Dusty, Radiation Pressure Dominated Photoionization. II. Multi-Wavelength Emission Line Diagnostics for Narrow Line Regions

Seyfert narrow line region (NLR) emission line ratios are remarkably uniform, displaying only ~0.5 dex variation between galaxies, and even less within an individual object. Previous photoionization and shock models of this region were unable to explain this observation without the introduction of arbitrary assumptions or additional parameters. Dusty, radiation pressure dominated photoionization models provide a simple physical mechanism which can reproduce this spectral uniformity between different objects. In the first paper of this series we described this model and its implementation in detail, as well as presenting grids of model emission lines and examining the model structures. Here we explore these models further, demonstrating their ability to reproduce the observed Seyfert line ratios on standard line diagnostic diagrams in both the optical and UV. We also investigate the effects that the variation of metallicity, density and ionizing spectrum have upon both the new paradigm and the standard photoionization models used hitherto. Along with the standard diagnostic diagrams we provide several new diagnostic diagrams in the UV, Optical and IR. These new diagrams can provide further tests of the dusty, radiation pressure photoionization paradigm as well as being used as diagnostics of the metallicity, density and ionizing spectrum of the emission line clouds.Comment: Accepted by ApJS, full pdf including figures can be obtained at http://www.mso.anu.edu.au/~bgroves/Papers/ApJS2.pd

Are the Narrow Line Regions in Active Galaxies Dusty and Radiation Pressure Dominated?

The remarkable similarity between emission spectra of narrow line regions (NLR) in Seyfert Galaxies has long presented a mystery. In photoionization models, this similarity implies that the ionization parameter is nearly always the same, about U ~ 0.01. Here we present dusty, radiation-pressure dominated photoionization models that can provide natural physical insight into this problem. In these models, dust and the radiation pressure acting on it provide the controlling factor in moderating the density, excitation and surface brightness of photoionized NLR structures. Additionally, photoelectric heating by the dust is important in determining the temperature structure of the models. These models can also explain the coexistence of the low-, intermediate- and coronal ionization zones within a single self-consistent physical structure. The radiation pressure acting on dust may also be capable of driving the fast (~3000 km/s) outflows such as are seen in the HST observations of NGC 1068.Comment: 23 pages, 8 figures, Accepted by Ap

Photoionization models for extreme Lyα\alpha λ\lambda1216 and HeII λ\lambda1640 ratios in quasar halos, and PopIII vs AGN diagnostics

We explore mechanisms to produce extremely high Ly-alpha/HeII flux ratios, or to enhance the observed number of Ly-alpha photons per incident ionizing photon, in extended AGN-photoionized nebulae at high-redshift. Using photoionization models, we explore the impact of ionization parameter, gas metallicity, ionizing spectrum, electron energy distribution, and cloud viewing angle on the relative fluxes of Ly-alpha, HeII and other lines, and on the observed number of Ly-alpha photons per incident ionizing photon. We find that low ionization parameter, a relatively soft or filtered ionizing spectrum, low gas metallicity, kappa-distributed electron energies, or reflection of Ly-alpha photons by HI can all result in significantly enhanced Ly-alpha relative to other lines (>10%), with log Ly-alpha/HeII reaching values up to 4.6. In the cases of low gas metallicity, reflection by HI, or a hard or filtered ionizing spectrum, the observed number of Ly-alpha photons per incident ionizing photon is itself significantly enhanced above the nominal Case B value of 0.66 due to collisional excitation, reaching values up to 5.3 in our 'extreme case' model. At low gas metallicity (e.g. 0.1 x Solar), the production of Ly-alpha is predominantly via collisional excitation rather than recombination. In addition, we find that collisional excitation of Ly-alpha becomes more efficient if the ionizing continuum is pre-filtered through an optically thin screen of gas closer to the AGN. We also show that Ly-alpha / HeII ratios of the z~3.5 quasars studied by Borisova et al. (2016) are consistent with AGN-photoionization of gas with moderate to low metallicity and/or low ionization parameter, without requiring exotic ionization/excitation mechanisms such as strong line-transfer effects. We also present UV-optical diagnostic diagrams to distinguish between photoionization by Pop III stars and AGN photoionization.Comment: Accepted for publication in A&A. 14 pages, 9 figures. Abstract slightly shortened to meet arxiv character limi

The AGN-starburst connection, Galactic superwinds, and M_BH - sigma

Recent observations of young galaxies at redshifts z ~ 3 have revealed simultaneous AGN and starburst activity, as well as galaxy-wide superwinds. I show that there is probably a close connection between these phenomena by extending an earlier treatment of the M_BH - sigma relation (King, 2003). As the black hole grows, an outflow drives a shell into the surrounding gas. This stalls after a dynamical time at a size determined by the hole's current mass and thereafter grows on the Salpeter timescale. The gas trapped inside this bubble cools and forms stars and is recycled as accretion and outflow. The consequent high metallicity agrees with that commonly observed in AGN accretion. Once the hole reaches a critical mass this region attains a size such that the gas can no longer cool efficiently. The resulting energy-driven flow expels the remaining gas as a superwind, fixing both the M_BH - sigma relation and the total stellar bulge mass at values in good agreement with observation. Black hole growth thus produces starbursts and ultimately a superwind.Comment: ApJ, in press, 4 page

Urinary Stone Proteins: An Update

The discovery of an organic component in kidney stones dates back to 1684. More than 150 years elapsed before the incrustation of this organic component, which is now called the matrix, was proposed as the mechanism of stone formation. The composition of the matrix remained largely unknown until the development of electron microscopy and the advances in biochemistry combined in the 1950\u27s to usher in the modern era of renal stone matrix investigation. Composed mainly of selectively incorporated proteins generally characterized by high glutamic and aspartic acid content and the frequent occurrence of y-carboxyglutamic acid, the matrix dis-plays a variable and complex composition and shares a few proteins in many stones. The embryonic stone may . first appear in the renal tubules where it can acquire the blood and cell membrane proteins recently found by analysis of stone protein extracts. The combination of supersaturation, an appropriate environment, the avail-ability of calcium binding proteins which may be abnormal, and the incorporation of proteins extracted from leukocytes and cell wall membranes may induce stone formation

A vestige low metallicity gas shell surrounding the radio galaxy 0943-242 at z=2.92

Observations are presented showing the doublet CIV 1550 absorption lines superimposed on the CIV emission in the radio galaxy 0943-242. Within the errors, the redshift of the absorption system that has a column density of N_CIV = 10^{14.5 +- 0.1} cm-2 coincides with that of the deep Ly-alpha absorption trough observed by Rottgering et al. (1995). The gas seen in absorption has a resolved spatial extent of at least 13 kpc (the size of the extended emission line region). We first model the absorption and emission gas as co-spatial components with the same metallicity and degree of excitation. Using the information provided by the emission and absorption line ratios of CIV and Ly-alpha, we find that the observed quantities are incompatible with photoionization or collisional ionization of cloudlets with uniform properties. We therefore reject the possibility that the absorption and emission phases are co-spatial and favour the explanation that the absorption gas has low metallicity and is located further away from the host galaxy (than the emission line gas). The estimated low metallicity for the absorption gas in 0943-242 (Z \~ 1% solar) and its proposed location -outer halo outside the radio cocoon- suggest that its existence preceeds the observed AGN phase and is a vestige of the initial starburst at the onset of formation of the parent galaxy.Comment: 11 pages,5 figures, A&A accepte