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13 results on '"National Centre for Radio Astrophysics [Pune] (NCRA)"'

1. The LOFAR Two-metre Sky Survey: I. Survey description and preliminary data release

Author

Jeremy J. Harwood, Matthias Steinmetz, W. van Driel, Leah K. Morabito, Emanuela Orru, Magdalena Kunert-Bajraszewska, D. A. Rafferty, Isabella Prandoni, A. Horneffer, Huub Röttgering, R. J. van Weeren, Adam Deller, Subhash C. Mandal, J. Sabater, G. Calistro Rivera, M. Sipior, Daniel J. Smith, Frank P. Israel, Aleksandar Shulevski, John McKean, Marijke Haverkorn, D. Engels, Krzysztof T. Chyzy, Chiara Ferrari, P. van der Werf, Philip Best, J. B. R. Oonk, A. Drabent, Elizabeth K. Mahony, Raffaella Morganti, Marisa Brienza, Timothy W. Shimwell, Michael W. Wise, Annalisa Bonafede, Martin J. Hardcastle, Rainer Beck, S. S. Sridhar, Marcus Brüggen, Neal Jackson, Dominik J. Schwarz, M. A. Garrett, Cathy Horellou, Matthias Hoeft, J. A. Zensus, Gianfranco Brunetti, N. R. Mohan, George K. Miley, Andra Stroe, John Conway, Anna D. Kapińska, E. Retana-Montenegro, D. J. McKay, A. O. Clarke, I. van Bemmel, Glenn J. White, George Heald, Volker Heesen, Heino Falcke, Matt J. Jarvis, F. de Gasperin, Huib Intema, D. N. Hoang, Cyril Tasse, R. Pizzo, Eskil Varenius, S. Fröhlich, A. P. Mechev, D. Cseh, Wendy L. Williams, Rossella Cassano, Jonathan T. L. Zwart, T. J. Dijkema, Leiden Observatory [Leiden], Universiteit Leiden, Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, Centre for Astrophysics Research, University of Hertfordshire [Hatfield] (UH), Netherlands Institute for Radio Astronomy (ASTRON), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Max-Planck-Institut für Radioastronomie (MPIFR), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Istituto di Radioastronomia [Bologna] (IRA), Istituto Nazionale di Astrofisica (INAF), Astronomical Observatory [Kraków], Uniwersytet Jagielloński w Krakowie = Jagiellonian University (UJ), Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], Radboud University [Nijmegen], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Oxford Astrophysics, University of Oxford, Department of Physics and Astronomy [Milton Keynes], The Open University [Milton Keynes] (OU), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Thüringer Landessternwarte Tautenburg (TLS), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Ruhr-Universität Bochum [Bochum], School of Physics and Astronomy [Southampton], University of Southampton, Joint Institute for VLBI in Europe (JIVE ERIC), Department of Earth and Space Sciences [Göteborg], The University of Western Australia (UWA), Torun Centre for Astronomy (TCfA), Nicolaus Copernicus University [Toruń], University of Oulu, National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), Universität Bielefeld, Leibniz-Institut für Astrophysik Potsdam (AIP), European Southern Observatory (ESO), University of the Western Cape (UWC), European Project: 320745,EC:FP7:ERC,ERC-2012-ADG_20120216,RADIOLIFE(2013), Astronomy, Kapteyn Astronomical Institute, Universiteit Leiden [Leiden], Harvard University [Cambridge]-Smithsonian Institution, Radboud university [Nijmegen], University of Oxford [Oxford], Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of the Western Cape, High Energy Astrophys. & Astropart. Phys (API, FNWI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Smithsonian Institution-Harvard University [Cambridge], Istituto di Radioastronomia INAF, Jagiellonian University [Krakow] (UJ), Onsala Space Observatory, Istituto di Radioastronomia (IRA), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Tata Institute of Fundamental Research [Bombay] (TIFR)

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Astronomy, radio continuum: general, FOS: Physical sciences, techniques: image processing, 01 natural sciences, Declination, Spectral line, RADIO RECOMBINATION LINES, techniques image processing, surveys, CALIBRATOR SURVEY, 0103 physical sciences, Calibration, radio-continuum, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Remote sensing, media_common, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], image processing [techniques], QUASAR SURVEY, Astronomy and Astrophysics, HERSCHEL-ATLAS, LOFAR, 1ST SURVEY, Galaxy, WIDE-FIELD, Space and Planetary Science, Sky, LUMINOSITY FUNCTION, general, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, general [radio continuum], CHANDRA OBSERVATIONS, Astrophysics - Instrumentation and Methods for Astrophysics, Right ascension, FOLLOW-UP, GALAXY CLUSTERS, surveys – catalogs – radio continuum: general – techniques: image processing, Geology, Noise (radio), catalogs, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient to produce ~5arcsec resolution images with a sensitivity of ~0.1mJy/beam and accomplish the main scientific aims of the survey which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Due to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extended and compact emission. For legacy value, the data are archived at high spectral and time resolution to facilitate subarcsecond imaging and spectral line studies. In this paper we provide an overview of the LoTSS. We outline the survey strategy, the observational status, the current calibration techniques, a preliminary data release, and the anticipated scientific impact. The preliminary images that we have released were created using a fully-automated but direction-independent calibration strategy and are significantly more sensitive than those produced by any existing large-area low-frequency survey. In excess of 44,000 sources are detected in the images that have a resolution of 25arcsec, typical noise levels of less than 0.5 mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45d00m00s to 57d00m00s)., Comment: 23 pages, 15 figures, 3 tables, accepted for publication in A&A

Published
2017

2. Measuring the expansion velocity of the outflows of LS I +61 303 through low-frequency radio observations

Author

Marcote, B., Ribó, M., Paredes, J.M., Ishwara-Chandra, C.H., Swinbank, J.D., Broderick, J.W., Markoff, S., Fender, R., Wijers, R.A.M.J., Pooley, G.G., Stewart, A.J., Bell, M.E., Breton, R.P., Carbone, D., Corbel, S., Eislöffel, J., Falcke, H., Grießmeier, J.-M., Kuniyoshi, M., Pietka, M., Rowlinson, A., Serylak, M., van der Horst, A.J., van Leeuwen, J., Wise, M.W., Zarka, P., Aharonian, F.A., Hofmann, W., Rieger, F.M., High Energy Astrophys. & Astropart. Phys (API, FNWI), Institut de Ciencies del Cosmos (ICCUB), Universitat de Barcelona (UB), National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute of Fundamental Research [Bombay] (TIFR), Department of Astrophysical Sciences [Princeton], Princeton University, University of Southampton, Sub-department of Astrophysics [Oxford], Department of Physics [Oxford], University of Oxford [Oxford]-University of Oxford [Oxford], Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), Mullard Radio Astronomy Observatory (MRAO), University of Cambridge [UK] (CAM), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Thüringer Landessternwarte Tautenburg (TLS), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], Netherlands Institute for Radio Astronomy (ASTRON), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Max-Planck-Institut für Radioastronomie (MPIFR), NAOJ Chile Observatory, National Astronomical Observatory of Japan (NAOJ), Oxford Astrophysics, University of Oxford [Oxford], SKA South Africa, Ska South Africa, Department of Physics, George Washington University, George Washington University (GW), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Tata Institute for Fundamental Research (TIFR), University of Oxford-University of Oxford, Jodrell Bank Centre for Astrophysics (JBCA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Radboud University [Nijmegen], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), University of Oxford, The George Washington University (GW), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)

Subjects
Physics, Giant Metrewave Radio Telescope, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, LOFAR, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, 01 natural sciences, Wind speed, Synchrotron, law.invention, 13. Climate action, Modulation, law, [SDU]Sciences of the Universe [physics], 0103 physical sciences, Maxima, Absorption (electromagnetic radiation), 010303 astronomy & astrophysics
Abstract

International audience; LS I +61 303 is a gamma-ray binary that exhibits an outburst at GHz frequencies each orbital cycle of 26.5 d and a superorbital modulation with a period of 4.6 yr. We have performed a detailed study of the low-frequency radio emission of LS I +61 303 by analyzing data from the Giant Metrewave Radio Telescope (GMRT) at 150, 235 and 610 MHz, and from the Low Frequency Array (LOFAR) at 150 MHz. We have detected the source for the first time at 150 MHz, which is also the first detection of a gamma-ray binary at such a low frequency. We have obtained the light-curves of the source at 150, 235 and 610 MHz, all of them showing orbital modulation. The light-curves at 235 and 610 MHz also show the existence of superorbital variability. A comparison with contemporaneous 15-GHz data shows remarkable differences with these light-curves. At 15 GHz we see clear outbursts, whereas at low frequencies we see variability with wide maxima. The light-curve at 235 MHz seems to be anticorrelated with the one at 610 MHz, implying a shift of about 0.5 orbital phases in the maxima. We model the shifts between the maxima at different frequencies as due to changes in the physical parameters of the emitting region assuming either free-free absorption or synchrotron self-absorption, obtaining expansion velocities for this region close to the stellar wind velocity with both mechanisms.

Published
2017

3. Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere

Author

Y. Tang, Anna M. M. Scaife, Steve Rawlings, Aris Karastergiou, Michael W. Wise, Harvey Butcher, B. Ciardi, S. Duscha, V. N. Pandey, Gianni Bernardi, John McKean, Charlotte Sobey, Emanuela Orrú, Chiara Ferrari, M. Kuniyoshi, H. Munk, Marcus Brüggen, Michael Kramer, Cyril Tasse, J. W. Broderick, E. de Geus, Ashish Asgekar, Jason W. T. Hessels, F. de Gasperin, Matthias Hoeft, George Heald, L. Kuiper, A. P. Schoenmakers, P. Maat, R. H. van de Brink, Sera Markoff, Dipanjan Mitra, Philip Best, G. Wright, Ralph A. M. J. Wijers, J. de Plaa, Heino Falcke, V. I. Kondratiev, Rahul Basu, A. Noutsos, T. Coenen, Benjamin Stappers, Michel Tagger, Frank Breitling, Giulia Macario, Rob Fender, Rene C. Vermeulen, Michael R. Bell, F. Batejat, A. Alexov, Marco Iacobelli, H. Paas, Sarod Yatawatta, Patrick Weltevrede, Tim Hassall, R. J. van Weeren, W. Reich, M. Pilia, Laura Birzan, W. Hermsen, Evan Keane, Aleksandar Shulevski, Mark J. Bentum, M. Serylak, Martin Bell, Annalisa Bonafede, J. van Leeuwen, A. Horneffer, Jochen Eislöffel, Maaijke Mevius, H. J. A. Röttgering, A. G. Polatidis, R. Morganti, I. M. Avruch, S. ter Veen, A. W. Gunst, Olaf Wucknitz, Matthias Steinmetz, M. Pandey-Pommier, K. Zagkouris, J. Sluman, Roberto Pizzo, Jean-Mathias Grießmeier, G. Kuper, Philippe Zarka, Joanna M. Rankin, M. A. Garrett, James Miller-Jones, Wilfred Frieswijk, Hermsen, W., Hessels, J.W.T., Kuiper, L., Van Leeuwen, J., Mitra, D., De Plaa, J., Rankin, J.M., Stappers, B.W., Wright, G.A.E., Basu, R., Alexov, A., Coenen, T., Grießmeier, J.-M., Hassall, T.E., Karastergiou, A., Keane, E., Kondratiev, V.I., Kramer, M., Kuniyoshi, M., Noutsos, A., Serylak, M., Pilia, M., Sobey, C., Weltevrede, P., Zagkouris, K., Asgekar, A., Avruch, I.M., Batejat, F., Bell, M.E., Bell, M.R., Bentum, M.J., Bernardi, G., Best, P., Bîrzan, L., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Butcher, H.R., Ciardi, B., Duscha, S., Eislöffel, J., Falcke, H., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M.A., De Gasperin, F., De Geus, E., Gunst, A.W., Heald, G., Hoeft, M., Horneffer, A., Iacobelli, M., Kuper, G., Maat, P., Macario, G., Markoff, S., McKean, J.P., Mevius, M., Miller-Jones, J.C.A., Morganti, R., Munk, H., Orrú, E., Paas, H., Pandey-Pommier, M., Pandey, V.N., Pizzo, R., Polatidis, A.G., Rawlings, S., Reich, W., Röttgering, H., Scaife, A.M.M., Schoenmakers, A., Shulevski, A., Sluman, J., Steinmetz, M., Tagger, M., Tang, Y., Tasse, C., Ter Veen, S., Vermeulen, R., Van De Brink, R.H., Van Weeren, R.J., Wijers, R.A.M.J., Wise, M.W., Wucknitz, O., Yatawatta, S., Zarka, P., SRON Netherlands Institute for Space Research (SRON), University of Amsterdam [Amsterdam] (UvA), National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), University of Vermont [Burlington], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Astronomy Centre, University of Sussex, Space Telescope Science Institute (STSci), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Oxford Astrophysics, University of Oxford, Centre for Astrophysics and Supercomputing, Swinburne University of Technology [Melbourne], Netherlands Institute for Radio Astronomy (ASTRON), Max-Planck-Institut für Radioastronomie (MPIFR), Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], University of Southampton, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, University of Edinburgh, Leiden Observatory [Leiden], Universiteit Leiden, Jacobs University [Bremen], Leibniz-Institut für Astrophysik Potsdam (AIP), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Thüringer Landessternwarte Tautenburg (TLS), Radboud University [Nijmegen], Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Medstar Research Institute, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Center for Information Technology CIT, Université de Groningen, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), National Radio Astronomy Observatory [Charlottesville] (NRAO), National Radio Astronomy Observatory (NRAO), School of Physics and Astronomy [Southampton], SKA South Africa, Ska South Africa, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, ANR-09-JCJC-0001,OPALES(2009), Kapteyn Astronomical Institute, Astronomy, Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), University of Oxford [Oxford], Harvard University [Cambridge]-Smithsonian Institution, Universiteit Leiden [Leiden], Radboud university [Nijmegen], Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Subjects
Electromagnetic field, POLARIZATION, Electromagnetic spectrum, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, FOS: Physical sciences, Magnetosphere, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, EMPIRICAL-THEORY, 01 natural sciences, Binary pulsar, Pulsar, Millisecond pulsar, 0103 physical sciences, 010306 general physics, XMM-NEWTON OBSERVATIONS, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, DRIFTING SUBPULSES, Multidisciplinary, B0943+10, Polarization (waves), GAMMA-RAY, [SDU]Sciences of the Universe [physics], 13. Climate action, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, RADIATION, EMISSION, Astrophysics - High Energy Astrophysical Phenomena, PHOTON IMAGING CAMERA, POWERED PULSARS, Radio wave
Abstract

Pulsars emit low-frequency radio waves through to high-energy gamma-rays that are generated anywhere from the surface out to the edges of the magnetosphere. Detecting correlated mode changes in the multi-wavelength emission is therefore key to understanding the physical relationship between these emission sites. Through simultaneous observations, we have detected synchronous switching in the radio and X-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio 'bright' mode, the X-rays show only an un-pulsed, non-thermal component. Conversely, when the pulsar is in a radio 'quiet' mode, the X-ray luminosity more than doubles and a 100%-pulsed thermal component is observed along with the non-thermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories., Paper published in Science including supplementary material

Published
2013

4. Orbital and superorbital variability of LS I +61 303 at low radio frequencies with GMRT and LOFAR

Author

Jochen Eislöffel, Heino Falcke, M. Pietka, D. Carbone, Jean-Mathias Grießmeier, Ph. Zarka, A. J. van der Horst, J. van Leeuwen, Adam Stewart, Rene P. Breton, Sera Markoff, Michael W. Wise, John D. Swinbank, Stephane Corbel, Marc Ribó, M. Kuniyoshi, Martin Bell, Ralph A. M. J. Wijers, Guy G. Pooley, J. W. Broderick, Benito Marcote, Rob Fender, C. H. Ishwara-Chandra, M. Serylak, J. M. Paredes, Antonia Rowlinson, Universitat de Barcelona, Departament d'Astronomia i Meteorologia [Barcelona] (DAM), Universitat de Barcelona (UB), National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute of Fundamental Research [Bombay] (TIFR), Department of Astrophysical Sciences [Princeton], Princeton University, Oxford Astrophysics, University of Oxford [Oxford], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Mullard Radio Astronomy Observatory (MRAO), University of Cambridge [UK] (CAM), University of Southampton, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Thüringer Landessternwarte Tautenburg (TLS), Radboud university [Nijmegen], Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Max-Planck-Institut für Radioastronomie (MPIFR), Netherlands Institute for Radio Astronomy (ASTRON), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), NASA grants NNX08AW31G and NNX11A043G, and NSF grants AST-0808050 and AST-1109911Spanish Ministerio de Econom´ıa y Competitividad (MINECO) under grants AYA2013-47447-C3-1-P, FPA2013-48381-C6-6-P, MDM-2014-0369 of ICCUB (Unidad de Excelencia ‘Mar´ıa de Maeztu’), and the Catalan DEC grant 2014 SGR 86., ANR-11-IDEX-0005-02/10-LABX-0023,UnivEarthS,Earth - Planets - Universe: observation, modeling, transfer(2011), European Project: 267697,EC:FP7:ERC,ERC-2010-AdG_20100224,4PI-SKY(2011), European Project: 332393,EC:FP7:PEOPLE,FP7-PEOPLE-2012-IIF,FAST TRANSIENTS(2014), Tata Institute for Fundamental Research (TIFR), University of Oxford, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Radboud University [Nijmegen], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ANR-11-IDEX-0005,USPC,Université Sorbonne Paris Cité(2011), High Energy Astrophys. & Astropart. Phys (API, FNWI), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)

Subjects
Astrofísica, 010504 meteorology & atmospheric sciences, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], media_common.quotation_subject, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Binary number, Estels binaris, Astrophysics, 01 natural sciences, Raigs gamma, Double stars, 0103 physical sciences, Absorption (electromagnetic radiation), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gamma rays, Astronomy and Astrophysics, LOFAR, radiation mechanisms: non-thermal – binaries: close – stars: individual: LS I + 61 303 – gamma-rays: stars – radio continuum: stars, Space and Planetary Science, Sky, Modulation, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Radio frequency, Maxima, Astrophysics - High Energy Astrophysical Phenomena
Abstract

LS I +61 303 is a gamma-ray binary that exhibits an outburst at GHz frequencies each orbital cycle of $\approx$ 26.5 d and a superorbital modulation with a period of $\approx$ 4.6 yr. We have performed a detailed study of the low-frequency radio emission of LS I +61 303 by analysing all the archival GMRT data at 150, 235 and 610 MHz, and conducting regular LOFAR observations within the Radio Sky Monitor (RSM) at 150 MHz. We have detected the source for the first time at 150 MHz, which is also the first detection of a gamma-ray binary at such a low frequency. We have obtained the light-curves of the source at 150, 235 and 610 MHz, all of them showing orbital modulation. The light-curves at 235 and 610 MHz also show the existence of superorbital variability. A comparison with contemporaneous 15-GHz data shows remarkable differences with these light-curves. At 15 GHz we see clear outbursts, whereas at low frequencies we see variability with wide maxima. The light-curve at 235 MHz seems to be anticorrelated with the one at 610 MHz, implying a shift of $\sim$ 0.5 orbital phases in the maxima. We model the shifts between the maxima at different frequencies as due to changes in the physical parameters of the emitting region assuming either free-free absorption or synchrotron self-absorption, obtaining expansion velocities for this region close to the stellar wind velocity with both mechanisms., 12 pages, 10 figures, accepted for publication in MNRAS

Published
2015

5. X-ray properties of the mode-switching pulsar PSR B0943+10

Author

Benjamin Stappers, A. Horneffer, Stefan Oslowski, Dipanjan Mitra, A. Possenti, Kevin Stovall, Jason W. T. Hessels, Roberto Turolla, Sandro Mereghetti, Michela Rigoselli, Joanna M. Rankin, W. Hermsen, M. Serylak, J. M. Griessmeier, Andrea Tiengo, Paolo Esposito, G. A. E. Wright, L. Kuiper, INAF - Osservatorio Astronomico di Milano (OAM), Istituto Nazionale di Astrofisica (INAF), SRON Netherlands Institute for Space Research (SRON), Scuola Universitaria Superiore Sant'Anna [Pisa] (SSSUP), Istituto Nazionale di Fisica Nucleare, Sezione di Pavia (INFN), Istituto Nazionale di Fisica Nucleare (INFN), Netherlands Institute for Radio Astronomy (ASTRON), Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), The University of New Mexico [Albuquerque], INAF - Osservatorio Astronomico di Cagliari (OAC), University of Vermont [Burlington], Universita degli Studi di Padova, National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], Max-Planck-Institut für Radioastronomie (MPIFR), University of the Western Cape, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Mereghetti, S, Kuiper, L, Tiengo, A, Hessels, J, Hermsen, W, Stovall, K, Possenti, A, Rankin, J, Esposito, P, Turolla, R, Mitra, D, Wright, G, Stappers, B, Horneffer, A, Oslowski, S, Serylak, M, Griessmeier, J, Rigoselli, M, and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Subjects
History, Astrophysics::High Energy Astrophysical Phenomena, Flux, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Physics and Astronomy(all), 01 natural sciences, Radio spectrum, Education, Radio telescope, stars: neutron, Pulsar, pulsars: general, 0103 physical sciences, X-rays: star, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, X-ray, LOFAR, Computer Science Applications, Magnetic field, pulsars: individual: PSR B0943+10, Astrophysics - High Energy Astrophysical Phenomena, Intensity (heat transfer)
Abstract

The mode-switching pulsar PSR B0943+10 has been extensively studied in the radio band for many years and, more recently, it has been found to vary also in X-rays, with a flux anticorrelated with the radio emission. Here we review the results of long observations of PSR B0943+10 carried out with XMM-Newton and the LOFAR, LWA and Arecibo radio telescopes in 2014. These results support a scenario in which both unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap (~1500 m2) with a strong non-dipolar magnetic field (~ 1014 G), are present during both radio modes and vary in intensity in a correlated way.

Published
2017

6. Star formation in the filament of S254-S258 OB complex: a cluster in the process of making

Author

Samal, M. R., Ojha, D. K., Jose, J., Zavagno, Annie, Takahashi, S., Neichel, B., Kim, J. S., Chauhan, N., Pandey, A. K., Zinchenko, I., Tamura, M., Ghosh, S. K., Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Tata Institute for Fundamental Research (TIFR), Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], Joint ALMA Observatory (JAO), European Southern Observatory (ESO)-National Radio Astronomy Observatory (NRAO), Steward Observatory, University of Arizona, Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Aryabhatta Research Institute of Observational Sciences, Aryabhatta Research Institute of Observational Sciences (ARIES), Institute of Applied Physics of RAS, Russian Academy of Sciences [Moscow] (RAS), National Astronomical Observatory of Japan (NAOJ), and National Centre for Radio Astrophysics [Pune] (NCRA)

Subjects
filament, Astrophysics of Galaxies (astro-ph.GA), infrared, individual: S254-S258 complex, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Astrophysics of Galaxies, young stellar objects, Astrophysics::Galaxy Astrophysics, star formation, dark cloud
Abstract

Infrared Dark Clouds are ideal laboratories to study the initial processes of high-mass star and star cluster formation. We investigated star formation activity of an unexplored filamentary dark cloud (~5.7pc x 1.9pc), which itself is part of a large filament (~20pc) located in the S254-S258 OB complex at a distance of 2.5kpc. Using MIPS Spitzer 24 micron data, we uncover 49 sources with SNR greater than 5. We identified 45 sources as candidate YSOs of Class I, Flat-spectrum & Class II nature. Additional 17 candidate YSOs (9 Class I & 8 Class II) are also identified using JHK and WISE photometry. We find that the protostar to Class II sources ratio (~2) and the protostar fraction (~70%) of the region are high. When the protostar fraction compared to other young clusters, it suggests that the star formation in the dark cloud was possibly started only 1 Myr ago. Combining the NIR photometry of the YSO candidates with the theoretical evolutionary models, we infer that most of the candidate YSOs formed in the dark cloud are low-mass (, 14 pages, 9 figures, Accepted by Astronomy & Astrophysics

Published
2015

7. Study of morphology and stellar content of the Galactic HII region IRAS 16148-5011

Author

Mallick, K., Ojha, D., Tamura, M., Samal, M., Ghosh, S., Linz, H., Tata Institute for Fundamental Research (TIFR), National Astronomical Observatory of Japan (NAOJ), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), National Centre for Radio Astrophysics [Pune] (NCRA), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Electron density, H II region, Infrared, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, Telescope, law, Ionization, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Black-body radiation, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Giant Metrewave Radio Telescope, Astronomy, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

An investigation of the IRAS 16148-5011 region - a cluster at a distance of 3.6 kpc - is presented here, carried out using multiwavelength data in near-infrared (NIR) from the 1.4m Infrared Survey Facility telescope, mid-infrared (MIR) from the archival Spitzer GLIMPSE survey, far-infrared (FIR) from the Herschel archive, and low-frequency radio continuum observations at 1280 and 843 MHz from the Giant Metrewave Radio Telescope (GMRT) and Molonglo Survey archive, respectively. A combination of NIR and MIR data is used to identify 7 Class I and 133 Class II sources in the region. Spectral Energy Distribution (SED) analysis of selected sources reveals a 9.6 Msolar, high-mass source embedded in nebulosity. However, Lyman continuum luminosity calculation using radio emission - which shows a compact HII, region - indicates the spectral type of the ionizing source to be earlier than B0-O9.5. Free-free emission SED modelling yields the electron density as 138 cm^{-3}, and thus the mass of the ionized hydrogen as ~16.4 Msolar. Thermal dust emission modelling, using the FIR data from Herschel and performing modified blackbody fits, helped us construct the temperature and column density maps of the region, which show peak values of 30 K and 3.3x10^{22} cm^{-2}, respectively. The column density maps reveal an AV > 20 mag extinction associated with the nebular emission, and weak filamentary structures connecting dense clumps. The clump associated with this IRAS object is found to have dimensions of ~1.1 pc x 0.8 pc, and a mass of 1023 Msolar., 20 pages, 12 figures, 3 tables, Accepted for publication in MNRAS

Published
2015

8. A stellar population synthesis model for the study of ultraviolet star counts of the Galaxy

Author

Swarna K. Ghosh, Annie C. Robin, Devendra K. Ojha, Ananta C. Pradhan, John J. Vickers, Tata Institute for Fundamental Research (TIFR), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), National Centre for Radio Astrophysics [Pune] (NCRA), Zentrum für Astronomie der Universität Heidelberg (ZAH), and Universität Heidelberg [Heidelberg]

Subjects
Stellar population, media_common.quotation_subject, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Star count, law.invention, Galaxy: disk, Telescope, law, Astrophysics::Solar and Stellar Astrophysics, stars: general, Astrophysics::Galaxy Astrophysics, media_common, ultraviolet: stars, Physics, Galaxy: stellar content, Astrophysics::Instrumentation and Methods for Astrophysics, White dwarf, Astronomy and Astrophysics, Horizontal branch, Astrophysics - Astrophysics of Galaxies, Galaxy, Galaxy: halo, Stars, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

GALEX, the first all sky imaging UV satellite, has imaged a large part of the sky providing an excellent opportunity for studying UV star counts. The aim of our study is to investigate in detail the observed UV star counts obtained by GALEX vis-a-vis the model simulated catalogs produced by the Besancon model of stellar population synthesis in various Galactic directions, and to explore the potential for studying the structure of our Galaxy from images in multiple NUV and FUV filters of the forthcoming Ultraviolet Imaging Telescope (UVIT) to be flown onboard ASTROSAT. We have upgraded the Besancon model of stellar population synthesis to include the UV bands of GALEX and UVIT. Depending on the availability of contiguous GALEX, SDSS, WISE and 2MASS overlapping regions, we have chosen a set of 19 GALEX fields which spread over a range of Galactic directions. We cross-matched GALEX sources with the WISE+2MASS and SDSS catalogs and UV stars in the GALEX catalog are identified by choosing a suitable IR colour, J - W1 (W1 is a WISE band at 3.4 microns). The IR colour cut method, which is used for the first time for separation of stars, is discussed in comparison with the GALEX+SDSS star counts method. We present the results of the UV star counts analysis carried out using the data from GALEX. We find that the Besancon model simulations represent the observed star counts of both the GALEX AIS and MIS well within the error bars in various Galactic directions. Based on the model analysis, we separated out white dwarfs of the disc and blue horizontal branch stars of the halo from the observed sample by selecting a suitable FUV - NUV colour. The Besancon model is now ready for further comparisons in the UV domain and will be used for prospective studies for the UVIT instrument to be flown onboard ASTROSAT., Comment: 17 pages, 13 figures, 1 table. Accepted for publication in Astronomy & Astrophysics

Published
2014

9. Astrophysics Pulse-to-pulse flux density modulation from pulsars at 8.35 GHz

Author

Maron, O, Serylak, M, Kijak, J, Krzeszowski, K, Mitra, D, Jessner, A, J. Kepler Institute of Astronomy, University of Zielona Góra, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), Max-Planck-Institut für Radioastronomie (MPIFR), and rant DEC-2012/05/B/ST9/03924 of the Polish National Science Centre

Subjects
[PHYS]Physics [physics], pulsars: individual: B1133+16, [SDU]Sciences of the Universe [physics], Astrophysics::High Energy Astrophysical Phenomena, pulsars: general, Astrophysics::Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Aims. We aim to investigate the flux density modulation from pulsars and the specific behaviour of the modulation index versus frequency. Methods. Several pulsars were observed with the Effelsberg radio telescope at 8.35 GHz. Their flux density time series were corrected for interstellar scintillation effects. Results. We present measurements of modulation indices for eight pulsars. We confirm the presence of a critical frequency at ∼1 GHz for these pulsars (including three new ones from this study). We derived intrinsic modulation indices for the resulting flux density time series. Our data analysis revealed strong single pulses detected from five pulsars.

Published
2013

10. A MULTI-WAVELENGTH HIGH-RESOLUTION STUDY OF THE S255 STAR-FORMING REGION: GENERAL STRUCTURE AND KINEMATICS

Author

Manash R. Samal, Sheng-Yuan Liu, Swarna K. Ghosh, Yu-Nung Su, Devendra K. Ojha, Stanley E. Kurtz, Igor Zinchenko, Institute of Applied Physics of RAS, Russian Academy of Sciences [Moscow] (RAS), Centro de Radioastronomia y Astrofisica (CRyA), Universidad Nacional Autónoma de México (UNAM), Tata Institute for Fundamental Research (TIFR), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), National Centre for Radio Astrophysics [Pune] (NCRA), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Solar mass, Continuum (measurement), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Spectral line, Deuterium, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Extremely high frequency, Thermal, Isotopologue, 010303 astronomy & astrophysics, Decimetre
Abstract

We present observational data for two main components (S255IR and S255N) of the S255 high mass star forming region in continuum and molecular lines obtained at 1.3 mm and 1.1 mm with the SMA, at 1.3 cm with the VLA and at 23 and 50 cm with the GMRT. The angular resolution was from ~ 2" to ~ 5" for all instruments. With the SMA we detected a total of about 50 spectral lines of 20 different molecules (including isotopologues). About half of the lines and half of the species (in particular N2H+, SiO, C34S, DCN, DNC, DCO+, HC3N, H2CO, H2CS, SO2) have not been previously reported in S255IR and partly in S255N at high angular resolution. Our data reveal several new clumps in the S255IR and S255N areas by their millimeter wave continuum emission. Masses of these clumps are estimated at a few solar masses. The line widths greatly exceed expected thermal widths. These clumps have practically no association with NIR or radio continuum sources, implying a very early stage of evolution. At the same time, our SiO data indicate the presence of high-velocity outflows related to some of these clumps. In some cases, strong molecular emission at velocities of the quiescent gas has no detectable counterpart in the continuum. We discuss the main features of the distribution of NH3, N2H+, and deuterated molecules. We estimate properties of decimeter wave radio continuum sources and their relationship with the molecular material., Comment: 21 pages, 26 figures, accepted for publication in Astrophysical Journal

Published
2012

11. First high-resolution radio study of the supernova remnant G338.3-0.0 associated with the gamma-ray source HESS J1640-465

Author

Elsa Beatriz Giacani, A. P. Rao, Bhal Chandra Joshi, G. Castelletti, Regis Terrier, Gloria Mabel Dubner, Instituto de Astronomía y Física del Espacio [Buenos Aires] (IAFE), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad de Buenos Aires [Buenos Aires] (UBA), National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), APC - Astrophysique des Hautes Energies (APC - AHE), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Tata Institute of Fundamental Research [Bombay] (TIFR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, and Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO)

Subjects
Optical telescopes, Astrophysics, 01 natural sciences, Pulsar wind nebula, law.invention, Gamma-ray emission, law, Associated gas, Emission lines, Radio telescopes, Emission spectrum, Radio frequencies, Supernova remnant, 010303 astronomy & astrophysics, ISM: supernova remnants, Physics, Spectral index, Molecular gas, Radio observation, supernova remnants [ISM], [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], individual objects [ISM], Gamma ray sources, individual objects: G338.3-0.0 [ISM], individual objects: HESS J1640-465 [ISM], Upper limits, Molecular materials, Atmospheric optics, radio continuum: ISM, Radio frequency, Compact arrays, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Spectral indices, Supernova remnants, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Multi frequency, Optical depth, Ionization of gases, Radio telescope, Telescope, Tellurium compounds, ISM: individual objects: G338.3-0.0, 0103 physical sciences, High resolution, Astrophysics::Galaxy Astrophysics, ISM: individual objects: HESS J1640-465, Giant metrewave radio telescopes, Giant Metrewave Radio Telescope, Ionized gas, 010308 nuclear & particles physics, Gamma rays, Australia, Radio flux, Archival data, Astronomy and Astrophysics, ISM [Radio continuum], Stars, Astrophysics - Astrophysics of Galaxies, Spectral properties, Flux densities, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA)
Abstract

We report on a multifrequency radio study of the supernova remnant (SNR) G338.3-0.0, in positional coincidence with the TeV source HESS J1640-465. To carry out this research we observed the SNR G338.3-0.0 using the Giant Metrewave Radio Telescope (GMRT) at 235, 610, and 1280 MHz. We also reprocessed archival data from the Australia Telescope Compact Array (ATCA) at 1290 and 2300 MHz. Also we conducted a search for radio pulsations towards a central point-like source, using the GMRT antennas at 610 and 1280 MHz. The molecular material in the region of the SNR was investigated based on observations made with the NANTEN telescope in the 12^CO (J=1-0) emission line. The new radio observations revealed a remnant with a bilateral morphology, which at 235 MHz has the western wing completely attenuated because of absorption due to foreground ionized gas. The quality of the new images allows us to provide accurate estimates for the total radio flux density of the whole SNR at different radio frequencies. From the new and existing flux density estimates between 235 and 5000 MHz we derived for the whole remnant a spectral index alpha=-0.51 +/-0.06 with a local free-free continuum optical depth at 235 MHz tau_{235}=0.9+/-0.3. No radio pulsations were detected towards the only radio point-like source within the HESS error circle. We derived upper limits of 2.0 and 1.0 mJy at 610 and 1280 MHz, respectively, for the pulsed flux towards this source. No radio counterpart was found for the pulsar wind nebula discovered in X-rays. The inspection of the interstellar molecular gas towards G338.3-0.0 and surroundings revealed that there is not any associated dense cloud that might explain a hadronic origin for the TeV detection., 7 pages, 4 figures. Accepted for publication in A&A

Published
2011

12. Observations of interplanetary scintillation during the 1998 Whole Sun Month: a comparison between EISCAT, ORT and Nagoya data

Author

P. J. Moran, S. Ananthakrishnan, V. Balasubramanian, A. R. Breen, A. Canals, R. A. Fallows, P. Janardhan, M. Tokumaru, P. J. S. Williams, EGU, Publication, Physics Department, University of Wales Aberywyth, National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, Solar-Terrestrial Environment Laboratory [Nagoya] (STEL), and Nagoya University

Subjects
Atmospheric Science, Astrophysics::High Energy Astrophysical Phenomena, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Latitude, Radio telescope, Interplanetary scintillation, Earth and Planetary Sciences (miscellaneous), Astrophysics::Solar and Stellar Astrophysics, lcsh:Science, Velocity measurement, Analysis method, Remote sensing, Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QC801-809, Astrophysics::Instrumentation and Methods for Astrophysics, Geology, Astronomy and Astrophysics, Method of analysis, lcsh:QC1-999, Solar wind, lcsh:Geophysics. Cosmic physics, Space and Planetary Science, Physics::Space Physics, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, lcsh:Q, Astrophysics::Earth and Planetary Astrophysics, lcsh:Physics
Abstract

Observations of interplanetary scintillation (IPS) allow accurate solar wind velocity measurements to be made at all heliographic latitudes and at a range of distances from the Sun. The data may be obtained with either single, double or multiple antennas, each requiring a different method of analysis. IPS data taken during the 1998 whole sun month (30th July-31st August 1998) by EISCAT, the ORT (Ooty Radio Telescope), India, and the Nagoya IPS system, Japan, allow the results of individual methods of analysis to be compared. Good agreement is found between the velocity measurements using each method, and when combined an improved understanding of the structure of the solar wind can be obtained.Key words: Interplanetary physics (solar wind plasma; sources of the solar wind) - Solar physics, astrophysics and astronomy (instruments and techniques)

Published
2000

13. STAR FORMATION ACTIVITY IN THE GALACTIC H II REGION Sh2-297

Author

Manash R. Samal, Anil Kumar Pandey, Lokesh K. Dewangan, Swarna K. Ghosh, K. K. Mallick, Bhuwan C. Bhatt, Motohide Tamura, Devendra K. Ojha, Tata Institute for Fundamental Research (TIFR), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Aryabhatta Research Institute of Observational Sciences, Aryabhatta Research Institute of Observational Sciences (ARIES), National Centre for Radio Astrophysics [Pune] (NCRA), Riken, and RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN)

Subjects
Physics, H II region, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010504 meteorology & atmospheric sciences, Star formation, Young stellar object, Near-infrared spectroscopy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Stars, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Spectral energy distribution, Emission spectrum, Spectroscopy, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

We present a multiwavelength study of the Galactic H II region Sh2-297, located in Canis Major OB1 complex. Optical spectroscopic observations are used to constrain the spectral type of ionizing star HD 53623 as B0V. The classical nature of this H II region is affirmed by the low values of electron density and emission measure, which are calculated to be 756 cm^-3 and 9.15 x 10^5 cm^-6 pc using the radio continuum observations at 610 and 1280 MHz, and VLA archival data at 1420 MHz. To understand local star formation, we identified the young stellar object (YSO) candidates in a region of area ~ 7.5' x 7.5' centered on Sh2-297 using grism slitless spectroscopy (to identify the Halpha emission line stars), and near infrared (NIR) observations. NIR YSO candidates are further classified into various evolutionary stages using color-color (CC) and color-magnitude (CM) diagrams, giving 50 red sources (H-K > 0.6) and 26 Class II-like sources. The mass and age range of the YSOs are estimated to be ~ 0.1 - 2 Msolar and 0.5 - 2 Myr using optical (V/V-I) and NIR (J/J-H) CM diagrams. The mean age of the YSOs is found to be ~ 1 Myr, which is of the order of dynamical age of 1.07 Myr of the H II region. Using the estimated range of visual extinction (1.1 - 25 mag) from literature and NIR data for the region, spectral energy distribution (SED) models have been implemented for selected YSOs which show masses and ages to be consistent with estimated values. The spatial distribution of YSOs shows an evolutionary sequence, suggesting triggered star formation in the region. The star formation seems to have propagated from the ionizing star towards the cold dark cloud LDN1657A located west of Sh2-297., 19 pages, 13 figures, 3 tables. Accepted for publication in The Astrophysical Journal

Published
2012

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