of warm and cold interstellar matter, elliptical galaxies are now commonly observed to host extended regions of neutral and ionized gas. Outside of the innermost nuclear regions of these galaxies, the favoured…
Line intensity mapping (LIM) is an emerging observational method to study the large-scale structure of the Universe and its evolution. LIM does not resolve individual sources but probes the fluctuations of integrated line emissions. A…
Optical diagnostic diagrams are frequently ambiguous as a test of the photoionization or fast shock models of the narrow line regions of active galaxies. Here, we present a set of UV line ratio diagrams which can discriminate between pure…
We report on observations of several optical emission lines toward a variety of newly revealed faint, large-scale H-alpha-emitting structures in the warm ionized medium (WIM) of the Galaxy. The lines include [N II] 6583, [N II] 5755, [S II]…
We analyze several key rest-optical emission-line ratios in a sample of 828 galaxies as well as composite spectra from JADES DR3 in the range $1.4 < z < 7$. These emission-line ratios include: [O III]$\lambda5008$/H$\beta$, [N II]$\lambda…
We develop an analytic approach to study inhomogeneous reionization on large scales by solving the equations of ionization balance and radiative transfer to first order in perturbations. Given the spatial distribution and spectrum of the…
Rest-frame optical emission line diagnostics are often used to help classify ionizing sources within galaxies. However, rest-frame optical tracers can miss sources with high dust attenuation, leading to misclassification of the dominant…
The Wisconsin H-Alpha Mapper (WHAM) is a new facility dedicated to the study of faint optical emission lines from diffuse interstellar gas. During its first 18 months of operation, WHAM carried out a survey of the interstellar H-alpha…
We compute synthetic, rest-frame optical and ultraviolet (UV) emission-line properties of galaxy populations at redshifts from z$\approx$0 to z=8 in a full cosmological framework. We achieve this by coupling, in post-processing, the…
In the context of observations of the rest-frame ultraviolet and optical emission from distant galaxies, we explore the emission-line properties of photoionization models of active and inactive galaxies. Our aim is to identify new…