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Browsing by Author "Gangadhara, R. T"

Browsing by Author "Gangadhara, R. T"

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  • Dynamical phenomena in sunspots. I. Time dependent relaxation to equilibrium 
    Gangadhara, R. T; Hasan, S. S (European Southern Observatory, 1997-11)
    We have adapted a general purpose time-dependent 2-D code to study dynamical phenomena in sunspots. In the first part of our investigation, we numerically simulate the dynamical relaxation to equilibrium of a sunspot. ...
  • Dynamics of charged particles in the radio emission region of pulsar magnetosphere 
    Thomas, R. M. C; Gangadhara, R. T (EDP Sciences, 2007-06)
    We consider the classical picture of three dimensional motion of charged particles in pulsar magnetosphere. We adopt a perturbative method to solve the equation of motion, and find the trajectory of particles as they move ...
  • Emission Altitude from Relativistic Phase Shift Due to Plasma Corotation in Pulsars 
    Gangadhara, R. T (The Royal Swedish Academy of Sciences, 2006)
    The radio emission from a relativistic plasma in a pulsar magnetosphere experiences a relativistic phase shift due to spin and difference in the emission altitude. Using the single pulse data of PSR B0329 + 54 at 325 MHz ...
  • Faraday rotation versus stimulated Raman scattering in intense sources 
    Gangadhara, R. T; Krishan, V (Astronomical Society of India, 1993)
    A coherent plasma process such as the stimulated Raman scattering plays significant role in bringing about the changes in polarization characteristics of radiation. It is found that some of the observed polarization ...
  • Generation of Magnetic Structures on the Solar Photosphere 
    Gangadhara, R. T; Krishan, V; Bhowmick, A. K; Chitre, S. M (IOP Publishing, 2014-06-20)
    The lower solar atmosphere is a partially ionized plasma consisting of electrons, ions, and neutral atoms. In this, which is essentially a three-fluid system, the Hall effect arises from the treatment of the electrons and ...
  • Influence of rotation on pulsar emission 
    Thomas, R. M. C; Gangadhara, R. T (Anita Publications, 2004-12)
    We analyze the motion of charged particles in rotating pulsar magnetosphere using the equation of motion, which was proposed earlier. We consider the projected magnetic field lines onto a 2D plane perpendicular to the ...
  • Influence of Rotation on Pulsar Radiation Characteristics 
    Ahmadi, P; Gangadhara, R. T (The American Astronomical Society, 2002-02)
    We present a relativistic model for pulsar radio emission by including the effect of rotation on coherent curvature radiation by bunches. We find that rotation broadens the width of the leading component compared to the ...
  • Influence of the polar cap current on pulsar polarization 
    Dinesh Kumar; Gangadhara, R. T (IOP Publishing, 2012-07-20)
    We have developed a model for the polarization of curvature radiation by taking into account the polar-cap-currentinduced perturbation on the dipolar magnetic field. We present the effects of the polar cap current on the ...
  • Mean-field dynamo in partially ionized plasmas – I 
    Krishan, V; Gangadhara, R. T (Blackwell Publishing, 2008-04)
    There are several astrophysical situations where one needs to study the dynamics of magnetic flux in partially ionized turbulent plasmas. In a partially ionized plasma, the magnetic induction is subjected to the ambipolar ...
  • Millisecond pulsar emission altitude from relativistic phase shift: PSR J0437-4715 
    Gangadhara, R. T; Thomas, R. M. C (Springer Netherlands, 2008)
    We have analyzed the profile of the millisecond pulsar PSR J0437-4715 at 1440 MHz by fitting the Gaussians to pulse components, and identified its 11 emission components. We propose that they form a emission beam with 5 ...
  • A Model for Simulating Realistic Profiles of Pulsars 
    Thomas, R. M. C; Gupta, Y; Gangadhara, R. T (American Institute of Physics, 2011-08)
    We devise an accurate method to compute the emission profile corresponding to a given set of pulsar emission parameters, for eg. inclination angle alpha, impact angle beta, frequency of emission omega, Lorentz factor gamma, ...
  • Modeling of polarization of radio pulsars 
    Gangadhara, R. T (Astronomical Society of the Pacific, 2009-09)
    We have generalized the coherent curvature radiation model to include the detailed geometry of the emission region in pulsar magnetosphere, and deduced the polarization state in terms the Stokes parameters. By considering ...
  • Modelling sunspot equilibrium through a solution of the time dependent MHD equations 
    Gangadhara, R. T; Hasan, S. S (Astronomical Society of India, 1996)
    We numerically simulate the dynamical relaxation to equilibrium of a sunspot. Treating the sunspot as a thick axisymmetric flux tube in cylindrical geometry, we solve the time dependent MHD equation to examine the evolution ...
  • The modulation of radiation in an electron-positron plasma 
    Gangadhara, R. T; Krishan, V; Shukla, P. K (Royal Astronomical Society, 1993-05-01)
    The modulational instability of a large-amplitude, linearly polarized electromagnetic wave propagating in an electron-positron plasma is considered, including the combined effect of relativistic mass variation of the plasma ...
  • Neutron star physics in the square kilometre array era: an Indian perspective 
    Konar, S; Bagchi, Manjari; Bandyopadhyay, Debades; Banik, Sarmistha; Bhattacharya, D; Bhattacharyya, S; Gangadhara, R. T; Gopakumar, A; Gupta, Y; Joshi, B. C; Maan, Yogesh; Maitra, Chandreyee; Mukherjee, D; Pai, Archana; Paul, B; Ray, A; Sutaria, F. K (Indian Academy of Sciences, 2016-12)
    It is an exceptionally opportune time for astrophysics when a number of next-generation mega-instruments are poised to observe the Universe across the entire electromagnetic spectrum with unprecedented data quality. The ...
  • Nonlinear Propagation of Intense Electromagnetic Waves in Quasar and Pulsar Plasmas 
    Gangadhara, R. T (Astronomical Society of India, 1997)
    We present the results of analytical as well as numerical investigations of radiation-plasma interaction instabilities in astrophysical plasmas. We consider the stimulated Raman and Compton scattering in the continuum ...
  • Nonlinear Propagation of Intense Electromagnetic Waves in Quasar and Pulsar Plasmas 
    Gangadhara, R. T (Indian Institute of Astrophysics, Bangalore, 1993-04)
  • On the method of estimating emission altitude from relativistic phase shift in pulsars 
    Gangadhara, R. T (The University of Chicago Press, 2005-08-01)
    The radiation by relativistic plasma particles is beamed in the direction of field-line tangents in the corotating frame, but in an inertial frame it is aberrated toward the direction of rotation. We have revised the ...
  • Parametric decay instability in 3C 273 
    Gangadhara, R. T; Krishan, V (Cambridge University Press, 1991)
    The parametric decay instability (PDI) causes anomalous absorption of strong electromagnetic (e.m) radiation under specific conditions of energy and momentum conservation. It is shown that in the source 3C 273, the conditions ...
  • Polarization Changes of Radiation through Stimulated Raman Scattering 
    Gangadhara, R. T; Krishan, V (The American Astronomical Society, 1993-10)
    We study change in the polarization of electromagnetic waves due to the stimulated Raman scattering in a plasma. In this process an electromagnetic wave undergoes coherent scattering off an electron plasma wave. It is found ...

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