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1. Multi-antenna probing of absorbing regions inside and outside Cassiopeia A

Author

Stanislavsky, Lev A., Bubnov, Ihor N., Stanislavsky, Aleksander A., Zarka, Philippe, Loh, Alan, Viou, Cedric, Konovalenko, Aleksander A., Brazhenko, Anatolii I., and Frantsuzenko, Anatolii V.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Context. Cassiopeia A occupies an important place among supernova remnants (SNRs) in low-frequency radio astronomy. The analysis of its continuum spectrum from low frequency observations reveals the evolution of the SNR absorption properties over time and suggests a method for probing unshocked ejecta and the SNR interaction with the circumstellar medium (CSM). Aims. In this paper we present low-frequency measurements of the integrated spectrum of Cassiopeia A to find the typical values of free-free absorption parameters towards this SNR in the middle of 2023. We also add new results to track its slowly evolving and decreasing integrated flux density. Methods. We used the New Extension in Nan\c{c}ay Upgrading LOFAR (NenuFAR) and the Ukrainian Radio Interferometer of NASU (URAN-2, Poltava) for measuring the continuum spectrum of Cassiopeia A within the frequency range of 8-66 MHz. The radio flux density of Cassiopeia A has been obtained on June-July, 2023 with two sub-arrays for each radio telescope, used as a two-element correlation interferometer. Results. We measured magnitudes of emission measure, electron temperature and an average number of charges of the ions for both internal and external absorbing ionized gas towards Cassiopeia A from its integrated spectrum. Generally, their values are comparable to those presented by Stanislavsky et al. (2023), but their slight changes show the evolution of free-free absorption parameters in this SNR. Based on high accuracy of the measurements, we have detected the SNR-CSM interaction. Conclusions. The integrated flux-density spectrum of Cassiopeia A obtained with the NenuFAR and URAN-2 interferometric observations opens up new possibilities for continuous monitoring the ionized gas properties in and around Cassiopeia A to observe theevolution of unshocked ejecta and the SNR-CSM interaction in future studies.

Published
2023
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2. Pilot study and early results of the Cosmic Filaments and Magnetism Survey with Nenufar: the Coma cluster field

Author

Etienne, Bonnassieux, Tremou, Evangelia, Girard, Julien N., Loh, Alan, Vacca, Valentina, Corbel, Stephane, Cecconi, Baptiste, Griessmeier, Jean-Mathias, Koopmans, Leon V. E., Tagger, Michel, Theureau, Gilles, and Zarka, Philippe

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

NenuFAR, the New Extension in Nancay Upgrading LOFAR, is currently in its early science phase. It is in this context that the Cosmic Filaments and Magnetism Pilot Survey is observing sources with the array as it is still under construction - with 57 (56 core, 1 distant) out of a total planned 102 (96 core, 6 distant) mini-arrays online at the time of observation - to get a first look at the low-frequency sky with NenuFAR. One of its targets is the Coma galaxy cluster: a well-known object, host of the prototype radio halo. It also hosts other features of scientific import, including a radio relic, along with a bridge of emission connecting it with the halo. It is thus a well-studied object. In this paper, we show the first confirmed NenuFAR detection of the radio halo and radio relic of the Coma cluster at 34.4 MHz, with associated intrinsic flux density estimates: we find an integrated flux value of 106.3 +- 3.5 Jy for the radio halo, and 102.0 +- 7.4 Jy for the radio relic. These are upper bound values, as they do not include point-source subtraction. We also give an explanation of the technical difficulties encountered in reducing the data, along with steps taken to resolve them. This will be helpful for other scientific projects which will aim to make use of standalone NenuFAR imaging observations in the future., Comment: 14 pages, 4 figures, special issue of the Galaxies journal

Published
2021
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3. Observations of shock propagation through turbulent plasma in the solar corona

Author

Carley, Eoin P., Cecconi, Baptiste, Reid, Hamish A., Briand, Carine, Raja, Sasikumar, Masson, Sophie, Dorovskyy, Vladimir V., Tiburzi, Caterina, Vilmer, Nicole, Zucca, Pietro, Zarka, Philippe, Tagger, Michel, Griessmeier, Jean-Mathias, Corbel, Stéphane, Theureau, Gilles, Loh, Alan, and Girard, Julien

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Eruptive activity in the solar corona can often lead to the propagation of shock waves. In the radio domain the primary signature of such shocks are type II radio bursts, observed in dynamic spectra as bands of emission slowly drifting towards lower frequencies over time. These radio bursts can sometimes have inhomogeneous and fragmented fine structure, but the cause of this fine structure is currently unclear. Here we observe a type II radio burst on 2019-March-20th using the New Extension in Nan\c{c}ay Upgrading LOFAR (NenuFAR), a radio interferometer observing between 10-85 MHz. We show that the distribution of size-scales of density perturbations associated with the type II fine structure follows a power law with a spectral index in the range of $\alpha=-1.7$ to -2.0, which closely matches the value of $-5/3$ expected of fully developed turbulence. We determine this turbulence to be upstream of the shock, in background coronal plasma at a heliocentric distance of $\sim$2 R$_{\odot}$. The observed inertial size-scales of the turbulent density inhomogeneities range from $\sim$62 Mm to $\sim$209 km. This shows that type II fine structure and fragmentation can be due to shock propagation through an inhomogeneous and turbulent coronal plasma, and we discuss the implications of this on electron acceleration in the coronal shock.

Published
2021
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4. First resolved observations of a highly asymmetric debris disc around HD 160305 with VLT/SPHERE

Author

Perrot, Clément, Thebault, Philippe, Lagrange, Anne-Marie, Boccaletti, Anthony, Vigan, Arthur, Desidera, Silvano, Augereau, Jean-Charles, Bonnefoy, Mickael, Choquet, Élodie, Kral, Quentin, Loh, Alan, Maire, Anne-Lise, Ménard, François, Messina, Sergio, Olofsson, Johan, Gratton, Raffaele, Biller, Beth, Brandner, Wolfgang, Buenzli, Esther, Chauvin, Gaël, Cheetham, Anthony, Daemgen, Sebastien, Delorme, Philippe, Feldt, Markus, Lagadec, Eric, Langlois, Maud, Lannier, Justine, Mesa, Dino, Mouillet, David, Peretti, Sébastien, Janin-Potiron, Pierre, Salter, Graeme, Sissa, Elena, Roux, Alain, Llored, Marc, Buey, Jean-Tristan, Pavlov, Alexei, Weber, Luc, and Petit, Cyril

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Context. Direct imaging of debris discs gives important information about their nature, their global morphology, and allows us to identify specific structures possibly in connection with the presence of gravitational perturbers. It is the most straightforward technique to observe planetary systems as a whole. Aims. We present the first resolved images of the debris disc around the young F-type star HD 160305, detected in scattered light using the VLT/SPHERE instrument in the near infrared. Methods. We used a post-processing method based on angular differential imaging and synthetic images of debris discs produced with a disc modelling code (GRaTer) to constrain the main characteristics of the disc around HD 160305. All of the point sources in the field of the IRDIS camera were analysed with an astrometric tool to determine whether they are bound objects or background stars. Results. We detect a very inclined (~ 82{\deg}) ring-like debris disc located at a stellocentric distance of about 86au (deprojected width ~27 au). The disc displays a brightness asymmetry between the two sides of the major axis, as can be expected from scattering properties of dust grains. We derive an anisotropic scattering factor g>0.5. A second right-left asymmetry is also observed with respect to the minor axis. We measure a surface brightness ratio of 0.73 $\pm$ 0.18 between the bright and the faint sides. Because of the low signal-to-noise ratio (S/N) of the images we cannot easily discriminate between several possible explanations for this left-right asymmetry, such as perturbations by an unseen planet, the aftermath of the breakup of a massive planetesimal, or the pericenter glow effect due to an eccentric ring. Two epochs of observations allow us to reject the companionship hypothesis for the 15 point sources present in the field., Comment: 13 pages

Published
2019
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5. MASER: A Science Ready Toolbox for Low Frequency Radio Astronomy

Author

Cecconi, Baptiste, Loh, Alan, Sidaner, Pierre Le, Savalle, Renaud, Bonnin, Xavier, Nguyen, Quynh Nhu, Lion, Sonny, Shih, Albert, Aicardi, Stéphane, Zarka, Philippe, Louis, Corentin, Coffre, Andrée, Lamy, Laurent, Denis, Laurent, Grießmeier, Jean-Mathias, Faden, Jeremy, Piker, Chris, André, Nicolas, Génot, Vincent, Erard, Stéphane, Mafi, Joseph N, King, Todd A, Sky, Jim, and Demleitner, Markus

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

MASER (Measurements, Analysis, and Simulation of Emission in the Radio range) is a comprehensive infrastructure dedicated to time-dependent low frequency radio astronomy (up to about 50 MHz). The main radio sources observed in this spectral range are the Sun, the magnetized planets (Earth, Jupiter, Saturn), and our Galaxy, which are observed either from ground or space. Ground observatories can capture high resolution data streams with a high sensitivity. Conversely, space-borne instruments can observe below the ionospheric cut-off (at about 10 MHz) and can be placed closer to the studied object. Several tools have been developed in the last decade for sharing space physics data. Data visualization tools developed by various institutes are available to share, display and analyse space physics time series and spectrograms. The MASER team has selected a sub-set of those tools and applied them to low frequency radio astronomy. MASER also includes a Python software library for reading raw data from agency archives., Comment: Submitted to Data Science Journal special issue after PV2018 conference

Published
2019
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6. Fermi/LAT detection of a transient gamma-ray flare in the vicinity of the binary star DG CVn

Author

Loh, Alan, Corbel, Stéphane, and Dubus, Guillaume

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Solar flares are regularly detected by the Large Area Telescope (LAT) on board the Fermi satellite, however no gamma-ray emission from other stellar eruptions has ever been captured. The Swift detection in April 2014 of a powerful outburst originating from DG CVn, with associated optical and radio emissions, enticed us to search for possible 0.1-100 GeV emission from this flaring nearby binary star using the Fermi/LAT. No gamma-ray emission is detected from DG CVn in 2014, but we report a significant gamma-ray excess in November 2012, at a position consistent with that of the binary. There are no reports of contemporary flaring at other wavelengths from DG CVn or any other source within the error circle of the gamma-ray source. We argue that the gamma-ray flare is more likely to have been associated with a background blazar than with DG CVn and identify a candidate for follow-up study., Comment: 6 pages, 4 figures, accepted for publication in MNRAS

Published
2017
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7. First detection in gamma-rays of a young radio galaxy: Fermi-LAT observations of the Compact Symmetric Object PKS 1718-649

Author

Migliori, Giulia, Siemiginowska, Aneta, Sobolewska, Malgorzata, Loh, Alan, Corbel, Stéphane, Ostorero, Luisa, and Stawarz, Łukasz

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report the $\gamma$-ray detection of a young radio galaxy, PKS 1718$-$649, belonging to the class of Compact Symmetric Objects (CSOs), with the Large Area Telescope (LAT) on board the {\it Fermi} satellite. The third {\it Fermi} Gamma-ray LAT catalog (3FGL) includes an unassociated $\gamma$-ray source, 3FGL J1728.0$-$6446, located close to PKS 1718$-$649. Using the latest Pass 8 calibration, we confirm that the best fit $1 \sigma$ position of the $\gamma$-ray source is compatible with the radio location of PKS 1718$-$649. Cross-matching of the $\gamma$-ray source position with the positions of blazar sources from several catalogs yields negative results. Thus, we conclude that PKS 1718$-$649 is the most likely counterpart to the unassociated LAT source. We obtain a detection test statistics TS$\sim 36$ ($>$5$\sigma$) with a best fit photon spectral index $\Gamma=$2.9$\pm$0.3 and a 0.1-100 GeV photon flux density $F_{\rm 0.1-100GeV}=$(11.5$\pm$0.3)$\times{\rm 10^{-9}}$ ph cm$^{-2}$ s$^{-1}$. We argue that the linear size ($\sim$2 pc), the kinematic age ($\sim$100 years), and the source distance ($z=0.014$) make PKS 1718$-$649 an ideal candidate for $\gamma$-ray detection in the framework of the model proposing that the most compact and the youngest CSOs can efficiently produce GeV radiation via inverse-Compton scattering of the ambient photon fields by the radio lobe non-thermal electrons. Thus, our detection of the source in $\gamma$-rays establishes young radio galaxies as a distinct class of extragalactic high-energy emitters, and yields an unique insight on the physical conditions in compact radio lobes interacting with the interstellar medium of the host galaxy., Comment: 7 pages, 2 figures, accepted for publication in ApJ Letters

Published
2016
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8. Characterizing X-ray and Radio emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence

Author

Rana, Vikram, Loh, Alan, Corbel, Stephane, Tomsick, John A., Chakrabarty, Deepto, Walton, Dominic J., Barret, Didier, Boggs, Steven E., Christensen, Finn E., Craig, William, Fuerst, Felix, Gandhi, Poshak, Grefenstette, Brian W., Hailey, Charles, Harrison, Fiona A., Madsen, Kristin K., Rahoui, Farid, Stern, Daniel, Tendulkar, Shriharsh, and Zhang, William W.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broad-band (0.3--30 keV) quiescent luminosity of the source is 8.9$\times$10$^{32}$ erg s$^{-1}$ for a distance of 2.4 kpc. The source shows clear variability on short time scales (an hour to a couple of hours) in radio, soft X-ray and hard X-ray bands in the form of multiple flares. The broad-band X-ray spectra obtained from XMM-Newton and NuSTAR can be characterized with a power-law model having photon index $\Gamma$=2.12$\pm$0.07 (90\% confidence errors); however, residuals at high energies indicate spectral curvature significant at a 3$\sigma$ confidence level with e-folding energy of the cutoff to be 20$^{+20}_{-7}$ keV. Such curvature can be explained using synchrotron emission from the base of a jet outflow. Radio observations using the VLA reveal that the spectral index evolves on very fast time-scales (as short as 10 min.), switching between optically thick and thin synchrotron emission, possibly due to instabilities in the compact jet or stochastic instabilities in accretion rate. We explore different scenarios to explain this very fast variability., Comment: 16 pages, 11 figures and 3 tables, Accepted for publication in The Astrophysical Journal

Published
2015
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15. ORN NDA JunoN EDR Dataset Specification

Author

Cecconi, Baptiste, Viou, Cedric, Lamy, Laurent, Renaud, Patrice, Loh, Alan, Zarka, Philippe, Coffre, Andrée, and Denis, Laurent

Abstract

This document describes the ORN NDA JunoN EDR Dataset Specification.

Published
2022
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17. Pilot Study and Early Results of the Cosmic Filaments and Magnetism Survey with Nenufar: The Coma Cluster Field

Author

Bonnassieux, Etienne, primary, Tremou, Evangelia, additional, Girard, Julien N., additional, Loh, Alan, additional, Vacca, Valentina, additional, Corbel, Stéphane, additional, Cecconi, Baptiste, additional, Grießmeier, Jean-Mathias, additional, Koopmans, Léon V. E., additional, Tagger, Michel, additional, Theureau, Gilles, additional, and Zarka, Philippe, additional

Published
2021
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18. Observations of Shock Propagation through Turbulent Plasma in the Solar Corona

Author

Carley, Eoin P., primary, Cecconi, Baptiste, additional, Reid, Hamish A., additional, Briand, Carine, additional, Raja, K. Sasikumar, additional, Masson, Sophie, additional, Dorovskyy, Vladimir, additional, Tiburzi, Caterina, additional, Vilmer, Nicole, additional, Zucca, Pietro, additional, Zarka, Philippe, additional, Tagger, Michel, additional, Grießmeier, Jean-Mathias, additional, Corbel, Stéphane, additional, Theureau, Gilles, additional, Loh, Alan, additional, and Girard, Julien N., additional

Published
2021
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19. JSON Implementation of Time-Frequency Radio Catalogues: TFCat

Author

Cecconi, Baptiste, Taylor, Mark, Bonnin, Xavier, and Loh, Alan

Abstract

TFCat (Time-Frequency Catalogue) is a data interchange format based on JSON. It defines several types of JSON objects and the manner in which they are combined to represent data about time-frequency features of a time spectrogram (a.k.a. dynamic spectrum), their properties, and their temporal and spectral extents.

Published
2021
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20. The low-frequency radio telescope NenuFAR

Author

Zarka, Philippe, Denis, Laurent, Tagger, Michel, Girard, Julien, Coffre, Andrée, Dumez-Viou, Cédric, Taffoureau, Christophe, Charrier, Didier, Bondonneau, Louis, Briand, Carine, Casoli, Fabienne, Cecconi, Baptiste, Cognard, Ismaël, Corbel, Stéphane, Dallier, Richard, Ferrari, Chiara, Grießmeier, Jean-Mathias, Loh, Alan, Martin, Lilian, Pommier, Mamta, Benoit, Semelin, Tasse, Cyril, Theureau, Gilles, Tremou, Evangelia, Capayrou, D, Censier, B, Cottet, P, Etieve, V, Floquet, F, Garnier, S, Georges, G, Gond, B, Jacquet, F, Joly, S, Gall, A, Roziere, C, Thetas, E, Vimon, J.-B, Guilbeau, R, Sandre, P, Courte, C, Desvignes, G, Marchand, A, Alves, M, Azarian, S, Bonnassieux, E, Brionne, M, Chassande-Mottin, E, Combes, F, Cornilleau-Wehrlin, N, Decoene, V, Gérard, E, Gusdorf, A, Lamy, L, Masson, S, Mertens, F, Mottez, F, Petri, J, Vilmer, N, Weber, R, Hellbourg, Greg, Konovalenko, Alexander, Koopmans, Leon, Tokarsky, Peter, Ulyanov, Oleg, Vermeulen, Rene, Zakharenko, Vyacheslav, Cecconi, Baptiste, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), 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), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / 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-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de physique subatomique et des technologies associées (SUBATECH), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), 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), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Observatoire astronomique de Strasbourg (ObAS), and Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], [PHYS.ASTR.IM] Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; NenuFAR is a new, large low-frequency radio telescope, in construction and commissioning at the Nançay Radioastronomy Observatory, that starts to provide high sensitivity observations in the 10-85 MHz range. NenuFAR’s 1938 dual polarization antennas are connected to a suite of receivers allowing the instrument to operate, simultaneously if needed, in 4 distinct modes : as a standalone beamformer, a standalone imager, a waveform snapshots recorder, and a giant low-frequency station of the LOFAR array. We provide here an overview of the antennas, receivers, data products, operation and scientific context of the instrument.

Published
2020

22. The B-Star Exoplanet Abundance Study: a co-moving 16–25 M Jup companion to the young binary system HIP 79098

Author

Carbillet, M., Maurel, D., Origné, A., Rigal, F., Sevin, A., De Boer, J., van Holstein, R. G., Dohlen, K., Snik, F., Keller, C. U., Ginski, C., Stam, D. M., Wahhaj, Z., Kasper, M., Rabou, P., Hugot, E., Perret, D., Martinez, P., Pragt, J., Coroller, H. Le, Dominik, C., Turatto, M., Udry, S., Beuzit, J. -L., Le Coroller, H., Mennesson, B., Bailey, V., Kasdin, J., Trauger, J., Absil, O., Akeson, R., Armus, L., Baudoz, P., Bellini, A., Bennett, D., Berriman, B., Calchi-Novati, S., Carpenter, K., Chen, C., Danchi, W., Debes, J., Defrere, D., Ertel, S., Frerking, M., Gelino, C., Girard, J. H., Groff, T., Kane, S., Helou, G., Kalirai, J., Krist, J., Kruk, J., Hasegawa, Y., Laine, S., Lowrance, P., Malhotra, S., Mandell, A., Marshall, P., McElwain, M., Meshkat, T., Millan-Gabet, R., Moustakas, L., Nemati, B., Paladini, R., Postman, M., Pueyo, L., Quintana, E., Ramirez, S., Rhodes, J., Riggs, A. J. E., Rizzo, M., Soummer, R., Stapelfeldt, K., Stark, C., Turnbull, M., van der Marel, R., Ygouf, M., Wyatt, M., Zhao, F., Zimmerman, N., Loh, Alan, Messina, Sergio, Brandner, Wolfgang, Buenzli, Esther, Daemgen, Sebastien, Lagadec, Eric, Mouillet, David, Peretti, Sébastien, Janin-Potiron, Pierre, Salter, Graeme, Roux, Alain, Llored, Marc, Buey, Jean-Tristan, Pavlov, Alexei, Petit, C., Pawellek, Nicole, Moór, Attila, Milli, Julien, Kóspál, Ágnes, Olofsson, Johan, Ábrahám, Péter, Keppler, Miriam, Kral, Quentin, Pohl, Adriana, Augereau, Jean-Charles, Choquet, Elodie, Engler, Natalia, Lee, Eve J., Thebault, Philippe, Lee, Eve, Podio, L., Bacciotti, F., Antoniucci, S., Codella, C., Dougados, C., Nisini, B., Schmid, H. M., Stolker, T., Baudino, J. L., Biller, Beth, Bonavita, M., Galicher, R., Grandjean, A., Lagrange, Anne-Marie, Lannier, Justine, Maire, Anne-Lise, Perrot, Clément, Delboulbé, A., Mignant, D. Le, Fantinel, D., Moeller-Nilsson, O., Weber, Luc, Sauvage, J. -F., Le Mignant, D., Möller-Nilsson, O., Mesa, Dino, Garufi, A., D'Orazi, V., Flasseur, O., Barbieri, M., Benisty, M., Henning, Thomas, Ligi, R., Sissa, Elena, Zurlo, Alice, Boccaletti, Anthony, Cantalloube, F., Cheetham, Anthony, De Caprio, V., Feldt, Markus, Fusco, T., Gluck, L., Hagelberg, J., Lagrange, A. -M., Lazzoni, C., Madec, F., Maire, A. -L., Ménard, F., Meyer, M., Ramos, J., Rickman, E. L., Rouan, D., Schmidt, T., van der Plas, G., D’Orazi, V., De Caprio, V, Lagrange, A-M, Maire, A-L, Van der Plas, G, Janson, Markus, Asensio-Torres, Ruben, André, Damien, Bonnefoy, Mickaël, Delorme, Philippe, Reffert, Sabine, Desidera, Silvano, Langlois, M, Chauvin, G., Gratton, Raffaele, Bohn, Alexander J., Eriksson, Simon C., Marleau, Gabriel-Dominique, Mamajek, Eric E., Vigan, Arthur, Carson, Joseph C., Bohn, Alexander, Eriksson, Simon, Mamajek, Eric, Carson, Joseph, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], 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), Faculty of Aerospace Engineering [Delft], Delft University of Technology (TU Delft), Department of International Development, University of Oxford [Oxford], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY PASADENA USA, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), California Institute of Technology (CALTECH), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Space Sciences, Technologies and Astrophysics Research Institute (STAR), Université de Liège, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), European Southern Observatory (ESO), 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), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astronomico di Roma (OAR), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Department of Biochemistry and Molecular Biology, Mayo Clinic, INAF - Osservatorio Astronomico di Padova (OAPD), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Collège de France (CdF (institution)), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Axe 4 : céramiques sous contraintes environnementales (SPCTS-AXE4), Science des Procédés Céramiques et de Traitements de Surface (SPCTS), Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Landessternwarte Königstuhl [ZAH] (LSW), Universität Heidelberg [Heidelberg], Centre de Recherche Astrophysique de Lyon (CRAL), 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), Stockholm University, Universität Heidelberg [Heidelberg] = Heidelberg University, 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), Departamento de Ingeniería Matemática [Santiago] (DIM), Universidad de Chile = University of Chile [Santiago] (UCHILE)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, Institut für Astronomie und Astrophysik [Tübingen] (IAAT), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Department of Physics and Astronomy [Rochester], University of Rochester [USA], College of Charleston, ANR-10-LABX-0056,OSUG@2020,Innovative strategies for observing and modelling natural systems(2010), and European Project: 678194,H2020,ERC-2015-STG,FALCONER(2016)

Subjects
planets and satellites: detection, Proper motion, 010504 meteorology & atmospheric sciences, Stellar mass, Brown dwarf, FOS: Physical sciences, Astrophysics, 01 natural sciences, Planet, 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Astronomy and Astrophysics, Mass ratio, stars: early-type, Exoplanet, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Circumbinary planet, Astrophysics - Earth and Planetary Astrophysics, brown dwarfs
Abstract

Wide low-mass substellar companions are known to be very rare among low-mass stars, but appear to become increasingly common with increasing stellar mass. However, B-type stars, which are the most massive stars within ~150 pc of the Sun, have not yet been examined to the same extent as AFGKM-type stars in that regard. In order to address this issue, we launched the ongoing B-star Exoplanet Abundance Study (BEAST) to examine the frequency and properties of planets, brown dwarfs, and disks around B-type stars in the Scorpius-Centaurus (Sco-Cen) association; we also analyzed archival data of B-type stars in Sco-Cen. During this process, we identified a candidate substellar companion to the B9-type spectroscopic binary HIP 79098 AB, which we refer to as HIP 79098 (AB)b. The candidate had been previously reported in the literature, but was classified as a background contaminant on the basis of its peculiar colors. Here we demonstrate that the colors of HIP 79098 (AB)b are consistent with several recently discovered young and low-mass brown dwarfs, including other companions to stars in Sco-Cen. Furthermore, we show unambiguous common proper motion over a 15-year baseline, robustly identifying HIP 79098 (AB)b as a bona fide substellar circumbinary companion at a 345+/-6 AU projected separation to the B9-type stellar pair. With a model-dependent mass of 16-25 Mjup yielding a mass ratio of, 9 pages, 6 figures, accepted for publication in A&A

Published
2019
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23. Python in Heliophysics Community Meeting

Author

Ware, Alexandria, Barnum, Julie, Candey, Robert, Cecconi, Baptiste, Christe, Steven, Faden, Jeremy, Grimes, Eric, Harris, Bernie, Harter, Bryan, Kilcommons, Liam, Loh, Alan, McGuire, Robert, Mumford, Stuart, Narock, Ayris, Nguyen, Quynh Nhu, Niehof, Jonathan, Maldonado, Armando, Murphy, Nicholas, Panneton, Russ, Pembroke, Asher, Piker, Chris, Reardon, Kevin, Roberts, D. Aaron, Rogers, Anthony, Ryan, Daniel, Savage, Sabrina, Stoneback, Russell, Watson, Fraser, and Woodraska, Don

Abstract

Summary of the November 2018 meeting of the Python in Heliophysics Community.

Published
2019
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24. MASER: A Science Ready Toolbox for Low Frequency Radio Astronomy

Author

Cecconi, Baptiste, primary, Loh, Alan, additional, Le Sidaner, Pierre, additional, Savalle, Renaud, additional, Bonnin, Xavier, additional, Nguyen, Quynh Nhu, additional, Lion, Sonny, additional, Shih, Albert, additional, Aicardi, Stéphane, additional, Zarka, Philippe, additional, Louis, Corentin, additional, Coffre, Andrée, additional, Lamy, Laurent, additional, Denis, Laurent, additional, Grießmeier, Jean-Mathias, additional, Faden, Jeremy, additional, Piker, Chris, additional, André, Nicolas, additional, Génot, Vincent, additional, Erard, Stéphane, additional, Mafi, Joseph N., additional, King, Todd A., additional, Sky, Jim, additional, and Demleitner, Markus, additional

Published
2020
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25. Exploration of the Potential of the Radio-Detection Technique for the Detection of High-Energy Gamma Rays

Author

Dallier, Richard, primary, Bondonneau, Louis, additional, Charrier, Didier, additional, Coffre, Andrée, additional, Corbel, Stephane, additional, Denis, Laurent, additional, Dumez-Viou, Cedric, additional, Escudie, Antony, additional, García-Fernàndez, Daniel, additional, Girard, Julien, additional, Grießmeier, Jean-Mathias, additional, Koopmans, Leon, additional, Loh, Alan, additional, Martin, Lilian, additional, Pandey-Pommier, Mamta, additional, Revenu, Benoît, additional, and Zarka, Philippe, additional

Published
2019
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26. First resolved observations of a highly asymmetric debris disc around HD 160305 with VLT/SPHERE

Author

Perrot, Clément, primary, Thebault, Philippe, additional, Lagrange, Anne-Marie, additional, Boccaletti, Anthony, additional, Vigan, Arthur, additional, Desidera, Silvano, additional, Augereau, Jean-Charles, additional, Bonnefoy, Mickael, additional, Choquet, Élodie, additional, Kral, Quentin, additional, Loh, Alan, additional, Maire, Anne-Lise, additional, Ménard, François, additional, Messina, Sergio, additional, Olofsson, Johan, additional, Gratton, Raffaele, additional, Biller, Beth, additional, Brandner, Wolfgang, additional, Buenzli, Esther, additional, Chauvin, Gaël, additional, Cheetham, Anthony, additional, Daemgen, Sebastien, additional, Delorme, Philippe, additional, Feldt, Markus, additional, Lagadec, Eric, additional, Langlois, Maud, additional, Lannier, Justine, additional, Mesa, Dino, additional, Mouillet, David, additional, Peretti, Sébastien, additional, Janin-Potiron, Pierre, additional, Salter, Graeme, additional, Sissa, Elena, additional, Roux, Alain, additional, Llored, Marc, additional, Buey, Jean-Tristan, additional, Pavlov, Alexei, additional, Weber, Luc, additional, and Petit, Cyril, additional

Published
2019
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27. Explosive Events in the Transient Sky

Author

Loh, Alan, Loh, Alan, 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), Université Paris Diderot (Paris 7), Stéphane Corbel, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and 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)

Subjects
Microquasar, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], X-ray binary, Gamma-ray astronomy, Binaire X, Jets astrophysiques, Radioastronomie, Accretion/ejection coupling, Astrophysical Jets, Radio astronomy, Astronomie gamma, Couplage accrétion/éjection, [PHYS.ASTR.HE] Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE]
Abstract

Accretion and ejection phenomena are encountered in a vast diversity of astrophysical objects: from star formation to active galactic nuclei (AGNs). Microquasars consist of a stellar-mass compact object, which is accreting matter from a companion star and sharing several physical properties with AGNs. They represent ideal laboratories for the study of accretion/ejection coupling due to their proximity, their high luminosity levels and their short evolution time scales.Their high energy gamma-ray emission (HE) remains poorly constrained. We intend here to characterize the HE radiation of microquasars with the Fermi/LAT space telescope and try to detect it originating from other binary classes in order to determine the required conditions for HE emission. The Fermi satellite operates in a sky survey mode which enables transient phenomenon studies. We have searched for HE emission after an exceptional stellar flare from the binary star DG CVn. However, the located emission excess around DG CVn seems to be associated with a background AGN activity. We have also considered the cataclysmic variable SS Cyg whose periodic outbursts are associated with relativistic jets. After 26 years in quiescence, the low-mass microquasar V404 Cyg awoke during a spectacular outburst. The Fermi/LAT studies that we conducted led to the first HE gamma-ray detection of V404 Cyg.The V404 Cyg radio observations with the VLA allow us to highlight the jet variability at short time scales in quiescence as well as the continuation of the accretion/ejection coupling at low luminosity. Finally, we detail the results of a simultaneous radio/X-rays observation campaign on the black hole candidate GRS 1739−278. Low luminosity state transitions are observed during two successive short outbursts, that are rarely seen in microquasars. We discuss the physical origin of this behaviour contrasting with its previous outbursts., Les phénomènes d’accrétion et d’éjection se retrouvent au sein d’une grande diversité d’objets astrophysiques : des étoiles en formation jusqu’aux noyaux actifs de galaxies (AGNs). Les microquasars sont composés d’un objet compact de masse stellaire, accrétant la matière d’une étoile compagnon et partageant de nombreuses propriétés avec les AGNs. Ils représentent des environnements idéaux pour l’étude du couplage accrétion/éjection du fait de la proximité des systèmes, des niveaux de luminosité atteints et des temps caractéristiques d’évolution relativement courts.Leur émission gamma de haute énergie (HE) demeure cependant peu contrainte. Nous nous attachons ici à caractériser ce rayonnement avec le télescope spatial Fermi/LAT dans les microquasars et tentons de le mettre en évidence pour d’autres classes de binaires afin de déterminer les conditions nécessaires à la production d’une telle émission. Le satellite Fermi surveille continûment le ciel gamma et est idéal pour l’étude des phénomènes transitoires. Nous avons notamment recherché une émission HE à la suite d’une éruption stellaire exceptionnelle de l’étoile double DG CVn, cependant, l’excès HE éventuellement repéré semble associé à l’activité d’un AGN en arrière plan. Nous nous sommes également intéressés à la variable cataclysmique SS Cyg dont les sursauts périodiques sont associés à la formation de jets relativistes. Après 26 ans de quiescence, le microquasar V404 Cyg de faible masse s’est réveillé lors d’une éruption spectaculaire. Les études avec Fermi/LAT que nous avons dirigées ont conduit pour la première fois à la détection de V404 Cyg en rayons gamma HE.Les observations radio effectuées avec le VLA de V404 Cyg, alors en quiescence, nous permettent de dévoiler la variabilité du jet à courte échelle temporelle ainsi que le maintien du couplage accrétion/éjection à basse luminosité. Pour finir, nous détaillons les résultats d’une campagne d’observations simultanées radio/rayons X du candidat trou noir GRS 1739−278. Des transitions d’état à faible luminosité sont observées lors de deux courts sursauts successifs, rarement mis en évidence dans les microquasars. Nous discutons l’origine physique de ce comportement en contraste avec ses précédentes éruptions.

Published
2016

28. MASER (Measuring Analyzing & Simulating Emissions in Radio frequencies), a Toolbox for Low Frequency Radio Astronomy

Author

Cecconi, Baptiste, primary, Loh, Alan, additional, Le Sidaner, Pierre, additional, Savalle, Renaud, additional, Bonnin, Xavier, additional, Nguyen, Quynh Nhu, additional, Lion, Sonny, additional, Shih, Albert, additional, Aicardi, Stéphane, additional, Zarka, Philippe, additional, Louis, Corentin, additional, Coffre, Andrée, additional, Lamy, Laurent, additional, Denis, Laurent, additional, Greißmeier, Jean-Mathias, additional, Pinçon, Jean-Louis, additional, Canu, Patrick, additional, Faden, Jeremy, additional, Piker, Christopher, additional, André, Nicolas, additional, Génot, Vincent, additional, Erard, Stéphane, additional, King, Todd A, additional, Mafi, Joseph N, additional, Sharlow, Mark, additional, Sky, Jim, additional, and Demleitner, Markus, additional

Published
2018
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29. The Low-Frequency Beamformer and Imager NenuFAR

Author

Zarka, Philippe, primary, Coffre, Andree, additional, Denis, Laurent, additional, Dumez-Viou, Cedric, additional, Girard, Julien, additional, Griessmeier, Jean-Mathias, additional, Loh, Alan, additional, and Tagger, Michel, additional

Published
2018
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30. The Low-Frequency Radiotelescope NenuFAR

Author

Zarka, Philippe, primary, Coffre, Andree, additional, Denis, Laurent, additional, Dumez-Viou, Cedric, additional, Girard, Julien, additional, Griessmeier, Jean-Mathias, additional, Loh, Alan, additional, and Tagger, Michel, additional

Published
2018
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31. NenuFAR : instrument description and science case

Author

Zarka, Philippe, Tagger, Michel, Azarian, Sylvain, Barsuglia, Matteo, Boone, F, Bosma, Albert, Briand, Carine, Cecconi, Baptiste, Célestin, Sébastien, Combes, Françoise, Corbel, Stéphane, Courte, Cyril, Dallier, Richard, Dumez-Viou, Cédric, Ferrari, Chiara, Fialkov, A, Girard, Julien N., Grießmeier, Jean-Mathias, Lamy, Laurent, Lanz, T, Levrier, F., Panchenko, M., Pandey-Pommier, M, Tasse, Cyril, Torchinsky, Steve, Atemkeng, M, Bonafede, A, Boyer, R, Branchesi, Marica, Chassande-Mottin, E, Coffre, Andrée, Cognard, Ismael, Dabbech, A, Denis, Laurent, El Korso, M. N., Falgarone, Edith, Ferrari, A, Ferrière, Katia, Fevotte, C, Fullekrug, M, Guiderdoni, Bruno, Guillemot, Lucas, Hess, Sébastien L G, Hessels, J, Kondratiev, Vlad, Konovalenko, A, Koopmans, Leon, Larzabal, P, Lehnert, M, Loh, Alan, Macario, G, Maintoux, J, Maintoux, J J, Martin, Lilian, Masson, Sophie, Miville-Deschenes, Marc-Antoine, Oberoi, D, Petiteau, Antoine, Pinçon, Jean-Louis, Revenu, B, Rible, F, Richard, C, Rucker, Helmut O, Salomé, Philippe, Semelin, Benoit, Serylak, Maciej, Smirnov, Oleg, Stappers, B, Theureau, Gilles, van Driel, Wim, Vaubaillon, Jérémie, Vazza, F, Vergani, S, and Was, M

Subjects
Radioastronomy, Low Frequency
Abstract

This document presents the NenuFAR (New Extension in Nançay Upgrading LOFAR) science case.&nbsp

Published
2014
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33. Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni During Quiescence

Author

Rana, Vikram, Loh, Alan, Corbel, Stephane, Tomsick, John A., Chakrabarty, Deepto, Walton, Dominic J., Barret, Didier, Boggs, Steven E., Christensen, Finn Erland, Craig, William, Fuerst, Felix, Gandhi, Poshak, Grefenstette, Brian W., Hailey, Charles, Harrison, Fiona A., Madsen, Kristin K., Rahoui, Farid, Stern, Daniel, Tendulkar, Shriharsh, Zhang, William W., Rana, Vikram, Loh, Alan, Corbel, Stephane, Tomsick, John A., Chakrabarty, Deepto, Walton, Dominic J., Barret, Didier, Boggs, Steven E., Christensen, Finn Erland, Craig, William, Fuerst, Felix, Gandhi, Poshak, Grefenstette, Brian W., Hailey, Charles, Harrison, Fiona A., Madsen, Kristin K., Rahoui, Farid, Stern, Daniel, Tendulkar, Shriharsh, and Zhang, William W.

Published
2016

34. CHARACTERIZING X-RAY AND RADIO EMISSION IN THE BLACK HOLE X-RAY BINARY V404 CYGNI DURING QUIESCENCE

Author

Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Chakrabarty, Deepto, Rana, Vikram, Loh, Alan, Corbel, Stephane, Tomsick, John A., Walton, Dominic J., Barret, Didier, Boggs, Steven E., Christensen, Finn E., Craig, William, Fuerst, Felix, Gandhi, Poshak, Grefenstette, Brian W., Hailey, Charles, Harrison, Fiona A., Madsen, Kristin K., Rahoui, Farid, Stern, Daniel, Tendulkar, Shriharsh, Zhang, William W., Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Chakrabarty, Deepto, Rana, Vikram, Loh, Alan, Corbel, Stephane, Tomsick, John A., Walton, Dominic J., Barret, Didier, Boggs, Steven E., Christensen, Finn E., Craig, William, Fuerst, Felix, Gandhi, Poshak, Grefenstette, Brian W., Hailey, Charles, Harrison, Fiona A., Madsen, Kristin K., Rahoui, Farid, Stern, Daniel, Tendulkar, Shriharsh, and Zhang, William W.

Abstract

United States. National Aeronautics and Space Administration (contract No. NNG08FD60C), United States. National Aeronautics and Space Administration (XMM-Newton Guest Observer grant NNX14AF08G), Sorbone Paris Cite. UnivEarthS Labex programme (ANR-10-LABX-0023), Sorbone Paris Cite. UnivEarthS Labex programme (ANR-11-IDEX-0005-02), French Research National Agency (CHAOS project ANR-12-BS05-00009)

Published
2016

35. CHARACTERIZING X-RAY AND RADIO EMISSION IN THE BLACK HOLE X-RAY BINARY V404 CYGNI DURING QUIESCENCE

Author

Rana, Vikram, primary, Loh, Alan, additional, Corbel, Stephane, additional, Tomsick, John A., additional, Chakrabarty, Deepto, additional, Walton, Dominic J., additional, Barret, Didier, additional, Boggs, Steven E., additional, Christensen, Finn E., additional, Craig, William, additional, Fuerst, Felix, additional, Gandhi, Poshak, additional, Grefenstette, Brian W., additional, Hailey, Charles, additional, Harrison, Fiona A., additional, Madsen, Kristin K., additional, Rahoui, Farid, additional, Stern, Daniel, additional, Tendulkar, Shriharsh, additional, and Zhang, William W., additional

Published
2016
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36. Measly compensation

Author

Loh, Alan and McWhirter, Alex

Subjects
Thai Airways International PCL -- Management, Airlines -- Management, Airline passengers -- Beliefs, opinions and attitudes, Compensation management, Company business management, Business, Travel, recreation and leisure
Abstract

I was denied boarding on THAI Airways flight TG419 flight on November 6, 2005 as indicated on the THAI International Airways letter of acknowledgment even though I had a confirmed [...]

Published
2006

38. First resolved observations of a highly asymmetric debris disc around HD 160305 with VLT/SPHERE

Author

Perrot, Clément, Thébault, Philippe, Lagrange, Anne-Marie, Boccaletti, Anthony, Vigan, Arthur, Desidera, Silvano, Ausgereau, Jean-Charles, Bonnefoy, Mickaël, Choquet, Élodie, Kral, Quentin, Loh, Alan, Maire, Anne-Lise, Ménard, François, Messina, Sergio, Olofsson, Johan, Gratton, Raffaele, Biller, Beth A., Brandner, Wolfgang, Buenzli, Esther, Chauvin, Gaël, Cheetham, Anthony, Daemgen, Sebastien, Delorme, Philippe, Feldt, Markus, Langlois, Maud, Lannier, Justine, Mesa, Dino, Mouillet, David, Peretti, Sébastien, Janin-Potiron, Pierre, Salter, Graeme, Sissa, Elena, Roux, Alain, Llored, Marc, Buey, Jean-Tristan, Pavlov, Alexei, Weber, Luc, and Petit, Cyril

Subjects
planet-disk interactions, 13. Climate action, scattering, techniques: high angular resolution, techniques: image processing, Astrophysics::Earth and Planetary Astrophysics, methods: observational, stars: individual: HD160305, Astrophysics::Galaxy Astrophysics
Abstract

Context. Direct imaging of debris discs gives important information about their nature, their global morphology, and allows us to identify specific structures possibly in connection with the presence of gravitational perturbers. It is the most straightforward technique to observe planetary systems as a whole. Aims. We present the first resolved images of the debris disc around the young F-type star HD 160305, detected in scattered light using the VLT/SPHERE instrument in the near infrared. Methods. We used a post-processing method based on angular differential imaging and synthetic images of debris discs produced with a disc modelling code (GRaTer) to constrain the main characteristics of the disc around HD 160305. All of the point sources in the field of the IRDIS camera were analysed with an astrometric tool to determine whether they are bound objects or background stars. Results. We detect a very inclined (~82°) ring-like debris disc located at a stellocentric distance of about 86 au (deprojected width ~27 au). The disc displays a brightness asymmetry between the two sides of the major axis, as can be expected from scattering properties of dust grains. We derive an anisotropic scattering factor g > 0.5. A second right-left asymmetry is also observed with respect to the minor axis. We measure a surface brightness ratio of 0.73 ± 0.18 between the bright and the faint sides. Because of the low signal-to-noise ratio (S/N) of the images we cannot easily discriminate between several possible explanations for this left-right asymmetry, such as perturbations by an unseen planet, the aftermath of the breakup of a massive planetesimal, or the pericenter glow effect due to an eccentric ring. Two epochs of observations allow us to reject the companionship hypothesis for the 15 point sources present in the field., Astronomy & Astrophysics, 626, ISSN:0004-6361, ISSN:1432-0746

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