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Browsing by Subject "Galaxies: nuclei"

Browsing by Subject "Galaxies: nuclei"

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  • Accretion disc sizes from continuum reverberation mapping of AGN selected from the ZTF survey 
    Jha, Vivek Kumar; Joshi, Ravi; Chand, Hum; Wu, Xue-Bing; Ho, Luis C; Rastogi, Shantanu; Ma, Qinchun (Oxford University Press on behalf of Royal Astronomical Society, 2022-04)
    We present the accretion disc-size estimates for a sample of 19 active galactic nuclei (AGNs) using the optical g-, r-, and i-band light curves obtained from the Zwicky Transient Facility survey. All the AGNs have reliable ...
  • Active galactic nucleus activity and black hole masses in low surface brightness galaxies 
    Ramya, S; Prabhu, T. P; Mousumi Das (Wiley-Blackwell, 2011-12)
    We present medium resolution optical spectroscopy of a sample of nine low surface brightness (LSB) galaxies. For those that show clear signatures of active galactic nucleus (AGN) emission, we have disentangled the AGN ...
  • The AGN and gas disk in the low surface brightness galaxy PGC045080 
    Das, M; Kantharia, N; Ramya, S; Prabhu, T. P; McGaugh, S. S; Vogel, S. N (Blackwell Publishing, 2007-07)
    We present radio observations and optical spectroscopy of the giant low surface brightness (LSB) galaxy PGC 045080 (or 1300+0144). PGC 045080 is a moderately distant galaxy having a highly inclined optical disc and massive ...
  • Automated detection of double nuclei galaxies using GOTHIC and the discovery of a large sample of dual AGN 
    Bhattacharya, Anwesh; Nehal, C. P; Mousumi Das; Paswan, Abhishek; Saha, Snehanshu; Combes, Françoise (Oxford University Press on behalf of Royal Astronomical Society, 2023-09)
    We present a novel algorithm to detect double nuclei galaxies (DNG) called GOTHIC (Graph-bOosTed iterated HIll Climbing) – that detects whether a given image of a galaxy has two or more closely separated nuclei. Our aim ...
  • Bar quenching: Evidence from star-formation-rate indicators 
    George, K; Subramanian, S (EDP Sciences, 2021-07)
    The central regions of star-forming barred spiral galaxies can be devoid of star formation because of the redistribution of gas along the length of the bar. However, there can be gas outside the length of the bar that can ...
  • Correlation between optical and γ -ray flux variations in bright flat spectrum radio quasars 
    Rajput, Bhoomika; Stalin, C. S; Sahayanathan, S (Oxford University Press on behalf of the Royal Astronomical Society, 2020-11)
    Blazars are known to show flux variations over a range of energies from low-energy radio to high-energy γ-rays. Cross-correlation analysis of the optical and γ-ray light curves in blazars shows that flux variations are ...
  • Correlation between optical flux and polarization variations in flat-spectrum radio quasars on diverse time-scales 
    Pandey, Ashwani; Bhoomika, R; Stalin, C. S (Oxford University Press on behalf of Royal Astronomical Society, 2022-02)
    Study of the polarization behaviour in blazars is a powerful tool to discern the role of the magnetic field in the variable emission process in their relativistic jets. We present here the results of our systematic ...
  • 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) ...
  • Estimation of the size and structure of the broad line region using Bayesian approach 
    Mandal, A. K; Rakshit, S; Stalin, C. S; Petrov, R. G; Mathew, B; Sagar, R (Oxford University Press on behalf of the Royal Astronomical Society, 2021-04)
    Understanding the geometry and kinematics of the broad line region (BLR) of active galactic nuclei (AGN) is important to estimate black hole masses in AGN and study the accretion process. The technique of reverberation ...
  • An FUV and optical study of star formation in closely interacting galaxies: star-forming rings, tidal arms, and nuclear outflows 
    Yadav, Jyoti; Mousumi, Das; Barway, Sudhanshu; Combes, Francoise (Oxford University Press on behalf of Royal Astronomical Society, 2023-11)
    We present a study of the morphology of star formation and the associated nuclear activity in a sample of eight closely interacting southern galaxies, which are in different stages of interaction, starting with nearly ...
  • Giant Low Surface Brightness Galaxies: Evolution in Isolation 
    Mousumi Das (Indian Academy of Sciences, 2013-03)
    Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more ...
  • Investigating AGN black hole masses and the MBH-σe relation for low surface brightness galaxies 
    Subramanian, S; Ramya, S; Das, M; George, K; Sivarani, T; Prabhu, T. P (Oxford University Press on behalf of the Royal Astronomical Society, 2016-01)
    We present an analysis of the optical nuclear spectra from the active galactic nuclei (AGN) in a sample of low surface brightness (LSB) galaxies. Using data from the Sloan Digital Sky Survey (SDSS), we derived the virial ...
  • Investigating the AGN activity and black hole masses in low surface brightness galaxies 
    Subramanian, S; Ramya, S; Das, M; George, K; Sivarani, T; Prabhu, T. P (International Astronomical Union, 2016-02)
    We present an analysis of the optical nuclear spectra from the active galactic nuclei (AGN) in a sample of giant low surface brightness (GLSB) galaxies. GLSB galaxies are extreme late type spirals that are large, isolated ...
  • Investigation of the correlation between optical and γ-ray flux variation in the blazar Ton 599 
    Rajput, Bhoomika; Mandal, Amit Kumar; Pandey, Ashwani; Stalin, C. S; Max-Moerbeck, Walter; Mathew, Blesson (Published by Oxford University Press on behalf of Royal Astronomical Society, 2024-02)
    The correlation between optical and γ-ray flux variations in blazars reveals a complex behaviour. In this study, we present our analysis of the connection between changes in optical and γ-ray emissions in the blazar Ton ...
  • Kinematics and Excitation of the Nuclear Spiral in the Active Galaxy Arp 102B 
    Couto, G. S; Storchi-Bergmann, T; Axon, D. J; Robinson, A; Kharb, P; Riffel, R. A (Oxford University Press on behalf of the Royal Astronomical Society, 2013-11-11)
    We present a two-dimensional analysis of the gaseous excitation and kinematics of the inner 2.5 × 1.7 kpc2 of the low-ionization nuclear emission-line region (LINER)/Seyfert 1 galaxy Arp 102B, from optical spectra obtained ...
  • Late time X-ray, IR and radio observations of the tidal disruption event galaxy NGC 5905 
    Raichur, H; Mousumi Das; Herrero, A. A; Shastri, P; Kantharia, N. G (Springer, 2015-04)
    NGC 5905 is one of the few galaxies with no prior evidence for an active galactic nucleus (AGN) in which an X-ray flare was detected by the ROSAT All Sky Survey (RASS) in 1990–1991. Follow-up studies showed that the X-ray ...
  • Long-term optical and infrared variability characteristics of Fermi blazars 
    Safna, P. Z; Stalin, C. S; Rakshit, S; Mathew, Blesson (Oxford University Press on behalf of the Royal Astronomical Society, 2020-11)
    We present long-term optical and near-infrared flux variability analysis of 37 blazars detected in the γ-ray band by the Fermi Gamma-Ray Space Telescope. Among them, 30 are flat spectrum radio quasars (FSRQs) and 7 are BL ...
  • M∙ − σ relation in spherical systems 
    Bhattacharyya, D; Mangalam, A (Indian Academy of Sciences, 2018-02)
    To investigate the M∙−σ relation, we consider realistic elliptical galaxy profiles that are taken to follow a single power-law density profile given by Ï (r)=Ï 0(r/r0)−γ or the Nuker intensity profile. We calculate ...
  • A physically-motivated perspective of Fanaroff–Riley classification of radio galaxies 
    Gopal-Krishna; Wiita, Paul J; Joshi, Ravi; Patra, Dusmanta (Indian Academy of Sciences, 2023-06)
    A small subset of extragalactic double radio sources, termed HYbrid MOrpholgy Radio Sources (HYMORS), is distinguished by a very unusual, hybrid morphology in terms of Fanaroff–Riley (FR) classification. In HYMORS, one ...
  • Probing the physics of narrow-line regions in active galaxies. III. accretion and cocoon shocks in the liner NGC 1052 
    Dopita, M. A; Ho, I-Ting; Dressel, L. L; Sutherland, R; Kewley, L; Davies, R; Hampton, E; Shastri, P; Kharb, P; Jose, Jessy; Bhatt, H. C; Ramya, S; Scharwachter, J; Jin, C; Banfield, J; Zaw, I; James, B; Juneau, S; Srivastava, S (IOP Publishing, 2015-03-01)
    We present Wide Field Spectrograph integral field spectroscopy and Hubble Space Telescope Faint Object Spectrograph spectroscopy for the low-ionization nuclear emission line region (LINER) galaxy NGC 1052. We infer the ...

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