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Browsing by Author "Mangalam, A"

Browsing by Author "Mangalam, A"

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  • On the injection spectrum of relativistic electrons in high-redshift radio galaxies 
    Gopal-Krishna; Mhaskey, Mukul; Mangalam, A (IOP Publishing, 2012-01-01)
    We point out that the remarkable linearity of the ultra-steep radio spectra of high redshift radio galaxies re ects a previously reported general trend for powerful radio galaxies, according to which the spectral curvature ...
  • Open and closed magnetic configurations of twisted flux tubes 
    Sen, Samrat; Mangalam, A (IOP Publishing, 2019-06-01)
    We construct two classes of magnetohydrostatic (MHS) equilibria for an axisymmetric vertical flux tube spanning from the photosphere to the lower part of the transition region within a realistic stratified solar atmosphere ...
  • Orbital signatures from observed light curves of blazars 
    Mangalam, A; Mohan, Prashanth (Indian Academy of Sciences, 2014-04)
    Variability in active galactic nuclei is observed in ultraviolet to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk ...
  • Parametric models of the periodogram 
    Mohan, Prashanth; Mangalam, A; Chattopadhyay, S (Indian Academy of Sciences, 2014-04)
    The maximum likelihood estimator is used to determine fit parameters for various parametric models of the Fourier periodogram followed by the selection of the best fit model amongst competing models using the Akaike ...
  • Parsec-scale jet properties of the quasar PG 1302-102 
    Mohan, P; An, T; Frey, S; Mangalam, A; Gabanyi, K. E; Kun, E (Oxford University Press on behalf of the Royal Astronomical Society, 2016-12-01)
    The quasar PG 1302−102 is believed to harbour a supermassive binary black hole (SMBBH) system. Using the available 15 GHz and 2–8 GHz, multi-epoch Very Long Baseline Array data, we constrain the pc-scale jet properties ...
  • A peculiar multiwavelength flare in the blazar 3C 454.3 
    Gupta, A. C; Mangalam, A; Wiita, J. Paul; Kushwaha, P; Gaur, H; Zhang, H; Gu, M. F; Liao, M; Dewangan, G. C; Ho, L. C; Mohan, P; Umeura, M; Sasada, M; Volvach, A. E; Agarwal, A; Aller, M. F; Aller, H. D; Bachev, R; Lahteenmaki, A; Semkov, E; Strigachev, A; Tornikoski, M; Volvach, L. N (Oxford University Press on behalf of the Royal Astronomical Society, 2017-11)
    The blazar 3C 454.3 exhibited a strong flare seen in γ -rays, X-rays and optical/near-infrared bands during 2009 December 3–12. Emission in the V and J bands rose more gradually than did the γ -rays and soft X-rays, ...
  • Physics and observations of tidal disruption events 
    Mangalam, A; Mageshwaran, T (Societe Royale des Sciences de Liege, 2018-04)
    We describe a model of tidal disruption events (TDEs) with input physical parameters that include the black hole (BH) mass M•, the specific orbital energy E, the angular momentum J, the star mass M? and radius R?. We ...
  • Physics of Supermassive Disks: Formation and Collapse 
    Mangalam, A (Astronomical Society of India, 2003)
    Supermassive disks are thought to be precursors of supermassive black holes that are believed to power quasars and exist at centers of galaxies. Formation scenarios of such disks are reviewed and it is argued that gas ...
  • Polarization and QPOs from jets in black hole systems 
    Mangalam, A (Indian Academy of Sciences, 2018-12)
    The historical observations of polarized jet emission for Blazars are reviewed and previous models are discussed. Motivated by this, a model for polarization of both steady and transient behavior using a helical magnetic ...
  • Probing magnetic fields with square kilometre array and its precursors 
    Roy, S; Sur, Sharanya; Subramanian, K; Mangalam, A; Seshadri, T. R; Chand, H (Indian Academy of Sciences, 2016-12)
    Origin of magnetic fields, its structure and effects on dynamical processes in stars to galaxies are not well understood. Lack of a direct probe has remained a problem for its study. The first phase of Square Kilometre ...
  • Re-Analysis of QPO in 3C 273 Light Curve 
    Mohan, Prashanth; Mangalam, A; Chand, H; Gupta, A. C (Indian Academy of Sciences, 2011-06)
    We have developed analysis tools to search for quasi periodic oscillations in light curves from active galactic nuclei, using the following time series techniques: Wavelets, periodogram, Lomb–Scargle periodogram, structure ...
  • Role of primordial black holes in the direct collapse scenario of supermassive black hole formation at high redshifts 
    Pandey, Kanhaiya L; Mangalam, A (Indian Academy of Sciences, 2018-02)
    In this paper, we explore the possibility of accreting primordial black holes as the source of heating for the collapsing gas in the context of the direct collapse black hole scenario for the formation of super-massive black ...
  • Separable solutions of force-free spheres and applications to solar active regions 
    Avijeet Prasad; Mangalam, A; Ravindra, B (IOP Publishing, 2014-05-10)
    In this paper, we present a systematic study of the force-free field equation for simple axisymmetric configurations in spherical geometry and apply it to the solar active regions. The condition of separability of solutions ...
  • Stellar and gas dynamical model for tidal disruption events in a quiescent galaxy 
    Mageshwaran, T; Mangalam, A (IOP Publishing, 2015-12-01)
    A detailed model of the tidal disruption events (TDEs) has been constructed using stellar dynamical and gas dynamical inputs that include black hole (BH) mass M•, specific orbital energy E and angular momentum J, star mass ...
  • Stellar Disruption by Supermassive Black Holes and the Quasar Radio Loudness Dichotomy 
    Gopal-Krishna; Mangalam, A; Wiita, P. J (The American Astronomical Society, 2008-06-10)
    The origin of the dichotomy of radio loudness among quasars can be explained using recent findings that the mass of the central supermassive black hole (SMBH) in extended radio-loud quasars is systematically a few times ...
  • Topological and statistical properties of nonlinear force-free fields 
    Mangalam, A; Prasad, A (Elsevier B.V, 2018-01)
    We use our semi-analytic solution of the nonlinear force-free field equation to construct three-dimensional magnetic fields that areapplicable to the solar corona and study their statistical properties for estimating the ...
  • A unified description of anti-dynamo conditions for incompressible flows 
    Mangalam, A (Anita Publications, 2004-12)
    A general type of mathematical argument is described, which applies to all the cases in which dynamo maintenance of a steady magnetic field by motion in a uniform density is known to be impossible. Previous work has ...
  • X-ray variability and the inner region in active galactic nuclei 
    Mohan, Prashanth; Mangalam, A (IOP Publishing, 2014-08-20)
    We present theoretical models of X-ray variability attributable to orbital signatures from an accretion disk including emission region size, quasi-periodic oscillations (QPOs), and its quality factor Q, and the emergence ...

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