| Name: | MUHAMMED IRSHAD P |
| Affiliation: | International Centre for Theoretical Sciences |
| Conference ID : | ASI2024_541 |
| Title : | Fluctuation dynamo in a collapsing plasma |
| Authors : | Muhammed Irshad P, Pallavi Bhat |
| Authors Affiliation: | Muhammed Irshad P, Pallavi Bhat Affiliation (International Centre for Theoretical Sciences (ICTS), Bengaluru - 560 089, India) |
| Mode of Presentation: | Oral |
| Abstract Category : | High Energy Phenomena, Fundamental Physics and Astronomy |
| Abstract : | Magnetic fields in astrophysical objects can be explained by the conversion of turbulent kinetic energy into magnetic energy, a process known as a turbulent dynamo. When the dynamo generates magnetic fields on scales smaller than the correlation scale of the flow, it is called a fluctuation dynamo. During its kinematic stage, when the Lorentz force is negligible, magnetic fields grow exponentially over time. Subsequently, the field reaches saturation in the nonlinear stage.
Astrophysical plasmas undergo collapse in various contexts including galaxy formation and star formation. How does this collapse influence the growth of the magnetic field in the kinematic stage of the fluctuation dynamo? The collapsing background can be transformed into a comoving frame. On redefining the variables to account for the presence of the scale factor, we obtain the original induction equation. This transformation allows us to analytically calculate the effect of a collapsing background on the evolution of the magnetic fields.
We show a super-exponential growth of the magnetic field during the kinematic stage of fluctuation dynamo in a homologous collapse of plasma, a phenomenon that had not been previously identified. This growth in magnetic field is in addition to that due to flux freezing.
Further, we have performed simulations of MHD equations using the comoving variables within a periodic box to study the fluctuation dynamo in collapsing plasma. These simulations confirmed the presence of the super-exponential growth of the magnetic field, which can have implications for the galactic magnetic fields in our universe. |
