Intergalactic Magnetic Field and Arrival Direction of Ultra-High-Energy Protons (2009)
Ryu, Dongsu, Das, Santabrata, Kang, Hyesung
We studied how the intergalactic magnetic field (IGMF) affects the propagation of super-GZK protons that originate from extragalactic sources within the local GZK sphere. Toward this end, we set up...
Studies of dissipative standing shock waves around black holes (2009)
Das, Santabrata, Chakrabarti, Sandip K., Mondal, Soumen
We investigate the dynamical structure of advective accretion flow around stationary as well as rotating black holes. For a suitable choice of input parameters, such as, accretion rate ($\dot {\cal...
Becker, Peter A., Das, Santabrata, Le, Truong
In this Letter, we present a new self-consistent theory for the production of the relativistic outflows observed from radio-loud black hole candidates and active galaxies as a result of particle...
Dynamical Structure of Viscous Accretion Disks with Shocks (2009)
Das, Santabrata, Becker, Peter A., Le, Truong
We develop and discuss global accretion solutions for viscous ADAF disks containing centrifugally supported isothermal shock waves. The fact that such shocks can exist at all in ADAF disks is a new...
Ryu, Dongsu, Kang, Hyesung, Das, Santabrata
Ultrahigh energy cosmic rays (UHECRs) are believed to originate from astrophysical sources, which should trace the large scale structure (LSS) of the universe. On the other hand, the magnetic field...
Dissipative accretion flows around a rotating black hole (2008)
Das, Santabrata, Chakrabarti, Sandip K.
We study the dynamical structure of a cooling dominated rotating accretion flow around a spinning black hole. We show that non-linear phenomena such as shock waves can be studied in terms of only...
Turbulence and Magnetic Fields in the Large Scale Structure of the Universe (2008)
Ryu, Dongsu, Kang, Hyesung, Cho, Jungyeon, Das, Santabrata
The nature and origin of turbulence and magnetic fields in the intergalactic space are important problems that are yet to be understood. We propose a scenario in which turbulent flow motions are...
Computation of mass loss from viscous accretion disc in presence of cooling (2008)
Das, Santabrata, Chattopadhyay, Indranil
Rotating accretion flow may undergo centrifugal pressure mediated shock transition even in presence of various dissipative processes, such as viscosity and cooling mechanism. The extra thermal...
Propagation of UHE Protons through Magnetized Cosmic Web (2008)
Das, Santabrata, Kang, Hyesung, Ryu, Dongsu, Cho, Jungyeon
If ultra-high-energy cosmic rays (UHECRs) originate from extragalactic sources, understanding the propagation of charged particles through the magnetized large scale structure (LSS) of the universe...
Properties of accretion shock waves in viscous flows with cooling effects (2007)
Das, Santabrata, Chakrabarti, Sandip K.
We study the properties of the shock waves for a viscous accretion flow having low angular momentum in presence of synchrotron cooling. We present all possible accretion solutions in terms of flow...
Parameter space study of magnetohydrodynamic flows around magnetized compact objects (2007)
Das, Santabrata, Chakrabarti, Sandip K.
We solve the magnetohydrodynamic (MHD) equations governing axisymmetric flows around neutron stars and black holes and found all possible solution topologies for adiabatic accretion. We divide the...
Propagation of UHE protons through a magnetized large scale structure (2007)
Kang, Hyesung, Das, Santabrata, Ryu, Dongsu, Cho, Jungyeon
The propagation of UHECRs is affected by the intergalactic magnetic fields that were produced during the course of the large scale structure formation of the universe. We adopt a novel model where...
Massloss from viscous advective disc (2006)
Chattopadhyay, Indranil, Das, Santabrata
Rotating transonic flows are long known to admit standing or oscillating shocks and that the excess thermal energy in the post shock flow drives a part of the infalling matter as bipolar outflows. We...
Behaviour of dissipative accretion flows around black holes (2006)
We investigate the behaviour of dissipative accreting matter close to a black hole as it provides the important observational features of galactic and extra-galactic black holes candidates. We find...
Properties of Accretion Shocks in Viscous Flows with Cooling Effects (2004)
Das, Santabrata, Chakrabarti, Sandip K.
Low angular momentum accretion flows can have standing and oscillating shock waves. We study the region of the parameter space in which multiple sonic points occur in viscous flows in presence of...
Properties of Accretion Shock Waves in Viscous Flows Around Black Holes (2004)
Chakrabarti, Sandip K., Das, Santabrata
Accretion flows having low angular momentum and low viscosity can have standing shock waves. These shocks arise due to the presence of multiple sonic points in the flow. We study the region of the...
Model Dependence of Transonic Properties of Accretion Flows Around Black Holes (2004)
Chakrabarti, S. K., Das, Santabrata
We analytically study how the behaviour of accretion flows changes when the flow model is varied. We study the transonic properties of the conical flow, a flow of constant height and a flow in...
Computation of outflow rates from accretion disks around black holes (2004)
Das, Santabrata, Chattopadhyay, Indranil, Nandi, A., Chakrabarti, Sandip K.
We self-consistently estimate the outflow rate from the accretion rates of an accretion disk around a black hole in which both the Keplerian and the sub-Keplerian matter flows simultaneously. While...
Radiatively driven electron-positron jets from two component accretion flows (2004)
Chattopadhyay, Indranil, Das, Santabrata, Chakrabarti, Sandip K.
Matter accreting onto black holes has long been known to have standing or oscillating shock waves. The post-shock matter puffs up in the form of a torus, which intercepts soft photons from the outer...
Standing Shocks around Black Holes: An Analytical Study (2001)
Das, Santabrata, Chattopadhyay, Indranil, Chakrabarti, Sandip K.
We compute locations of sonic points and standing shock waves in a thin, axisymmetric, adiabatic flow around a Schwarzschild black hole. We use completely analytical method to achieve our goal. Our...