IIA Institutional Repository: Recent submissions

  • AstroSat view of GRS 1915+105 during the soft state: detection of HFQPOs and estimation of mass and spin 
    Sreehari, H; Nandi, Anuj; Das, Santabrata; Agrawal, V. K; Mandal, Samir; Ramadevi, M. C; Katoch, Tilak (Oxford University Press on behalf of the Royal Astronomical Society, 2020-12)
    We report the results of AstroSat observations of GRS 1915+105 obtained using 100 ks Guaranteed Time during the soft state. The colour–colour diagram indicates a variability class of δ with the detection of high-frequency ...
  • Kilonova Luminosity Function Constraints Based on Zwicky Transient Facility Searches for 13 Neutron Star Merger Triggers during O3 
    Kasliwal, Mansi M; Anand, Shreya; Ahumada, Tomas; Stein, Robert; Carracedo, Ana Sagues; Andreoni, Igor; Coughlin, Michael W; Singer, Leo P; Kool, Erik C; Kishalay De; Harsh Kumar; Waratkar, Gaurav; Webb, Sara; Yu, Po-Chieh; Zhang, Bin-Bin; Zhou, Rongpu; Zolkower, Jeffry; AlMualla, Mouza; Yao, Yuhan; Bulla, Mattia; Dobie, Dougal; Reusch, Simeon; Perley, Daniel A; Cenko, S. Bradley; Bhalerao, Varun; Kaplan, David L; Sollerman, Jesper; Goobar, Ariel; Copperwheat, Christopher M; Bellm, Eric C; Anupama, G. C; Corsi, Alessandra; Nissanke, Samaya; Agudo, Ivan; Bagdasaryan, Ashot; Barway, Sudhanshu; Belicki, Justin; Bloom, Joshua S; Bolin, Bryce; Buckley, David A. H; Burdge, Kevin B; Burruss, Rick; Caballero-Garcia, Maria D; Cannella, Chris; Castro-Tirado, Alberto J; Cook, David O; Cooke, Jeff; Cunningham, Virginia; Dahiwale, Aishwarya; Deshmukh, Kunal; Dichiara, Simone; Duev, Dmitry A; Anirban Dutta; Feeney, Michael; Franckowiak, Anna; Frederick, Sara; Fremling, Christoffer; Gal-Yam, Avishay; Gatkine, Pradip; Ghosh, Shaon; Goldstein, Daniel A; Zach Golkhou, V; Graham, Matthew J; Graham, Melissa L; Hankins, Matthew J; Helou, George; Youdong Hu; Ip, Wing-Huen; Jaodand, Amruta; Karambelkar, Viraj; Kong, Albert K. H; Kowalski, Marek; Khandagale, Maitreya; Kulkarni, S. R; Brajesh Kumar; Laher, Russ R; Li, K. L; Mahaba, Ashish; Masci, Frank J; Miller, Adam A; Mogotsi, Moses; Mohite, Siddharth; Mooley, Kunal; Mroz, Przemek; Newman, Jeffrey A; Ngeow, Chow-Choong; Oates, Samantha R; Patil, Atharva Sunil; Pandey, S. B; Pavana, M; Pian, Elena; Riddle, Reed; Sanchez-Ramirez, Ruben; Sharma, Yashvi; Singh, A; Smith, Roger; Soumagnac, Maayane T; Taggart, Kirsty; Tan, Hanjie; Tzanidakis, Anastasios; Troja, Eleonora; Valeev, Azamat F; Walters, Richard (IOP Publishing, 2020-12-20)
    We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and ...
  • Band-limited integrated scatter measurements on super polished optical mirrors 
    Ventaka, S; Prasad, B. R; Natarajan, V; Kamath, P. U; Kathiravan, S (SPIE-The International Society for Optical Engineering, 2020-08)
    Scattering of light from a surface depends on its microroughness. In general, total integrated scattering of a surface is expressed in terms of root-mean-square microroughness (σrms) using empirical relations. These ...
  • Evolution of lithium in low-mass giants: an observational perspective 
    Bharat Kumar, Yerra; Reddy, B. E (Indian Academy of Sciences, 2020-12)
    The overabundance of lithium in low-mass red giants has been a topic of interest for over four decades. Low-mass stars are expected to destroy lithium gradually throughout their lifetimes. Against this expectation, about ...
  • Quasar catalogue for the astrometric calibration of the forthcoming ILMT survey 
    Mandal, A. K; Pradhan, Bikram; Surdej, Jean; Stalin, C. S; Sagar, R; Mathew, B (Indian Academy of Sciences, 2020-12)
    Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax. The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will ...
  • Distance, magnetic field, and kinematics of the filamentary cloud LDN 1157 
    Sharma, Ekta; Maheswar, G; Archana Soam; Lee, Chang Won; Kim, Shinyoung; Ghosh, Tuhin; Anandmayee Tej; Kim, Gwanjeong; Sharma, Neha; Saha, Piyali (EDP Sciences, 2020-07)
    Context. LDN 1157 is one of several clouds that are situated in the cloud complex LDN 1147/1158. The cloud presents a coma-shaped morphology with a well-collimated bipolar outflow emanating from a Class 0 protostar, LDN ...
  • K-band spectra of selected post-AGB candidates 
    Parthasarathy, M; Muthumariappan, C; Muneer, S (Springer Nature, 2020-07)
    We present medium resolution (1000) K-band spectra of 12 post-AGB candidates and related stars. For several objects in our sample, these spectra were obtained for the first time. The Brγ line in emission is detected in ...
  • UVIT/AstroSat studies of blue straggler stars and post-mass transfer systems in star clusters: detection of one more blue lurker in M67 
    Subramaniam, A; Pnadey, Sindhu; Jadhav, Vikrant V; Snehalata Sahu (Indian Academy of Sciences, 2020-12)
    The blue straggler stars (BSSs) are main-sequence (MS) stars, which have evaded stellar evolution by acquiring mass while on the MS. The detection of extremely low mass (ELM) white dwarf (WD) companions to two BSSs and one ...
  • Discovery of soft and hard X-ray time lags in low-mass AGNs 
    Mallick, L; Wilkins, D. R; Alston, W. N; Markowitz, A; Marco, B. De; Parker, M. L; Lohfink, A. M; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-05)
    The scaling relations between the black hole (BH) mass and soft lag properties for both active galactic nuclei (AGNs) and BH X-ray binaries (BHXRBs) suggest the same underlying physical mechanism at work in accreting BH ...
  • UVIT-HST-Gaia-VISTA study of Kron 3 in the small magellanic cloud: a cluster with an extended red clump in ultraviolet 
    Nayak, P. K; Subramaniam, A; Subramanian, S; Sahu, S; Mondal, C; Cioni, Maria-Rosa L; Bell, Cameron P. M; Bandyopadhyay, A; Chung, Chul (Oxford University Press on behalf of the Royal Astronomical Society, 2021-06)
    We have demonstrated the advantage of combining multiwavelength observations, from the ultraviolet (UV) to near-infrared, to study Kron 3, a massive star cluster in the Small Magellanic Cloud. We have estimated the radius ...
  • Mid-term periodicities in solar radio emission corresponding to sunspot number during solar cycle 23 
    Aroori, Mahender; Vemareddy, P; Chowdhury, Partha; Yellaiah, G (Springer, 2021-03)
    We present a systematic time-series analysis of solar radio emission in nine different frequencies to compare with that of daily sunspot number (SSN) during Solar Cycle 23 (1996-2009). Owing to the contribution from quiet-sun ...
  • Nonthermal hot dark matter from inflaton or moduli decay: Momentum distribution and relaxation of the cosmological mass bound 
    Bhattacharya, Sukannya; Das, Subinoy; Dutta, Koushik; Gangopadhyay, Mayukh Raj; Mahanta, Ratul; Maharana, Anshuman (American Physical Society, 2021-03-15)
    Decay of the inflaton or moduli which dominated the energy density of the universe at early times leads to a matter to radiation transition epoch. We consider nonthermal sterile dark matter (DM) particles produced as decay ...
  • Description of the methylene amidogene radical and its anion with an economical treatment of correlation effects using density functional theory orbitals 
    Chaudhuri, R. K; Chattopadhyay, Sudip (American Chemical Society, 2021-01-21)
    The ground and low-lying excited state electronic structural properties (such as equilibrium geometries, harmonic frequencies, excitation energies, barrier energy, and so on) of the methylene amidogene radical (H2CN) and ...
  • Determining the variations of Ca–K index and features using century-long equal-contrast images from Kodaikanal observatory 
    Singh, J; Priyal, M; Ravindra, B (IOP Publishing, 2021-02-20)
    In an earlier analysis of Ca–K spectroheliograms obtained at the Kodaikanal Observatory, the "Good" images were used to investigate variations in the chromosphere. However, the contrast of the images varied on a day-to-day ...
  • A machine learning approach for classification of accretion states of black hole binaries 
    Sreehari, H; Nandi, Anuj (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    In this paper, we employ Machine Learning algorithms on multimission observations for the classification of accretion states of outbursting black hole X-ray binaries for the first time. Archival data from RXTE, Swift, MAXI, ...
  • SN 2017hpa: a carbon-rich Type Ia supernova 
    Anirban Dutta; Singh, A; Anupama, G. C; Sahu, D. K; Brajesh Kumar (Oxford University Press on behalf of the Royal Astronomical Society, 2021-05)
    We present the optical (UBVRI) and ultraviolet (Swift-Ultraviolet and Optical Telescope) photometry, and optical spectroscopy of Type Ia supernova SN 2017hpa. We study broad-band ultraviolet (UV)+optical light curves and ...
  • Ultraviolet Imaging Telescope (UVIT) observation of the Galactic globular cluster NGC 7492 
    Kumar, R; Pradhan, A. C; Mohapatra, Abhisek; Moharana, Ayush; Ojha, D. K; Parthasarathy, M; Murthy, J (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    We present detailed photometric observations of the Galactic globular cluster NGC 7492 using the data obtained with two far-ultraviolet (FUV; 1300–1800 Å) and three near-ultraviolet (NUV; 2000–3000 Å) filters of Ultraviolet ...
  • Host star metallicity of directly imaged wide-orbit planets: implications for planet formation 
    Swastik, C; Banyal, R. K; Narang, Mayank; Manoj, P; Sivarani, T; Reddy, B. E; Rajaguru, S. P (IOP Publishing, 2021-03-01)
    Directly imaged planets (DIPs) are self-luminous companions of pre-main-sequence and young main-sequence stars. They reside in wider orbits (~tens to thousands of astronomical units) and generally are more massive compared ...
  • Are there transit timing variations for the exoplanet qatar-1b? 
    Su, Li-Hsin; Jiang, Ing-Guey; Sariya, Devesh P; Lee, Chiao-Yu; Yeh, Li-Chin; Mannaday, Vineet Kumar; Thaku, Parijat; Chand, Swadesh; Shlyapnikov, A. A; Moskvin, V. V; Ignatov, Vladimir; Mkrtichian, David; Griv, Evgeny; Sahu, D. K (IOP Publishing, 2021-03-01)
    Motivated by the unsettled conclusion on whether there are any transit timing variations (TTVs) for the exoplanet Qatar-1b, 10 new transit light curves are presented and a TTV analysis with a baseline of 1400 epochs is ...
  • Properties of polarized synchrotron emission from fluctuation-dynamo action – I. application to galaxy clusters 
    Sur, Sharanya; Basu, Aritra; Subramanian, Kandaswamy (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    Using magnetohydrodynamic simulations of fluctuation dynamos, we perform broad-bandwidth synthetic observations to investigate the properties of polarized synchrotron emission and the role that Faraday rotation plays in ...

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