IIA Institutional Repository: Recent submissions

  • The pulsar radio emission and polarization 
    Roy, Tridib (Indian Institute of Astrophysics, 2020-06)
    The thesis is mainly focused on the modeling of pulsar radio emission and polarization. The radio emission mechanism of pulsar is not fully understood, because of the lack of understanding about the kinematical processes ...
  • The nature of non-Gaussianity and statistical isotropy of the 408 MHz Haslam synchrotron map 
    Fazlu Rahman; Pravabati, C; Ghosh, Tuhin (IOP Publishing, 2021-07)
    Accurate component separation of full-sky maps in the radio and microwave frequencies, such as the cosmic microwave background (CMB), relies on a thorough understanding of the statistical properties of the Galactic foreground ...
  • Turbulent proton heating rate in the solar wind from 5–45 R⊙ 
    Sasikumar Raja, K; Subramanian, P; Ingale, M; Ramesh, R; Maksimovic, Milan (IOP Publishing, 2021-06-20)
    Various remote sensing observations have been used so far to probe the turbulent properties of the solar wind. Using the recently reported density modulation indices that are derived using angular broadening observations ...
  • A theoretical model of the near-surface shear layer of the Sun 
    Jha, Bibhuti K; Choudhuri, A. R (Oxford University Press on behalf of the Royal Astronomical Society, 2021-09)
    The Sun has a near-surface shear layer (NSSL), within which the angular velocity decreases rapidly with radius. We provide an explanation of this layer based on the thermal wind balance equation. Since convective motions ...
  • Prototype tracking system for observing the Sun at decimeter and meter wavelengths 
    Sayuf, Shaik (Indian Institute of Astrophysics, 2021-07)
    The outer atmosphere of the Sun is observed to be a very hot plasma medium. Since the frequency of electromagnetic wave emission from a plasma medium depends on the electron number density, high frequency radio waves ...
  • Design and development of atmospheric dispersion corrector and fiber positioner for TMT-HROS 
    Manjunath, B (Indian Institute of Astrophysics, 2021-07)
    Earth’s atmosphere is one of the significant factors affecting the quality of ground-based observations. For off-zenith observations with ground-based astronomical telescopes, the image size on the telescope's focal plane ...
  • Development of wavefront sensing system for high order AO system 
    Shubham Jankiram, Ghatul (Indian Institute of Astrophysics, 2021-07)
    The ground-based stellar astronomy suffers from the atmospheric turbulence diminishing minute details in the images taken of celestial objects. Adaptive Optics is a tool that comes to the rescue of the astronomers who wish ...
  • Multiwavelength studies of nova systems 
    Pavana, M (Indian Institute of Astrophysics, 2020-09)
    Novae are interacting binary star systems consisting of a Roche-lobe filling secondary on or near the main sequence, losing hydrogen-rich material through the inner-Lagrangian point onto an accretion disc surrounding the ...
  • Relativistic dynamics in black hole systems and implications for observations 
    Prerna Rana (Indian Institute of Astrophysics, 2020-08)
  • Scattering theory and radiative transfer in spherically symmetric moving atmospheres 
    Megha, A (Indian Institute of Astrophysics, 2020-05)
    Magnetic fields are ubiquitous in astrophysical plasmas. They are responsible for most of the stellar activities and they manifest in numerous ways in the stellar atmospheres. The Sun being our nearest star is the natural ...
  • The optical-GeV connection in fermi blazars 
    Bhoomika (Indian Institute of Astrophysics, 2020-07)
    Blazars are a class of active galactic nuclei (AGN) that have relativistic jets that are oriented close to the observers line of sight. They display ux variability across the en- tire accessible electromagnetic spectrum ...
  • Design and development of closed-loop AO system for 2-m class telescope at IIA 
    Satya Ranjan Behera (Indian Institute of Astrophysics, 2020)
    Adaptive Optics (AO) is a real time wave-front correction technique, through which the light coming from the stars can be corrected for the effects of atmospheric turbulence. This enables the ground based telescope to reach ...
  • Low frequency view of GRB 190114C reveals time varying shock micro-physics 
    Misra, K; Resmi, L; Kann, D. A; Marongiu, M; Moin, A; Klose, S; Bernardi, G; de Ugarte Postigo, A; Jaiswal, V. K; Schulze, S; Perley, D. A; Ghosh, A; Dimple; Kumar, H; Gupta, R; Michałowski, M. J; Martin, S; Cockeram, A; Cherukuri, S. V; Bhalerao, V; Anderson, G. E; Pandey, S. B; Anupama, G. C; Thone, C. C; Barway, Sudhanshu; Wieringa, M. H; Fynbo, J. P. U; Habeeb, N (Oxford University Press on behalf of the Royal Astronomical Society, 2021-07)
    We present radio and optical afterglow observations of the TeV-bright long gamma-ray burst 190114C at a redshift of z = 0.425, which was detected by the Major Atmospheric Gamma Imaging Cherenkov telescope. Our observations ...
  • Some glimpses of the plasma processes involved in power spectra of radio pulsars 
    Roy, Tridib (Oxford University Press on behalf of the Royal Astronomical Society, 2021-07)
    Although more than a half-century since pulsar discovery, the field of pulsar astronomy has attained an unprecedented level of success and has opened several windows in astronomy, very few theories have been put forwarded ...
  • Jet properties of XTE J1752−223 during its 2009–2010 outburst 
    Debnath, Dipak; Chatterjee, Kaushik; Chatterjee, Debjit; Jana, Arghajit; Chakrabarti, S. K (Oxford University Press on behalf of the Royal Astronomical Society, 2021-07)
    Galactic short orbital period black hole candidate (BHC) XTE J1752−223 was discovered on 2009 October 21 by the Rossi X-ray Timing Explorer (RXTE). We study the spectral properties of this outburst using transonic flow ...
  • Appearance versus disappearance of broad absorption line troughs in quasars 
    Mishra, Sapna; Vivek, M; Chand, Hum; Joshi, Ravi (Oxford University Press on behalf of the Royal Astronomical Society, 2021-07)
    We present a new set of 84 broad absorption line (BAL) quasars (1.7 < zem < 4.4) exhibiting an appearance of C IV BAL troughs over 0.3–4.8 rest-frame years by comparing the Sloan Digital Sky Survey Data Release (SDSSDR)-7, ...
  • Galaxy flybys: evolution of the bulge, disc, and spiral arms 
    Ankit Kumar; Mousumi Das; Kataria, Sandeep Kumar (Oxford University Press on behalf of the Royal Astronomical Society, 2021-09)
    Galaxy flybys are as common as mergers in low-redshift Universe and are important for galaxy evolution as they involve the exchange of significant amounts of mass and energy. In this study, we investigate the effect of ...
  • Evolution of primordial dark matter planets in the early Universe 
    Kiren, O. V; Arun, K; Sivarani, C (Elsevier B. V, 2021-08-15)
    In a recent paper we had discussed possibility of DM at high redshifts forming primordial planets composed entirely of DM to be oneof the reasons for not detecting DM (as the flux of ambient DM particles would be consequently ...
  • In-orbit performance of UVIT over the past 5 years 
    Ghosh, S. K; Joseph, P; Kumar, A; Postma, J; Stalin, C. S; Subramaniam, A; Tandon, S. N; Barve, Indrajit V; Devaraj, A; George, K; Girish, V; Hutchings, J. B; Kamath, P. U; Kathiravan, S; Lancelot, J. P; Leahy, D; Mahesh, P. K; Mohan, R; Nagabhushana, S; Pati, A. K; Kameswara Rao, N; Sankarasubramanian, K; Sreekumar, P; Sriram, S (Indian Academy of Sciences, 2021-10)
    Over the last 5 years, UVIT has completed observations of more than 500 proposals with ∼800 unique pointings. In addition, regular planned monitoring observations have been made and from their analysis various key parameters ...
  • Is the binding energy of galaxies related to their core black hole mass? 
    Sivaram, C; Arun, K (Indian Academy of Sciences, 2021-10)
    Most of the large galaxies host a supermassive black hole, but their origin is still not well understood. In this paper, we look at a possible connection between the gravitational binding energies of large galaxies, etc., ...

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