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Browsing by Author "Mangalam, A"

Browsing by Author "Mangalam, A"

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  • Accretion and wind dynamics in tidal disruption events 
    Mageshwaran, T; Mangalam, A (International Astronomical Union, 2017-06)
    We have constructed self similar models of time dependent and non relativistic ac- cretion disks in both sub and super-Eddington phase of TDEs with wind outflows for a general viscosity prescription which is a function ...
  • Astrophysically relevant bound trajectories around a Kerr black hole 
    Prerna Rana; Mangalam, A (IOP Publishing, 2019-02-21)
    We derive alternate and new closed-form analytic solutions for the nonequatorial eccentric bound trajectories, {φ (r, θ), t(r, θ), r(θ)}, around a Kerr black hole by using the transformation 1/r = µ (1 + e cos χ). The ...
  • Black hole demographics from TDE modeling 
    Mageshwaran, T; Mangalam, A (Cambridge University Press, 2018-05)
    The occurence rate of tidal disruption events (TDEs) by survey missions depend on the black hole mass function of the galaxies, properties of the stellar cusp and mass of the central black hole. Using a power law density ...
  • Bound orbit domains in the phase space of the Kerr geometry 
    Prerna Rana; Mangalam, A (World Scientific Publishing, 2022)
    We derive the conditions for a non-equatorial eccentric bound orbit to exist around a Kerrblack hole in two-parameter spaces: the energy, angular momentum of the test particle,spin of the black hole, and Carter’s constant ...
  • The changing interstellar medium of massive elliptical galaxies and cosmic evolution of radio galaxies and quasars 
    Mangalam, A; Gopal-Krishna; Wiita, Paul J (Blackwell Publishing, 2009-06-03)
    The recently discovered apparent dramatic expansion in the effective radii of massive elliptical galaxies from z≃ 2 to ≃0.1 has been interpreted in terms of either galaxy mergers or the rapid loss of cold gas due to ...
  • Constrained Violent Relaxation to a Spherical Halo 
    Mangalam, A; Nityananda, R; Sridhar, S (The American Astronomical Society, 1999-10)
    Violent relaxation during the collapse of a galaxy halo is known to be incomplete in realistic cases such as cosmological infall or mergers. We adopt a physical picture of strong but short-lived interactions between potential ...
  • Constraints on dynamo action 
    Mangalam, A (Springer Netherlands, 2008)
    We discuss first geometrical constraints on dynamo action. Magnetic field decay is unavoidable under certain conditions of symmetry. These known results are encompassed by a calculation for flows described in terms of a ...
  • Core shift effect in blazars 
    Agarwal, A; Mohan, P; Gupta, A. C; Mangalam, A; Volvach, A. E; Aller, M. F; Aller, H. D; Gu, M. F; Lahteenmaki, A; Tornikoski, M; Volvach, L. N (Oxford University Press on behalf of the Royal Astronomical Society, 2017-07)
    We studied the pc-scale core shift effect using radio light curves for three blazars, S5 0716+714, 3C 279 and BL Lacertae, which were monitored at five frequencies (ν) between 4.8 and 36.8 GHz using the University of ...
  • Cosmic evolution of AGN using self-consistent black hole energetics 
    Mangalam, A (Astronomical Society of India, 2015)
    We consider a model that takes into account the mass and spin accreted by the hole and the angular momentum torque due to an electrodynamical jet. The spin evolution is calculated with and without accretion; if the accretion ...
  • Cosmic Spin and Mass Evolution of Black Holes and Its Impact 
    Bhattacharyya, Dipanweeta; Mangalam, A (IOP Publishing, 2020-06-01)
    We build an evolution model of the central black hole that depends on the processes of gas accretion, the capture of stars, mergers, and electromagnetic torque. In the case of gas accretion in the presence of cooling ...
  • Dynamics of accretion and winds in tidal disruption events 
    Mageshwaran, T; Mangalam, A (Elsevier B. V, 2021-02)
    We have constructed self-similar models of a time-dependent accretion disk in both sub and super-Eddington phases with wind outflows for tidal disruption events (TDEs). The physical input parameters are the black hole (BH) ...
  • Eccentric equatorial trajectories around a Kerr black hole asa QPO model for M82X-1 
    Prerna Rana; Mangalam, A (World Scientific Publishing, 2022)
    We study the bound orbit conditions for equatorial and eccentric orbits around a Kerrblack hole both in the parameter space (E,L,a) representing the energy, angular mo-mentum of the test particle, and spin of the black ...
  • Energy distribution of solar flare events 
    Sen, Samrat; Mangalam, A; Ramesh, R (Cambridge University Press, 2018-02)
    The coronal field typically reorganizes itself to attain a force-free field configuration. We have evaluated the power law index of the energy distribution f(E) = f0E−α by using a model of relaxation incorporating ...
  • Evolution of the M•-σ relation 
    Bhattacharyya, D; Mangalam, A (Cambridge University Press, 2018-05)
    Black holes at the centers of the galaxies grow mainly by the processes of accretion, mergers, and consumption of stars. In the case of gas accretion with cooling sources, the flow is momentum driven, after which the black ...
  • Flux tube model in the solar atmosphere 
    Sen, Samrat; Mangalam, A (Cambridge University Press, 2018-02)
    We construct two classes of the magnetohydrostatic equilibria of the axisymmetric flux tubes with twisted magnetic fields in the stratified solar atmosphere that span from the photosphere to the transition region. We built ...
  • Formation of a proto-quasar from accretion flows in a halo 
    Mangalam, A (E D P Sciences, 2001-12)
    We present a detailed model for the formation of massive objects at the centers of galaxies. The effects of supernovae heating and the conditions of gas loss are revisited. The escape time of the gas is compared with the ...
  • Frequency-dependent core shifts and parameter estimation for the blazar 3C 454.3 
    Mohan, Prashanth; Agarwal, A; Mangalam, A; Gupta, A. C; Wiita, P. J; Volvach, A. E; Aller, M. F; Aller, H. D; Gu, M. F; Lahteenmaki, A; Tornikoski, M; Volvach, L. N (Oxford University Press on behalf of the Royal Astronomical Society, 2015-09-11)
    We study the core shift effect in the parsec-scale jet of the blazar 3C 454.3 using the 4.8– 36.8 GHz radio light curves obtained from three decades of continuous monitoring. From a piecewise Gaussian fit to each flare, ...
  • A Geometric Origin for Quasi-periodic Oscillations in Black Hole X-Ray Binaries 
    Prerna Rana; Mangalam, A (IOP Publishing, 2020-11-10)
    We expand the relativistic precession model to include nonequatorial and eccentric trajectories and apply it to quasi-periodic oscillations (QPOs) in black hole X-ray binaries (BHXRBs) and associate their frequencies with ...
  • A Global galactic dynamo with a corona constrained by relative helicity 
    Avijeet Prasad; Mangalam, A (IOP Publishing, 2016-01)
    We present a model for a global axisymmetric turbulent dynamo operating in a galaxy with a corona that treats the parameters of turbulence driven by supernovae and by magneto-rotational instability under a common ...
  • Kinematics of and emission from helically orbiting blobs in a relativistic magnetized jet 
    Mohan, Prashanth; Mangalam, A (IOP Publishing, 2015-07-01)
    We present a general relativistic (GR) model of jet variability in active galactic nuclei due to orbiting blobs in helical motion along a funnel or cone-shaped magnetic surface anchored to the accretion disk near the black ...

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