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Browsing IIAP Publications by Author "Bhattacharya, D"

Browsing IIAP Publications by Author "Bhattacharya, D"

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  • Comprehensive multiwavelength modelling of the afterglow of GRB 050525A 
    Resmi, L; Misra, K; Johannesson, G; Castro-Tirado, A. J; Gorosabel, J; Jelınek, M; Bhattacharya, D; Kubanek, P; Anupama, G. C; Sota, A; Sahu, D. K; de Ugarte Postigo, A; Pandey, S. B; Sanchez-Ramırez, R; Bremer, M; Sagar, R (Wiley-Blackwell, 2012-11)
    The Swift era has posed a challenge to the standard blast-wave model of gamma-ray burst (GRB) afterglows. The key observational features expected within the model are rarely observed, such as the achromatic steepening ...
  • The dark nature of GRB 051022 and its host galaxy 
    Castro-Tirado, A. J; Bremer, M; McBreen, S; Gorosabel, J; Guziy, S; Fakthullin, T. A; Sokolov, V. V; González Delgado, R. M; Bihain, G; Pandey, S. B; Jelínek, M; de Ugarte Postigo, A; Misra, K; Sagar, R; Bama, P; Kamble, A. P; Anupama, G. C; Licandro, J; Pérez-Ramírez, D; Bhattacharya, D; Aceituno, F. J; Neri, R (EDP Sciences, 2007-11)
    Aims.We present multiwavelength (X-ray/optical/near-infrared/millimetre) observations of GRB 051022 between 2.5 h and ~1.15 yr after the event. It is the most intense gamma-ray burst (~10-4 erg cm-2) detected by HETE-2, ...
  • 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 ...
  • Early optical and millimeter observations of GRB 030226 afterglow 
    Pandey, S. B; Sagar, R; Anupama, G. C; Bhattacharya, D; Sahu, D. K; Castro-Tirado, A. J; Bremer, M (EDP Sciences, 2004-04)
    The CCD magnitudes in Johnson UBV and Cousins RI photometric passbands for the afterglow of the long duration GRB 030226 are presented. Upper limits of a few mJy to millimeter wave emission at the location of optical are ...
  • A flattening in the optical light curve of SN 2002ap 
    Pandey, S. B; Anupama, G. C; Sagar, R; Bhattacharya, D; Sahu, D. K; Pandey, J. C (Royal Astronomical Society, 2003-04)
    We present the UBVRcIc broad-band optical photometry of the Type Ic supernova SN 2002ap obtained during 2002 February 6-March 23 in the early decline phases and also later on 2002 August 15. Combining these data with the ...
  • A Flattening in the Optical Light Curve of SN 2002ap. 
    Pandey, S. B; Anupama, G. C; Sagar, R; Bhattacharya, D; Sahu, D. K; Pandey, J. C (Blackwell Publishing, Edinburge, UK, 1994)
  • General relativistic spectra of accretion discs around rapidly rotating neutron stars: effect of light bending 
    Bhattacharyya, S; Bhattacharya, D; Thampan, A. V (Royal Astronomical Society, 2001-08)
    We present computed spectra, as seen by a distant observer, from the accretion disc around a rapidly rotating neutron star. Our calculations are carried out in a fully general relativistic framework, with an exact treatment ...
  • Implications of kHz quasi-periodic brightness oscillations in X-ray binaries for neutron star structure 
    Thampan, A. V; Bhattacharya, D; Datta, B (Blackwell Science Ltd., 1999-02)
    Kilohertz quasi-periodic oscillations (QPOs) in low-mass X-ray binaries (LMXBs) may represent the orbital frequencies of the innermost Keplerian orbits around accreting neutron stars. Attempts have recently been made to ...
  • Multiwavelength study of different flaring and low-activity states of blazar 4C+21.35 
    Bhattacharya, D; Krishna Mohana, A; Bhattacharyya, S; Bhatt, N; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    Blazars, a class of active galactic nuclei, emit over the entire accessible electromagnetic spectrum and modelling of their broad-band spectral energy distribution (SED) is the key to constrain the underlying emission ...
  • Neutron star physics in the square kilometre array era: an Indian perspective 
    Konar, S; Bagchi, Manjari; Bandyopadhyay, Debades; Banik, Sarmistha; Bhattacharya, D; Bhattacharyya, S; Gangadhara, R. T; Gopakumar, A; Gupta, Y; Joshi, B. C; Maan, Yogesh; Maitra, Chandreyee; Mukherjee, D; Pai, Archana; Paul, B; Ray, A; Sutaria, F. K (Indian Academy of Sciences, 2016-12)
    It is an exceptionally opportune time for astrophysics when a number of next-generation mega-instruments are poised to observe the Universe across the entire electromagnetic spectrum with unprecedented data quality. The ...
  • A Numerical Survey of Neutron Star Crustal Density Profiles 
    Datta, B; Thampan, A. V; Bhattacharya, D (Indian Academy of Sciences, 1995-12)
    An accurate numerical survey of the density profiles corresponding to the crusts of neutron stars for representative equation of state models is presented. This will find application in calculations of thermal and magnetic ...
  • Ohmic decay of magnetic flux expelled from neutron star interiors 
    Bhattacharya, D; Datta, B (Royal Astronomical Society, 1996-10)
    We study Ohmic diffusion of magnetic flux expelled from the superconducting core of a neutron star to its crust owing to spindown-induced field evolution. We find that Ohmic decay time-scales in the range 10^7.5-10^9 yr ...
  • The optical afterglow of the not so dark GRB 021211 
    Pandey, S. B; Anupama, G. C; Sagar, R; Bhattacharya, D; Castro-Tirado, A. J; Sahu, D. K; Parihar, P. S; Prabhu, T. P (The European Southern Observatory, 2003-09)
    We determine Johnson B,V and Cousins R,I photometric CCD magnitudes for the afterglow of GRB 021211 during the first night after the GRB trigger. The afterglow was very faint and would have been probably missed if no prompt ...
  • Optical observations of GRB 060124 afterglow: a case for an injection break 
    Misra, K; Bhattacharya, D; Sahu, D. K; Sagar, R; Anupama, G. C; Castro-Tirado, A. J; Guziy, S. S; Bhatt, B. C (EDP Sciences, 2007-03)
    Aims.We present broad band optical afterglow observations of a long duration GRB 060124 using the 1.04-m Sampurnanand Telescope at ARIES, Nainital and the 2.01-m HCT at IAO, Hanle, including the earliest ground-based ...
  • Optical observations of the bright long duration peculiar GRB 021004 afterglow. 
    Pandey, S. B; Sahu, D. K; Resmi, L; Sagar, R; Anupama, G. C; Bhattacharya, D; Mohan, V; Prabhu, T. P; Bhatt, B. C; Pandey, J. C; Parihar, P. S; Castro-Tirado, A. J (Astronomical Society of India, 2003)
    The CCD magnitudes in Johnson B,V and Cousins R and I photometric passbands are determined for the bright long duration GRB 021004 afterglow from 2002 October 4 to 16 starting ~ 3 hours after the γ - ray burst. Light curves ...
  • Probing into emission mechanisms of GRB 190530A using time-resolved spectra and polarization studies: synchrotron origin? 
    Gupta, Rahul; Gupta, S; Chattopadhyay, T; Lipunov, V; Castro-Tirado, A. J; Bhattacharya, D; Pandey, S. B; Oates, S. R; Kumar, Amit; Hu, Y-D; Valeev, A. F; Minaev, P. Yu; Kumar, H; Vinko, J; Dimple; Sharma, V; Aryan, A; Castellon, A; Gabovich, A; Moskvitin, A; Ordasi, A; Pal, A; Pozanenko, A; Zhang, B-B; Kumar, B; Svinkin, D; Saraogi, D; Vlasenko, D; Fernandez-Garcia, E; Gorbovskoy, E; Anupama, G. C; Misra, K; Sarneczky, K; Kriskovics, L; Castro-Tirado, M. A; Caballero-Garcia, M. D; Tiurina, N; Balanutsa, P; Lopez, R. R; Sanchez-Ramirez, R; Szakats, R; Belkin, S; Guziy, S; Iyyani, S; Tiwari, S. N; Vadawale, Santosh V; Sun, T; Bhalerao, V; Kornilov, V; Sokolov, V. V (Oxford University Press on behalf of Royal Astronomical Society, 2022-04)
    Multipulsed GRB 190530A, detected by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope onboard Fermi, is the sixth most fluent GBM burst detected so far. This paper presents the timing, spectral, and polarimetric ...
  • Radio, millimeter and optical monitoring of GRB 030329 afterglow: constraining the double jet model 
    Resmi, L; Ishwara-Chandra, C. H; Castro-Tirado, A. J; Bhattacharya, D; Rao, A. P; Bremer, M; Pandey, S. B; Sahu, D. K; Bhatt, B. C; Sagar, R; Anupama, G. C; Subramaniam, A; Lundgren, A; Gorosabel, J; Guziy, S; de Ugarte Postigo, A; Castro Cerón, J. M; Wiklind, T (EDP Sciences, 2005-09)
    We present radio, millimeter and optical observations of the afterglow of GRB 030329. $UBVR_{\rm C}I_{\rm C}$ photometry is presented for a period of 3 h to 34 days after the burst. Radio monitoring at 1280 MHz has been ...
  • SN 2002ap, the Hypernova of Class Ic 
    Pandey, S. B; Sahu, D. K; Anupama, G. C; Bhattacharya, D; Sagar, R (Astronomical Society of India, 2003)
    The supernova SN 2002ap was discovered in the outer regions of the nearby spiral M74 on January 29.4 UT. Early photometric and spectroscopic observations indicate the supernova belongs to the class of Ic hypernova. Late ...

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