We present a new library of fully-radiative shock models calculated with the MAPPINGS III shock and photoionization code. The library consists of grids of models with shock velocities in the range v=100-1000 km/s and magnetic parameters B/sqrt(n) of 10^-4 - 10 muG cm^(3/2) for five different atomic abundance sets, and for a pre-shock density of 1.0 cm^(-3). Additionally, Solar abundance model grids have been calculated for densities of 0.01, 0.1, 10, 100, and 1000 cm^(-3) with the same range in v and B/sqrt(n). Each model includes components of both the radiative shock and its photoionized precursor, ionized by the EUV and soft X-ray radiation generated in the radiative gas. We present the details of the ionization structure, the column densities, and the luminosities of the shock and its precursor. Emission line ratio predictions are separately given for the shock and its precursor as well as for the composite shock+precursor structure to facilitate comparison with observations in cases where the shock and its precursor are not resolved. Emission line ratio grids for shock and shock+precursor are presented on standard line ratio diagnostic diagrams, and we compare these grids to observations of radio galaxies and a sample of AGN and star forming galaxies from the Sloan Digital Sky Survey. This library is available online, along with a suite of tools to enable the analysis of the shocks and the easy creation of emission line ratio diagnostic diagrams. These models represent a significant increase in parameter space coverage over previously available models, and therefore provide a unique tool in the diagnosis of emission by shocks.Comment: 39 pages, 34 figures, accepted for publication in ApJS, April 200

We use the chemical evolution predictions of cosmological hydrodynamic simulations with our latest theoretical stellar population synthesis, photoionization and shock models to predict the strong line evolution of ensembles of galaxies from z = 3 to the present day. In this paper, we focus on the brightest optical emission-line ratios, [N II]/Hα and [O III]/Hβ. We use the optical diagnostic Baldwin-Phillips-Terlevich (BPT) diagram as a tool for investigating the spectral properties of ensembles of active galaxies. We use four redshift windows chosen to exploit new near-infrared multi-object spectrographs. We predict how the BPT diagram will appear in these four redshift windows given different sets of assumptions. We show that the position of star-forming galaxies on the BPT diagram traces the ISM conditions and radiation field in galaxies at a given redshift. Galaxies containing AGN form a mixing sequence with purely star-forming galaxies. This mixing sequence may change dramatically with cosmic time, due to the metallicity sensitivity of the optical emission-lines. Furthermore, the position of the mixing sequence may probe metallicity gradients in galaxies as a function of redshift, depending on the size of the AGN narrow line region. We apply our latest slow shock models for gas shocked by galactic-scale winds. We show that at high redshift, galactic wind shocks are clearly separated from AGN in line ratio space. Instead, shocks from galactic winds mimic high metallicity starburst galaxies. We discuss our models in the context of future large near-infrared spectroscopic surveys.

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Abstract. We present radio observations for 29 southern Seyfert galaxies selected from a volume limited sample with cz < 3600 km s −1 , and declination δ < 0 • . Objects with declination −30• < δ < 0 • were observed with the Very Large Array (VLA) at 6 cm (4.9 GHz) and objects with δ < −30• were observed with the Australia Telescope Compact Array (ATCA) at 3.5 cm (8.6 GHz). Both the VLA and the ATCA observations have a resolution of ∼ 1 . These new observations cover more than 50% of the southern sample with all but two of the 29 objects detected above our limit of 0.15 mJy. Combining these data with data available from the literature gives almost 85% coverage of the southern sample and further expands the radio observations of a distance limited sample by 22%.Collecting additional sources from the literature, consisting of known Seyferts with cz < 4600 km s −1 , we find that 38% of the sources are unresolved at arcsecond resolution, and 34% have linear radio structure. Our results expand upon and are consistent with earlier studies. We confirm a correlation between the size of the radio structure and the radio luminosity. A comparison between Seyfert types 1 and 2 finds that type 2s tend to have a larger linear size. There is no statistically significant difference in radio power between types 1 and 2, although all the most powerful objects appear to be Seyfert 2's. No significant difference has been found in the spectral indices.

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 shock and photoionization modes of excitation, and to some extent, also discriminate shocks with ionized precursors from photoionization. These diagrams use relatively bright emission lines and reddening insensitive ratios and provide a practical observational test for separating the excitation mechanisms of the narrow line regions of active galaxies. The most useful diagrams are those involving the various ionization stages of Carbon, ([O III] λ5007/Hβ) vs. (C IV λ1549/He II λ1640) and the purely UV ratio pair (C II] λ2326/C III] λ1909) vs. (C IV λ1549/C III] λ1909). Temperature sensitive FUV lines C III λ977 and N III λ991 also provide good discriminants. The models are compared to observations of nearby AGN, and also to high redshift objects where the UV lines are shifted into the optical.

This paper presents long-slit spectral maps of the bicone-shaped extended narrow-line region (ENLR) in the Seyfert galaxy NGC 2992. We investigate the physical properties of the ENLR via emission-line diagnostics and compare the observations to shock and photoionization models for the excitation mechanism of the gas. The line ratios vary as a function of position in the ENLR, and the loci of the observed points on line ratio diagrams are shown to be most consistent with shock ] precursor model grids. We consider the energetics of a nuclear ionizing source for the ENLR and perform the q-test in which the rate of ionizing photons from the nucleus is inferred from measurements of the density and ionization parameter. The q-test is shown to be invalid in the case of NGC 2992 because of the limitations of the [S II] j6717/j6731 density diagnostic. The excitation of the gas is shown to be broadly consistent with the kinematics, with higher [N II] j6583/Ha present in the more dynamically active region. We also show that the pressure associated with the X-rayÈemitting plasma may provide a large fraction of the pressure required to power the ENLR via shocks.

We report results from XMM-Newton observations of thirteen X-ray bright BL Lacertae objects, selected from the Einstein Slew Survey sample. The survey was designed to look for evidence of departures of the X-ray spectra from a simple power law shape (i.e., curvature and/or line features), and to find objects worthy of deeper study. Our data are generally well fit by power-law models, with three cases having hard (Γ < 2; dN/dE ∝ E −Γ) spectra that indicate synchrotron peaks at E > ∼ 5 keV. Previous data had suggested a presence of absorption features in the X-ray spectra of some BL Lacs. In contrast, none of these spectra show convincing examples of line features, either in absorption or emission, suggesting that such features are rare amongst BL Lacs, or, more likely, artifacts caused by instrumental effects. We find significant evidence for intrinsic curvature (steepening by dΓ/d(logE) = 0.4 ± 0.15) in fourteen of the seventeen X-ray spectra. This cannot be explained satisfactorily via excess absorption, since the curvature is essentially constant from 0.5 − 6 keV, an observation which is inconsistent with the modest amounts of absorption that would be required. We use the XMM-Newton Optical Monitor data with concurrent radio monitoring to derive broadband spectral energy distributions and peak frequency estimates. From these we examine models of synchrotron emission and model the spectral curvature we see as the result of episodic particle acceleration.