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arXiv · 1007.0900

Indicators of Intrinsic AGN Luminosity: a Multi-Wavelength Approach

Stephanie M. LaMassa·Timothy M. Heckman·Andrew Ptak·Lucimara Martins·Vivienne Wild·Paule Sonnentrucker·Christy Tremonti
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Abstract

We consider five indicators for intrinsic AGN luminosity: the luminosities of the [OIII]$λ$5007 line, the [OIV]25.89$μ$m line, the mid-infrared (MIR) continuum emission by the torus, and the radio and hard X-ray (E $>$ 10keV) continuum emission. We compare these different proxies using two complete samples of low-redshift type 2 AGN selected in a homogeneous way based on different indicators: an optically selected [OIII] sample and a mid-infrared selected 12$μ$m sample. We examine the correlations between all five different proxies, and find better agreement for the [OIV], MIR, and [OIII] luminosities than for the hard X-ray and radio luminosities. Next, we compare the ratios of the fluxes of the different proxies to their values in unobscured Type 1 AGN. The agreement is best for the ratio of the [OIV] and MIR fluxes, while the ratios of the hard X-ray to [OIII], [OIV], and MIR fluxes are systematically low by about an order-of-magnitude in the Type 2 AGN, indicating that hard X-ray selected samples do not represent the full Type 2 AGN population. In a similar spirit, we compare different optical and MIR diagnostics of the relative energetic contributions of AGN and star formation processes in our samples of Type 2 AGN. We find good agreement between the various diagnostic parameters, such as the equivalent width of the MIR polycyclic aromatic hydrocarbon features, the ratio of the MIR [OIV]/[NeII] emission-lines, the spectral index of the MIR continuum, and the commonly used optical emission-line ratios. Finally, we test whether the presence of cold gas associated with star-formation leads to an enhanced conversion efficiency of AGN ionizing radiation into [OIII] or [OIV] emission. We find that no compelling evidence exists for this scenario for the luminosities represented in this sample (L$_{bol}$ $\approx$ 10$^{9}$ - 8 $\times$ 10$^{11}$ L$_{\sun}$). (abridged)

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Stephanie M. LaMassa, Timothy M. Heckman, Andrew Ptak, Lucimara Martins, Vivienne Wild, Paule Sonnentrucker, Christy Tremonti. 2010-07-06. Indicators of Intrinsic AGN Luminosity: a Multi-Wavelength Approach. https://doi.org/10.1088/0004-637x%2F720%2F1%2F786

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