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Manoj Ghosh

Publications and source records attributed to Manoj Ghosh.

2 recordsLinked to original sources

Mapping a Quasar Outflow from Parsec to Kiloparsec Scales: A Combined HST Absorption and VLT Emission Investigation

Linking nuclear winds to galactic-scale outflows remains a major observational challenge in understanding the multiscale physics of active galactic nuclei feedback. Here we present VLT/KMOS integral-field spectroscopy and SDSS observations of the $z = 0.9655$ quasar PKS J0352$-$0711. Our analysis reveals complex, multi-ionization emission, including a fast, unresolved nuclear wind and a spatially resolved galactic-scale outflow. We integrate the [O III] emission properties with those deduced from the mini-broad-absorption-line outflows detected in HST/COS observations of this quasar. This unique combination of datasets allows us to trace, for the first time, the physical progression of a quasar outflow from $\sim$ 10 pc to 10 kpc. The multiscale kinematics support a unified evolutionary scenario where the inner, constant-velocity ($\sim-3800 \textrm{ km s}^{-1}$) expansion of the wind is traced jointly in absorption ($\sim 9$ pc) and emission ($\gtrsim 40$ pc). As the wind propagates to $\sim$ 500 pc, the intermediate absorption system reveals a deceleration to $\sim-2100 \textrm{ km s}^{-1}$, consistent with mass-loading from the interstellar medium. Finally, our spatially resolved observations capture the gas breaking out of the inner galaxy, in the form of a wide-angle blueshifted outflow expanding beyond 8 kpc, with a velocity of $\sim -1000 \textrm{ km s}^{-1}$. Despite the three orders of magnitude variation in spatial scale, and a factor-of-four deceleration, the momentum fluxes remain consistent within uncertainties across all scales. These results suggest that the distinct outflow components represent the integrated history of a sustained feedback cycle from nuclear to galactic scales.

astro-ph.GA

Ambipolar diffusion velocity and magnetic field evolution in magnetar core: Generalised theoretical approach

The magnetic field associated with neutron stars is generally believed to be threaded inside the star. In the presence of a magnetic field, the plasma present in the interior of the star goes through several processes that lead to magnetic field evolution. It is thought that magnetar activities are mainly due to field decay. The most important process of field decay inside the core of the star is the ambipolar diffusion of the charged particles present in the interior plasma. The decay rate due to ambipolar diffusion is directly connected to the ambipolar velocity of the charged particles under the influence of the present magnetic field. The ambipolar velocity of the charged particles depends on the internal dynamics of the particles. We outline a general method to solve the particle dynamics in the presence of a magnetic field using a magnetohydrodynamic equation for ambipolar velocity. The equation is general and applies to all possible surrounding conditions \eg temperature, and matter states like normal or superfluid.

astro-ph.HE