A Hydrodynamical Thermal Irradiated Wind from the Outer Thin Accretion Disk in Low-luminosity Active Galactic Nuclei

Evidently, low-luminosity active galactic nuclei (LLAGNs) are comprised of an inner advective disk and an outer geometrically thin disk. Wind is inevitable in LLAGNs, mainly interpreted in an indirect way; also, the evidence is growing for the presence of wind in the outer thin disk. We present a hydrodynamics (HD) model for wind from the outer thin disk, where the main driver is the inner disk irradiation (which is parameterized by a number x in hydrostatic equilibrium equation) and the heating mechanism is photoionization. The model works for low-intensity irradiation or from a height zs in the optically thin medium. We solve the model equations in cylindrical coordinates along the z-axis for a given radius r assuming a tiny vertical speed vz (<< cs sound speed). The sonic point conditions assure an isobaric regime above the sonic height ( zmax ); in addition to the height zf(<< zmax ), the radial pressure gradient also supports the fluid rotation, and both jointly assure a wind ejection from the zmax with fluid speed. The zmax increases with x, and beyond a large zmax (say ztmax corresponding to maximum x), there is no physical solution. We start the computation from the outer radius rothin to the inner rinthin with a Bondi mass accretion rate MBondi to explore the r dependency of the mass inflow rate M and wind properties. We constrain the model by fixing M at rinthin from the observations of NGC 1097 and check the feasibility of the model by comparing the energetics with the observed bolometric luminosity. The wind is equatorial with a viewing angle i > 85 degrees and capable of generating red/blueshifted lines, which would be a general characteristics for LLAGNs.