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Browsing by Author "Shastri, P"

Browsing by Author "Shastri, P"

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  • 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 ...
  • Milliarcsec-scale radio structure of a matched sample of Seyfert 1 and Seyfert 2 galaxies 
    Lal, D. V; Shastri, P; Gabuzda, D. C (EDP Sciences, 2004-10)
    We have obtained mas-scale resolution very long baseline interferometry (VLBI) images of a sample of Seyfert 1 and Seyfert 2 galaxies at 5 GHz (wavelength, lamda = 6 cm). The Seyferts of the two types were chosen to be ...
  • O VI Asymmetry and an Accelerated Outflow in an Obscured Seyfert: FUSE and HST STIS Spectroscopy of Mrk 533 
    Shastri, P; Murthy, J; Whittle, Mark; Wills, B. J (The American Astronomical Society, 2006-07-20)
    We present far-ultraviolet spectra of the Seyfert 2 galaxy Mrk 533 obtained with FUSE. These spectra show narrow asymmetrical O VI λλ1032,1038 emission lines with stronger wings shortward of the peak wavelength, but the ...
  • Optical and radio variability of the BL Lacertae object AO 0235+16: A possible 5-6 year periodicity 
    Raiteri, C. M; Villata, M; Aller, H. D; Aller, M. F; Heidt, J; Kurtanidze, O. M; Lanteri, L; Maesano, M; Massaro, E; Montagni, F; Nesci, R.; Nilsson, K; Nikolashvili, M. G; Nurmi, P; Ostorero, L; Pursimo, T; Rekola, R; Sillanpää, A; Takalo, L. O; Teräsranta, H; Tosti, G; Balonek, T. J; Feldt, M; Heines, A; Heisler, C; Hu, J.; Kidger, M; Mattox, J. R; McGrath, E. J; Pati, A. K; Robb, R; Sadun, A. C; Shastri, P; Wagner, S. J; Wei, J; Wu, X (E D P Sciences, 2001-10)
    The BL Lacertae object AO 0235+16 is well known for its extreme optical and radio variability. New optical and radio data have been collected in the last four years by a wide international collaboration, which confirm the ...
  • Optical Nuclei of Radio-loud AGN and the Fanaroof-Riley Divide 
    Kharb, P; Shastri, P (EDP Sciences, 2004-10)
    We investigate the nature of the point-like optical nuclei that have been found in the centres of the host galaxies of a majority of radio galaxies by the Hubble Space Telescope. We examine the evidence that these optical ...
  • The parsec-scale central components of FR I radio galaxies 
    Kharb, P; Shastri, P (International Astronomical Union, 2001)
    A majority of a complete sample of 3CR FR I radio galaxies show unresolved optical nuclear sources on the scales of 0.1 arcsec. These Compact Central Cores (CCC) have been interpreted as the optical counterparts of the ...
  • Parsec-scale magnetic field structures in HEAO-1 BL Lacs 
    Kharb, P; Gabuzda, D; Shastri, P (Blackwell Publishing, 2008-02)
    We present very long baseline interferometry polarization images of an X-ray-selected sample of BL Lacertae objects belonging to the first HEAO-1 and the ROSAT–Green Bank (RGB) surveys. These are primarily high-energy-peaked ...
  • Parsec-scale radio morphology in Seyfert galaxies 
    Lal, D. V; Shastri, P; Gabuzda, D. C (The Astronomical Society of the Pacific, 2001)
  • Pc-scale study of radio galaxies and BL Lacs 
    Kharb, P; Shastri, P; Gabuzda, D. C (Elsevier, 2003-10)
    We study two aspects of the differences between Active Galactic Nuclei (AGN) of the two Fanaroff-Riley types in order to investigate the causes of the F-R divide. We: (a) contrast the properties of the optical cores in ...
  • Polarization study of BL Lacertae objects on pc-scales 
    Kharb, P; Gabuzda, D; Shastri, P (Astronomical Society of India, 2002-09)
    We present results of the VLBA3 polarization observations of "X-ray selected" BL Lac objects from the HEAO-l survey and also a few from the ROSAT-Green Bank (RGB) sample. These primarily high energy peaked BL Lacs (HBLs) ...
  • A polarization study of three blazars using uGMRT at ∼600 MHz 
    Baghel, J; Silpa, S; Kharb, P; Sebastian, B; Shastri, P (Indian Academy of Sciences, 2022-12)
    We present results from our radio polarimetric study with the upgraded giant metrewave radio telescope (uGMRT) at band 4 (550–850 MHz) of three blazars: radio-loud quasars 3C390.3, 4C71.07 and BL Lac object 1ES 2344+514. ...
  • Probing the physics of narrow line regions in active galaxies. II. the siding spring southern seyfert spectroscopic snapshot survey (S7) 
    Dopita, M. A; Shastri, P; Davies, R; Kewley, L; Hampton, E; Scharwachter, J; Sutherland, R; Kharb, P; Jose, J; Bhatt, H. C; Ramya, S; Jin, C; Banfield, J; Zaw, I; Juneau, S; James, B; Shweta Srivastava (IOP Publishing, 2015-03)
    Here we describe the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) and present results on 64 galaxies drawn from the first data release. The S7 uses the Wide Field Spectrograph mounted on the ANU 2.3 m ...
  • 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 ...
  • Probing the Physics of Narrow-line Regions in Active Galaxies. IV. Full Data Release of the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) 
    Thomas, A. D; Dopita, M. A; Shastri, P; Davies, R; Hampton, E; Kewley, L; Banfield, J; Groves, B; James, B. L; Jin, C; Juneau, S; Kharb, P; Lalitha, S; Scharwachter, J; Shalima, P; Sundar, M. N; Sutherland, R; Zaw, I (IOP Publishing, 2017-09)
    We present the second and final data release of the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). Data are presented for 63 new galaxies not included in the first data release, and we provide 2D ...
  • Probing the physics of narrow-line regions of Seyfert galaxies, I. The case of NGC 5427 
    Dopita, M. A; Scharwachter, J; Shastri, P; Kewley, L. J; Davies, R; Sutherland, R; Kharb, P; Jose, J; Hampton, E; Jin, C; Banfield, J; Basurah, H; Fischer, S (EDP Sciences, 2014-06)
    Context. The spectra of the extended narrow-line regions (ENLRs) of Seyfert 2 galaxies probe the physics of the central active galaxy nucleus (AGN), since they encode the energy distribution of the ionising photons, the ...
  • Probing the physics of Seyfert galaxies using their emission-line regions 
    Shastri, P; Dopita, M; Scharwachter, J; Kewley, L; Davies, R; Sutherland, R; Kharb, P; Banfield, J; Jose, J; Ramya, S; Srivastava, S; Bhatt, H. C; Hampton, E; Jin, J; Basurah, H; Fischer, S; Gupta, M; Panda, S; Sundar, M. N; Radhakrishnan, V (AIP Publishing, 2015-12)
    Active galaxies have powerhouses of radiation in their nuclear regions that are driven by accreting super-massive black holes. The accretion system also generates outflows of ionized gas and synchrotron-emitting bipolar ...
  • 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.
  • Relativistic beaming and central components of radio galaxies 
    Kharb, P; Shastri, P (Astronomical Society of India, 2001)
    We present results of our study of the parsec-scale components of radio galaxies as observed at radio and optical wavelengths, in the framework of the Unified Scheme.
  • The role of radiation pressure in the narrow line regions of Seyfert host galaxies 
    Davies, R. L; Dopita, M. A; Kewley, L; Groves, B; Sutherland, R; Hampton, E. J; Shastri, P; Kharb, P; Bhatt, H. C; Scharwachter, J; Jin, C; Banfield, J; Zaw, I; James, B; Juneau, S; Srivastava, S (IOP Publishing, 2016-06-10)
    We investigate the relative significance of radiation pressure and gas pressure in the extended narrow line regions (ENLRs) of four Seyfert galaxies from the integral field Siding Spring Southern Seyfert Spectroscopic ...
  • Rotation measures across parsec-scale jets of fanaroff-Riley Type I radio galaxies 
    Kharb, P; Gabuzda, D. C; O'Dea, C. P; Shastri, P; Baum, S. A (Institute of Physics, 2009-04)
    We present the results of a parsec-scale polarization study of three FRI radio galaxies—3C66B, 3C78, and 3C264—obtained with Very Long Baseline Interferometry at 5, 8, and 15 GHz. Parsec-scale polarization has been detected ...

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