Structure of a hot accretion flow in the presence of outflow and convection with large ordered magnetic field

Hydrodynamics and magnetohydrodynamic simulations of hot accretion flow have indicated that there is an inward decreasing of mass accretion rate with decreasing radius. Consequently, we have a flatter density profile ($\rho \propto r^{-p}$ with $p\propto 1.5-s$ in the case of $\dot{M}\propto r^{s}$, $0 \leq s<1$) compared to the case of a constant accretion rate (($\rho \propto r^{-\frac{3}{2}}$). In order to describe this behavior two models have been proposed: inflow-outflow solution and convection-dominated accretion flows. We have studied the properties of a hot accretion flow in the presence of convection, large scale magnetic field and outflow. We consider an axisymmetric viscous flow in the steady state. We used the self-similar solutions to solve the 1.5 dimensional inflow-outflow equations. We have assumed that the convection as a free parameter in our model for simplicity. We have considered two components of magnetic field (toroidal and vertical) in this paper. We have shown that the strong convection makes the inflow accretes and rotates slower while it becomes hotter and thicker. We have found that the thickness of the disc deviates from non-convective solutions obviously. We have represented that two components of magnetic field have the opposite effects on the thickness of the disc and similar effects on the radial and angular velocities of the flow.Comment: 7 pages, 4 Figures, Accepted for publication in MNRAS. arXiv admin note: text overlap with arXiv:1705.0835

Self-similar structure of a hot magnetized flow with thermal conduction

We have explored the structure of hot magnetized accretion flow with thermal conduction. The importance of thermal conduction in hot accretion flows has been confirmed by observations of the hot gas surrounding Sgr $A^*$ and a few other nearby galactic nuclei. For a steady state structure of such accretion flows a set of self similar solutions are presented. In this paper, we have actually tried to re-check the solution presented by Abbassi et al. (2008) using a physical constrain. In this study we find that Eq 29 places a new constrain that limits answers presented by Abbassi et al. 2008. In that paper the parameter space in which it is established in the new constrain was plotted. However, the new requirement makes up only a small parameter space with physically acceptable solutions. And now in this manuscript we have followed the idea with more effort, and tried to find out how thermal conduction influences the structur of the disks in a physical parameter space. We have found out that the existence of thermal conduction will lead to reduction of accretion and radial and azimuthal velocities as well as the vertical thickness of the disk, which is slightly reduced. Moreover, the surface density of the disk will increase when the thermal conduction becomes important in the hot magnetized flow.Comment: Accepted for publication, AP

Assessment of Salt Tolerance in Pepper Using Chlorophyll Fluorescence and Mineral Compositions

In this study, leaf chlorophyll fluorescence and mineral compositions was used to compare pepper (Capsicum annuum L.) cultivars response to salt stress. Twentysix pepper cultivars were exposed to salt stress (100 mM NaCl) during two weeks. Thereafter, chlorophyll fluorescence components, stress tolerance index (STI), sodium, potassium and calcium content were measured. The results showed that a significant difference has been found among pepper cultivars for all studied characteristics. Reduced chlorophyll fluorescence parameters under salinity treatment were different between pepper cultivars. Fo/Fm, Fv/Fm was declined, with NaCl treatment in all cultivars. Fv/Fo, Fv/Fm, Φexc, ΦPSII, ETR, qp, K+, K+/Na+ and Ca++/Na+ were decreased but leaf Na+ content was increased by salinity stress. A significant correlation was found between salt stress tolerance index and fluorescence characteristics such as Fo/Fm, Fv/Fo, Fv/Fm, Fv/Fm diminishing, Φexc, ΦPSII, ETR, and qp. Furthermore, there was a significant correlation between Na+, K+, K+/ Na+ and Ca++/Na+ with salt stress tolerance index. Overall, chlorophyll fluorescence parameters followed by Na+, K+, K+/Na+ and Ca++/Na+ could be useful tool to screen salt tolerance pepper cultivars