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Browsing by Subject "Accretion"

Browsing by Subject "Accretion"

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  • The 1995-96 decline of R Coronae Borealis: high-resolution optical spectroscopy 
    Kameswara Rao, N; Lambert, D. L; Adams, M. T; Doss, D. R; Gonzalez, G; Hatzes, A. P; James, C. R; Johns-Krull, C. M; Luck, R. E; Pandey, G; Reinsch, K; Tomkin, J; Woolf, V. M (The Royal Astronomical Society, 1999-12)
    A set of high-resolution optical spectra of R CrB acquired before, during and after its 1995-96 decline is discussed. All of the components reported from earlier declines are seen. This novel data set provides new information ...
  • 2.5-dimensional solution of the advective accretion disk: a self-similar approach 
    Ghosh, S; Mukhopadhyay, B (Institute of Physics, 2009-02)
    We provide a 2.5-dimensional solution to a complete set of viscous hydrodynamical equations describing accretion-induced outflows and plausible jets around black holes/compact objects. We prescribe a self-consistent advective ...
  • 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 ...
  • Accretion flow properties of GRS 1915+105 during Its θ class using AstroSat data 
    Banerjee, Anuvab; Bhattacharjee, Ayan; Chatterjee, Debjit; Debnath, Dipak; Chakrabarti, S. K; Katoch, Tilak; Antia, H. M (IOP Publishing, 2021-08-01)
    The Galactic microquasar GRS 1915+105 shows rich variability that is categorized into different classes. In this paper, we report the temporal and spectral analysis of GRS 1915+105 to study the properties of the accretion ...
  • Accretion properties of MAXI J1813-095 during its failed outburst in 2018 
    Jana, Arghajit; Jaisawal, G. K; Naik, Sachindra; Neeraj Kumari; Chatterjee, Debjit; Chatterje, Kaushik; Bhowmick, Riya; Chakrabarti, S. K; Chang, H.-K; Debnath, Dipak (IOP Publishing, 2021-05)
    We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI J1813–095 using Swift, NICER, and NuSTAR observations during its 2018 outburst. The timing behavior of the source is ...
  • Advective flow paradigm of disks and outflows around black holes 
    Chakrabarti, S. K (Astronomical Society of India, 2002)
    For the past fifty years, accretion process is being studied initially on normal stars and later, on compact object, such as black holes and neutron stars. In this Review, I present the modern development of this subject ...
  • Analytical study of standing shocks around black hole 
    Das, S; Chakrabarti, S. K (Astronomical Society of India, 2002)
    Shocks from around black holes as the matter slows down by centifugal barrier. At the shocks, kinetic energy is converted into thermal energy and hard-X rays, outflows etc. are produced which are observed. We compute the ...
  • Anomalous nature of outbursts of black hole candidate 4U 1630-472 
    Chatterjee, Kaushik; Debnath, Dipak; Bhowmick, Riya; Nath, Sujoy Kumar; Chatterjee, Debjit (Oxford University Press on behalf of Royal Astronomical Society, 2022-02)
    The Galactic black hole candidate (BHC) 4U 1630−472 has gone through several outbursts (13 to be particular) in the last two and a half decades starting from the RXTE era till date. Like the outbursts of other transient ...
  • AstroSat view of GRS 1915+105 during the soft state: detection of HFQPOs and estimation of mass and spin 
    Sreehari, H; Nandi, Anuj; Das, Santabrata; Agrawal, V. K; Mandal, Samir; Ramadevi, M. C; Katoch, Tilak (Oxford University Press on behalf of the Royal Astronomical Society, 2020-12)
    We report the results of AstroSat observations of GRS 1915+105 obtained using 100 ks Guaranteed Time during the soft state. The colour–colour diagram indicates a variability class of δ with the detection of high-frequency ...
  • Broadband X-Ray Spectral Analysis of the ULX NGC 1313 X-1 Using JeTCAF: Origin of the ULX Bubble 
    Palit, Biswaraj; Mondal, Santanu (IOP Publishing, 2023-05)
    NGC 1313 X-1 is a mysterious ultraluminous X-ray (ULX) source whose X-ray-powering mechanism and bubblelike structure surrounding the source are topics of intense study. Here, we perform an X-ray spectroscopic study of the ...
  • Correlated X-ray timing and spectral behavior in GX 349+2 
    Agrawal, V. K; Bhattacharyya, S (The European Southern Observatory, 2003-01)
    We present a detailed and systematic investigation of correlated spectral and timing properties of the Z source GX 349+2, using extensive data ( ~ 221 ks) obtained from the Proportional-Counter-Array on-board RXTE satellite, ...
  • 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 ...
  • Discovery of soft and hard X-ray time lags in low-mass AGNs 
    Mallick, L; Wilkins, D. R; Alston, W. N; Markowitz, A; Marco, B. De; Parker, M. L; Lohfink, A. M; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-05)
    The scaling relations between the black hole (BH) mass and soft lag properties for both active galactic nuclei (AGNs) and BH X-ray binaries (BHXRBs) suggest the same underlying physical mechanism at work in accreting BH ...
  • Effect of beam-plasma instabilities on accretion disk flares 
    Krishan, V; Wiita, P. J; Ramadurai, S (European Southern Observatory, 2000-04)
    We show that a certain class of flare models for variability from accretion disk coronae are subject to beam-plasma instabilities. These instabilities can prevent significant direct acceleration and greatly reduce the ...
  • Emission lines from X-ray illuminated accretion disc in black hole binaries 
    Mondal, Santanu; Adhikari, Tek P; Singh, Chandra B (Oxford University Press on behalf of the Royal Astronomical Society, 2021-07)
    X-ray flux from the inner hot region around central compact object in a binary system illuminates the upper surface of an accretion disc and it behaves like a corona. This region can be photoionized by the illuminating ...
  • Flux and spectral variability of Mrk 421 during its moderate activity state using NuSTAR: Possible accretion disc contribution? 
    Mondal, S; Priyanka Rani; Stalin, C. S; Chakrabarti, S. K; Rakshit, S (EDP Sciences, 2022-07)
    Context. The X-ray emission in BL Lac objects is believed to be dominated by synchrotron emission from their relativistic jets. However, when the jet emission is not strong, one could expect signatures of X-ray emission ...
  • 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 ...
  • A General Relativistic Calculation of Boundary Layer and Disc Luminosity for Accreting Non-magnetic Neutron Stars in Rapid Rotation 
    Thampan, A. V; Datta, B (The Royal Astronomical Society, 1998-06)
    We calculate the disc and boundary layer luminosities for accreting rapidly rotating neutron stars with low magnetic fields in a fully general relativistic manner. Rotation increases the disc luminosity and decreases the ...
  • General relativistic spectra of accretion discs around rapidly rotating neutron stars: effect of light bending 
    Bhattacharyya, S; Bhattacharya, D; Thampan, A. V (Royal Astronomical Society, 2001-08)
    We present computed spectra, as seen by a distant observer, from the accretion disc around a rapidly rotating neutron star. Our calculations are carried out in a fully general relativistic framework, with an exact treatment ...
  • 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 ...

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