IIA Institutional Repository: Recent submissions

  • Bar quenching: Evidence from star-formation-rate indicators 
    George, K; Subramanian, S (EDP Sciences, 2021-07)
    The central regions of star-forming barred spiral galaxies can be devoid of star formation because of the redistribution of gas along the length of the bar. However, there can be gas outside the length of the bar that can ...
  • Local patch analysis for testing statistical isotropy of the Planck convergence map 
    Goyal, Priya; Pravabati, C (IOP Publishing, 2021-08)
    The small but measurable effect of weak gravitational lensing on the cosmic microwave background radiation provide information about the large-scale distribution of matter in the universe. We use the all sky distribution ...
  • Accretion flow properties of GRS 1915+105 during Its θ class using AstroSat data 
    Banerjee, Anuvab; Bhattacharjee, Ayan; Chatterjee, Debjit; Debnath, Dipak; Chakrabarti, S. K; Katoch, Tilak; Antia, H. M (IOP Publishing, 2021-08-01)
    The Galactic microquasar GRS 1915+105 shows rich variability that is categorized into different classes. In this paper, we report the temporal and spectral analysis of GRS 1915+105 to study the properties of the accretion ...
  • Development of Spectrograph in FUV region for a possible ISRO flight 
    Jadhav, Sujay Vijay (Indian Institute of Astrophysics, 2021-07)
    The FUV (900-1800 Å) is the richest part of the spectrum in terms of emission lines – O VI (1032/1038 Å) and C IV (1548/1550 Å) from hot gas, C III (977 Å) and N III (1750 Å) from warm gas, and the Lyman and Werner bands ...
  • A triple active galactic nucleus in the NGC 7733–7734 merging group 
    Yadav, Jyoti; Mousumi Das; Barway, Sudhanshu; Combes, Francoise (EDP Sciences, 2021-07)
    Context. Galaxy interactions and mergers can lead to supermassive black hole (SMBH) binaries, which become active galactic nucleus (AGN) pairs when the SMBHs start accreting mass. If there is a third galaxy involved in the ...
  • Accretion flow properties of GRS 1716-249 during its 2016–17 failed outburst 
    Chatterjee, Kaushik; Debnath, Dipak; Chatterjee, Debjit; Jana, Arghajit; Sujoy Kumar Nath; Bhowmick, Riya; Chakrabarti, S. K (Springer Nature, 2021-07)
    In 2016–17, the Galactic transient black hole candidate GRS 1716-249 exhibited an outburst event after a long quiescence period of almost 23 years. The source remained in the outbursting phase for almost 9 months. We study ...
  • Early mass-varying neutrino dark energy: nugget formation and Hubble anomaly 
    Gogoi, Antareep; Sharma, Ravi Kumar; Chanda, Prolay; Das, Subinoy (IOP Publishing, 2021-07-10)
    We present a novel scenario in which light (~few eV) dark fermions (sterile neutrinos) interact with a scalar field as in mass-varying neutrino dark energy theories. As the eV sterile states naturally become nonrelativistic ...
  • 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 ...

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