IIA Institutional Repository: Recent submissions

  • The first GeV outburst of the radio-loud narrow-line Seyfert 1 galaxy PKS 1502+036 
    Paliya, Vaidehi S; Stalin, C. S (IOP Publishing, 2016-03)
    The γ-ray-loud narrow-line Seyfert 1 (γ-NLSy1) galaxy PKS 1502+036 (z = 0.409) exhibited its first γ-ray outburst on 2015 December 20. In the energy range of 0.1–300 GeV, the highest flux measured by the Fermi-Large Area ...
  • 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 ...
  • Interstellar medium and star formation studies with the square kilometre array 
    Manoj, P; Vig, S; Maheswar, G; Kamath, U. S (Indian Academy of Sciences, 2016-12)
    Stars and planetary systems are formed out of molecular clouds in the interstellar medium. Although the sequence of steps involved in star formation are generally known, a comprehensive theory which describes the details ...
  • UVIT open cluster study. I. detection of a white dwarf companion to a blue straggler in M67: evidence of formation through mass transfer 
    Sindhu, N; Subramaniam, A; Jadhav, V. V; Chatterjee, Sourav; Geller, Aaron M; Knigge, Christian; Leigh, Nathan; Puzia, Thomas H; Shara, Michael; Simunovic, Mirko (IOP Publishing, 2019-09-01)
    The old open cluster M67, populated with blue straggler stars (BSSs), is a well-known test bed to study the BSS formation pathways. Here, we report the first direct detection of a white dwarf (WD) companion to a BSS in ...
  • Dark Matter Objects: Possible New Source of Gravitational Waves 
    Sivaram, C; Arun, K (Springer, 2019-10)
    Gravitational waves from mergers of black holes and neutron stars are now being detected by LIGO. Here we look at a new source of gravitational waves, i.e., a class of dark matter objects whose properties were earlier ...
  • First sub-parsec-scale mapping of magnetic fields in the vicinity of a very-low-luminosity object, L1521F-IRS 
    Archana Soam; Lee, C. W; Andersson, B.G; Maheswar, G; Juvela, Mika; Liu, Tie; Kim, Gwanjeong; Ramprasad Rao; Chung, E.J; Kwon, Woojin; Ekta, S S (IOP Publishing, 2019-09-20)
    L1521F is found to be forming multiple cores and it is cited as an example of the densest core with an embedded VeLLO in a highly dynamical environment. We present the core-scale magnetic fields (B-fields) in the near ...
  • 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 ...
  • Chemical compositions and kinematics of the Hercules stream 
    Ramya, P; Reddy, B. E; Lambert, D. L; Musthafa, M. M (Oxford University Press on behalf of the Royal Astronomical Society, 2016-08)
    An abundance analysis is reported of 58-K giants identified by Famaey et al. ( 2005 , A&A, 430, 165) as highly probable members of the Hercules stream selected from stars north of the celestial equator in the Hippar ...
  • An upper limit on the ratio between the extreme ultraviolet and the bolometric luminosities of stars hosting habitable planets 
    Sengupta, S (Indian Academy of Sciences, 2016-07)
    An abundance analysis is reported of 58-K giants identified by Famaey et al. ( 2005 , A&A, 430, 165) as highly probable members of the Hercules stream selected from stars north of the celestial equator in the Hippar ...
  • Statistical study of network jets observed in the solar transition region: a comparison between coronal holes and quiet-sun regions 
    Narang, Nancy; Arbacher, R. T; Tian, H; Banerjee, D; Cranmer, S. R; DeLuca, Ed E; McKillop, S (Springer, 2014-04)
    Recent IRIS observations have revealed a prevalence of intermittent small-scale jets with apparent speeds of 80 – 250 km s−1, emanating from small-scale bright regions inside network boundaries of coronal holes. We find ...
  • Spectroscopic study of Be-shell stars : 4 Her and 88 Her 
    Bhat, S. S; Paul, K. T; Subramaniam, A; Mathew, B (IOP Publishing, 2016-06)
    We present an optical spectroscopic study based on 41 spectr a of 4 Her and 32 spectra of 88 Her, obtained over a period of 6 months. We estimate the rotationa l velocity of these stars from He I lines in the blue ...
  • 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 ...
  • Stochastic modeling of multiwavelength variability of the classical BL Lac Object OJ 287 on timescales ranging from decades to hours 
    Goyal, A; Stawarz, L; Zola, S; Marchenko, V; Soida, M; Nilsson, K; Ciprini, S; Baran, A; Ostrowski, M; Wiita, P. J; Gopal-Krishna; iemiginowska, A; Sobolewska, M; Jorstad, S; Marscher, A; Aller, M. F; Aller, H. D; Hovatta, T; Caton, D. B; Reichart, D; Matsumoto, K; Sadakane, K; Gazeas, K; Kidger, M; Piirola, V; Jermak, H; Alicavus, F; Baliyan, K. S; Baransky, A; Berdyugin, A; Blay, P; Boumis, P; Boyd, D; Bufan, Y; Campas Torrent, M; Campos, F; Carrillo Gomez, J; Dalessio, J; Debski, B; Dimitrov, D; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Gafton, E; Garcia, F; Godunova, V; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Haque, S; Harmanen, J; Hudec, R; Hurst, G; Ivarsen, K. M; Joshi, A; Kagitani, M; Karaman, N; Karjalainen, R; Kaur, N; Koziel-Wierzbowska, D; Kuligowska, E; Kundera, T; Kurowski, S; Kvammen, A; LaCluyze, A. P; Lee, B. C; Liakos, A; Lozano de Haro, J; Moore, J. P; Mugrauer, M; Naves Nogues, R; Neely, A. W; Ogloza, W; Okano, S; Pajdosz, U; Pandey, J. C; Perri, M; Poyner, G; Provencal, J; Pursimo, T; Raj, A; and 29 co-authors (IOP Publishing, 2018-08-20)
    We present the results of our power spectral density analysis for the BL Lac object OJ 287, utilizing the Fermi-LAT survey at high-energy γ-rays, Swift-XRT in X-rays, several ground-based telescopes and the Kepler satellite ...
  • Authenticating the presence of a relativistic massive black hole binary in OJ 287 using Its general relativity centenary flare: improved orbital parameters 
    Dey, L; Valtonen, M. J; Gopakumar, A; Zola, S; Hudec, R; Pihajoki, P; Ciprini, S; Matsumoto, K; Sadakane, K; Kidger, M; Nilsson, K; Mikkola, S; Sillanpaa, A; Takalo, L. O; Lehto, H. J; Berdyugin, A; Piirola, V; Jermak, H; Baliyan, K. S; Pursimo, T; Caton, D. B; Alicavus, F; Baransky, A; Blay, P; Boumis, P; Boyd, D; Campas Torrent, M; Campos, F; Carrillo Gomez, J; Chandra, S; Chavushyan, V; Dalessio, J; Debski, B; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Gafton, E; Ganesh, S; Garcia, F; Gazeas, K; Godunova, V; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Harmanen, J; Hurst, G; Janik, J; Jelinek, M; Joshi, A; Kagitani, M; Karjalainen, R; Kaur, N; Keel, W. C; Kouprianov, V. V; Kundera, T; Kurowski, S; Kvammen, A; LaCluyze, A. P; Lee, B. C; Liakos, A; Lindfors, E; Lozano de Haro, J; Mugrauer, M; Naves Nogues, R; Neely, A. W; Nelson, R. H; Ogloza, W; Okano, S; Pajdosz-Smierciak, U; Pandey, J. C; Perri, M; Poyner, G; Provencal, J; Raj, A; and 27 co-authors (IOP Publishing, 2018-10-10)
    Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the ...
  • Gravity of accelerations on quantum scales and its consequences 
    Sivaram, C; Arun, K; Kiren, O. V; Sreenath, B. N (Hadronic Press Inc, 2015-12)
    Gravity stands apart from other fundamental interactions in that it is locally equivalent to an accelerated frame and can be transformed away. Again it is indistinguishable from the geometry of space-time (which is an arena ...
  • Science at high-altitude sites of ARIES-astrophysics and atmospheric sciences 
    Sagar, R; Naja, M; Maheswar, G; Srivastava, A. K (Indian National Science Academy, 2014-11)
    In this article we discuss various frontline research activities those are being carried out in the fields of Astronomy and Astrophysics and Atmospheric Sciences at Aryabhatta Research Institute of Observational Sciences ...
  • Association of calcium network bright points with underneath photospheric magnetic patches 
    Narang, Nancy; Banerjee, D; Chandrashekhar, K; Pant, V (Springer, 2019-04)
    Recent dedicated Hinode polar region campaigns revealed the presence of concentrated kilogauss patches of the magnetic field in the polar regions of the Sun, which are also shown to be correlated with facular bright points ...
  • Temperate Earth-sized planets transiting a nearby ultracool dwarf star 
    Gillon, M; Jehin, E; Lederer, S. M; Delrez, L; De Wit, J; Burdanov, A; Van Grootel, V; Burgasser, A. J; Triaud, A. H. M. J; Opitom, C; Demory, Brice-Olivier; Sahu, D. (Nature Publishing Group, 2016-05)
    Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as ‘ultracool dwarfs’1. This heterogeneous group includes stars of extremely low mass as well as brown dwarfs (substellar objects ...
  • Degree of electric current neutralization and the activity in solar active regions 
    Vemareddy, P (Oxford University Press on behalf of the Royal Astronomical Society, 2019-07)
    Using time-sequence vector magnetic field observation from Helioseismic and Magnetic Imager, we examined the connection of non-neutralized currents and the observed activity in 20 solar active regions (ARs). The net current ...
  • RR Lyrae stars and the horizontal branch of NGC 5904 (M5) 
    Ferro, A. A; Luna, A; Bramich, D. M; Giridhar, S; Ahumada, J. A; Muneer, S (Springer, 2016-05)
    We report the distance and [Fe/H] value for the globular cluster NGC 5904 (M5) derived from the Fourier decomposition of the light curves of selected RRab and RRc stars. The aim in doing this was to bring these ...

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