A5048173786- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Atomic and Molecular Physics
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Laser-induced spectroscopy and plasma
- Solar and Space Plasma Dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- History and Developments in Astronomy
- Adaptive optics and wavefront sensing
- Ionosphere and magnetosphere dynamics
- Advanced Chemical Physics Studies
- Scientific Research and Discoveries
- Quantum, superfluid, helium dynamics
- Molecular Spectroscopy and Structure
- Atomic and Subatomic Physics Research
- Calibration and Measurement Techniques
- Plasma Diagnostics and Applications
University of Kentucky
2016-2025
Max Planck Institute for Extraterrestrial Physics
2024
Queen's University Belfast
2014-2019
Florence (Netherlands)
2019
Polish Academy of Sciences
2016-2018
Nicolaus Copernicus Astronomical Center
2016-2018
University of Strathclyde
2017
Institute of Astronomy
1979-2009
University of Cambridge
1980-2009
University of Florida
2009
ABSTRACT CLOUDY is a large‐scale spectral synthesis code designed to simulate fully physical conditions within an astronomical plasma and then predict the emitted spectrum. Here we describe version 90 (C90) of code, paying particular attention changes in atomic database numerical methods that have affected predictions since last publicly available version, C84. The computational uncertainties are outlined together with direction future development will take. freely widely used analysis...
view Abstract Citations (1439) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Atomic Data for Astrophysics. II. New Analytic FITS Photoionization Cross Sections of Atoms and Ions Verner, D. A. ; Ferland, G. J. Korista, K. T. Yakovlev, We present a complete set analytic fits to the nonrelativistic photoionization cross sections ground states atoms ions elements from H through Si, S, Ar, Ca, Fe. Near ionization thresholds, are based on Opacity...
view Abstract Citations (502) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS What Heats the Hot Phase in Active Nuclei? Mathews, William G. ; Ferland, Gary J. The authors summarize some constraints on continuum active galactic nuclei and discuss implications for hot intercloud medium. First, there is now good evidence that peak of energy distribution may actually occur extreme ultraviolet 200 Å ≤ λ ≤1000 Å. Second, it shown Compton...
Aims.We present a comparison between independent computer codes, modeling the physics and chemistry of interstellar photon dominated regions (PDRs). Our goal was to understand mutual differences in PDR codes their effects on physical chemical structure model clouds, converge output different common solution.
view Abstract Citations (500) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Are there any shock-heated galaxies ? Ferland, G. J. ; Netzer, H. Attention is given to the spectra of low-ionization nuclear emission-line regions (Liners) as compared other active galactic nuclei. Results are presented for extensive photoionization model calculations which employed investigation line ratio diagrams. The diagrams show that broad-line objects,...
We describe the 2017 release of spectral synthesis code Cloudy. A major development since previous has been exporting atomic data into external files. This greatly simplifies updates and maintenance data. Many large datasets have incorporated with result that we can now predict well over an order magnitude more emission lines when all databases are fully used. The use such is not realistic for most calculations due to time memory needs, limited subset by default. Despite fact significantly...
We describe the 2023 release of spectral synthesis code Cloudy. Since previous major release, migrations our online services motivated us to adopt git as version control system. This change alone led an annual scheme, accompanied by a short paper, present being inaugural. Significant changes atomic and molecular data have improved accuracy Cloudy predictions: we upgraded instance Chianti database from 7 10; H- He-like collisional rates theoretical values; most recent LAMDA database, several...
We present a simple yet powerful column density diagnostic for plasmas enabled by X-ray microcalorimeter observations. With the recent developments of spectral simulation code inspired high resolution X-Ray Imaging and Spectroscopy Mission (XRISM) Advanced Telescope High Energy Astrophysics (Athena), we make predictions intensity ratio resolved fine-structure lines Lyα_1 Lyα_2 H-like ions. show that this can be observationally constrained used as plasma indicator. demonstrate with an XRISM...
▪ Abstract Quasar (QSO) elemental abundances provide unique probes of high-redshift star formation and galaxy evolution. There is growing evidence from both the emission intrinsic absorption lines that QSO environments have roughly solar or higher metallicities out to redshifts >4. The range not well known, but a few times metallicity appears be typical. also for in more luminous objects generally enhanced N/C Fe/α compared with ratios. These results identify QSOs vigorous,...
view Abstract Citations (304) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Atomic Data for Astrophysics. I. Radiative Recombination Rates H-like, He-like, Li-like, and Na-like Ions over a Broad Range of Temperature Verner, D. A. ; Ferland, G. J. We present new calculations analytic fits to the rates radiative recombination towards Li-like ions all elements from H through Zn (Z=30). The are valid wide range temperature, 3 K 10**9 K....
view Abstract Citations (378) References (114) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Chemical Evolution of QSOs and the Implications for Cosmology Galaxy Formation Hamann, Fred ; Ferland, Gary We examine chemical evolution QSO broad-line gas by applying spectral synthesis enrichment models to N V/C IV V/He II emission-line ratios. indicate that BLR metallicities are typically ∼1 perhaps ≳10 times solar. must occur in ≲1 Gyr sources where...
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The similarity of quasar line spectra has been taken as an indication that the emission clouds have preferred parameters, suggesting environment is subject to a fine tuning process. We show here observed spectrum natural consequence powerful selection effects. computed large grid photoionization models covering widest possible range cloud gas density and distance from central continuum source. For each only narrow source results in maximum reprocessing efficiency, corresponding ``locally...
view Abstract Citations (292) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Anisotropic Line Emission and the Geometry of Broad-Line Region in Active Galactic Nuclei Ferland, G. J. ; Peterson, B. M. Horne, K. Welsh, W. F. Nahar, S. N. The rapid response broad emission lines to continuum variations Seyfert galaxy NGC 5548 implies that line-emitting regions are very close source. As described this contribution, photoionization models must be...
We present graphically the results of several thousand photoionization calculations broad emission-line clouds in quasars, spanning 7 orders magnitude hydrogen ionizing flux and particle density. The equivalent widths 42 quasar emission lines are presented as contours density-ionizing plane for a typical incident continuum shape, solar chemical abundances, cloud column density N(H) = 1023 cm-2. Results similarly given small subset two other densities (1022 1024 cm-2), five shapes, gas...
We study the physical conditions in damped Lyman α systems (DLAs), using a sample of 33 towards 26 quasi-stellar objects (QSOs) acquired for recently completed survey H2 by Ledoux, Petitjean & Srianand. use column densities different rotational levels, together with those C i, i*, i**, ii* and singly ionized atomic species to discuss kinetic temperature, density hydrogen electronic gas ambient ultraviolet (UV) radiation field. Detailed comparisons are made between observed properties DLAs,...
Abstract Swift intensive accretion disk reverberation mapping of four AGN yielded light curves sampled ∼200–350 times in 0.3–10 keV X-ray and six UV/optical bands. Uniform reduction cross-correlation analysis these data sets yields three main results: (1) The X-ray/UV correlations are much weaker than those within the UV/optical, posing severe problems for lamp-post reprocessing model which variations a central corona drive power surrounding disk. (2) interband lags generally consistent with...
We present the first results from ongoing, intensive, multi-wavelength monitoring program of luminous Seyfert 1 galaxy Mrk 817. While this AGN was, in part, selected for its historically unobscured nature, we discovered that X-ray spectrum is highly absorbed, and there are new blueshifted, broad narrow UV absorption lines, which suggest a dust-free, ionized obscurer located at inner line region partially covers central source. Despite obscuration, measure optical continuum reverberation lags...
ABSTRACT Using ≈190 000 spectra from the 17th data release of Sloan Digital Sky Survey (SDSS), we investigate ultraviolet emission line properties in z ≈ 2 quasars. Specifically, quantify how shape C iv λ1549 and equivalent width (EW) He ii λ1640 depend on black hole mass Eddington ratio inferred Mg λ2800. Above L/LEdd ≳ 0.2, there is a strong dependence both blueshift EW. Large blueshifts are observed only regions with high accretion rate. Including X-ray measurements for subsample 5000...
Abstract We present star formation rates (SFRs), the mass–metallicity relation (MZR), and SFR-dependent MZR across redshifts 4–10 using 81 star-forming galaxies observed by JWST NIRSpec employing both low-resolution PRISM medium-resolution gratings, including from Advanced Deep Extragalactic Survey (JADES) GOODS-N GOODS-S fields, JWST-PRIMAL Legacy Survey, additional literature in A2744, SMACS-0723, RXJ2129, BDF, COSMOS, MACS1149 fields. These span a 3 dex stellar mass range of 10 7 < M *...
▪ Abstract Photoionized clouds are ubiquitous. They define the endpoints of stellar evolution (H II regions and planetary nebulae), constitute interstellar intergalactic media, found in high redshift quasars star-forming galaxies. The spectra these objects dominated by emission lines that sensitive to details emitting gas. These include microscopic atomic processes cause gas glow; density, composition, temperature gas; radiation field central continuum source. Large-scale numerical codes...