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Browsing IIAP Publications by Subject "Galaxies: active"

Browsing IIAP Publications by Subject "Galaxies: active"

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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 ...
  • Active galactic nucleus feedback in NGC 3982 
    Joseph, P; George, K; Paul, K. T (EDP Sciences, 2022-11)
    The energetic feedback from supermassive black holes can influence star formation at the centres of galaxies. Observational evidence for active galactic nucleus (AGN) impact on star formation can be searched for in galaxies ...
  • 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 ...
  • AT2020ohl: its nature and probable implications 
    Roy, Rupak; Mandal, Samir; Sahu, D. K; Anupama, G. C; Nandi, Sumana; Kumar, Brijesh (Oxford University Press on behalf of Royal Astronomical Society., 2024-03)
    ASASSN-20hx, a.k.a AT2020ohl, is an ambiguous nuclear transient, which was discovered in the nearby galaxy NGC6297 by the All-Sky Automated Survey for Supernovae. We have investigated the evolution of AT2020ohl using a ...
  • 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 ...
  • Awakening of the high-redshift blazar CGRaBS J0809+5341 
    Paliya, Vaidehi S; Parker, M. L; Stalin, C. S; Fabian, A. C; Ramya, S; Covino, S; Tagliaferri, G; Sahayanathan, S; Ravikumar, C. D (IOP Publishing, 2015-04)
    CGRaBS J0809+5341, a high-redshift blazar at z = 2.144, underwent a giant optical outburst on 2014 April 19 when it brightened by ~5 mag and reached an unfiltered apparent magnitude of 15.7 mag. This implies an absolute ...
  • Broad-band study of OQ 334 during its flaring state 
    Prince, Raj; Khatoon, Rukaiya; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-04)
    The blazar OQ 334 displayed a γ-ray flare in 2018, after being in the long quiescent γ-ray state since 2008. Subsequent to the flare, the source was in a higher γ-ray flux state and again flared in 2020. We present here ...
  • Broadband observations of high redshift blazars 
    Paliya, Vaidehi S; Parker, M. L; Fabian, A. C; Stalin, C. S (IOP Publishing, 2016-07-01)
    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 (z = 3.37), CGRaBS J0225+1846 (z = 2.69), BZQ J1430+4205 (z = 4.72), and 3FGL J1656.2−3303 (z = 2.40) using quasi-simultaneous data from the ...
  • Broadband observations of the gamma-ray emitting narrow line Seyfert 1 galaxy SBS 0846+513 
    Paliya, Vaidehi S; Rajput, Bhoomika; Stalin, C. S; Pandey, S. B (IOP Publishing, 2016-03)
    We present the results of our broadband study of the γ -ray emitting narrow line Seyfert 1 ( NLSy1 ) galaxy SBS 0846 + 513 ( z = 0.585 ) . This includes multiband fl ux variations, γ -ray spectral analysis, ...
  • A candidate dual AGN in a double-peaked emission-line galaxy with precessing radio jets 
    Rubinur, K; Mousumi Das; Kharb, P; Honey, M (Oxford University Press on behalf of the Royal Astronomical Society, 2017-03)
    We present high-resolution radio continuum observations with the Karl G. Jansky very large array at 6, 8.5, 11.5 and 15 GHz of the double-peaked emission-line galaxy 2MASXJ12032061+1319316. The radio emission has a prominent ...
  • A Catalog of Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey Data Release 12 
    Rakshit, S; Stalin, C. S; Chand, H; Zhang, Xue-Guang (IOP Publishing, 2017-04)
    We present a new catalog of narrow-line Seyfert 1 (NLSy1) galaxies from the Sloan Digital Sky Survey Data Release 12 (SDSS DR12). This was obtained by a systematic analysis through modeling of the continuum and emission ...
  • 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 ...
  • Coronal Proerties of the Seyfert 1 Galaxy 3C 120 with NuSTAR 
    Priyanka Rani; Stalin, C. S (IOP Publishing, 2018-04-01)
    We present a measurement of the cut-off energy, a proxy for the temperature of the corona in the nuclear continuum of the Seyfert 1 galaxy 3C 120 using ~120 ks of observation from NuSTAR. The quality broadband spectrum ...
  • 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 and γ-ray flux variations in BL Lacs 
    Rajput, Bhoomika; Shah, Zahir; Stalin, C. S; Sahayanathan, S; Rakshit, S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-06)
    We report here results of the analysis of correlated flux variations between the optical and GeV γ-ray bands in three bright BL Lac objects, namely AO 0235+164, OJ 287, and PKS 2155−304. This was based on the analysis of ...
  • 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 ...
  • 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 ...
  • 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 ...
  • Detection of minute-timescale γ-ray variability in BL Lacertae by Fermi-LAT 
    Pandey, Ashwani; Stalin, C. S (EDP Sciences, 2022-12)
    BL Lacertae, the prototype of the BL Lacertae (BL Lac) category of blazars, underwent a giant γ-ray flare in April 2021. The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (hereafter Fermi-LAT) ...

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