arXiv subjects

Camelia Jana

Publications and source records attributed to Camelia Jana.

4 recordsLinked to original sources

arXiv2026

Influence of winds on shocked magnetized viscous accretion flows around rotating black holes

We study global transonic solution for a relativistic, magnetized, viscous advective accretion flow around a rotating black hole, incorporating the effects of mass and angular momentum loss through winds. Our model considers dominant toroidal magnetic fields with synchrotron radiation as the primary cooling mechanism. To self-consistently model mass loss, the mass accretion rate is prescribed to decrease inward as a power-law with disk radius. With this, we solve the governing equations that describe the accretion flows in presence of winds and obtain the flow structure in terms of the inflow parameters (energy $\mathcal{E}$, angular momentum $λ$, plasma-$β$, accretion rate $\dot{m}$, and viscosity $α_{\rm B}$), the wind parameters ($p$, governing mass loss; and $l$, governing angular momentum transport by winds), and the black hole spin ($a_{\rm k}$). Our analysis reveals that winds substantially modify the accretion flow leading to a significant decrease in disk luminosity. We specifically identify global solutions that admit standing shocks and find that winds profoundly alter shock properties, such as the shock radius ($x_{\rm s}$), compression ratio ($R$), and shock strength ($S$). Furthermore, we determine the critical wind parameter $p^{\rm crit}$ beyond which steady shock solutions cease to exist. We demonstrate that increased viscosity and strong angular momentum extraction by winds lead to reduce $p^{\rm crit}$. These findings evidently highlight a complex interplay between viscosity and winds in governing the dynamics of shock formation in accretion disks.

astro-ph.HE↗

arXiv2025

Study of mass outflows from magnetized accretion disks around rotating black holes with thermal conduction

We examine mass outflows from a low-angular momentum, viscous, advective, and magnetized accretion disk around a rotating black hole in presence of thermal conduction. We consider the disk is primarily threaded by the toroidal component of the magnetic field and an effective potential satisfactorily mimicked the spacetime geometry around the rotating black hole. With this, we self-consistently solve the coupled governing equations for inflow and outflow and compute the mass outflow rate $R_{\dot m}$ (ratio of mass flux of inflow to outflow) in terms of the inflow parameters, namely energy ($\mathcal{E}$), angular momentum ($λ$), plasma-$β$ and conduction parameter ($Υ_{\rm s}$) around weakly rotating ($a_{\rm k} \rightarrow 0$) as well as rapidly rotating ($a_{\rm k} =0.99$) black holes. Our findings reveal that the present formalism admits coupled inflow-outflow solutions across a wide range of inflow parameters yielding substantial mass loss. We observe that $R_{\dot m}$ monotonically increases with $Υ_{\rm s}$, irrespective of black hole spin. We also find that for a fixed $Υ_{\rm s}$, when energy, angular momentum, and magnetic field strength of the inflowing matter is increased, $R_{\dot{\rm m}}$ is enhanced resulting the outflows even more pronounced. We further estimate the maximum outflow rate ($R^{\rm max}_{\dot{\rm m}}$) by varying the inflow parameters and find that thermal conduction leads to maximum mass outflow rate $R^{\rm max}_{\dot{\rm m}} \sim 25\%$ for rapidly rotating black hole of spin $a_{\rm k} = 0.99$. Finally, we employ our formalism to explain the kinetic jet power of $68$ radio-loud low-luminosity active galactic nuclei (LLAGNs), indicating that it is potentially promising to account for the observed jet power of substantial number of LLAGNs.

astro-ph.HE↗

arXiv2025

Effect of thermal conduction on accretion shocks in relativistic magnetized flows around rotating black holes

We examine the effects of thermal conduction on relativistic, magnetized, viscous, advective accretion flows around rotating black holes considering bremsstrahlung and synchrotron cooling processes. Assuming the toroidal component of magnetic fields as the dominant one, we self-consistently solve the steady-state fluid equations to derive the global transonic accretion solutions for a black hole of spin $a_{\rm k}$. Depending on the model parameters, the magnetized accretion flow undergoes shock transitions and shock-induced global accretion solutions persist over a wide range of model parameters including the conduction parameter ($Υ_{\rm s}$), plasma-$β$, and viscosity parameter ($α_{\rm B}$). We find that the shock properties -- such as shock radius ($r_{\rm s}$), compression ratio ($R$), and shock strength ($S$) -- are regulated by $Υ_{\rm s}$, plasma $β$, and $α_{\rm B}$. Furthermore, we compute the critical conduction parameter ($Υ_{\rm s}^{\rm cri}$), a threshold beyond which shock formation ceases to exist, and investigate its dependence on plasma-$β$ and $α_{\rm B}$ for both weakly rotating ($a_{\rm k} \rightarrow 0$) and rapidly rotating ($a_{\rm k} \rightarrow 1$) black holes. Finally, we examine the spectral energy distribution (SED) of the accretion disc and observe that increased thermal conduction and magnetic field strength lead to more luminous emission spectra from black hole sources.

astro-ph.HE↗

arXiv2024

Study of mass outflow rates from magnetized advective accretion disk around rotating black holes

We develop and discuss a model formalism to study the properties of mass outflows that are emerged out from a relativistic, magnetized, viscous, advective accretion flow around a rotating black hole. In doing so, we consider the toroidal component as the dominant magnetic fields and synchrotron process is the dominant cooling mechanism inside the accretion disk. With this, we self-consistently solve the coupled accretion-ejection governing equations in the steady state and obtain the shock-induced global inflow-outflow solutions in terms of the inflow parameters, namely plasma-$β$ ($=p_{\rm gas}/p_{\rm mag}$, $p_{\rm gas}$ and $p_{\rm mag}$ being gas and magnetic pressures), accretion rates ($\dot m$) and viscosity ($α_{\rm B}$), respectively. Using these solutions, we compute the mass outflow rate ($R_{\dot m}$, the ratio of outflow to inflow mass flux) and find that mass loss from the magnetized accretion disk continues to take place for wide range of inflow parameters and black hole spin ($a_{\rm k}$). We also observe that $R_{\dot m}$ strongly depends on plasma-$β$, $\dot m$, $α_{\rm B}$ and $a_{\rm k}$, and it increases as the magnetic activity inside the accretion disk is increased. Further, we compute the maximum mass outflow rate ($R^{\rm max}_{\dot m}$) by freely varying the inflow parameters and find that for magnetic pressure dominated disk, $R^{\rm max}_{\dot m} \sim 24\%$ ($\sim 30\%$) for $a_{\rm k}=0.0$ ($0.99$). Finally, while discussing the implication of our model formalism, we compute the maximum jet kinetic power using $R^{\rm max}_{\dot m}$ which appears to be in close agreement with the observed jet kinetic power of several black hole sources.

astro-ph.HE↗