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  • AGN Feedback in Galaxy Groups: A Joint GMRT/X‐ray Study 
    Giacintucci, S.; Vrtilek, J. M.; O’Sullivan, E.; Raychaudhury, S.; David, L. P.; Venturi, T.; ATHREYA, RAMANA; Gitti, M. (AIP Publishing, 2009-12)
    We present an ongoing study of 18 nearby galaxy groups, chosen for the availability of Chandra and/or XMM‐Newton data and evidence for AGN/hot intragroup gas interaction. We have obtained 235 and 610 MHz observations at ...
  • AGN feedback in groups of galaxies: a joint X‐ray/low‐frequency radio study 
    Giacintucci, S.; O’Sullivan, E.; Vrtilek, J. M.; Raychaudhury, S.; David, L. P.; Venturi, T.; ATHREYA, RAMANA; Gitti, M. (AIP Publishing, 2010-07)
    We present an ongoing, low‐frequency radio/X‐ray study of 18 nearby galaxy groups, chosen for the evidence, either in the X‐ray or radio images, of AGN/intragroup gas interaction. We have obtained radio observations at 235 ...
  • The very steep spectrum radio halo in Abell 697 
    Macario, G.; Venturi, T.; Brunetti, G.; Dallacasa, D.; Giacintucci, S.; Cassano, R.; Bardelli, S.; ATHREYA, RAMANA (EDP Sciences, 2010-07)
    Aims. We present a detailed study of the giant radio halo in the galaxy cluster Abell 697 to constrain its origin and connection with the cluster dynamics. Methods. We performed high sensitivity GMRT observations at 325 ...
  • An elusive radio halo in the merging cluster Abell 781? 
    Venturi, T.; Giacintucci, G.; Dallacasa, D.; Brunetti, G.; Cassano, R.; Macario, G; ATHREYA, RAMANA (Oxford University Press, 2011-01)
    Deep radio observations of the galaxy cluster Abell 781 have been carried out using the Giant Metrewave Radio Telescope at 325 MHz and have been compared to previous 610-MHz observations and to archival Very Large Array ...
  • Detection of off-pulse emission from PSR B0525+21 And PSR B2045-16 
    Basu, Rahul; ATHREYA, RAMANA; Mitra, Dipanjan (IOP Publishing, 2011-02)
    We report the detection of off-pulse emission from two long-period pulsars PSR B0525+21 and PSR B2045-16 using the Giant Metrewave Radio Telescope. We recorded high time resolution interferometric data at 325 MHz and gated ...
  • Sustainable Bird Based Tourism in India's Remote North-East Frontier 
    Mohan, Dhananjai; ATHREYA, RAMANA (Emerald Publishing, 2011-03)
    Arunachal Pradesh is the most biodiverse Indian state situated in its north-east with the second highest breeding bird diversity in the world. Despite this, the area did not exist in bird-based tourism map till as late as ...
  • A combined low-radio frequency/x-ray study of galaxy groups. I. Giant metrewave radio telescope observations at 235 MHz and 610 MHz 
    Giacintucci, Simona; O'Sullivan, Ewan; Vrtilek, Jan; David, Laurence P.; Raychaudhury, Somak; Venturi, Tiziana; ATHREYA, RAMANA; Clarke, Tracy E.; Murgia, Matteo; Mazzotta, Pasquale; Gitti, Myriam; Ponman, Trevor; Ishwara Chandra, C. H.; Jones, Christine; Forman, William R. (IOP Publishing, 2011-04)
    We present new Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz of 18 X-ray bright galaxy groups. These observations are part of an extended project, presented here and in future papers, which combines ...
  • Localized H I 21-cm absorption towards a double-lobed z=0.24 radio galaxy 
    Curran, S. J.; Whiting, M. T.; Webb, J. K.; ATHREYA, RAMANA (Oxford University Press, 2011-06)
    We present the results of a mini-survey for associated HI 21-cm absorption at z≤ 0.42 with the Giant Metrewave Radio Telescope. Our targets are radio galaxies, selected on the basis that the γ ≈ 1216 Å luminosities are ...
  • Gated interferometric imaging of pulsars to detect off-pulse emission 
    ATHREYA, RAMANA; Basu, Rahul; Mitra, Dipanjan (IEEE, 2011-08)
    We detected off-pulse emission from two pulsars, B0525+21 and B204516, at 325 MHz using the Giant Metrewave radio telescope. Using the instrument as a high time resolution interferometer and off-line gating we imaged the ...
  • An unlikely radio halo in the low X-ray luminosity galaxy cluster RXC J1514.9-1523 (Research Note) 
    Giacintucci, S.; Dallacasa, D.; Venturi, T.; Brunetti, G.; Cassano, R.; Markevitch, M.; ATHREYA, RAMANA (EDP Sciences, 2011-10)
    We report the discovery of a giant radio halo in the galaxy cluster RXC J1514.9-1523 at z = 0.22 with a relatively low X-ray luminosity, LX[0.1−2.4 kev] ~ 7 × 1044 erg s-1. This faint, diffuse radio source is detected with ...
  • Seyfert Galaxies: Radio Continuum Emission Properties and the Unification Scheme 
    Singh, Veeresh; Shastri, Prajval; ATHREYA, RAMANA (Springer Nature, 2011-12)
    Seyfert galaxies are classified mainly into type 1 and type 2 depending on the presence and absence of broad permitted emission lines in their optical spectra, respectively. Unification scheme hypothesizes that the observed ...
  • Recurrent Radio Outbursts at the Center of the NGC 1407 Galaxy Group 
    Giacintucci, Simona; O'Sullivan, Ewan; Clarke, Tracy E.; Murgia, Matteo; Vrtilek, Jan M.; Venturi, Tiziana; David, Laurence P.; Raychaudhury, Somak; ATHREYA, RAMANA (IOP Publishing, 2012-08)
    We present deep Giant Metrewave Radio Telescope (GMRT) radio observations at 240, 330, and 610 MHz of the complex radio source at the center of the NGC 1407 galaxy group. Previous GMRT observations at 240 MHz revealed ...
  • On the Nature of off-pulse emission from pulsars 
    Basu, Rahul; Mitra, Dipanjan; ATHREYA, RAMANA (IOP Publishing, 2012-10)
    In our earlier studies, we reported the detection of off-pulse emission from two long-period pulsars B0525+21 and B2045-16. The pulsars were observed at a single epoch using the 325 MHz frequency band of the Giant Meterwave ...
  • A survey for H I in the distant Universe: the detection of associated 21-cm absorption at z = 1.28 
    Curran, S. J.; Whiting, M. T.; Tanna, A.; Sadler, E. M.; Pracy, M. B.; ATHREYA, RAMANA (Oxford University Pres, 2013-03)
    We have undertaken a survey for H I 21-cm absorption within the host galaxies of z ∼ 1.2-1.5 radio sources, in the search of the cool neutral gas currently ‘missing’ at z ≳ 1. This deficit is believed to be due to the ...
  • 153 MHz GMRT follow-up of steep-spectrum diffuse emission in galaxy clusters 
    Macario, G.; Venturi, T.; Intema, H. T.; Dallacasa, D.; Brunetti, G.; Cassano, R.; Giacintucci, S.; Ferrari, C.; Ishwara-Chandra, C. H.; ATHREYA, RAMANA (EDP Sciences, 2013-03)
    Aims. We present new high-sensitivity 153 MHz Giant Meterwave Radio Telescope follow-up observations of the diffuse steep-spectrum cluster radio sources in the galaxy clusters Abell 521, Abell 697, and Abell 1682. Abell 521 ...
  • Low-frequency radio observations of Seyfert galaxies: A test of the unification scheme 
    Singh, V.; Shastri, P.; Ishwara-Chandra, C. H.; ATHREYA, RAMANA (EDP Sciences, 2013-06)
    Aims. We present low-frequency radio imaging and spectral properties of a well-defined sample of Seyfert galaxies using GMRT 240/610 MHz dual frequency observations. Radio spectra of Seyfert galaxies over 240 MHz to 5.0 ...
  • The Extended GMRT Radio Halo Survey I. New upper limits on radio halos and mini-halos 
    Kale, R.; Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Macario, G.; ATHREYA, RAMANA (EDP Sciences, 2013-09)
    Context. A fraction of galaxy clusters host diffuse radio sources called radio halos, radio relics and mini-halos. These are associated with the relativistic electrons and magnetic fields present on similar to Mpc scales ...
  • Revalidation of Natrix clerki Wall, 1925, an overlooked species in the genus Amphiesma Duméril, Bibron & Duméril, 1854 (Squamata: Natricidae) 
    David, P.; Agarwal, I.; ATHREYA, RAMANA; Mathew, R.; Vogel, G.; Mistry, V.K (Magnolia Press, 2015-02)
    Natrix clerki Wall, 1925, previously known from its sole holotype and considered a synonym of Amphiesma parallelum (Boulenger, 1890), is resurrected in the genus Amphiesma on the basis of the analysis of morphological ...
  • The Extended GMRT Radio Halo Survey II. Further results and analysis of the full sample 
    Kale, R.; Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Cuciti, V.; Macario, G.; ATHREYA, RAMANA (EDP Sciences, 2015-07)
    The intra-cluster medium contains cosmic rays and magnetic fields that are manifested through the large scale synchrotron sources, termed radio haloes, relics, and mini-haloes. The Extended Giant Metrewave Radio Telescope ...
  • A search for H I and OH absorption in z ≳ 3 CO emitters 
    Curran, S. J.; Allison, J. R.; Whiting, M. T.; Sadler, E. M.; Combes, F.; Pracy, M. B.; Bignell, C.; ATHREYA, RAMANA (Oxford University Press, 2016-02)
    We present the results of a survey for H I 21 cm and OH 18 cm absorption in seven strong CO emitters at z ≳ 3. Despite reaching limits comparable to those required to detect 21 cm absorption at lower redshifts, we do not ...