Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the ...proceedings of “Walking the Line”, a 3-day conference held in 2018 that brought together scientists working on different aspects of emission line simulations, in order to share knowledge and discuss the methodology. Emission lines across the spectrum from the millimeter to the UV were discussed, with most of the focus on the interstellar medium, but also some topics on the circumgalactic medium. The most important quality of a useful model is a good synergy with observations and experiments. Challenges in simulating line emission are identified, some of which are already being worked upon, and others that must be addressed in the future for models to agree with observations. Recent advances in several areas aiming at achieving that synergy are summarized here, from micro-physical to galactic and circum-galactic scale.
ABSTRACT
The depletion of elements onto dust grains is characterized using a generalized depletion strength F* for any sightline, and trend-line parameters AX, BX, and zX. The parameters AX, BX, and ...zX define the relative depletion pattern, for which values are published in previous works. The present study uses these parameters to calculate post-depleted gas-phase abundances of 15 different elements while varying F* from 0 to 1. An analysis of emergent strong spectral line intensities, obtained by inputting the calculated abundances into a cloudy model, shows that the depletion strength has a non-trivial effect on predicted emission lines and the thermal balance of the ionized cloud. The amount by which elements deplete also affects the coolant abundances in the gas. Furthermore, it was found that each of the parameters – metallicity, ionization parameter U, and depletion strength F* have degenerate effects on the emission-line strengths, and thermal balance of the interstellar medium (ISM). Finally, comparing our results to a sample of H ii regions using data obtained from the Mapping Nearby Galaxies at Apache Point Observatory survey (MaNGA) revealed that the best-fit F* was approximately 0.5. However, this best-fitting value does not work well for all metallicities. Removing the sulfur depletion and changing the nitrogen abundance pattern can improve the fit. As a result, extra observational evidence is required to verify the choices of parameters and better constrain the typical depletion strength in galaxies.
ABSTRACT
Atomic species in the interstellar medium transition out of their gas phase mainly by depletion on to dust. In this study, we examine if there is any change to the spectral-line ratio ...predictions from a photoionization model of the Orion H ii region when the degree of dust depletions is altered according to the most recently published model. We use equations and parameters published by previous works, in order to streamline the calculation of depleted abundances within cloudy. Our aim is for cloudy users to be able to vary the level of depletion using a single parameter in the input file. This makes it possible to explore predictions for a large range of depletions more efficiently. Finally, we discuss the results obtained for a model of the Orion Nebula when the degree of depletions are manipulated in this way. We found that the intensity of line ratios are significantly affected by depletions on to dust grains. Further, we found that adjusting dust abundances along with depletion affects the structure and the overall temperature of the H+ layer across the H ii region.
ABSTRACT
The flux ratios of high-ionization lines are commonly assumed to indicate the metallicity of the broad emission-line region in luminous quasars. When accounting for the variation in their ...kinematic profiles, we show that the N v/C iv, (Si iv + O iv)/C iv, and N v/Ly α line ratios do not vary as a function of the quasar continuum luminosity, black hole mass, or accretion rate. Using photoionization models from cloudy, we further show that the observed changes in these line ratios can be explained by emission from gas with solar abundances, if the physical conditions of the emitting gas are allowed to vary over a broad range of densities and ionizing fluxes. The diversity of broad-line emission in quasar spectra can be explained by a model with emission from two kinematically distinct regions, where the line ratios suggest that these regions have either very different metallicity or density. Both simplicity and current galaxy evolution models suggest that near-solar abundances, with parts of the spectrum forming in high-density clouds, are more likely. Within this paradigm, objects with stronger outflow signatures show stronger emission from gas that is denser and located closer to the ionizing source, at radii consistent with simulations of line-driven disc-winds. Studies using broad-line ratios to infer chemical enrichment histories should consider changes in density and ionizing flux before estimating metallicities.
Abstract
In this paper, we discuss atomic processes modifying the soft X-ray spectra from optical depth effects like photoelectric absorption and electron scattering suppressing the soft X-ray lines. ...We also show the enhancement in soft X-ray line intensities in a photoionized environment via continuum pumping. We quantify the suppression/enhancement by introducing a “line modification factor (
f
mod
).” If 0 ≤
f
mod
≤ 1, the line is suppressed, which could be the case in both collisionally ionized and photoionized systems. If
f
mod
≥ 1, the line is enhanced, which occurs in photoionized systems. Hybrid astrophysical sources are also very common, where the environment is partly photoionized and partly collisionally ionized. Such a system is V1223 Sgr, an Intermediate Polar binary. We show the application of our theory by fitting the first-order Chandra Medium Energy Grating (MEG) spectrum of V1223 Sgr with a combination of
Cloudy
-simulated additive cooling-flow and photoionized models. In particular, we account for the excess flux for O
vii
, O
viii
, Ne
ix
, Ne
x
, and Mg
xi
lines in the spectrum found in a recent study, which could not be explained with an absorbed cooling-flow model.
ABSTRACT
Ram pressure stripping (RPS) is an important mechanism for galaxy evolution. In this work, we present results from HST and APEX observations of one RPS galaxy, ESO 137-002 in the closest ...rich cluster Abell 3627. The galaxy is known to host prominent X-ray and H α tails. The HST data reveal significant features indicative of RPS in the galaxy, including asymmetric distribution of dust in the galaxy, dust filaments, and dust clouds in ablation generally aligned with the direction of ram pressure, and young star clusters immediately upstream of the residual dust clouds that suggest star formation (SF) triggered by RPS. The distribution of the molecular gas is asymmetric in the galaxy, with no CO upstream and abundant CO downstream and in the inner tail region. A total amount of ∼5.5 × 109 M⊙ of molecular gas is detected in the galaxy and its tail. On the other hand, we do not detect any active SF in the X-ray and H α tails of ESO 137-002 with the HST data and place a limit on the SF efficiency in the tail. Hence, if selected by SF behind the galaxy in the optical or UV (e.g. surveys like GASP or using the Galex data), ESO 137-002 will not be considered a ‘jellyfish’ galaxy. Thus, galaxies like ESO 137-002 are important for our comprehensive understanding of RPS galaxies and the evolution of the stripped material. ESO 137-002 also presents a great example of an edge-on galaxy experiencing a nearly edge-on RPS wind.
ABSTRACT We present new ultraviolet, optical, and X-ray data on the Phoenix galaxy cluster (SPT-CLJ2344-4243). Deep optical imaging reveals previously undetected filaments of star formation, ...extending to radii of ∼50-100 kpc in multiple directions. Combined UV-optical spectroscopy of the central galaxy reveals a massive (2 × 109 M ), young (∼4.5 Myr) population of stars, consistent with a time-averaged star formation rate of 610 50 M yr−1. We report a strong detection of O vi λλ1032,1038, which appears to originate primarily in shock-heated gas, but may contain a substantial contribution (>1000 M yr−1) from the cooling intracluster medium (ICM). We confirm the presence of deep X-ray cavities in the inner ∼10 kpc, which are among the most extreme examples of radio-mode feedback detected to date, implying jet powers of 2-7 × 1045 erg s−1. We provide evidence that the active galactic nucleus inflating these cavities may have only recently transitioned from "quasar-mode" to "radio-mode," and may currently be insufficient to completely offset cooling. A model-subtracted residual X-ray image reveals evidence for prior episodes of strong radio-mode feedback at radii of ∼100 kpc, with extended "ghost" cavities indicating a prior epoch of feedback roughly 100 Myr ago. This residual image also exhibits significant asymmetry in the inner ∼200 kpc (0.15R500), reminiscent of infalling cool clouds, either due to minor mergers or fragmentation of the cooling ICM. Taken together, these data reveal a rapidly evolving cool core which is rich with structure (both spatially and in temperature), is subject to a variety of highly energetic processes, and yet is cooling rapidly and forming stars along thin, narrow filaments.
ABSTRACT
We present the results from the HST WFC3 and ACS data on an archetypal galaxy undergoing ram pressure stripping (RPS), ESO 137-001, in the nearby cluster Abell 3627. ESO 137-001 is known to ...host a prominent stripped tail detected in many bands from X-rays, H α to CO. The HST data reveal significant features indicative of RPS such as asymmetric dust distribution and surface brightness as well as many blue young star complexes in the tail. We study the correlation between the blue young star complexes from HST, H ii regions from H α (MUSE), and dense molecular clouds from CO (ALMA). The correlation between the HST blue star clusters and the H ii regions is very good, while their correlation with the dense CO clumps are typically not good, presumably due in part to evolutionary effects. In comparison to the starburst99 + cloudy model, many blue regions are found to be young (<10 Myr) and the total star formation (SF) rate in the tail is 0.3–0.6 M⊙ yr−1 for sources measured with ages less than 100 Myr, about 40 per cent of the SF rate in the galaxy. We trace SF over at least 100 Myr and give a full picture of the recent SF history in the tail. We also demonstrate the importance of including nebular emissions and a nebular to stellar extinction correction factor when comparing the model to the broad-band data. Our work on ESO 137-001 demonstrates the importance of HST data for constraining the SF history in stripped tails.
Atomic and molecular data are required to conduct the detailed calculations of microphysical processes performed by cloudy to predict the spectra of a theoretical model. cloudy now utilizes three ...atomic and molecular databases, one of which is CHIANTI version 7.1. CHIANTI version 10.0.1 is available, but its format has changed. cloudy is incompatible with the newer version. We have developed a script to convert the version 10.0.1 database into its version 7.1 format so that cloudy does not have to change every time there is a new CHIANTI version with an evolved format. This study outlines the steps taken by the script for this version format change. We have also found a modest number of significant changes to spectral line intensities/luminosities calculated by cloudy with the adoption of CHIANTI version 10.0.1. These changes are a result of improvements to collision strength data.
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