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Browsing by Subject "Black hole physics"

Browsing by Subject "Black hole physics"

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  • 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 ...
  • 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 ...
  • Authenticating the presence of a relativistic massive black hole binary in OJ 287 using Its general relativity centenary flare: improved orbital parameters 
    Dey, L; Valtonen, M. J; Gopakumar, A; Zola, S; Hudec, R; Pihajoki, P; Ciprini, S; Matsumoto, K; Sadakane, K; Kidger, M; Nilsson, K; Mikkola, S; Sillanpaa, A; Takalo, L. O; Lehto, H. J; Berdyugin, A; Piirola, V; Jermak, H; Baliyan, K. S; Pursimo, T; Caton, D. B; Alicavus, F; Baransky, A; Blay, P; Boumis, P; Boyd, D; Campas Torrent, M; Campos, F; Carrillo Gomez, J; Chandra, S; Chavushyan, V; Dalessio, J; Debski, B; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Gafton, E; Ganesh, S; Garcia, F; Gazeas, K; Godunova, V; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Harmanen, J; Hurst, G; Janik, J; Jelinek, M; Joshi, A; Kagitani, M; Karjalainen, R; Kaur, N; Keel, W. C; Kouprianov, V. V; Kundera, T; Kurowski, S; Kvammen, A; LaCluyze, A. P; Lee, B. C; Liakos, A; Lindfors, E; Lozano de Haro, J; Mugrauer, M; Naves Nogues, R; Neely, A. W; Nelson, R. H; Ogloza, W; Okano, S; Pajdosz-Smierciak, U; Pandey, J. C; Perri, M; Poyner, G; Provencal, J; Raj, A; and 27 co-authors (IOP Publishing, 2018-10-10)
    Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the ...
  • 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 Evolution of Black Holes and the M.—σ relation 
    Bhattacharyya, Dipanweeta (Indian Institute of Astrophysics, 2020-01)
    The connection of the SMBHs to their host galaxies is evidenced by the strong correlation between the mass of SMBH and velocity dispersion, σ, of the stars in rest of the galaxy. This is somewhat surprising because the ...
  • 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 ...
  • Cosmological magnetic braking and the formation of high-redshift, super-massive black holes 
    Pandey, Kanhaiya L; Sethi, Shiv K; Ratra, Bharat (Oxford University Press on behalf of the Royal Astronomical Society, 2019-06)
    We study the effect of magnetic braking due to a primordial magnetic field in the context of the formation of massive (≳104M⊙) direct-collapse black holes (DCBHs) at high redshifts. Under the assumption of axial symmetry, ...
  • Deep J -band imaging of high redshift QSO candidates with the Himalayan Chandra Telescope 
    Goto, T; Ojha, D (Astronomical Society of India, 2006)
    High redshift QSOs (redshift >5.7) are highly important ob jects. If such QSOs may be found, their spectra will reveal the onset of reionization of the intergalactic medium (Gunn-Peterson trough), and provide precious in ...
  • The detection of Diffuse Extended Structure in 3C 273: implications for jet power 
    Punsly, B; Kharb, P (IOP Publishing, 2016-12-10)
    We present deep Very Large Array imaging of 3C 273 in order to determine the diffuse, large scale radio structure of this famous radio-loud quasar. Diffuse extended structure (radio lobes) is detected for the first time ...
  • 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 ...
  • Does black hole spin play a key role in the FSRQ/BL Lac dichotomy? 
    Bhattacharya, D; Sreekumar, P; Mukhopadhyay, B; Tomar, I (IOP Publishing, 2016-04)
    Blazars are characterized by large intensity and spectral v ariations across the electromagnetic spectrum It is believed that jets emerging from them are almo st aligned with the line-of-sight. The major- ity of ...
  • 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) ...
  • Evolution of low-frequency quasi-periodic oscillations in GX 339-4 during its 2021 outburst using AstroSat data 
    Mondal, Santanu; Salgundi, Anirudh; Chatterjee, Debjit; Jana, Arghajit; Chang, H. K; Naik, Sachindra (Oxford University Press on behalf of Royal Astronomical Society, 2023-12)
    The black hole X-ray binary GX 339-4 showed an X-ray outburst during 2021. The AstroSat captured this outburst when the source entered into the intermediate flux state while the count rate was declining. The source showed ...
  • The extreme ultraviolet deficit: jet connection in the quasar 1442+101 
    Punsly, B; Marziani, P; Kharb, P; O'Dea, C. P; Vestergaard, M (IOP Publishing, 2015-10-10)
    In previous studies, it has been shown that the long-term time-averaged jet power, Q, is correlated with spectral index in the extreme ultraviolet (EUV), αEUV (defined by n ~ n-a F EUV computed between 700 and 1100 Å ). ...
  • 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 ...
  • Gravitational waves: some less discussed intriguing issues 
    Sivaram, C (World Scientific Publishing Co., 2015-10)
    Attempts to detect gravitational waves is actively in progress with sophisticated devices like LIGO setup across continents. Despite being predicted almost 100 years ago, there has so far been no direct detection of these ...
  • 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 ...
  • Low-frequency quasi-periodic oscillations and shocks in accretion on to black hole 
    Singh, Chandra B; Mondal, Santanu; Garofalo, David (Oxford University Press on behalf of Royal Astronomical Society, 2022-02)
    Low-frequency quasi-periodic oscillations (LFQPOs) have been routinely observed in black hole X-ray binaries (BHXRBs). These LFQPOs can be explained by axisymmetric shock oscillation in accretion flow around a rotating ...
  • A machine learning approach for classification of accretion states of black hole binaries 
    Sreehari, H; Nandi, Anuj (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    In this paper, we employ Machine Learning algorithms on multimission observations for the classification of accretion states of outbursting black hole X-ray binaries for the first time. Archival data from RXTE, Swift, MAXI, ...

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