Publication Date:
2016-12-16
Description:
In order to reveal the origin of the ultrafast outflows (UFOs) that are frequently observed in active galactic nuclei (AGNs), we perform two-dimensional radiation hydrodynamics simulations of the line-driven disc winds, which are accelerated by the radiation force due to the spectral lines. The line-driven winds are successfully launched for the range of M BH = 10 6–9 M and = 0.1–0.5, and the resulting mass outflow rate ( $\dot{M_{\rm w}}$ ), momentum flux ( $\dot{p_{\rm w}}$ ), and kinetic luminosity ( $\dot{E_{\rm w}}$ ) are in the region containing 90 per cent of the posterior probability distribution in the $\dot{M}_{\rm w}$ – L bol plane, $\dot{p}_{\rm w}$ – L bol plane, and $\dot{E}_{\rm w}$ – L bol plane shown in Gofford et al., where M BH is the black hole mass, is the Eddington ratio, and L bol is the bolometric luminosity. The best-fitting relations in Gofford et al., ${\rm d}\log \dot{M_{\rm w}}/{\rm d}\log {L_{\rm bol}}\sim 0.9$ , ${\rm d}\log \dot{p_{\rm w}}/{\rm d}\log {L_{\rm bol}}\sim 1.2$ , and ${\rm d}\log \dot{E_{\rm w}}/{\rm d}\log {L_{\rm bol}}\sim 1.5$ , are roughly consistent with our results, ${\rm d}\log \dot{M_{\rm w}}/{\rm d}\log {L_{\rm bol}}\sim 9/8$ , ${\rm d}\log \dot{p_{\rm w}}/{\rm d}\log {L_{\rm bol}}\sim 10/8$ , and ${\rm d}\log \dot{E_{\rm w}}/{\rm d}\log {L_{\rm bol}}\sim 11/8$ . In addition, our model predicts that no UFO features are detected for the AGNs with 0.01, since the winds do not appear. Also, only AGNs with M BH 10 8 M exhibit the UFOs when ~ 0.025. These predictions nicely agree with the X-ray observations. These results support that the line-driven disc wind is the origin of the UFOs.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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