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Ionized outflows in luminous type 2 AGNs at z < 0.6: no evidence for significant impact on the host galaxies

M. Villar-Martín, S. Arribas, B. Emonts, A. Humphrey, C. N. Tadhunter, P. S. Bessiere, A. Cabrera Lavers, C. Ramos Almeida

Abstract
We investigate the presence of extended ionized outflows in 18 luminous type 2 AGNs (11 quasars and 7 high-luminosity Seyfert 2s) at 0.3 < z < 0.6 based on VLT-FORS2 spectroscopy. We infer typical lower limits on the radial sizes of the outflows Ro ≳ several × 100 pc and upper limits Ro ≲ 1-2 kpc. Our results are inconsistent with related studies which suggest that large scale (Ro ~ several-15 kpc) are ubiquitous in QSO2. We study the possible causes of discrepancy and propose that seeing smearing is the cause of the large inferred sizes. The implications in our understanding of the feedback phenomenon are important since the mass Mo (through the density), mass injection dot{M}_o and energy injection Ėo rates of the outflows become highly uncertain. One conclusion seems unavoidable: Mo, skew3dot{M}_o and Ėo are modest or low compared with previous estimations. We obtain typically Mo ≲ (0.4-22) × 106 M (median 1.1 × 106 M) assuming n = 1000 cm-3. These are ~102-104 times lower than values reported in the literature. Even under the most favourable assumptions, we obtain dot{M}_o ≲ 10 M yr-1 in general, 100-1000 times lower than claimed in related studies. Although the uncertainties are large, it is probable that these are lower than typical star-forming rates. In conclusion, no evidence is found supporting that typical outflows can affect the interstellar medium of the host galaxies across spatial scales ≳ 1-2 kpc.

Keywords
galaxies: active, galaxies: evolution, quasars: emission lines, quasars: general

Monthly Notices of the Royal Astronomical Society
Volume 460, Issue 1, Page 130
2016 July

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia