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Browsing by Author "Singh, V"

Browsing by Author "Singh, V"

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  • From nearby low luminosity AGN to High Redshift Radio Galaxies: science interests with square kilometre array 
    Kharb, P; Lal, D. V; Singh, V; Bagchi, J; Ishwara-Chandra, C. H; Hota, A; Konar, C; Wadadekar, Yogesh; Shastri, P; Mousumi Das; Baliyan, K; Nath, B. B; M. Pandey-Pommier (Springer, 2016-12)
    We present detailed science cases that a large fraction of the Indian AGN community is interested in pursuing with the upcoming Square Kilometre Array (SKA). These interests range from understanding low luminosity active ...
  • A GMRT study of Seyfert galaxies NGC 4235 and NGC 4594: evidence of episodic activity? 
    Kharb, P; Srivastava, S; Singh, V; Gallimore, J. F; Ishwara-Chandra, C. H; Ananda, H (Oxford University Press on behalf of the Royal Astronomical Society, 2016-06)
    Low-frequency observations at 325 and 610 MHz have been carried out for two ‘radio-loud’ Seyfert galaxies, NGC 4235 and NGC 4594 (Sombrero galaxy), using the Giant Meterwave Radio Telescope (GMRT). The 610 MHz total ...
  • Kiloparsec-scale radio emission in Seyfert and LINER galaxies 
    Singh, V; Ishwara-Chandra, C. H; Wadadekar, Yogesh; Beelen, Alexandre; Kharb, P (Oxford University Press on behalf of the Royal Astronomical Society, 2015-01-01)
    Seyfert and LINER galaxies are known to exhibit compact radio emission on ∼10–100 pc scales, but larger Kiloparsec-Scale Radio structures (KSRs) often remain undetected in sub-arcsec high-resolution observations. We ...
  • Low frequency radio emission from seyfert galaxies 
    Singh, V; Shastri, P; Athreya, R (Astronomical Society of the Pacific, 2009-09)
    Seyfert galaxies are low-luminosity, radio-quiet, nearby active galaxies. The high-frequency radio observations of several Seyfert galaxies show jet-like features, which tend to be confined within the host galaxy, whereas ...
  • Low-frequency radio observations of Seyfert galaxies: A test of the unification scheme 
    Singh, V; Shastri, P; Ishwara-Chandra, C. H; Athreya, R (EDP Sciences, 2013-06)
    Aims. We present low-frequency radio imaging and spectral properties of a well-defined sample of Seyfert galaxies using GMRT 240/610 MHz dual frequency observations. Radio spectra of Seyfert galaxies over 240 MHz to 5.0 ...
  • Measuring the level of nuclear activity in Seyfert galaxies and the unification scheme 
    Singh, V; Shastri, P; Risaliti, G (EDP Sciences, 2011-09)
    Context. The unification scheme of Seyfert galaxies hypothesizes that Seyfert type 1s and type 2s are intrinsically similar and the observed differences between the two subtypes are solely due to the differing orientations ...
  • Radio and X-ray Emission from Low-Luminosity AGNs: Testing Unification Hypothesis 
    Singh, V; Shastri, P; Risaliti, G; Athreya, R (Astronomical Society of the Pacific, 2010-10)
    We investigate the low-frequency radio properties and the X-ray spectral properties of a sample of Seyfert galaxies in order to compare the two subtypes of Seyferts and rigorously test the predictions of Seyfert unification.
  • Seyfert Galaxies: Radio Continuum Emission Properties and the Unification Scheme 
    Singh, V; Shastri, P; Athreya, R (Indian Academy of Sciences, 2011-12)
    Seyfert galaxies are classified mainly into type 1 and type 2 depending on the presence and absence of broad permitted emission lines in their optical spectra, respectively. Unification scheme hypothesizes that the ...
  • Spitzer Mid-IR Spectroscopy of Powerful 2JY and 3CRR Radio Galaxies. II. AGN Power Indicators and Unification 
    Dicken, D; Tadhunter, C; Morganti, R; Axon, D; Robinson, A; Magagnoli, M; Kharb, P; Almeida, C. R; Mingo, B; Hardcastle, M; Nesvadba, N. P. H; Singh, V; Kouwenhoven, M. B. N; Rose, M; Spoon, H; Inskip, K. J; Holt, J (IOP Publishing, 2014-06-20)
    It remains uncertain which continuum and emission line diagnostics best indicate the bolometric powers of active galactic nuclei (AGNs), especially given the attenuation caused by the circumnuclear material and the possible ...
  • Suzaku X-ray spectral study of the Compton-thick Seyfert galaxy NGC 5135 
    Singh, V; Risaliti, G; Braito, V; Shastri, P (Wiley-Blackwell, 2012-01)
    We present the 0.5–50 keV Suzaku broad-band X-ray spectral study of the Compton-thick active galactic nucleus (AGN) in NGC 5135. The Suzaku observation provides the first detection of NGC 5135 above 10 keV that allowed us, ...
  • X-ray emission from seyfert galaxies: surroundings of their supermassive black holes 
    Singh, V; Shastri, P (American Institute of Physics, 2008-08)
    We study the systematics of the X-ray emission from Seyfert nuclei in the frame work of unification. In order to do this rigorously a sample with types 1 and 2 matched in orientation-independent parameters is studied. The ...
  • X-ray spectral properties of Seyfert galaxies and the unification scheme 
    Singh, V; Shastri, P; Risaliti, G (EDP Sciences, 2011-08)
    Context. The unification scheme of Seyfert galaxies predicts that the observed differences between types 1 and 2 Seyfert galaxies are solely due to the differing orientations of the toroidal-shaped obscuring material around ...

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