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 the code, paying particular attention to changes in the atomic database and numerical methods that have affected predictions since the last publicly available version, C84. The computational methods and uncertainties are outlined together with the direction future development will take. The code is freely available and is widely used in the analysis and interpretation of emission‐line spectra. Web access to the Fortran source for CLOUDY, its documentation Hazy, and an independent electronic form of the atomic database is also described.

Cloudy: Numerical simulation of plasmas and their spectra

The launch of the Infrared Space Observatory and new atomic data have opened a window for the study of high-ionization gas in active galactic nuclei (AGNs). We present the results of a large number of photoionization simulations of the "coronal line" region in AGNs, employing new atomic data from the Opacity and Iron Projects. Our grid of line emission spans 8 orders of magnitude in gas density and 14 orders of magnitude in ionizing flux in an effort to identify the optimal conditions in which these lines form. We show that coronal lines form at distances from just outside the broad-line region to ~400L1/243.5 pc, in gas with ionization parameter -2.0 log U(H) 0.75, corresponding to gas densities of 102-108.5 cm-3, with electron temperatures ~12,000-150,000 K. A large range of distances from the central source implies significant line width variation among the coronal lines. We identify several line ratios that could be used to measure relative abundances, and we use these to show that the coronal line gas is likely to be dust free.

Physical Conditions of the Coronal Line Region in Seyfert Galaxies

Nowadays, the efficacies of 68Ga-based tracers are comparable to that of 18F-based agents and have stimulated researchers to investigate the potential of 68Ga-based positron emission tomography (PET) imaging agents. In this study, the human absorbed dose of 68Ga labeled with ethylenecysteamine cysteine 68Ga-ECC and 67Ga-ECC was estimated based on biodistribution data in mice by the medical internal radiation dose (MIRD) method. For biodistribution of 67Ga/68Ga-ECC, three mice were killed by CO2 asphyxiation at each selected times after injection (15, 30, 45, 60, 120 min for 68Ga-ECC and 0.5, 2 and 48 h for 67Ga-ECC), and then the tissue (heart, lung, brain, intestine, skin, stomach, kidneys, liver, muscle and bone) was removed. 68Ga-ECC as a new PET renal imaging agent was prepared with radiochemical purity of >97 % in less than 30 min. The biodistribution data for 68Ga-ECC showed that the most of the activity extracted from the urinary tract very fast. Comparison between human absorbed dose estimation for these two agents indicated that the absorbed dose of the most organs after injection of 67Ga-ECC is approximately tenfold higher than the amount after 68Ga-ECC injection. The results showed that 68Ga-ECC is a more appropriate agent rather than 67Ga-ECC and generally can be a good candidate for PET renal imaging applications.

Estimated human absorbed dose for 68 Ga-ECC based on mice data: comparison with 67 Ga-ECC

We present a Chandra ACIS observations of N157B, a young supernova remnant (SNR) located in the 30 Doradus star formation region of the Large Magellanic Cloud. This remnant contains the most energetic pulsar known (PSR J053747.39-691020.2; Ė = 4.8 × 1038 ergs s-1), which is surrounded by a X-ray-bright nonthermal nebula that likely represents a toroidal pulsar wind terminal shock observed edge-on. Two of the eight pointlike X-ray sources detected in the observation are shown to have near-IR and optical counterparts (within 05 offsets), which are identified as massive stellar systems in the Cloud. We confirm the nonthermal nature of the comet-shaped X-ray emission feature and show that the spectral steepening of this feature away from the pulsar is quantitatively consistent with synchrotron cooling of shocked pulsar wind particles flowing downstream at a bulk velocity close to the speed of light. Around the cometary nebula we unambiguously detect a spatially resolved thermal component, which accounts for about 1/3 of the total 0.5-10 keV flux from the remnant. This thermal component is distributed among various clumps of metal-enriched plasma embedded in the low surface brightness X-ray-emitting diffuse gas. The relative metal enrichment pattern suggests that the mass of the supernova progenitor is 20 M☉. A comparison of the X-ray data with Hubble Space Telescope optical images now suggests that the explosion site is close to a dense cloud, against which a reflection shock is launched. The interaction between the reflected material and the nebula has likely produced both its cometary shape and the surrounding thermal emission enhancement. SNR N157B is apparently expanding into the hot low-density interior of the surrounding superbubble formed by the young OB association LH 99, as revealed by Spitzer mid-infrared images. This scenario naturally explains the exceptionally large sizes of both the thermal and nonthermal components, as well as the lack of an outer shell of the SNR. However, the real situation in the region is likely to be more complicated. We find that a partially round soft X-ray-emitting clump with distinct spectral properties may result from a separate oxygen-rich remnant. These results provide a rare glimpse into the SNR structure and evolution in a region of recent star formation.

Chandra spectroscopy of N157B -- a young composite supernova remnant in a superbubble

Effective collision strengths for hyperfine structure transitions of possible astrophysical interest

Hyperfine structure lines of highly-charged ions may open a new window in observations of hot rarefied astrophysical plasmas. In this paper we discuss spectral lines of isotopes and ions abundant at temperatures 10 − 10 K, characteristic for warm-hot intergalactic medium, hot interstellar medium, starburst galaxies, their superwinds and young supernova remnants. Observations of these lines will allow to study bulk and turbulent motions of the observed target and will broaden the information about the gas ionization state, chemical and isotopic composition. The most prospective is the line of the major nitrogen isotope having wavelength λ = 5.65 mm (Sunyaev & Churazov, 1984). Wavelength of this line is well-suited for observation of objects at z ≈ 0.15− 0.6 when it is redshifted to 6.5− 9 mm spectral band widely-used in ground-based radio observations, and, for example, for z ≥ 1.3, when the line can be observed in 1.3 cm band and at lower frequencies. Modern and future radio telescopes and interferometers are able to observe the absorption by N VII in the warmhot intergalactic medium at redshifts above z ≈ 0.15 in spectra of brightest mm-band sources. Sub-millimeter emission lines of several most abundant isotopes having hyperfine splitting might also be detected in spectra of young supernova remnants. PACS: 32.10.Fn, 98.62.Ra, 98.38.-j, 98.58.-w, 32.30.Bv

https://edoc.ub.uni-muenchen.de/8730/1/Docenko_Dmitrijs.pdf

Spectroscopy of high-Z ions as a way to understanding the nature of Cas A knots and intergalactic shocks

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Spectroscopy of high-Z ions as a way to understanding the nature of Cas A knots and intergalactic shocks