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177 results on '"WIESEMEYER, H."'

151. The high activity of 3C 454.3 in autumn 2007

Author

Raiteri, C. M., primary, Villata, M., additional, Chen, W. P., additional, Hsiao, W.-S., additional, Kurtanidze, O. M., additional, Nilsson, K., additional, Larionov, V. M., additional, Gurwell, M. A., additional, Agudo, I., additional, Aller, H. D., additional, Aller, M. F., additional, Angelakis, E., additional, Arkharov, A. A., additional, Bach, U., additional, Böttcher, M., additional, Buemi, C. S., additional, Calcidese, P., additional, Charlot, P., additional, D'Ammando, F., additional, Donnarumma, I., additional, Forné, E., additional, Frasca, A., additional, Fuhrmann, L., additional, Gómez, J. L., additional, Hagen-Thorn, V. A., additional, Jorstad, S. G., additional, Kimeridze, G. N., additional, Krichbaum, T. P., additional, Lähteenmäki, A., additional, Lanteri, L., additional, Latev, G., additional, Le Campion, J.-F., additional, Lee, C.-U., additional, Leto, P., additional, Lin, H.-C., additional, Marchili, N., additional, Marilli, E., additional, Marscher, A. P., additional, Nesci, R., additional, Nieppola, E., additional, Nikolashvili, M. G., additional, Ohlert, J., additional, Ovcharov, E., additional, Principe, D., additional, Pursimo, T., additional, Ragozzine, B., additional, Sadun, A. C., additional, Sigua, L. A., additional, Smart, R. L., additional, Strigachev, A., additional, Takalo, L. O., additional, Tavani, M., additional, Thum, C., additional, Tornikoski, M., additional, Trigilio, C., additional, Uckert, K., additional, Umana, G., additional, Valcheva, A., additional, Vercellone, S., additional, Volvach, A., additional, and Wiesemeyer, H., additional

Published
2008
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152. Large Excess of Heavy Nitrogen in Both Hydrogen Cyanide and Cyanogen from Comet 17P/Holmes

Author

Bockelée-Morvan, D., primary, Biver, N., additional, Jehin, E., additional, Cochran, A. L., additional, Wiesemeyer, H., additional, Manfroid, J., additional, Hutsemékers, D., additional, Arpigny, C., additional, Boissier, J., additional, Cochran, W., additional, Colom, P., additional, Crovisier, J., additional, Milutinovic, N., additional, Moreno, R., additional, Prochaska, J. X., additional, Ramirez, I., additional, Schulz, R., additional, and Zucconi, J.-M., additional

Published
2008
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153. First detection of the 63 μm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA.

Author

Rezac, L., Hartogh, P., Güsten, R., Wiesemeyer, H., Hübers, H. -W., Jarchow, C., Richter, H., Klein, B., and Honingh, N.

Subjects
MARTIAN atmosphere, THERMOSPHERE, OXYGEN, PHOTOCHEMISTRY, RADIATIVE transfer
Abstract

Context. The Stratospheric Observatory for Infrared Astronomy (SOFIA) with its 2.5 m telescope provides new science opportunities for spectroscopic observations of planetary atmospheres in the far-infrared wavelength range. Aims. This paper presents first results from the 14 May, 2014 observing campaign of the Martian atmosphere at 4.7 THz using the German REceiver for Astronomy at Terahertz frequencies (GREAT) instrument. Methods. The atomic oxygen 63 μm transition, OI, was detected in absorption against the Mars continuum, with a high signal-to-noise ratio (∼35). A beam-averaged atomic oxygen from a global circulation model was used as input to the radiative transfer simulations of the observed line area and to obtain a new estimate on the column density using a grid-search method. Results. Minimizing di erences between the calculated and observed line intensities in the least-square sense yields an atomic oxygen column density of (1:1 ± 0:2) × 10-17 cm-2. This value is about twice as low as predicted by a modern photochemical model of Mars. The radiative transfer simulations indicate that the line forms in the upper atmospheric region over a rather extended altitude region of 70-120 km. Conclusions. For the first time, a far-infrared transition of the atomic oxygen line was detected in the atmosphere of Mars. The absorption depth provides an estimate on the column density, and this measurement provides additional means to constrain the photochemical models in global circulation models and airglow studies. The lack of other means for monitoring the atomic oxygen in the Martian upper atmosphere makes future observations with the SOFIA observatory highly desirable. [ABSTRACT FROM AUTHOR]

Published
2015
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156. A 230 GHz heterodyne receiver array for the IRAM 30 m telescope

Author

Schuster, K.-F., primary, Boucher, C., additional, Brunswig, W., additional, Carter, M., additional, Chenu, J.-Y., additional, Foullieux, B., additional, Greve, A., additional, John, D., additional, Lazareff, B., additional, Navarro, S., additional, Perrigouard, A., additional, Pollet, J.-L., additional, Sievers, A., additional, Thum, C., additional, and Wiesemeyer, H., additional

Published
2004
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159. SiO maser polarization in evolved stars: magnetic field.

Author

Herpin, F., Baudry, A., Thum, C., Wiesemeyer, H., and Morris, D.

Subjects
COSMIC magnetic fields, MAGNETIC fields, MAGNETICS, CIRCUMSTELLAR matter, ASTROPHYSICS, PHYSICS
Abstract

We have measured the polarization of the SiO maser emission in a representative sample of evolved stars. We made simultaneous spectroscopic measurement of the 4 Stokes parameters, from which we derive the circular and linear polarization levels. These observations allow us to discuss the existent SiO maser models, to derive the strength of the magnetic field, and thus to determine the real influence of this magnetic field in the life of these evolved objects. The magnetic field strength we derive varies between 0 and 18 Gauss, with a mean value of 3.5 G and may follow a 1/r law throughout the circumstellar envelope. As a consequence, the magnetic field has a real influence on the life of these evolved objects: it definitively plays the role of a collimating, and more generally, of a shaping, agent in evolved objects. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2005
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160. A study of λBootis type stars in the wavelength region beyond 7000 Å ***

Author

Paunzen, E., Kamp, I., Weiss, W. W., Wiesemeyer, H., Paunzen, E., Kamp, I., Weiss, W. W., and Wiesemeyer, H.

Abstract

The group of λBootis type stars comprises late B- to early F-type, Population I objects which are basically metal weak, in particular the Fe group elements, but with the clear exception of C, N, O and S. One of the theories to explain the abundance pattern of these stars involves circumstellar or interstellar matter around the objects. Hence, we have compiled all available data from the literature of well established members of the λBootis group redward of 7000 Å  in order to find evidence for matter around these objects. Furthermore, we present unpublished ISO as well as submillimeter continuum and CO (2–1) line measurements to complete the data set. In total, measurements for 34 (26 with data redward of 20 μm) well established λBootis stars are available. There is evidence for an infrared excesses in six stars (HD 31295, HD 74873, HD 110411, HD 125162, HD 198160/1 and HD 210111) and two are doubtful cases (HD 11413 and HD 192640) resulting in a percentage of 23% (excluding the two doubtful cases). Dust models for these objects show fractional dust luminosities comparable to the Vega-type stars and slightly higher dust temperatures. ISO-SWS spectroscopy for HD 125162 and HD 192640 resulted in the detection of pure stellar H ilines ruling out an active accretion disk (as found for several Herbig Ae/Be stars) around these objects. The submillimeter measurements gave only upper limits for the line and continuum fluxes.

Published
2003
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161. A simultaneous 3.5 and 1.3mm polarimetric survey of active galactic nuclei in the northern sky.

Author

Agudo, I., Thum, C., Gómez, J. L., and Wiesemeyer, H.

Subjects
POLARIMETRY, ACTIVE galactic nuclei, NORTHERN sky (Astronomy), SYNCHROTRON radiation, RADIO jets (Astrophysics), FARADAY effect
Abstract

Context. Short millimeter observations of radio-loud active galactic nuclei (AGN) offer an excellent opportunity to study the physics of their synchrotron-emitting relativistic jets from where the bulk of radio and millimeter emission is radiated. On one hand, AGN jets and their emission cores are significantly less affected by Faraday rotation and depolarization than at longer wavelengths. On the other hand, the millimeter emission of AGN is dominated by the compact innermost regions in the jets, where the jet cannot be seen at longer wavelengths due to synchrotron opacity. Aims. We present the first simultaneous dual frequency 86?GHz and 229?GHz polarimetric survey of all four Stokes parameters for a large sample of 211 radio-loud active galactic nuclei, designed to be flux limited at 1?Jy at 86?GHz. Methods. Most of the observations were made in mid-August 2010 using the XPOL polarimeter on the IRAM 30?m millimetric radio telescope. Results. Linear polarization detections above a 3s median level of ~ 1.0% are reported for 183 sources at 86?GHz and for 23 sources at 229?GHz, where the median 3s level is ~ 6.0%. We show a clear excess of the linear polarization degree that is detected at 229?GHz with regard to that at 86?GHz by a factor of ~ 1.6. This implies a progressively better ordered magnetic field for blazar jet regions that are located progressively upstream in the jet. We show that the linear polarization angle at 86 and 229?GHz and the jet structural position angle for both quasars and BL Lacs do not show a clear preference to align in either parallel or perpendicular directions. Our variability study with regard to the 86?GHz data from our previous survey points out a large degree of variation. In particular, we report total flux and linear polarization changes in time scales of years by median factors of ~ 1.5 in total flux and ~ 1.7 in linear polarization degree (with maximum variations by factors up to 6.3 and ~ 5, respectively). Moreover, 86% of sources show linear polarization angles evenly distributed with regard to our previous measurements. [ABSTRACT FROM AUTHOR]

Published
2014
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162. The ionized and hot gas in M17 SW SOFIA/GREAT THz observations of [C II] and 12CO J = 13-12.

Author

Perez-Beaupuits, J. P., Wiesemeyer, H., Ossenkopf, V., Stutzki, J., Güsten, R., Simon, R., Hübers, H.-W., and Ricken, O.

Subjects
*IONIZED gases, *EMISSIONS (Air pollution), *MOLECULAR clouds, *INTERSTELLAR molecules, *SPECTRUM analysis
Abstract

Aims. With new THz maps that cover an area of ∼3.3 x 2.1 pc² we probe the spatial distribution and association of She ionized, neutral and molecular gas components in the M17 SW nebula. Methods. We used the dual hand receiver GREAT on board the SOFIA airborne telescope to obtain a 5'.7 x 3'.7 map of the 12CO J = 13-12 transition and the [C II] 158 μm fine-structure line in M17 SW and compare the spectroscopically resolved maps with corresponding ground-baaed data for low- and mid-J CO and [C 1] emission. Results. For the first time SOFIA/GREAT allow us to compare velocity-reaolved [C II] emission maps with molecular tracers. We see a large pail of the [C II] emission, both spatially and in velocity, that is completely non-associated with the other tracers of photon- dominated regions (PDR). Only particular narrow channel maps of the velocity-resolved [C II] spectra show a correlation between the different gas components, which is not seen at all in the integrated intensity maps. These a how different morphology in all lines but give hardly any information on the origin of the emission. The [C II] 158 μm emission extends for more than 2 pc into the M17 SW molecular cloud and its line profile covers a broader velocity range than the 12CO J = 13-12 and [CI] emissions, which we interpret as several clumps and layers of ionized carbon gas within the telescope beam. The high-J 12CO emission emerges from a dense region between the ionized and neutral carbon emissions, indicating the presence of high-density clumps that allow the fast formation of hot CO in the irradiated complex structure of M17 SW. The [CII] observations in the southern PDR cannot be explained with stratified or clumpy PDR models. [ABSTRACT FROM AUTHOR]

Published
2012
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163. High-resolution absorption spectroscopy of the OH 2Π3/2 ground state line.

Author

Wiesemeyer, H., Güsten, R., Heyminck, S., Jacobs, K., Menten, K. M., Neufeld, D. A., Requena-Torres, M. A., and Stutzki, J.

Subjects
*HIGH resolution electron microscopy, *GAS phase reactions, *HYDRIDES, *SPECTRUM analysis, *INTERSTELLAR medium
Abstract

The chemical composition of the interstellar medium is determined by gas phase chemistry, assisted by grain surface reactions, and by shock chemistry. The aim of this study is to measure the abundance of the hydroxyl radical (OH) in diffuse spiral arm clouds as a contribution to our understanding of the underlying network of chemical reactions. Owing to their high critical density, the ground states of light hydrides provide a tool to directly estimate column densities by means of absorption spectroscopy against bright background sources. We observed onboard the SOFIA observatory the ²Π3/2, J = 5/2 ← 3/2 2.5 THz line of ground-state OH in the diffuse clouds of the Carina-Sagittarius spiral arm. OH column densities in the spiral arm clouds along the sightlines to W49N, W51 and G34.26+0. 15 were found to be of the order of H2O cm-2, which corresponds to a fractional abundance of 10-7 to 10-8-8, which is comparable to that of H2O. The absorption spectra of both species have similar velocity components, and the ratio of the derived H2O to OH column densities ranges from 0.3 to 1.0. In W49N we also detected the corresponding line of 18OH. [ABSTRACT FROM AUTHOR]

Published
2012
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164. SOFIA observations of CO (12-11) emission along the L1157 bipolar outflow.

Author

Eislölel, J., Nisini, B., Güsten, R., Wiesemeyer, H., and Gusdorf, A.

Subjects
CARBON monoxide, BIPOLAR outflows (Astrophysics), MOLECULAR emission cavity analysis, COLD gases, PHOSPHORIMETRY
Abstract

Context. Carbon monoxide is an excellent tracer of the physical conditions of gas in molecular outflows from young stars. Aims. To understand the outflow mechanism we need to investigate the origin of the molecular emission and the structure and interaction of the outflowing molecular gas. Deriving the physical parameters of the gas will help us to trace and understand the various gas components in the how. Methods. We observed CO (12-11) line emission at various positions along the LI 157 bipolar outflow with GREAT aboard SOFIA. Results. Comparing these new data with CO (2-1), we find basically constant line ratios along the outflow and even at the position of the source. These line ratios lead us to estimates of l0~ to 106 cm3 for the gas density and 60 to 100 K for the gas temperature of the outflowing gas. Conclusions. The constrained density and temperature values indicate that we are mostly tracing a low-velocity gas component everywhere along the outflow, which is intermediate between the already known cold gas component, which gets entrained into the flow, and the hot gas, which gets shocked in the outflow. [ABSTRACT FROM AUTHOR]

Published
2012
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165. GREAT/SOFIA atmospheric calibration.

Author

X. Guan, Stutzki, J., Graf, U. U., Güsten, R., Okada, Y., Requena-Tones, M. A., Simon, R., and Wiesemeyer, H.

Subjects
SPECTROMETERS, MATHEMATICAL models, PHYSICAL measurements, CALIBRATION, ATMOSPHERIC radiation
Abstract

The GREAT observations need frequency-selective calibration across the passband for the residual atmospheric opacity at flight altitude. At these altitudes the atmospheric opacity has both narrow and broad spectral features. To determine the atmospheric transmission at high spectral resolution, GREAT compares the observed atmospheric emission with atmospheric model predictions, and therefore depends on the validity of the atmospheric models. We discuss the problems identified in this comparison with respect to the observed data and the models, and describe the strategy used to calibrate the science data from GREAT/SOFIA during the first observing periods. [ABSTRACT FROM AUTHOR]

Published
2012
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166. The high activity of 3C?454.3 in autumn 2007

Author

Raiteri, C., Villata, M., Chen, W., Hsiao, W.-S., Kurtanidze, O., Nilsson, K., Larionov, V., Gurwell, M., Agudo, I., Aller, H., Aller, M., Angelakis, E., Arkharov, A., Bach, U., B?ttcher, M., Buemi, C., Calcidese, P., Charlot, P., D'Ammando, F., Donnarumma, I., Forn?, E., Frasca, A., Fuhrmann, L., G?mez, J., Hagen-Thorn, V., Jorstad, S., Kimeridze, G., Krichbaum, T., L?hteenm?ki, A., Lanteri, L., Latev, G., Le Campion, J.-F., Lee, C.-U., Leto, P., Lin, H.-C., Marchili, N., Marilli, E., Marscher, A., Nesci, R., Nieppola, E., Nikolashvili, M., Ohlert, J., Ovcharov, E., Principe, D., Pursimo, T., Ragozzine, B., Sadun, A., Sigua, L., Smart, R., Strigachev, A., Takalo, L., Tavani, M., Thum, C., Tornikoski, M., Trigilio, C., Uckert, K., Umana, G., Valcheva, A., Vercellone, S., Volvach, A., and Wiesemeyer, H.

Abstract

Context. The quasar-type blazar 3C 454.3 underwent a phase of high activity in summer and autumn?2007 that was intensively monitored in the radio-to-optical bands by the Whole Earth Blazar Telescope (WEBT). The ?-ray satellite Astro-rivelatore Gamma a Immagini LEggero (AGILE) detected this source first in late July, and then in November?December 2007.Aims. We present the multifrequency data collected by the WEBT and collaborators during the second AGILE observing period, complemented by contemporaneous data from the UltraViolet and Optical Telescope (UVOT) onboard the Swift satellite. The aim is to trace in detail the behaviour of the synchrotron emission from the blazar jet, and to investigate the contribution from the thermal emission component.Methods. Optical data from about twenty telescopes have been homogeneously calibrated and carefully assembled to construct an R-band light curve containing about 1340?data points over 42?days. This extremely well-sampled optical light curve allows us to follow the dramatic flux variability of the source in detail. In addition, we show radio-to-UV spectral energy distributions (SEDs) at different epochs, which represent different brightness levels.Results. In the considered period, the source varied by 2.6?mag over two weeks in the R?band. Many episodes of fast (i.e.?intranight) variability were observed, most notably on December?12, when a flux increase of about 1.1?mag in 1.5?h was detected, followed by a steep decrease of about 1.2?mag in 1?h. The contribution by the thermal component is difficult to assess, due to the uncertainties in the Galactic, and possibly also intrinsic, extinction in the UV?band. However, polynomial fitting of radio-to-UV?SEDs reveals an increasing spectral bending towards fainter states, suggesting a UV?excess likely due to the thermal emission from the accretion disc.Conclusions. Once the AGILE data are completely analysed, the low-frequency observations presented in this letter will offer a powerful tool to investigate optical-? flux correlations, i.e.?the relationship between the synchrotron and inverse-Compton emission components.

Published
2008

167. Planck intermediate results. XXXII. The relative orientation between the magnetic field and structures traced by interstellar dust

Author

Adam, R, Ade, P, Aghanim, N, Alves, M, Arnaud, M, Arzoumanian, D, Ashdown, M, Aumont, J, Baccigalupi, C, Banday, A, Barreiro, R, Bartolo, N, Battaner, E, Benabed, K, Benoit Levy, A, Bernard, J, Bersanelli, M, Bielewicz, P, Bonaldi, A, Bonavera, L, Bond, J, Borrill, J, Bouchet, F, Boulanger, F, Bracco, A, Burigana, C, Butler, R, Calabrese, E, Cardoso, J, Catalano, A, Chamballu, A, Chiang, H, Christensen, P, Colombi, S, Colombo, L, Combet, C, Couchot, F, Crill, B, Curto, A, Cuttaia, F, Danese, L, Davies, R, Davis, R, de Bernardis, P, de Rosa, A, de Zotti, G, Delabrouillel, J, Dickinson, C, Diego, J, Dole, H, Donzelli, S, Dore, O, Douspis, M, Ducout, A, Dupac, X, Efstathiou, G, Elsner, F, Ensslin, T, Eriksen, H, Falgarone, E, Ferriere, K, Finelli, F, Forni, O, Frailis, M, Fraisse, A, Franceschi, E, Frejse, A, Galeotta, S, Gai, S, Ganga, K, Ghosh, T, Giard, M, Gjerlow, E, Gonzalez Nuevo, J, Gorski, K, Gregorio, A, Gruppuso, A, Guillet, V, Hansen, K, Hanson, D, Harrison, D, Henrot Versille, S, Hernandez Monteagudo, C, Herranz, D, Hildebrandt, S, Hivon, E, Hobson, M, Holmes, W, Hovest, W, Huffenberger, K, Hurier, G, Jaffe, A, Jaffe, T, Jones, W, Juvela, M, Keihanen, E, Keskitalo, R, Kisner, T, Kneiss, R, Knoche, J, Kunz, M, Kurki Suonio, H, Lagache, G, Lamarre, J, Lasenby, A, Lattanzi, M, Lawrence, C, Leonardi, R, Levrier, F, Liguori, M, Lilje, P, Linden Vornle, M, Lopez Caniego, M, Lubin, P, Macias Perez, J, Maffei, B, Maino, D, Mandolesi, N, Maris, M, Marshal, D, Martin, P, Martinez Gonzalez, E, Masi, S, Matarrese, S, Mazzotta, P, Melchiorri, A, Mendes, L, Mennella, A, Migliaccio, M, Miville Descheness, M, Moneti, A, Montier, L, Morgante, G, Mortlock, D, Munshi, D, Murphy, J, Naselsky, P, Natoli, P, Norgaard Nielsen, H, Noviello, F, Novikov, D, Novikov, I, Oppermann, N, Oxborrow, C, Pagano, L, Pajot, F, Paoletti, D, Pasian, F, Perdereau, O, Perotto, L, Perrotta, F, Pettorino, V, Piacentini, F, Piat, M, Plaszczynski, S, Pointecouteau, E, Polenta, G, Ponthieu, N, Popa, L, Pratt, G, Prunet, S, Puget, J, Rachen, J, Reach, W, Reinecke, M, Remazeilles, M, Renault, C, Ristorcelli, I, Rocha, G, Roudier, G, Rubino Martin, J, Rusholme, B, Sandri, M, Santos, D, Savini, G, Scott, D, Soler, J, Spencer, L, Stolyarov, V, Sudiwala, R, Sunyaev, R, Sutton, D, Suur Uski, A, Sygnet, J, Tauber, J, Terenzi, L, Toffolatti, L, Tomasi, M, Tristram, M, Tucci, M, Umana, G, Valenziano, L, Valiviita, J, Van Tent, B, Vielva, P, Villa, F, Wade, L, Wandelt, B, Wehus, I, Wiesemeyer, H, Yvon, D, Zacchei, A, Zonca, A, Planck, C, European Commission, European Research Council, Consejo Superior de Investigaciones Científicas (España), Junta de Andalucía, European Space Agency, Centre National de la Recherche Scientifique (France), Istituto Nazionale di Astrofisica, National Aeronautics and Space Administration (US), Science and Technology Facilities Council (UK), Academy of Finland, Center for Science (Finland), Agenzia Spaziale Italiana, Department of Energy (US), UK Space Agency, Fundação para a Ciência e a Tecnologia (Portugal), Science Foundation Ireland, DTU Space (Denmark), Swiss Space Office, Max Planck Society, German Centre for Air and Space Travel, Ministerio de Economía y Competitividad (España), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), 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), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), 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), 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), Laboratoire de l'Accélérateur Linéaire (LAL), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Théorique d'Orsay [Orsay] (LPT), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Planck, European Project: 267934,EC:FP7:ERC,ERC-2010-AdG_20100224,MISTIC(2011), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), 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), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), 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), 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), Science and Technology Facilities Council (STFC), Adam, R., Ade, P. A. R., Aghanim, N., Alves, M. I. R., Arnaud, M., Arzoumanian, D., Ashdown, M., Aumont, J., Baccigalupi, C., Banday, A. J., Barreiro, R. B., Bartolo, N., Battaner, E., Benabed, K., Benoit Lévy, A., Bernard, J. P., Bersanelli, M., Bielewicz, P., Bonaldi, A., Bonavera, L., Bond, J. R., Borrill, J., Bouchet, F. R., Boulanger, F., Bracco, A., Burigana, C., Butler, R. C., Calabrese, E., Cardoso, J. F., Catalano, A., Chamballu, A., Chiang, H. C., Christensen, P. R., Colombi, S., Colombo, L. P. L., Combet, C., Couchot, F., Crill, B. P., Curto, A., Cuttaia, F., Danese, L., Davies, R. D., Davis, R. J., de Bernardis, P., de Rosa, A., de Zotti, G., Delabrouille, J., Dickinson, C., Diego, J. M., Dole, H., Donzelli, S., Doré, O., Douspis, M., Ducout, A., Dupac, X., Efstathiou, G., Elsner, F., Enßlin, T. A., Eriksen, H. K., Falgarone, E., Ferrière, K., Finelli, F., Forni, O., Frailis, M., Fraisse, A. A., Franceschi, E., Frejsel, A., Galeotta, S., Galli, S., Ganga, K., Ghosh, T., Giard, M., Gjerløw, E., González Nuevo, J., Górski, K. M., Gregorio, Anna, Gruppuso, A., Guillet, V., Hansen, F. K., Hanson, D., Harrison, D. L., Henrot Versillé, S., Hernández Monteagudo, C., Herranz, D., Hildebrandt, S. R., Hivon, E., Hobson, M., Holmes, W. A., Hovest, W., Huffenberger, K. M., Hurier, G., Jaffe, A. H., Jaffe, T. R., Jones, W. C., Juvela, M., Keihänen, E., Keskitalo, R., Kisner, T. S., Kneissl, R., Knoche, J., Kunz, M., Kurki Suonio, H., Lagache, G., Lamarre, J. M., Lasenby, A., Lattanzi, M., Lawrence, C. R., Leonardi, R., Levrier, F., Liguori, M., Lilje, P. B., Linden Vørnle, M., López Caniego, M., Lubin, P. M., Macías Pérez, J. F., Maffei, B., Maino, D., Mandolesi, N., Maris, M., Marshall, D. J., Martin, P. G., Martínez González, E., Masi, S., Matarrese, S., Mazzotta, P., Melchiorri, A., Mendes, L., Mennella, A., Migliaccio, M., Miville Deschênes, M. A., Moneti, A., Montier, L., Morgante, G., Mortlock, D., Munshi, D., Murphy, J. A., Naselsky, P., Natoli, P., Nørgaard Nielsen, H. U., Noviello, F., Novikov, D., Novikov, I., Oppermann, N., Oxborrow, C. A., Pagano, L., Pajot, F., Paoletti, D., Pasian, F., Perdereau, O., Perotto, L., Perrotta, F., Pettorino, V., Piacentini, F., Piat, M., Plaszczynski, S., Pointecouteau, E., Polenta, G., Ponthieu, N., Popa, L., Pratt, G. W., Prunet, S., Puget, J. L., Rachen, J. P., Reach, W. T., Reinecke, M., Remazeilles, M., Renault, C., Ristorcelli, I., Rocha, G., Roudier, G., Rubiño Martín, J. A., Rusholme, B., Sandri, M., Santos, D., Savini, G., Scott, D., Soler, J. D., Spencer, L. D., Stolyarov, V., Sudiwala, R., Sunyaev, R., Sutton, D., Suur Uski, A. S., Sygnet, J. F., Tauber, J. A., Terenzi, L., Toffolatti, L., Tomasi, M., Tristram, M., Tucci, M., Umana, G., Valenziano, L., Valiviita, J., Van Tent, B., Vielva, P., Villa, F., Wade, L. A., Wandelt, B. D., Wehus, I. K., Wiesemeyer, H., Yvon, D., Zacchei, A., Zonca, A., Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), 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), École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Magnetohydrodynamics (MHD), magnetic field [ISM], Astronomy, cloud [ISM], SM: clouds, ISM: magnetic fields, ISM: structure, magnetohydrodynamics (MHD), polarization, turbulence, Astrophysics, ISM: clouds, 7. Clean energy, 01 natural sciences, Magnetohydrodynamics, Polarization, Astrophysics::Solar and Stellar Astrophysics, FILAMENTARY CLOUDS, 010303 astronomy & astrophysics, Physics, Linear polarization, MASS STAR-FORMATION, Polarization (waves), magnetohydrodynamics, Magnetic field, GAS, Physical Sciences, symbols, MILKY-WAY, Astrophysics::Earth and Planetary Astrophysics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], clouds [ISM], INFRARED POLARIMETRY, Astrophysics::High Energy Astrophysical Phenomena, astro-ph.GA, SPIRAL ARMS, FOS: Physical sciences, POLARIZATION MAPS, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, NO, ISM: Clouds, ISM: Magnetic fields, ISM: Structure, Turbulence, Astronomy and Astrophysics, Space and Planetary Science, symbols.namesake, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Planck, Astrophysics::Galaxy Astrophysics, Cosmic dust, Science & Technology, 010308 nuclear & particles physics, Molecular cloud, magnetic fields [ISM], TAURUS MOLECULAR CLOUD, Astrophysics - Astrophysics of Galaxies, GOULD BELT, Interstellar medium, 0201 Astronomical And Space Sciences, 13. Climate action, Astrophysics of Galaxies (astro-ph.GA), structure [ISM]
Abstract

Interstellar and circumstellar matter.-- et al., The role of the magnetic field in the formation of the filamentary structures observed in the interstellar medium (ISM) is a debated topic owing to the paucity of relevant observations needed to test existing models. The Planck all-sky maps of linearly polarized emission from dust at 353 GHz provide the required combination of imaging and statistics to study the correlation between the structures of the Galactic magnetic field and of interstellar matter over the whole sky, both in the diffuse ISM and in molecular clouds. The data reveal that structures, or ridges, in the intensity map have counterparts in the Stokes Q and/or U maps. We focus our study on structures at intermediate and high Galactic latitudes, which cover two orders of magnitude in column density, from 1020 to 1022 cm-2. We measure the magnetic field orientation on the plane ofthe sky from the polarization data, and present an algorithm to estimate the orientation of the ridges from the dust intensity map. We use analytical models to account for projection effects. Comparing polarization angles on and off the structures, we estimate the mean ratio between the strengths of the turbulent and mean components of the magnetic field to be between 0.6 and 1.0, with a preferred value of 0.8. We find that the ridges are usually aligned with the magnetic field measured on the structures. This statistical trend becomes more striking for increasing polarization fraction and decreasing column density. There is no alignment for the highest column density ridges. We interpret the increase in alignment with polarization fraction as a consequence of projection effects. We present maps to show that the decrease in alignment for high column density is not due to a loss of correlation between the distribution of matter and the geometry of the magnetic field. In molecular complexes, we also observe structures perpendicular to the magnetic field, which, statistically, cannot be accounted for by projection effects. This first statistical study of the relative orientation between the matter structures and the magnetic field in the ISM points out that, at the angular scales probed by Planck, the field geometry projected on the plane of the sky is correlated with the distribution of matter. In the diffuse ISM, the structures of matter are usually aligned with the magnetic field, while perpendicular structures appear in molecular clouds. We discuss our results in the context of models and MHD simulations, which attempt to describe the respective roles of turbulence, magnetic field, and self-gravity in the formation of structures in the magnetized ISM., The development of Planck has been supported by: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MICINN, JA, and RES (Spain); Tekes, AoF, and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and PRACE (EU). The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement No. 267934.

168. Sub-Millimeter View of the Galactic Center

Author

Garcia-Marin, M., Eckart, A., Weiss, A., Witzel, G., Bremer, M., Zamaninasab, M., Schodel, R., Kunneriath, D., Sabha, N., Baganoff, F., Michal Dovciak, Duschl, W. J., Moultaka, J., Karas, V., Najarro, F., Muzic, K., Straubmeier, C., Vogel, S. N., Krips, M., and Wiesemeyer, H.

169. Probing Sagittarius A* and its Environment at the Galactic Centre: VLT and APEX Working in Synergy

Author

Eckart, A., Schödel, R., García-Marín, M., Witzel, G., Weiss, A., Baganoff, F., Morris, M.R., Bertram, T., Dovčiak, M., Downes, D., Duschl, W., Karas, V., König, S., Krichbaum, T., Krips, M., Kunneriath, D., Lu, R.-S., Markoff, S., Mauerhan, J., Meyer, L., Moultaka, J., Mužić, K., Najarro, F., Pott, J.-U., Schuster, K., Sjouwerman, L., Straubmeier, C., Thum, C., Vogel, S., Wiesemeyer, H., Zamaninasab, M., Zensus, A., and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

On 3 June 2008 an international team of researchers observed one of the brightest near-infrared flares close to SgrA*, the black hole at the centre of the Milky Way. For the very first time the flare emission was detected in infrared light, with one of the VLT telescopes, and time delayed in sub-millimetre radiation with the APEX telescope. Recent simultaneous X-ray and infrared flares from SgrA* have been detected and can be explained by spots on relativistic orbits around the central, accreting supermassive black hole. The observations of flares now also show some evidence for time evolution of the spot properties. The investigation of dusty stars and filaments in the central stellar cluster also indicates the presence of a wind from the central region - possibly with a contribution from SgrA* itself.

170. Detection of OD towards the low-mass protostar IRAS 16293-2422 [Letter]

Author

Parise, Berengere, Du, F., Liu, F. -C., Belloche, A., Wiesemeyer, H., Güsten, R., Menten, K. M., Huebers, H. -W., and Klein, B.

Subjects
QB
Abstract

Context. Although water is an essential and widespread molecule in star-forming regions, its chemical formation pathways are still not very well constrained. Observing the level of deuterium fractionation of OH, a radical involved in the water chemical network, is a promising way to infer its chemical origin.\ud Aims. We aim at understanding the formation mechanisms of water by investigating the origin of its deuterium fractionation. This can be achieved by observing the abundance of OD towards the low-mass protostar IRAS 16293−2422, where the HDO distribution is already known.\ud Methods. Using the GREAT receiver on board SOFIA, we observed the ground-state OD transition at 1391.5 GHz towards the low-mass protostar IRAS 16293−2422. We also present the detection of the HDO 111-000 line using the APEX telescope. We compare the OD/HDO abundance ratio inferred from these observations with the predictions of chemical models.\ud Results. The OD line is detected in absorption towards the source continuum. This is the first detection of OD outside the solar system. The SOFIA observation, coupled to the observation of the HDO 111-000 line, provides an estimate of the abundance ratio OD/HDO ~ 17–90 in the gas where the absorption takes place. This value is fairly high compared with model predictions. This may be reconciled if reprocessing in the gas by means of the dissociative recombination of H2DO+ further fractionates OH with respect to water.\ud Conclusions. The present observation demonstrates the capability of the SOFIA/GREAT instrument to detect the ground transition of OD towards star-forming regions in a frequency range that was not accessible before. Dissociative recombination of H2DO+ may play an important role in setting a high OD abundance. Measuring the branching ratios of this reaction in the laboratory will be of great value for chemical models.

171. NIKA 150 GHz polarization observations of the Crab nebula and its spectral energy distribution

Author

Ritacco, A., Macías-Pérez, J. F., Ponthieu, N., Adam, R., Ade, P., André, P., Aumont, J., Beelen, A., Benoît, A., Bideaud, A., Billot, N., Bourrion, O., Bracco, A., Calvo, M., Catalano, A., Coiffard, G., Comis, B., Antonio D'Addabbo, Petris, M., Désert, F. -X, Doyle, S., Goupy, J., Kramer, C., Lagache, G., Leclercq, S., Lestrade, J. -F, Mauskopf, P., Mayet, F., Maury, A., Monfardini, A., Pajot, F., Pascale, E., Perotto, L., Pisano, G., Rebolo-Iglesias, M., Revéret, V., Rodriguez, L., Romero, C., Roussel, H., Ruppin, F., Schuster, K., Sievers, A., Siringo, G., Thum, C., Triqueneaux, S., Tucker, C., Wiesemeyer, H., and Zylka, R.

172. A sensitive upper limit to the circular polarization of the Crab nebula at λ3 mm

Author

Wiesemeyer, H., Thum, C., Morris, D., Aumont, J., and Rosset, C.

Abstract

A new observation of the distribution of the circular polarization over the Crab Nebula supernova remnant yields an upper limit of  <0.2% at a radio frequency of 89.2 GHz. This limit is set by the uncertainty in correcting for the instrumental polarization. The raw data were dominated by the conversion of the strong linear polarization to circular in the crosspolarized sidelobes of the 30 m telescope. They were modeled as due to a differential phase gradient between the orthogonally linearly polarized far-field radiation patterns of the two receivers. As the source is tracked these rotate with respect to the radio source distribution on the sky since the telescope has an alt-azimuth mount and a Nasmyth focus. This allows the model to be fit to the raw data and a correction can be made. Our limit of  <0.2% is to be compared with  <0.03% derived at 610 MHz (Wilson & Weiler 1997, ApJ, 475, 661) and  <6% measured at 23 GHz (Wright & Forster 1980, ApJ, 239, 873). These limits are consistent with the polarization expected from an optically thin synchrotron source with the known physical properties of the Crab Nebula. This non-detection does not allow an estimate to be made of the relative contribution to the radio emission from electrons and positrons.

Published
2011
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173. The awakening of BL Lacertae: observations by Fermi, Swift, and the GASP-WEBT

Author

V. T. Doroshenko, A. Berdyugin, M. I. Carnerero, Filippo D'Ammando, Stoyanka Peneva, Evgeni Semkov, D. O. Mirzaqulov, D. Carosati, A. C. Sadun, Elina Lindfors, M. J. Arévalo, J. Phipps, Dmitry A. Blinov, Rumen Bachev, Evgeni Ovcharov, S. G. Sergeev, Givi N. Kimeridze, K. A. Stoyanov, Svetlana G. Jorstad, Valeri M. Larionov, Neelam Panwar, Y. Metodieva, Y. Jadhav, R. Ligustri, Meenakshi Kohli, V. Kadenius, Alan P. Marscher, Antoniya Valcheva, N. Smith, I. M. McHardy, Sh. A. Ehgamberdiev, Sunay Ibryamov, Elena G. Larionova, Paul S. Smith, A. Sillanpää, R. Reinthal, C. M. Raiteri, A. Strigachev, Tatiana S. Konstantinova, Iván Agudo, M. G. Nikolashvili, V. Bozhilov, N. G. Pulatova, S. V. Nazarov, Carolina Casadio, Helmut Wiesemeyer, David Hiriart, G. A. Borman, Ivan S. Troitsky, R. D. Schwartz, Ekaterina Koptelova, Markus Böttcher, M. Villata, Kari Nilsson, E. N. Kopatskaya, Wen Ping Chen, B. McBreen, J. A. Ros, L. V. Larionova, Lorand A. Sigua, J. A. Acosta-Pulido, Ann E. Wehrle, Mark Gurwell, S. A. Klimanov, Manasvita Joshi, M. Pasanen, Erika Benítez, D. N. Okhmat, L. O. Takalo, N. V. Efimova, Brian W. Taylor, Omar M. Kurtanidze, Clemens Thum, Sol N. Molina, D. A. Morozova, Pedro A. Gonzalez-Morales, Yu. S. Efimov, José L. Gómez, Raiteri CM, Villata M, DAmmando F, Larionov VM, Gurwell MA, Mirzaqulov DO, Smith PS, Acosta-Pulido JA, Agudo I, Arevalo MJ, Bachev R, Benitez E, Berdyugin A, Blinov DA, Borman GA, Bottcher M, Bozhilov V, Carnerero MI, Carosati D, Casadio C, Chen WP, Doroshenko VT, Efimova YS, Efimova NV, Ehgamberdiev SA, Gomez JL, Gonzalez-Morales PA, Hiriart D, Ibryamov S, Jadhav Y, Jorstad SG, Joshi M, Kadenius V, Klimanov SA, Kohli M, Konstantinova TS, Kopatskaya EN, Koptelova E, Kimeridze G, Kurtanidze OM, Larionova EG, Larionova LV, Ligustri R, Lindfors E, Marscher AP, McBreen B, McHardy IM, Metodieva Y, Molina SN, Morozova DA, Nazarov SV, Nikolashvili MG, Nilsson K, Okhmat DN, Ovcharov E, Panwar N, Pasanen M, Peneva S, Phipps J, Pulatova NG, Reinthal R, Ros JA, Sadun AC, Schwartz RD, Semkov E, Sergeev SG, Sigua LA, Sillanpaa A, Smith N, Stoyanov K, Strigachev A, Takalo LO, Taylor B, Thum C, Troitsky IS, Valcheva A, Wehrle AE, and Wiesemeyer H

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Cosmology and Nongalactic Astrophysics (astro-ph.CO), ta115, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Polarization (waves), law.invention, Telescope, Wavelength, Space and Planetary Science, Observatory, law, Degree of polarization, galaxies: active, BL Lacertae objects: general, BL Lacertae objects: individual: BL Lacertae, galaxies: jets, Blazar, Astrophysics - High Energy Astrophysical Phenomena, BL Lac object, Fermi Gamma-ray Space Telescope, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Since the launch of the Fermi satellite, BL Lacertae has been moderately active at gamma-rays and optical frequencies until May 2011, when the source started a series of strong flares. The exceptional optical sampling achieved by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) in collaboration with the Steward Observatory allows us to perform a detailed comparison with the daily gamma-ray observations by Fermi. Discrete correlation analysis between the optical and gamma-ray emission reveals correlation with a time lag of 0 +- 1 d, which suggests cospatiality of the corresponding jet emitting regions. A better definition of the time lag is hindered by the daily gaps in the sampling of the extremely fast flux variations. In general, optical flares present more structure and develop on longer time scales than corresponding gamma-ray flares. Observations at X-rays and at millimetre wavelengths reveal a common trend, which suggests that the region producing the mm and X-ray radiation is located downstream from the optical and gamma-ray-emitting zone in the jet. The mean optical degree of polarisation slightly decreases over the considered period and in general it is higher when the flux is lower. The optical electric vector polarisation angle (EVPA) shows a preferred orientation of about 15 deg, nearly aligned with the radio core EVPA and mean jet direction. Oscillations around it increase during the 2011-2012 outburst. We investigate the effects of a geometrical interpretation of the long-term flux variability on the polarisation. A helical magnetic field model predicts an evolution of the mean polarisation that is in reasonable agreement with the observations. These can be fully explained by introducing slight variations in the compression factor in a transverse shock waves model., 17 pages, 17 figures, 1 table, accepted for publication in MNRAS

Published
2013

174. The high activity of 3C 454.3 in autumn 2007. Monitoring by the WEBT during the AGILE detection

Author

C. M. Raiteri, M. Villata, W. P. Chen, W.-S. Hsiao, O. M. Kurtanidze, K. Nilsson, V. M. Larionov, M. A. Gurwell, I. Agudo, H. D. Aller, M. F. Aller, E. Angelakis, A. A. Arkharov, U. Bach, M. Böttcher, C. S. Buemi, P. Calcidese, P. Charlot, F. D'Ammando, I. Donnarumma, E. Forné, A. Frasca, L. Fuhrmann, J. L. Gómez, V. A. Hagen-Thorn, S. G. Jorstad, G. N. Kimeridze, T. P. Krichbaum, A. Lähteenmäki, L. Lanteri, G. Latev, J.-F. Le Campion, C.-U. Lee, P. Leto, H.-C. Lin, N. Marchili, E. Marilli, A. P. Marscher, R. Nesci, E. Nieppola, M. G. Nikolashvili, J. Ohlert, E. Ovcharov, D. Principe, T. Pursimo, B. Ragozzine, A. C. Sadun, L. A. Sigua, R. L. Smart, A. Strigachev, L. O. Takalo, M. Tavani, C. Thum, M. Tornikoski, C. Trigilio, K. Uckert, G. Umana, A. Valcheva, S. Vercellone, A. Volvach, H. Wiesemeyer, INAF - Osservatorio Astrofisico di Torino (OATo), Istituto Nazionale di Astrofisica (INAF), Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale, Laboratoire de chimie bactérienne (LCB), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Fujian Institute of Research on the Structure of Matter, National Engineering Research Center for Optoelectronic Crystalline Materials, Chinese Academy of Sciences, Insitute of Geology China Earthquake Administration Beijing 100029, China (X.X., G.C., W.C.) (INSITUTE OF GEOLOGY), Insitute of Geology, ECE Dept., University of Wisconsin-Madison, Harbin Institute of Technology (HIT), Department of Information Science and Media Studies [Bergen], University of Bergen (UIB), Institute of Geology, Chinese Academy of Sciences [Changchun Branch] (CAS), Linköping University (LIU), Department of Mechanical Engineering, National Chung-Hsing University, Research Center for Environmental Changes, Institute of Earthquake Prediction Research, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université du Littoral Côte d'Opale (ULCO)-Centre National de la Recherche Scientifique (CNRS), Department of Information Science and Media Studies [Bergen] (UiB), University of Bergen (UiB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Raiteri CM, Villata M, Chen WP, Hsiao WS, Kurtanidze OM, Nilsson K, Larionov VM, Gurwell MA, Agudo I, Aller HD, Aller MF, Angelakis E, Arkharov AA, Bach U, Bottcher M, Buemi CS, Calcidese P, Charlot P, DAmmando F, Donnarumma I, Forne E, Frasca A, Fuhrmann L, Gomez JL, Hagen-Thorn VA, Jorstad SG, Kimeridze GN, Krichbaum TP, Lahteenmaki A, Lanteri L, Latev G, Le Campion JF, Lee CU, Leto P, Lin HC, Marchili N, Marilli E, Marscher AP, Nesci R, Nieppola E, Nikolashvili MG, Ohlert J, Ovcharov E, Principe D, Pursimo T, Ragozzine B, Sadun AC, Sigua LA, Smart RL, Strigachev A, Takalo LO, Tavani M, Thum C, Tornikoski M, Trigilio C, Uckert K, Umana G, Valcheva A, Vercellone S, Volvach A, and Wiesemeyer H

Subjects
Brightness, Swift Gamma-Ray Burst Mission, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Extinction (astronomy), galaxies: active, FOS: Physical sciences, Flux, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, galaxies: active -- galaxies: quasars: general -- galaxies: quasars: individual: 3C 454.3, 01 natural sciences, law.invention, Telescope, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], law, 0103 physical sciences, galaxies: quasars: individual: 3C 454.3, Blazar, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics (astro-ph), Astronomy and Astrophysics, Light curve, galaxies: quasars: general, Space and Planetary Science, Satellite
Abstract

The quasar-type blazar 3C 454.3 underwent a phase of high activity in summer and autumn 2007, which was intensively monitored in the radio-to-optical bands by the Whole Earth Blazar Telescope (WEBT). The gamma-ray satellite AGILE detected this source first in late July, and then in November-December 2007. In this letter we present the multifrequency data collected by the WEBT and collaborators during the second AGILE observing period, complemented by a few contemporaneous data from UVOT onboard the Swift satellite. The aim is to trace in detail the behaviour of the synchrotron emission from the blazar jet, and to investigate the contribution from the thermal emission component. Optical data from about twenty telescopes have been homogeneously calibrated and carefully assembled to construct an R-band light curve containing about 1340 data points in 42 days. This extremely well-sampled optical light curve allows us to follow the dramatic flux variability of the source in detail. In addition, we show radio-to-UV spectral energy distributions (SEDs) at different epochs, which represent different brightness levels. In the considered period, the source varied by 2.6 mag in a couple of weeks in the R band. Many episodes of fast (i.e. intranight) variability were observed, most notably on December 12, when a flux increase of about 1.1 mag in 1.5 hours was detected, followed by a steep decrease of about 1.2 mag in 1 hour. The contribution by the thermal component is difficult to assess, due to the uncertainties in the Galactic, and possibly also intrinsic, extinction in the UV band. However, polynomial fitting of radio-to-UV SEDs reveals an increasing spectral bending going towards fainter states, suggesting a UV excess likely due to the thermal emission from the accretion disc., 5 pages, 4 figures, accepted for publication in Astronomy & Astrophysics Letters

Published
2008

175. Multiwavelength behaviour of the blazar OJ 248 from radio to gamma-rays

Author

M. I. Carnerero, Sofia O. Kurtanidze, J. A. Acosta-Pulido, E. N. Kopatskaya, Paolo Leto, C. S. Lin, A. B. Grinon-Marin, Sol N. Molina, D. A. Morozova, H. C. Lin, R. Bachev, Neelam Panwar, A. I. Manilla-Robles, M. Orienti, Valeri M. Larionov, Marcello Giroletti, J. L. Gomez, P. A. González-Morales, Antoniya Valcheva, Carolina Casadio, Anne Lähteenmäki, Helmut Wiesemeyer, Uwe Bach, Goran Damljanović, Corrado Trigilio, Y. T. Metodieva, D. O. Mirzaqulov, Sunay Ibryamov, Elena G. Larionova, A. Bueno Bueno, T. S. Grishina, H. Y. Hsiao, V. Ramakrishnan, G. Umana, D. Carosati, Wen Ping Chen, Arkady A. Arkharov, V. Bozhilov, Ivan Agudo, Mark Gurwell, A. Pastor Yabar, I. M. McHardy, David Hiriart, Carla Buemi, Manasvita Joshi, A. Strigachev, Alan P. Marscher, S. G. Jorstad, A. Di Paola, Lorand A. Sigua, L. V. Larionova, M. J. Arévalo, N. V. Efimova, D. Blinov, Erika Benítez, C. M. Raiteri, Brian W. Taylor, Omar M. Kurtanidze, I. Puerto Giménez, Evgeni Ovcharov, Yu. V. Troitskaya, M. G. Nikolashvili, Sergio Velasco, Ann E. Wehrle, A. A. Mokrushina, Paul S. Smith, M. Villata, Ivan S. Troitsky, Sh. A. Ehgamberdiev, Merja Tornikoski, M. Rossini, G. M. Richter, Filippo D'Ammando, C. Lázaro, O. Vince, Carnerero MI, Raiteri CM, Villata M, Acosta-Pulido JA, DAmmando F, Smith PS, Larionov VM, Agudo I, Arevalo MJ, Arkharov AA, Bach U, Bachev R, Benitez E, Blinov DA, Bozhilov V, Buemi CS, Bueno AB, Carosati D, Casadio C, Chen WP, Damljanovic G, Di Paola A, Efimova NV, Ehgamberdiev SA, Giroletti M, Gomez JL, Gonzalez-Morales PA, Grinon-Marin AB, Grishina TS, Gurwell MA, Hiriart D, Hsiao HY, Ibryamov S, Jorstad SG, Joshi M, Kopatskaya EN, Kurtanidze OM, Kurtanidze SO, Lahteenmaki A, Larionova EG, Larionova LV, Lazaro C, Leto P, Lin CS, Lin HC, Manilla-Robles AI, Marscher AP, McHardy IM, Metodieva Y, Mirzaqulov DO, Mokrushina AA, Molina SN, Morozova DA, Nikolashvili MG, Orienti M, Ovcharov E, Panwar N, Yabar AP, Gimenez IP, Ramakrishnan V, Richter GM, Rossini M, Sigua LA, Strigachev A, Taylor B, Tornikoski M, Trigilio C, Troitskaya YV, Troitsky IS, Umana G, Valcheva A, Velasco S, Vince O, Wehrle AE, Wiesemeyer H, Anne Lähteenmäki Group, Department of Radio Science and Engineering, Aalto-yliopisto, and Aalto University

Subjects
active [Galaxies], Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, ta221, galaxies: active, ta1171, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, law.invention, Telescope, Observatory, law, quasars: general, Emission spectrum, Blazar, ta216, Physics, individual: OJ 248 [Quasars], ta115, ta213, ta114, Linear polarization, quasars: individual: OJ 248, Astronomy, Astronomy and Astrophysics, general [Quasars], galaxies: active, galaxies: jets, quasars: general, quasars: individual: OJ 248, galaxies: jets, Light curve, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, jets [Galaxies], Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract

We present an analysis of the multiwavelength behaviour of the blazar OJ 248 at z = 0.939 in the period 2006-2013. We use low-energy data (optical, near-infrared, and radio) obtained by 21 observatories participating in the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT), as well as data from the Swift (optical-UV and X-rays) and Fermi (gamma-rays) satellites, to study flux and spectral variability and correlations among emissions in different bands. We take into account the effect of absorption by the Damped Lyman Alpha intervening system at z = 0.525. Two major outbursts were observed in 2006-2007 and in 2012-2013 at optical and near-IR wavelengths, while in the high-frequency radio light curves prominent radio outbursts are visible peaking at the end of 2010 and beginning of 2013, revealing a complex radio-optical correlation. Cross-correlation analysis suggests a delay of the optical variations after the gamma-ray ones of about a month, which is a peculiar behaviour in blazars. We also analyse optical polarimetric and spectroscopic data. The average polarization percentage P is less than 3 per cent, but it reaches about 19 per cent during the early stage of the 2012-2013 outburst. A vague correlation of P with brightness is observed. There is no preferred electric vector polarisation angle and during the outburst the linear polarization vector shows wide rotations in both directions, suggesting a complex behaviour or structure of the jet and possible turbulence. The analysis of 140 optical spectra acquired at the Steward Observatory reveals a strong Mg II broad emission line with an essentially stable flux of 6.2 e-15 erg cm-2 s-1 and a full width at half-maximum of 2053 km s-1., Comment: 16 pages, 20 figures, 2 tables, in press for MNRAS

Published
2015

176. Direct detection of atomic oxygen on the dayside and nightside of Venus.

Author

Hübers HW, Richter H, Graf UU, Güsten R, Klein B, Stutzki J, and Wiesemeyer H

Abstract

Atomic oxygen is a key species in the mesosphere and thermosphere of Venus. It peaks in the transition region between the two dominant atmospheric circulation patterns, the retrograde super-rotating zonal flow below 70 km and the subsolar to antisolar flow above 120 km altitude. However, past and current detection methods are indirect and based on measurements of other molecules in combination with photochemical models. Here, we show direct detection of atomic oxygen on the dayside as well as on the nightside of Venus by measuring its ground-state transition at 4.74 THz (63.2 µm). The atomic oxygen is concentrated at altitudes around 100 km with a maximum column density on the dayside where it is generated by photolysis of carbon dioxide and carbon monoxide. This method enables detailed investigations of the Venusian atmosphere in the region between the two atmospheric circulation patterns in support of future space missions to Venus., (© 2023. The Author(s).)

Published
2023
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177. Astrophysical detection of the helium hydride ion HeH .

Author

Güsten R, Wiesemeyer H, Neufeld D, Menten KM, Graf UU, Jacobs K, Klein B, Ricken O, Risacher C, and Stutzki J

Abstract

During the dawn of chemistry 1,2 , when the temperature of the young Universe had fallen below some 4,000 kelvin, the ions of the light elements produced in Big Bang nucleosynthesis recombined in reverse order of their ionization potential. With their higher ionization potentials, the helium ions He 2+ and He + were the first to combine with free electrons, forming the first neutral atoms; the recombination of hydrogen followed. In this metal-free and low-density environment, neutral helium atoms formed the Universe's first molecular bond in the helium hydride ion HeH + through radiative association with protons. As recombination progressed, the destruction of HeH + created a path to the formation of molecular hydrogen. Despite its unquestioned importance in the evolution of the early Universe, the HeH + ion has so far eluded unequivocal detection in interstellar space. In the laboratory the ion was discovered 3 as long ago as 1925, but only in the late 1970s was the possibility that HeH + might exist in local astrophysical plasmas discussed 4-7 . In particular, the conditions in planetary nebulae were shown to be suitable for producing potentially detectable column densities of HeH + . Here we report observations, based on advances in terahertz spectroscopy 8,9 and a high-altitude observatory 10 , of the rotational ground-state transition of HeH + at a wavelength of 149.1 micrometres in the planetary nebula NGC 7027. This confirmation of the existence of HeH + in nearby interstellar space constrains our understanding of the chemical networks that control the formation of this molecular ion, in particular the rates of radiative association and dissociative recombination.

Published
2019
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