Outflows in the disks of active galaxies

Abstract

Recent advances in observations have provided a wealth of measurements of the expansions of outflows in galactic disks out to large radii in a variety of galactic hosts. To provide an updated baseline for the interpretation of such data, and to assess to what extent the present status of the modeling is consistent with the existing observations, we provide a compact two-dimensional description for the expansion of active galactic nucleus (AGN)-driven shocks in realistic galactic disks with exponential gas density profiles in a disk geometry. We derive solutions for the outflow expansion and the mass outflow rates in different directions with respect to the plane of the disk. These are expressed in terms of the global properties of the host galaxy and of the central AGN to allow for an easy and direct comparison with existing observations in a variety of galactic hosts with measured properties, and out to distances of ~10 kpc from the center. The results are compared with a state-of-the-art compilation of observed outflows in 19 galaxies with different measured gas and dynamical mass, allowing for a detailed, one-by-one comparison with the model predictions. The agreement we obtain for a wide range of host galaxy gas mass (${10}^{9}\,{M}_{\odot }\lesssim {M}_{\mathrm{gas}}\lesssim {10}^{12}\,{M}_{\odot }$) and AGN bolometric luminosity (${10}^{43}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\lesssim {L}_{\mathrm{AGN}}\lesssim {10}^{47}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$) provides a quantitative systematic test for the modeling of AGN-driven outflows in galactic disks. We also consider a larger sample of 48 objects in galaxies with no reliable measurements of the gas and dynamical mass. In this case, we perform a comparison of the model predictions for different bins of AGN luminosities assuming different reference values for the gas mass and dynamical mass derived from average scaling relations. Finally, we reconsider the AGN wind scaling laws empirically derived by many authors in light of the results from our updated models. The encouraging, quantitative agreement of the model predictions with a wide set of existing observations constitutes a baseline for the interpretation of forthcoming data, and for a more detailed treatment of AGN feedback in galaxy formation models.

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