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862 results on '"Agudo, I."'

101. Another look at the BL Lacertae flux and spectral variability

Author

Raiteri, C. M., Villata, M., Bruschini, L., Capetti, A., Kurtanidze, O. M., Larionov, V. M., Romano, P., Vercellone, S., Agudo, I., Aller, H. D., Aller, M. F., Arkharov, A. A., Bach, U., Berdyugin, A., Blinov, D. A., Böttcher, M., Buemi, C. S., Calcidese, P., Carosati, D., Casas, R., Chen, W. -P., Coloma, J., Diltz, C., Di Paola, A., Dolci, M., Efimova, N. V., Forné, E., Gómez, J. L., Gurwell, M. A., Hakola, A., Hovatta, T., Hsiao, H. Y., Jordan, B., Jorstad, S. G., Koptelova, E., Kurtanidze, S. O., Lähteenmäki, A., Larionova, E. G., Leto, P., Lindfors, E., Ligustri, R., Marscher, A. P., Morozova, D. A., Nikolashvili, M. G., Nilsson, K., Ros, J. A., Roustazadeh, P., Sadun, A. C., Sillanpää, A., Sainio, J., Takalo, L. O., Tornikoski, M., Trigilio, C., Troitsky, I. S., and Umana, G.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies. During this period, high-energy observations were performed by XMM-Newton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. The GASP-WEBT observations show an optical flare in 2008 February-March, and oscillations of several tenths of mag on a few-day time scale afterwards. The radio flux is only mildly variable. The UV data from both XMM-Newton and Swift seem to confirm a UV excess that is likely caused by thermal emission from the accretion disc. The X-ray data from XMM-Newton indicate a strongly concave spectrum, as well as moderate flux variability on an hour time scale. The Swift X-ray data reveal fast (interday) flux changes, not correlated with those observed at lower energies. We compare the spectral energy distribution (SED) corresponding to the 2008 low-brightness state, which was characterised by a synchrotron dominance, to the 1997 outburst state, where the inverse-Compton emission was prevailing. A fit with an inhomogeneous helical jet model suggests that two synchrotron components are at work with their self inverse-Compton emission. Most likely, they represent the radiation from two distinct emitting regions in the jet. We show that the difference between the source SEDs in 2008 and 1997 can be explained in terms of pure geometrical variations. The outburst state occurred when the jet-emitting regions were better aligned with the line of sight, producing an increase of the Doppler beaming factor. Our analysis demonstrates that the jet geometry can play an extremely important role in the BL Lacertae flux and spectral variability., Comment: 12 pages, 10 figures, accepted for publication in A&A

Published
2010
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102. The Multifrequency Campaign on 3C 279 in January 2006

Author

Collmar, W., Böttcher, M., Krichbaum, T. P., Agudo, I., Bottacini, E., Bremer, M., Burwitz, V., Cuccchiara, A., Grupe, D., and Gurwell, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results of a multifrequency campaign from radio to hard X-ray energies on the blazar 3C 279 during an optical high-state in January 2006. We give the observational results (multifrequency light curves and spectra) and compile an SED. This complements an SED from an optical low-state in June 2003. Surprisingly the two SEDs differ only in their high-energy synchrotron emission (near-IR - UV), while the low-energy inverse-Compton emission (X- to Gamma-rays) remained unchanged. By interpreting with a steady-state leptonic emission model, the variability among the SED can be reproduced by a change solely of the low-energy cutoff of the relativistic electron distribution. In an internal shock model for blazar emission, such a change could e.g. achieved through a varying relative Lorentz factor of colliding shells producing internal shocks in the jet., Comment: 11 pages, 9 figures, A&A accepted

Published
2010
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103. The redshift and broad band spectral energy distribution of NRAO 150

Author

Acosta-Pulido, J. A., Agudo, I., Barrena, R., Almeida, C. Ramos, Manchado, A., and Rodríguez-Gil, P.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Context. NRAO 150 is one of the brightest radio and mm AGN sources on the northern sky. It has been revealed as an interesting source where to study extreme relativistic jet phenomena. However, its cosmological distance has not been reported so far, because of its optical faintness produced by strong Galactic extinction. Aims. Aiming at measuring the redshift of NRAO 150, and hence to start making possible quantitative studies from the source. Methods. We have conducted spectroscopic and photometric observations of the source in the near-IR, as well as in the optical. Results. All such observations have been successful in detecting the source. The near-IR spectroscopic observations reveal strong H$\alpha$ and H$\beta$ emission lines from which the cosmological redshift of NRAO 150 ($z=1.517\pm0.002$) has been determined for the first time. We classify the source as a flat-spectrum radio-loud quasar, for which we estimate a large super-massive black-hole mass $\sim5\times 10^{9} \mathrm{M_\odot}$. After extinction correction, the new near-IR and optical data have revealed a high-luminosity continuum-emission excess in the optical (peaking at $\sim2000$\,\AA, rest frame) that we attribute to thermal emission from the accretion disk for which we estimate a high accretion rate, $\sim30$\,% of the Eddington limit. Conclusions. Comparison of these source properties, and its broad-band spectral-energy distribution, with those of Fermi blazars allow us to predict that NRAO 150 is among the most powerful blazars, and hence a high luminosity -although not detected yet- $\gamma$-ray emitter., Comment: 8 pages, 4 figures

Published
2010
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104. Multiwavelength observations of 3C 454.3. III. Eighteen months of AGILE monitoring of the 'Crazy Diamond'

Author

Vercellone, S., D'Ammando, F., Vittorini, V., Donnarumma, I., Pucella, G., Tavani, M., Ferrari, A., Raiteri, C. M., Villata, M., Romano, P., Krimm, H., Tiengo, A., Chen, A. W., Giovannini, G., Venturi, T., Giroletti, M., Kovalev, Y. Y., Sokolovsky, K., Pushkarev, A. B., Lister, M. L., Argan, A., Barbiellini, G., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Cocco, V., Costa, E., Del Monte, E., De Paris, G., Di Cocco, G., Evangelista, Y., Feroci, M., Fiorini, M., Fornari, F., Froysland, T., Fuschino, F., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Longo, F., Giuliani, A., Marisaldi, M., Mereghetti, S., Morselli, A., Pellizzoni, A., Pacciani, L., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Rapisarda, M., Rappoldi, A., Sabatini, S., Soffitta, P., Striani, E., Trifoglio, M., Trois, A., Vallazza, E., Zambra, A., Zanello, D., Pittori, C., Verrecchia, F., Santolamazza, P., Giommi, P., Colafrancesco, S., Salotti, L., Agudo, I., Aller, H. D., Aller, M. F., Arkharov, A. A., Bach, U., Bachev, R., Beltrame, P., Benitez, E., Boettcher, M., Buemi, C. S., Calcidese, P., Capezzali, D., Carosati, D., Chen, W. P., Da Rio, D., Di Paola, A., Dolci, M., Dultzin, D., Forne, E., Gomez, J. L., Gurwell, M. A., Hagen-Thorn, V. A., Halkola, A., Heidt, J., Hiriart, D., Hovatta, T., Hsiao, H. Y., Jorstad, S. G., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O., Lahteenmaki, A., Larionov, V. M., Leto, P., Ligustri, R., Lindfors, E., Lopez, J. M., Marscher, A. P., Mujica, R., Nikolashvili, M., and Nilsson, K.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on 18 months of multiwavelength observations of the blazar 3C 454.3 (Crazy Diamond) carried out in July 2007-January 2009. We show the results of the AGILE campaigns which took place on May-June 2008, July-August 2008, and October 2008-January 2009. During the May 2008-January 2009 period, the source average flux was highly variable, from an average gamma-ray flux F(E>100MeV) > 200E-8 ph/cm2/s in May-June 2008, to F(E>100MeV)~80E-8 ph/cm2/s in October 2008-January 2009. The average gamma-ray spectrum between 100 MeV and 1 GeV can be fit by a simple power law (Gamma_GRID ~ 2.0 to 2.2). Only 3-sigma upper limits can be derived in the 20-60 keV energy band with Super-AGILE. During July-August 2007 and May-June 2008, RXTE measured a flux of F(3-20 keV)= 8.4E-11 erg/cm2/s, and F(3-20 keV)=4.5E-11 erg/cm2/s, respectively and a constant photon index Gamma_PCA=1.65. Swift/XRT observations were carried out during all AGILE campaigns, obtaining a F(2-10 keV)=(0.9-7.5)E-11 erg/cm2/s and a photon index Gamma_XRT=1.33-2.04. BAT measured an average flux of ~5 mCrab. GASP-WEBT monitored 3C 454.3 during the whole 2007-2008 period from the radio to the optical. A correlation analysis between the optical and the gamma-ray fluxes shows a time lag of tau=-0.4 days. An analysis of 15 GHz and 43 GHz VLBI core radio flux observations shows an increasing trend of the core radio flux, anti- correlated with the higher frequency data. The modeling SEDs, and the behavior of the long-term light curves in different energy bands, allow us to compare the jet properties during different emission states, and to study the geometrical properties of the jet on a time-span longer than one year., Comment: Accepted for publication in ApJ. Adapted Abstract. 17 pages, 19 Figures, 5 Tables

Published
2010
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105. Non-radial motion in the TeV blazar S5 0716+714 The pc-scale kinematics of a BL Lac Object

Author

Britzen, S., Kam, V. A., Witzel, A., Agudo, I., Aller, M. F., Aller, H. D., Karouzos, M., Eckart, A., and Zensus, J. A.

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

For the BL Lac object S5 0716+714 conflicting apparent velocities of jet component motion have been reported in the literature. This object is an intra-day variable source and suited to investigate a possible correlation between kinematic properties and flux-density variability on different timescales. We (re-)analyze 50 VLBI observations obtained with the VLBA at 5 different frequencies (5 to 43 GHz) between 1992.73 and 2006.32. We analyze the jet component motion in detail taking care not only to account for motion in the radial but also in the orthogonal direction. We study the evolution of the jet ridge line and search for correlations between radio band light curves and the kinematic properties of the jet components. We present an alternative kinematic scenario for jet component motion in S5 0716+714 with apparent stationarity of jet components (with regard to their core separation) with time. Jet components, however, do seem to move significantly non-radially with regard to their position angle and in a direction perpendicular to the major axis of the jet. We discuss a possible correlation between the long-term radio flux-density variability and the kinematics. We conclude that a geometric contribution to the origin of the long-term variability might not be negligible. Subluminal motion has been reported for most of the TeV blazars. Our analysis also confirms this for S5 0716+714. This result increases the number of TeV blazars showing apparent subluminal motion to 7.

Published
2010
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106. A 3.5mm Polarimetric Survey of Radio-loud Active Galactic Nuclei

Author

Agudo, I., Thum, C., Wiesemeyer, H., and Krichbaum, T. P.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results from the first large (>100 source) 3.5 mm polarimetric survey of radio loud active galactic nuclei (AGN). The I, Q, U, and V Stokes parameter observations were performed with the XPOL polarimeter at the IRAM 30m Telescope. Our sample consists of 145 flat-radio-spectrum AGN with declination >-30 deg. (J2000.0) and flux density >~1Jy at 86GHz, as measured at the IRAM 30 m Telescope from 1978 to 1994. We detected linear and circular polarization (above 3 sigma levels of ~1.6%, and ~0.3%) for 76%, and 6% of the sample, respectively. We find a clear excess in degree of linear polarization detected at 86 GHz with regard to that at 15 GHz by a factor of ~2. Over our entire source sample, the luminosity of the jets is inversely proportional to the degree of linear polarization. Consistent with previous findings claiming larger Doppler factors for brighter gamma-ray blazars, quasars listed in our sample, and in the Fermi-LBAS catalog, show larger luminosities than non-LBAS ones, but our data do not allow us to confirm the same for BL Lac objects. We do not find a clear relation between the linear polarization angle and the jet structural position angle for any source class in our sample. We interpret this as the consequence of a markedly non-axisymmetric character of the 3 mm emitting region in the jets. We find that intrinsic circular polarization is the most likely mechanism for generation of the circular polarization detected in our observations. Our new data can be used to estimate the 3 mm AGN contribution to measurements of the linear polarization of the cosmic microwave background, such as those performed by the Planck satellite., Comment: Published in the Astrophysical Journal Supplement Series. 25 pages, 2 tables & 13 figures

Published
2009
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107. AGILE detection of a rapid gamma-ray flare from the blazar PKS 1510-089 during the GASP-WEBT monitoring

Author

D'Ammando, F., Pucella, G., Raiteri, C. M., Villata, M., Vittorini, V., Vercellone, S., Donnarumma, I., Longo, F., Tavani, M., Argan, A., Barbiellini, G., Boffelli, F., Bulgarelli, A., Caraveo, P., Cattaneo, P. W., Chen, A. W., Cocco, V., Costa, E., Del Monte, E., De Paris, G., Di Cocco, G., Evangelista, Y., Feroci, M., Ferrari, A., Fiorini, M., Froysland, T., Fuschino, F., Galli, M., Gianotti, F., Giuliani, A., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Marisaldi, M., Mereghetti, S., Morselli, A., Pacciani, L., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Prest, M., Rapisarda, M., Rappoldi, A., Sabatini, S., Soffitta, P., Trifoglio, M., Trois, A., Vallazza, E., Zambra, A., Zanello, D., Agudo, I., Aller, M. F., Aller, H. D., Arkharov, A. A., Bach, U., Benitez, E., Berdyugin, A., Blinov, D. A., Buemi, C. S., Chen, W. P., Di Paola, A., Di Rico, G., Dultzin, D., Fuhrmann, L., Gomez, J. L., Gurwell, M. A., Jorstad, S. G., Heidt, J., Hiriart, D., Hsiao, H. Y., Kimeridze, G., Konstantinova, T. S., Kopatskaya, E. N., Koptelova, E., Kurtanidze, O., Larionov, V. M., Leto, P., Lindfors, E., Lopez, J. M., Marscher, A. P., McHardy, I. M., Melnichuk, D. A., Mommert, M., Mujica, R., Nilsson, K., Pasanen, M., Roca-Sogorb, M., Sorcia, M., Takalo, L. O., Taylor, B., Trigilio, C., Troitsky, I. S., Umana, G., Antonelli, L. A., Colafrancesco, S., Cutini, S., Gasparrini, D., Pittori, C., Preger, B., Santolamazza, P., Verrecchia, F., Giommi, P., and Salotti, L.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We report the detection by the AGILE satellite of a rapid gamma-ray flare from the powerful gamma-ray quasar PKS 1510-089, during a pointing centered on the Galactic Center region from 1 March to 30 March 2008. This source has been continuosly monitored in the radio-to-optical bands by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT). Moreover, the gamma-ray flaring episode triggered three ToO observations by the Swift satellite in three consecutive days, starting from 20 March 2008. In the period 1-16 March 2008, AGILE detected gamma-ray emission from PKS 1510-089 at a significance level of 6.2-sigma with an average flux over the entire period of (84 +/- 17) x 10^{-8} photons cm^{-2} s^{-1} for photon energies above 100 MeV. After a predefined satellite re-pointing, between 17 and 21 March 2008, AGILE detected the source at a significance level of 7.3-sigma, with an average flux (E > 100 MeV) of (134 +/- 29) x 10^{-8} photons cm^{-2} s^{-1} and a peak level of (281 +/- 68) x 10^{-8} photons cm^{-2} s^{-1} with daily integration. During the observing period January-April 2008, the source also showed an intense and variable optical activity, with several flaring episodes and a significant increase of the flux was observed at millimetric frequencies. Moreover, in the X-ray band the Swift/XRT observations seem to show an harder-when-brighter behaviour of the source spectrum. The spectral energy distribution of mid-March 2008 is modelled with a homogeneous one-zone synchrotron self Compton emission plus contributions from inverse Compton scattering of external photons from both the accretion disc and the broad line region. Indeed, some features in the optical-UV spectrum seem to indicate the presence of Seyfert-like components, such as the little blue bump and the big blue bump., Comment: 10 pages, 4 figures and 2 tables, accepted for publication in A&A

Published
2009
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108. Synthetic synchrotron emission maps from MHD models for the jet of M87

Author

Gracia, J., Vlahakis, N., Agudo, I., Tsinganos, K., and Bogovalov, S. V.

Subjects
Astrophysics - Galaxy Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present self-consistent global, steady-state MHD models and synthetic optically thin synchrotron emission maps for the jet of M87. The model consist of two distinct zones: an inner relativistic outflow, which we identify with the observed jet, and an outer cold disk-wind. While the former does not self-collimate efficiently due to its high effective inertia, the latter fulfills all the conditions for efficient collimation by the magneto-centrifugal mechanism. Given the right balance between the effective inertia of the inner flow and the collimation efficiency of the outer disk wind, the relativistic flow is magnetically confined into a well collimated beam and matches the measurements of the opening angle of M87 over several orders of magnitude in spatial extent. The synthetic synchrotron maps reproduce the morphological structure of the jet of M87, i.e. center-bright profiles near the core and limb-bright profiles away from the core. At the same time, they also show a local increase of brightness at some distance along the axis associated to a recollimation shock in the MHD model. Its location coincides with the position of the optical knot HST-1. In addition our best fitting model is consistent with a number of observational constraints such as the magnetic field in the knot HST-1, and the jet-to-counterjet brightness ratio., Comment: 9 pages, 9 figures, accepted by ApJ

Published
2009
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109. MAGIC detection of GRB 201216C at z = 1.1

Author

Abe, H, primary, Abe, S, additional, Acciari, V A, additional, Agudo, I, additional, Aniello, T, additional, Ansoldi, S, additional, Antonelli, L A, additional, Engels, A Arbet, additional, Arcaro, C, additional, Artero, M, additional, Asano, K, additional, Baack, D, additional, Babić, A, additional, Baquero, A, additional, de Almeida, U Barres, additional, Barrio, J A, additional, Batković, I, additional, Baxter, J, additional, González, J Becerra, additional, Bednarek, W, additional, Bernardini, E, additional, Bernete, J, additional, Berti, A, additional, Besenrieder, J, additional, Bigongiari, C, additional, Biland, A, additional, Blanch, O, additional, Bonnoli, G, additional, Bošnjak, Ž, additional, Burelli, I, additional, Busetto, G, additional, Campoy-Ordaz, A, additional, Carosi, A, additional, Carosi, R, additional, Carretero-Castrillo, M, additional, Castro-Tirado, A J, additional, Ceribella, G, additional, Chai, Y, additional, Cifuentes, A, additional, Cikota, S, additional, Colombo, E, additional, Contreras, J L, additional, Cortina, J, additional, Covino, S, additional, D’Amico, G, additional, D’Elia, V, additional, Da Vela, P, additional, Dazzi, F, additional, De Angelis, A, additional, De Lotto, B, additional, Del Popolo, A, additional, Delfino, M, additional, Delgado, J, additional, Mendez, C Delgado, additional, Depaoli, D, additional, Di Pierro, F, additional, Di Venere, L, additional, Prester, D Dominis, additional, Donini, A, additional, Dorner, D, additional, Doro, M, additional, Elsaesser, D, additional, Emery, G, additional, Escudero, J, additional, Fari na, L, additional, Fattorini, A, additional, Foffano, L, additional, Font, L, additional, Fukami, S, additional, Fukazawa, Y, additional, López, R J García, additional, Garczarczyk, M, additional, Gasparyan, S, additional, Gaug, M, additional, Paiva, J G Giesbrecht, additional, Giglietto, N, additional, Giordano, F, additional, Gliwny, P, additional, Godinović, N, additional, Grau, R, additional, Green, D, additional, Green, J G, additional, Hadasch, D, additional, Hahn, A, additional, Hassan, T, additional, Heckmann, L, additional, Herrera, J, additional, Hrupec, D, additional, Hütten, M, additional, Imazawa, R, additional, Inada, T, additional, Iotov, R, additional, Ishio, K, additional, Martínez, I Jiménez, additional, Jormanainen, J, additional, Kerszberg, D, additional, Kluge, G W, additional, Kobayashi, Y, additional, Kouch, P M, additional, Kubo, H, additional, Kushida, J, additional, Lezáun, M Láinez, additional, Lamastra, A, additional, Leone, F, additional, Lindfors, E, additional, Linhoff, L, additional, Lombardi, S, additional, Longo, F, additional, López-Coto, R, additional, López-Moya, M, additional, López-Oramas, A, additional, Loporchio, S, additional, Lorini, A, additional, Lyard, E, additional, de Oliveira Fraga, B Machado, additional, Majumdar, P, additional, Makariev, M, additional, Maneva, G, additional, Mang, N, additional, Manganaro, M, additional, Mangano, S, additional, Mannheim, K, additional, Mariotti, M, additional, Martínez, M, additional, Mas-Aguilar, A, additional, Mazin, D, additional, Menchiari, S, additional, Mender, S, additional, Mićanović, S, additional, Miceli, D, additional, Miener, T, additional, Miranda, J M, additional, Mirzoyan, R, additional, González, M Molero, additional, Molina, E, additional, Mondal, H A, additional, Moralejo, A, additional, Morcuende, D, additional, Nanci, C, additional, Nava, L, additional, Neustroev, V, additional, Rosillo, M Nievas, additional, Nigro, C, additional, Nikolić, L, additional, Nilsson, K, additional, Nishijima, K, additional, Ekoume, T Njoh, additional, Noda, K, additional, Nozaki, S, additional, Ohtani, Y, additional, Okumura, A, additional, Otero-Santos, J, additional, Paiano, S, additional, Palatiello, M, additional, Paneque, D, additional, Paoletti, R, additional, Paredes, J M, additional, Pavletić, L, additional, Pavlović, D, additional, Persic, M, additional, Pihet, M, additional, Pirola, G, additional, Podobnik, F, additional, Moroni, P G Prada, additional, Prandini, E, additional, Principe, G, additional, Priyadarshi, C, additional, Rhode, W, additional, Ribó, M, additional, Rico, J, additional, Righi, C, additional, Sahakyan, N, additional, Saito, T, additional, Satalecka, K, additional, Saturni, F G, additional, Schleicher, B, additional, Schmidt, K, additional, Schmuckermaier, F, additional, Schubert, J L, additional, Schweizer, T, additional, Sciaccaluga, A, additional, Sitarek, J, additional, Sliusar, V, additional, Sobczynska, D, additional, Spolon, A, additional, Stamerra, A, additional, Strišković, J, additional, Strom, D, additional, Strzys, M, additional, Suda, Y, additional, Suutarinen, S, additional, Tajima, H, additional, Takahashi, M, additional, Takeishi, R, additional, Tavecchio, F, additional, Temnikov, P, additional, Terauchi, K, additional, Terzić, T, additional, Teshima, M, additional, Tosti, L, additional, Truzzi, S, additional, Tutone, A, additional, Ubach, S, additional, van Scherpenberg, J, additional, Acosta, M Vazquez, additional, Ventura, S, additional, Verguilov, V, additional, Viale, I, additional, Vigorito, C F, additional, Vitale, V, additional, Vovk, I, additional, Walter, R, additional, Will, M, additional, Yamamoto, T, additional, Gomboc, A, additional, Jordana-Mitjans, N, additional, Melandri, A, additional, Mundell, C G, additional, Shrestha, M, additional, and Steele, I A, additional

Published
2023
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110. The first X-ray polarimetric observation of the black hole binary LMC X-1

Author

Podgorný, J, primary, Marra, L, additional, Muleri, F, additional, Cavero, N Rodriguez, additional, Ratheesh, A, additional, Dovčiak, M, additional, Mikušincová, R, additional, Brigitte, M, additional, Steiner, J F, additional, Veledina, A, additional, Bianchi, S, additional, Krawczynski, H, additional, Svoboda, J, additional, Kaaret, P, additional, Matt, G, additional, García, J A, additional, Petrucci, P-O, additional, Lutovinov, A, additional, Semena, A, additional, Di Marco, A, additional, Negro, M, additional, Weisskopf, M C, additional, Ingram, A, additional, Poutanen, J, additional, Beheshtipour, B, additional, Chun, S, additional, Hu, K, additional, Mizuno, T, additional, Sixuan, Z, additional, Tombesi, F, additional, Zane, S, additional, Agudo, I, additional, Antonelli, L A, additional, Bachetti, M, additional, Baldini, L, additional, Baumgartner, W H, additional, Bellazzini, R, additional, Bongiorno, S D, additional, Bonino, R, additional, Brez, A, additional, Bucciantini, N, additional, Capitanio, F, additional, Castellano, S, additional, Cavazzuti, E, additional, Chen, C, additional, Ciprini, S, additional, Costa, E, additional, De Rosa, A, additional, Del Monte, E, additional, Di Gesu, L, additional, Di Lalla, N, additional, Donnarumma, I, additional, Doroshenko, V, additional, Ehlert, S R, additional, Enoto, T, additional, Evangelista, Y, additional, Fabiani, S, additional, Ferrazzoli, R, additional, Gunji, S, additional, Hayashida, K, additional, Heyl, J, additional, Iwakiri, W, additional, Jorstad, S G, additional, Karas, V, additional, Kislat, F, additional, Kitaguchi, T, additional, Kolodziejczak, J J, additional, Monaca, F La, additional, Latronico, L, additional, Liodakis, I, additional, Maldera, S, additional, Manfreda, A, additional, Marin, F, additional, Marinucci, A, additional, Marscher, A P, additional, Marshall, H L, additional, Massaro, F, additional, Mitsuishi, I, additional, Ng, C-Y, additional, O’Dell, S L, additional, Omodei, N, additional, Oppedisano, C, additional, Papitto, A, additional, Pavlov, G G, additional, Peirson, A L, additional, Perri, M, additional, Pesce-Rollins, M, additional, Pilia, M, additional, Possenti, A, additional, Puccetti, S, additional, Ramsey, B D, additional, Rankin, J, additional, Roberts, O J, additional, Romani, R W, additional, Sgró, C, additional, Slane, P, additional, Soffitta, P, additional, Spandre, G, additional, Swartz, D A, additional, Tamagawa, T, additional, Tavecchio, F, additional, Taverna, R, additional, Tawara, Y, additional, Tennant, A F, additional, Thomas, N E, additional, Trois, A, additional, Tsygankov, S S, additional, Turolla, R, additional, Vink, J, additional, Wu, K, additional, and Xie, F, additional

Published
2023
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111. Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and γ-ray brightness levels

Author

Raiteri, C M, primary, Villata, M, additional, Carnerero, M I, additional, Savchenko, S S, additional, Kurtanidze, S O, additional, Vlasyuk, V V, additional, Marchini, A, additional, Matsumoto, K, additional, Lorey, C, additional, Joner, M D, additional, Gazeas, K, additional, Carosati, D, additional, Mirzaqulov, D O, additional, Acosta Pulido, J A, additional, Agudo, I, additional, Bachev, R, additional, Benítez, E, additional, Borman, G A, additional, Calcidese, P, additional, Chen, W P, additional, Damljanovic, G, additional, Ehgamberdiev, S A, additional, Elsässer, D, additional, Feige, M, additional, Frasca, A, additional, Gaur, H, additional, Grishina, T S, additional, Gupta, A C, additional, Hiriart, D, additional, Holland, M, additional, Horst, B, additional, Ibryamov, S, additional, Ivanidze, R Z, additional, Jensen, J, additional, Jithesh, V, additional, Jovanovic, M D, additional, Kiehlmann, S, additional, Kimeridze, G N, additional, Kishore, S, additional, Kopatskaya, E N, additional, Kurtanidze, O M, additional, Larionova, E G, additional, Lin, H C, additional, Mannheim, K, additional, Marinelli, C, additional, Moreira Reyes, J, additional, Morozova, D A, additional, Nikolashvili, M G, additional, Reinhart, D, additional, Romanov, F D, additional, Semkov, E, additional, Seufert, J, additional, Shishkina, E V, additional, Sigua, L A, additional, Skalidis, R, additional, Spiridonova, O I, additional, Stojanovic, M, additional, Strigachev, A, additional, Troitskaya, Y V, additional, Troitskiy, I S, additional, Tsai, A, additional, Vasilyev, A A, additional, Vince, O, additional, Vrontaki, K, additional, Wani, K, additional, Watts, D, additional, and Zhovtan, A V, additional

Published
2023
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112. Observations of the Crab Nebula and Pulsar with the Large-sized Telescope Prototype of the Cherenkov Telescope Array

Author

Abe, H., primary, Abe, K., additional, Abe, S., additional, Aguasca-Cabot, A., additional, Agudo, I., additional, Crespo, N. Alvarez, additional, Antonelli, L. A., additional, Aramo, C., additional, Arbet-Engels, A., additional, Arcaro, C., additional, Artero, M., additional, Asano, K., additional, Aubert, P., additional, Baktash, A., additional, Bamba, A., additional, Larriva, A. Baquero, additional, Baroncelli, L., additional, de Almeida, U. Barres, additional, Barrio, J. A., additional, Batkovic, I., additional, Baxter, J., additional, González, J. Becerra, additional, Bernardini, E., additional, Bernardos, M. I., additional, Medrano, J. Bernete, additional, Berti, A., additional, Bhattacharjee, P., additional, Biederbeck, N., additional, Bigongiari, C., additional, Bissaldi, E., additional, Blanch, O., additional, Bonnoli, G., additional, Bordas, P., additional, Borghese, A., additional, Bulgarelli, A., additional, Burelli, I., additional, Buscemi, M., additional, Cardillo, M., additional, Caroff, S., additional, Carosi, A., additional, Cassol, F., additional, Cauz, D., additional, Ceribella, G., additional, Chai, Y., additional, Cheng, K., additional, Chiavassa, A., additional, Chikawa, M., additional, Chytka, L., additional, Cifuentes, A., additional, Contreras, J. L., additional, Cortina, J., additional, Costantini, H., additional, D’Amico, G., additional, Dalchenko, M., additional, De Angelis, A., additional, de Bony de Lavergne, M., additional, De Lotto, B., additional, de Menezes, R., additional, Deleglise, G., additional, Delgado, C., additional, Delgado Mengual, J., additional, Volpe, D. della, additional, Dellaiera, M., additional, Depaoli, D., additional, Di Piano, A., additional, Di Pierro, F., additional, Di Tria, R., additional, Di Venere, L., additional, Díaz, C., additional, Dominik, R. M., additional, Prester, D. Dominis, additional, Donini, A., additional, Dorner, D., additional, Doro, M., additional, Elsässer, D., additional, Emery, G., additional, Escudero, J., additional, Ramazani, V. Fallah, additional, Ferrara, G., additional, Ferrarotto, F., additional, Fiasson, A., additional, Coromina, L. Freixas, additional, Fröse, S., additional, Fukami, S., additional, Fukazawa, Y., additional, Garcia, E., additional, Garcia López, R., additional, Gasbarra, C., additional, Gasparrini, D., additional, Geyer, F., additional, Paiva, J. Giesbrecht, additional, Giglietto, N., additional, Giordano, F., additional, Giro, E., additional, Gliwny, P., additional, Godinovic, N., additional, Grau, R., additional, Green, D., additional, Green, J., additional, Gunji, S., additional, Hackfeld, J., additional, Hadasch, D., additional, Hahn, A., additional, Hashiyama, K., additional, Hassan, T., additional, Hayashi, K., additional, Heckmann, L., additional, Heller, M., additional, Llorente, J. Herrera, additional, Hirotani, K., additional, Hoffmann, D., additional, Horns, D., additional, Houles, J., additional, Hrabovsky, M., additional, Hrupec, D., additional, Hui, D., additional, Hütten, M., additional, Iarlori, M., additional, Imazawa, R., additional, Inada, T., additional, Inome, Y., additional, Ioka, K., additional, Iori, M., additional, Ishio, K., additional, Iwamura, Y., additional, Jacquemont, M., additional, Martinez, I. Jimenez, additional, Jurysek, J., additional, Kagaya, M., additional, Karas, V., additional, Katagiri, H., additional, Kataoka, J., additional, Kerszberg, D., additional, Kobayashi, Y., additional, Kong, A., additional, Kubo, H., additional, Kushida, J., additional, Lainez, M., additional, Lamanna, G., additional, Lamastra, A., additional, Le Flour, T., additional, Linhoff, M., additional, Longo, F., additional, López-Coto, R., additional, López-Moya, M., additional, López-Oramas, A., additional, Loporchio, S., additional, Lorini, A., additional, Luque-Escamilla, P. L., additional, Majumdar, P., additional, Makariev, M., additional, Mandat, D., additional, Manganaro, M., additional, Manicò, G., additional, Mannheim, K., additional, Mariotti, M., additional, Marquez, P., additional, Marsella, G., additional, Martí, J., additional, Martinez, O., additional, Martínez, G., additional, Martínez, M., additional, Marusevec, P., additional, Mas-Aguilar, A., additional, Maurin, G., additional, Mazin, D., additional, Guillen, E. Mestre, additional, Micanovic, S., additional, Miceli, D., additional, Miener, T., additional, Miranda, J. M., additional, Mirzoyan, R., additional, Mizuno, T., additional, Gonzalez, M. Molero, additional, Molina, E., additional, Montaruli, T., additional, Monteiro, I., additional, Moralejo, A., additional, Morcuende, D., additional, Morselli, A., additional, Mrakovcic, K., additional, Murase, K., additional, Nagai, A., additional, Nagataki, S., additional, Nakamori, T., additional, Nickel, L., additional, Nievas, M., additional, Nishijima, K., additional, Noda, K., additional, Nosek, D., additional, Nozaki, S., additional, Ohishi, M., additional, Ohtani, Y., additional, Oka, T., additional, Okazaki, N., additional, Okumura, A., additional, Orito, R., additional, Otero-Santos, J., additional, Palatiello, M., additional, Paneque, D., additional, Pantaleo, F. R., additional, Paoletti, R., additional, Paredes, J. M., additional, Pech, M., additional, Pecimotika, M., additional, Peresano, M., additional, Pérez, A., additional, Pietropaolo, E., additional, Pirola, G., additional, Plard, C., additional, Podobnik, F., additional, Poireau, V., additional, Polo, M., additional, Pons, E., additional, Prandini, E., additional, Prast, J., additional, Principe, G., additional, Priyadarshi, C., additional, Prouza, M., additional, Rando, R., additional, Rhode, W., additional, Ribó, M., additional, Rizi, V., additional, Fernandez, G. Rodriguez, additional, Ruiz, J. E., additional, Saito, T., additional, Sakurai, S., additional, Sanchez, D. A., additional, Šarić, T., additional, Sato, Y., additional, Saturni, F. G., additional, Schleicher, B., additional, Schmuckermaier, F., additional, Schubert, J. L., additional, Schussler, F., additional, Schweizer, T., additional, Arroyo, M. Seglar, additional, Silvia, R., additional, Sitarek, J., additional, Sliusar, V., additional, Spolon, A., additional, Strišković, J., additional, Strzys, M., additional, Suda, Y., additional, Sunada, Y., additional, Tajima, H., additional, Takahashi, H., additional, Takahashi, M., additional, Takata, J., additional, Takeishi, R., additional, Tam, P. H. T., additional, Tanaka, S. J., additional, Tateishi, D., additional, Tejedor, L. A., additional, Temnikov, P., additional, Terada, Y., additional, Terauchi, K., additional, Terzic, T., additional, Teshima, M., additional, Tluczykont, M., additional, Tokanai, F., additional, Torres, D. F., additional, Travnicek, P., additional, Truzzi, S., additional, Tutone, A., additional, Uhlrich, G., additional, Vacula, M., additional, Vallania, P., additional, van Scherpenberg, J., additional, Acosta, M. Vázquez, additional, Verguilov, V., additional, Viale, I., additional, Vigliano, A., additional, Vigorito, C. F., additional, Vitale, V., additional, Voutsinas, G., additional, Vovk, I., additional, Vuillaume, T., additional, Walter, R., additional, Will, M., additional, Yamamoto, T., additional, Yamazaki, R., additional, Yoshida, T., additional, Yoshikoshi, T., additional, Zywucka, N., additional, Bernlöhr, K., additional, Gueta, O., additional, Kosack, K., additional, Maier, G., additional, and Watson, J., additional

Published
2023
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113. The X-ray polarization of the Seyfert 1 galaxy IC 4329A

Author

Ingram, A, primary, Ewing, M, additional, Marinucci, A, additional, Tagliacozzo, D, additional, Rosario, D J, additional, Veledina, A, additional, Kim, D E, additional, Marin, F, additional, Bianchi, S, additional, Poutanen, J, additional, Matt, G, additional, Marshall, H L, additional, Ursini, F, additional, De Rosa, A, additional, Petrucci, P-O, additional, Madejski, G, additional, Barnouin, T, additional, Gesu, L Di, additional, Dovčiak, M, additional, Gianolli, V E, additional, Krawczynski, H, additional, Loktev, V, additional, Middei, R, additional, Podgorny, J, additional, Puccetti, S, additional, Ratheesh, A, additional, Soffitta, P, additional, Tombesi, F, additional, Ehlert, S R, additional, Massaro, F, additional, Agudo, I, additional, Antonelli, L A, additional, Bachetti, M, additional, Baldini, L, additional, Baumgartner, W H, additional, Bellazzini, R, additional, Bongiorno, S D, additional, Bonino, R, additional, Brez, A, additional, Bucciantini, N, additional, Capitanio, F, additional, Castellano, S, additional, Cavazzuti, E, additional, Chen, C-T, additional, Ciprini, S, additional, Costa, E, additional, Del Monte, E, additional, Lalla, N Di, additional, Marco, A Di, additional, Donnarumma, I, additional, Doroshenko, V, additional, Enoto, T, additional, Evangelista, Y, additional, Fabiani, S, additional, Ferrazzoli, R, additional, García, J A, additional, Gunji, S, additional, Heyl, J, additional, Iwakiri, W, additional, Jorstad, S G, additional, Kaaret, P, additional, Karas, V, additional, Kislat, F, additional, Kitaguchi, T, additional, Kolodziejczak, J J, additional, Monaca, F La, additional, Latronico, L, additional, Liodakis, I, additional, Maldera, S, additional, Manfreda, A, additional, Marscher, A P, additional, Mitsuishi, I, additional, Mizuno, T, additional, Muleri, F, additional, Negro, M, additional, Ng, C-Y, additional, O’Dell, S L, additional, Omodei, N, additional, Oppedisano, C, additional, Papitto, A, additional, Pavlov, G G, additional, Peirson, A L, additional, Perri, M, additional, Pesce-Rollins, M, additional, Pilia, M, additional, Possenti, A, additional, Ramsey, B D, additional, Rankin, J, additional, Roberts, O J, additional, Romani, R W, additional, Sgrò, C, additional, Slane, P, additional, Spandre, G, additional, Swartz, D A, additional, Tamagawa, T, additional, Tavecchio, F, additional, Taverna, R, additional, Tawara, Y, additional, Tennant, A F, additional, Thomas, N E, additional, Trois, A, additional, Tsygankov, S S, additional, Turolla, R, additional, Vink, J, additional, Weisskopf, M C, additional, Wu, K, additional, Xie, F, additional, and Zane, S, additional

Published
2023
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114. The geometry of the hot corona in MCG-05-23-16 constrained by X-ray polarimetry

Author

Tagliacozzo, D, primary, Marinucci, A, additional, Ursini, F, additional, Matt, G, additional, Bianchi, S, additional, Baldini, L, additional, Barnouin, T, additional, Cavero Rodriguez, N, additional, De Rosa, A, additional, Di Gesu, L, additional, Dovčiak, M, additional, Harper, D, additional, Ingram, A, additional, Karas, V, additional, Kim, D E, additional, Krawczynski, H, additional, Madejski, G, additional, Marin, F, additional, Middei, R, additional, Marshall, H L, additional, Muleri, F, additional, Panagiotou, C, additional, Petrucci, P-O, additional, Podgorny, J, additional, Poutanen, J, additional, Puccetti, S, additional, Soffitta, P, additional, Tombesi, F, additional, Veledina, A, additional, Zhang, W, additional, Agudo, I, additional, Antonelli, L A, additional, Bachetti, M, additional, Baumgartner, W H, additional, Bellazzini, R, additional, Bongiorno, S D, additional, Bonino, R, additional, Brez, A, additional, Bucciantini, N, additional, Capitanio, F, additional, Castellano, S, additional, Cavazzuti, E, additional, Chen, C-T, additional, Ciprini, S, additional, Costa, E, additional, Del Monte, E, additional, Di Lalla, N, additional, Di Marco, A, additional, Donnarumma, I, additional, Doroshenko, V, additional, Ehlert, S R, additional, Enoto, T, additional, Evangelista, Y, additional, Fabiani, S, additional, Ferrazzoli, R, additional, Garcia, J A, additional, Gunji, S, additional, Heyl, J, additional, Iwakiri, W, additional, Jorstad, S G, additional, Kaaret, P, additional, Kislat, F, additional, Kitaguchi, T, additional, Kolodziejczak, J J, additional, La Monaca, F, additional, Latronico, L, additional, Liodakis, I, additional, Maldera, S, additional, Manfreda, A, additional, Marscher, A P, additional, Massaro, F, additional, Mitsuishi, I, additional, Mizuno, T, additional, Negro, M, additional, Ng, C-Y, additional, O’Dell, S L, additional, Omodei, N, additional, Oppedisano, C, additional, Papitto, A, additional, Pavlov, G G, additional, Peirson, A L, additional, Perri, M, additional, Pesce-Rollins, M, additional, Pilia, M, additional, Possenti, A, additional, Ramsey, B D, additional, Rankin, J, additional, Ratheesh, A, additional, Roberts, O J, additional, Romani, R W, additional, Sgrò, C, additional, Slane, P, additional, Spandre, G, additional, Swartz, D A, additional, Tamagawa, T, additional, Tavecchio, F, additional, Taverna, R, additional, Tawara, Y, additional, Tennant, A F, additional, Thomas, N E, additional, Trois, A, additional, Tsygankov, S S, additional, Turolla, R, additional, Vink, J, additional, Weisskopf, M C, additional, Wu, K, additional, Xie, F, additional, and Zane, S, additional

Published
2023
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115. Spectral evolution of superluminal components in parsec-scale jets

Author

Mimica, P., Aloy, M. A., Agudo, I., Marti, J. M., Gomez, J. L., and Miralles, J. A.

Subjects
Astrophysics
Abstract

(Abridged) We present numerical simulations of the spectral evolution and emission of radio components in relativistic jets. We have developed an algorithm (SPEV) for the transport of a population of non-thermal electrons including radiative losses. For large values of the ratio of gas pressure to magnetic field energy density, \ab \sim 6\times 10^4, quiescent jet models show substantial spectral evolution, with observational consequences only above radio frequencies. Larger values of the magnetic field (\ab \sim 6\times 10^2), such that synchrotron losses are moderately important at radio frequencies, present a larger ratio of shocked-to-unshocked regions brightness than the models without radiative losses, despite the fact that they correspond to the same underlying hydrodynamic structure. We also show that jets with a positive photon spectral index result if the lower limit \gamma_min of the non-thermal particle energy distribution is large enough. A temporary increase of the Lorentz factor at the jet inlet produces a traveling perturbation that appears in the synthetic maps as a superluminal component. We show that trailing components can be originated not only in pressure matched jets, but also in over-pressured ones, where the existence of recollimation shocks does not allow for a direct identification of such features as Kelvin-Helmholtz modes, and its observational imprint depends on the observing frequency. If the magnetic field is large (\ab \sim 6\times 10^2), the spectral index in the rarefaction trailing the traveling perturbation does not change much with respect to the same model without any hydrodynamic perturbation. If the synchrotron losses are considered the spectral index displays a smaller value than in the corresponding region of the quiescent jet model., Comment: Accepted for publication in ApJ. A PDF with high-resolution figures and animations referenced in the article can be found at http://www.uv.es/aloy/SPEV_MOVIES

Published
2008
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116. Simultaneous polarization monitoring of supernovae SN2008D/XT080109 and SN2007uy: isolating geometry from dust

Author

Gorosabel, J., Postigo, A. de Ugarte, Castro-Tirado, A. J., Agudo, I., Jelinek, M., Leon, S., Augusteijn, T., Fynbo, J. P. U., Hjorth, J., Michalowski, M. J., Xu, D., Ferrero, P., Kann, D. A., Klose, S., Rossi, A., Madrid, J. P., LLorente, A., Bremer, M., and Winters, J. -M.

Subjects
Astrophysics
Abstract

The possible existence of a continuum encompassing the diversity of explosive stellar deaths,ranging from ordinary SNe to relativistic hypernovae associated with long duration GRBs, is under intense debate. In this context, SN2008D associated with XT080109 could represent a paradigmatic case, since it might exemplify a potential borderline event. The main aim is to infer geometric information of SN2008D through the evolution of its linear optical polarization. We also report the polarization evolution of SN2007uy, and discuss the properties of the host ISM towards the XT. The final goal is to compare the polarization properties, and hence the geometries of both SNe, which shone contemporaneously in NGC2770. This fortunate coincidence brought us the opportunity to observe both SNe simultaneously, and most importantly, with identical instrumental setups. The observations span 74.9 days, starting 3.6 days after the XT and are distributed in 11 visits. In addition we performed observations in the mm range in order to identify the dominant polarization. We report positive linear polarization detections at several epochs for SN2008D at a level of ~1% and at ~1.5% for SN2007uy. SN2007uy shows constant polarization, which could be described by the host interstellar polarization plus a constant eccentricity expansion on the sky plane. A statistical analysis of the distribution of the SN2008D Stokes parametres suggests that it could show an intrinsic variable polarization component. Assuming the SN2007uy polarization is constant, we find that the evolution of the intrinsic SN2008D polarization could be explained by an aspherical axisymmetric expansion with variable eccentricity. We come to the same result even if we make no assumption on SN2007uy, although at a lower significance level. We suggest that at least the projected, if not the intrinsic, geometries of both SNe could differ., Comment: 10 pages, 3 figures, accepted for publication in A&A

Published
2008
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117. Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71, III. Rapid and correlated flux density variability from radio to sub-mm bands

Author

Fuhrmann, L., Krichbaum, T. P., Witzel, A., Kraus, A., Britzen, S., Bernhart, S., Impellizzeri, C. M. V., Agudo, I., Klare, J., Sohn, B. W., Angelakis, E., Bach, U., Gab'anyi, K. 'E., K"ording, E., Pagels, A., Zensus, J. A., Wagner, S. J., Ostorero, L., Ungerechts, H., Grewing, M., Tornikoski, M., Apponi, A. J., Vila-Vilar'o, B., Ziurys, L. M., and Strom, R. G.

Subjects
Astrophysics
Abstract

The BL Lac object S5 0716+71 was observed in a global multi-frequency campaign to search for rapid and correlated flux density variability and signatures of an inverse-Compton (IC) catastrophe during the states of extreme apparent brightness temperatures. The observing campaign involved simultaneous monitoring at radio to IR/optical wavelengths centered around a 500-ks INTEGRAL pointing (November 10-17, 2003). We present the combined analysis and results of the cm- to sub-mm observations including a detailed study of the inter- to intra-day variability and spectral characteristics of 0716+714. We further constrain the variability brightness temperatures (T_B) and Doppler factors (delta) comparing the radio-bands with the hard X-ray emission (3-200 keV). 0716+714 was in an exceptionally high state (outburst) and different (slower) phase of short-term variability. The flux density variability in the cm- to mm-bands is dominated by a correlated, ~4 day time scale amplitude increase of up to ~35% systematically more pronounced towards shorter wavelengths. This contradicts expectations from standard interstellar scintillation (ISS) and suggests a source-intrinsic origin of the variability. The derived lower limits to T_B exceed the 10^12 K IC-limit by up to 3-4 orders of magnitude. Assuming relativistic boosting, we obtain robust and self-consistent lower limits of delta >= 5-33, in good agreement with delta_VLBI obtained from VLBI studies and the IC-Doppler factors delta_IC > 14-16 obtained from the INTEGRAL data. Since a strong contribution from ISS can be excluded and a simultaneous IC catastrophe was not observed, we conclude that relativistic Doppler boosting naturally explains the apparent violation of the theoretical limits within standard synchrotron-self-Compton (SSC) jet models of AGN., Comment: 20 pages, accepted for publication in A&A

Published
2008
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118. Hydrodynamics of a perturbation in the jet of 3C111

Author

Perucho, M., Agudo, I., Gomez, J. L., Kadler, M., Ros, E., and Kovalev, Y. Y.

Subjects
Astrophysics
Abstract

We present results on the modelling of the ejection of a superluminal component in the jet of 3C111. We propose that the component is generated by an injection of dense material followed by a decrease in the injection rate of bulk particles in the jet. Our model is supported by 1D relativistic hydrodynamics and emission simulations, and is capable of reproducing the brightness evolution of two features, as revealed by 15 GHz VLBA observations. We show that other scenarios, such as an increase of the Lorentz factor in the material of the perturbation, fails to reproduce the observed evolution of this flare., Comment: 4 pages. To be published in the proceedings of "The Central Kiloparsec: Active Galactic Nuclei and their hosts" held in Crete. 4-6 June 2008. Corrected typos

Published
2008

119. On the nature of an ejection event in the jet of 3C111

Author

Perucho, M., Agudo, I., Gomez, J. L., Kadler, M., Ros, E., and Kovalev, Y. Y.

Subjects
Astrophysics
Abstract

We present a possible scenario for the ejection of a superluminal component in the jet of the Broad Line Radio Galaxy 3C111 in early 1996. VLBI observations at 15 GHz discovered the presence of two jet features on scales smaller than one parsec. The first component evolves downstream, whereas the second one fades out after 1 parsec. We propose the injection of a perturbation of dense material followed by a decrease in the injection rate of material in the jet as a plausible explanation. This scenario is supported by 1D relativistic hydrodynamics and emission simulations. The perturbation is modeled as an increase in the jet density, without modifying the original Lorentz factor in the initial conditions. We show that an increase of the Lorentz factor in the material of the perturbation fails to reproduce the observed evolution of this flare. We are able to estimate the lifetime of the ejection event in 3C111 to be 36\pm7 days., Comment: Accepted for publication in Astronomy & Astrophysics Letters

Published
2008
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120. Stratification in polarization and Faraday rotation in the jet of 3C 120

Author

Gomez, J. L., Agudo, I., Marscher, A. P., Jorstad, S. G., and Roca-Sogorb, M.

Subjects
Astrophysics
Abstract

Very long baseline interferometric observations of the radio galaxy 3C 120 show a systematic presence of gradients in Faraday rotation and degree of polarization across and along the jet. These are revealed by the passage of multiple superluminal components throughout the jet as they move out from the core in a sequence of 12 monthly polarimetric observations taken with the VLBA at 15, 22, and 43 GHz. The degree of polarization has an asymmetric profile in which the northern side of the jet is more highly polarized. The Faraday rotation measure is also stratified across the jet width, with larger values for the southern side. Superposed on this structure we find a localized region of high Faraday rotation measure (about 6000 rad/m^2) between approximately 3 and 4 mas from the core. This region of enhanced Faraday rotation may result from the interaction of the jet with the ambient medium, which may also explain the stratification in degree of polarization. The data are also consistent with a helical magnetic field in a two-fluid jet model, consisting of an inner emitting jet and a sheath of nonrelativistic electrons., Comment: To be published by the Memorie della Societa Astronomica Italiana, Vol. 79, in the Proceedings of the Workshop: "The Central Kiloparsec: Active Galactic Nuclei and Their Hosts", eds. A.Lobanov, E.Angelakis, M.Perucho, and A.Zensus. 4 pages (including 4 figures)

Published
2008

121. Faraday rotation and polarization gradients in the jet of 3C~120: Interaction with the external medium and a helical magnetic field?

Author

Gomez, J. -L., Marscher, A. P., Jorstad, S. G., Agudo, I., and Roca-Sogorb, M.

Subjects
Astrophysics
Abstract

We present a sequence of 12 monthly polarimetric 15, 22, and 43 GHz VLBA observations of the radio galaxy 3C 120 revealing a systematic presence of gradients in Faraday rotation and degree of polarization across and along the jet. The degree of polarization increases with distance from the core and toward the jet edges, and has an asymmetric profile in which the northern side of the jet is more highly polarized. The Faraday rotation measure is also stratified across the jet width, with larger values for the southern side. We find a localized region of high Faraday rotation measure superposed on this structure between approximately 3 and 4 mas from the core, with a peak of about 6000 rad/m^2. Interaction of the jet with the external medium or a cloud would explain the confined region of enhanced Faraday rotation, as well as the stratification in degree of polarization and the flaring of superluminal knots when crossing this region. The data are also consistent with a helical field in a two-fluid jet model, consisting of an inner, emitting jet and a sheath containing nonrelativistic electrons. However, this helical magnetic field model cannot by itself explain the localized region of enhanced Faraday rotation. The polarization electric vectors, predominantly perpendicular to the jet axis once corrected for Faraday rotation, require a dominant component parallel to the jet axis (in the frame of the emitting plasma) for the magnetic field in the emitting region., Comment: Accepted for publication in ApJ Letters. 4 pages (including 5 figures)

Published
2008
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122. A VLBI Search for the Origin of Wobbling in Blazar Jets

Author

Agudo, I.

Subjects
Astrophysics
Abstract

An increasing number of blazars have been reported to show jet wobbling (i.e., non-regular rotations of the structural position angle of their innermost jets in the plane of the sky with amplitudes between 20 deg. and 50 deg., and time scales between 2 yr. and 20 yr.). The physical origin for the observed jet wobbling is still poorly understood, but as this phenomenon is triggered in the innermost regions of the jets, it must be tied to fundamental properties of the inner regions of the accretion system. Thus, jet wobbling may be an interesting potential tool for supermassive black hole, accretion and jet launching studies. As part of a joint theoretical/numerical and observational effort to characterize the observational properties and differences between these three possible scenarios we have started a long-term polarimetric phase-reference 43 GHz VLBA monitoring program to observe the jet structure and the absolute motion of the jet core of four of the blazars which have shown some of the clearest evidence of large amplitude jet wobbling: NRAO 150, OJ 287, 3C 273, and 3C 345 . Here we present this project and we argue about its suitability for future VSOP-2 observations., Comment: To be published by the Astronomical Society of the Pacific Conference Series (ASPCS), in the Proceedings of the Symposium: "Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and Technology", eds. Y.Hagiwara, E.Fomalont, M.Tsuboi, and Y.Murata. 7 pages (including 6 figures)

Published
2008

123. The Influence of Helical Magnetic Fields in the Dynamics and Emission of Relativistic Jets

Author

Roca-Sogorb, M., Perucho, M., Gomez, J. L., Marti, J. M., Anton, L., Aloy, M. A., and Agudo, I.

Subjects
Astrophysics
Abstract

We present numerical relativistic magnetohydrodynamic and emission simulations aimed to study the role played by the magnetic field in the dynamics and emission of relativistic jets in Active Galactic Nuclei. We focus our analysis on the study of the emission from recollimation shocks since they may provide an interpretation for the stationary components seen at parsec-scales in multiple sources. We show that the relative brightness of the knots associated with the recollimation shocks decreases with increasing jet magnetization, suggesting that jets presenting stationary components may have a relatively weak magnetization, with magnetic fields of the order of equipartition or below., Comment: 4 pages, 3 figures. Proceedings from Astronomical Society of the Pacific Conference Series (ASPCS)

Published
2008

124. The Trails of Superluminal Jet Components in 3C111

Author

Kadler, M., Ros, E., Perucho, M., Kovalev, Y. Y., Homan, D. C., Agudo, I., Kellermann, K. I., Aller, M. F., Aller, H. D., Lister, M. L., and Zensus, J. A.

Subjects
Astrophysics
Abstract

In 1996, a major radio flux-density outburst occured in the broad-line radio galaxy 3C111. It was followed by a particularly bright plasma ejection associated with a superluminal jet component, which has shaped the parsec-scale structure of 3C111 for almost a decade. Here, we present results from 18 epochs of Very Long Baseline Array (VLBA) observations conducted since 1995 as part of the VLBA 2 cm Survey and MOJAVE monitoring programs. This major event allows us to study a variety of processes associated with outbursts of radio-loud AGN in much greater detail than has been possible in other cases: the primary perturbation gives rise to the formation of a leading and a following component, which are interpreted as a forward and a backward-shock. Both components evolve in characteristically different ways and allow us to draw conclusions about the work flow of jet-production events; the expansion, acceleration and recollimation of the ejected jet plasma in an environment with steep pressure and density gradients are revealed; trailing components are formed in the wake of the primary perturbation possibly as a result of coupling to Kelvin-Helmholtz instability pinching modes from the interaction of the jet with the external medium. The interaction of the jet with its ambient medium is further described by the linear-polarization signature of jet components traveling along the jet and passing a region of steep pressure/density gradients., Comment: 16 pages, 11 figures, 3 tables, accepted for publication in the Astrophysical Journal; a reference is updated

Published
2008
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125. Superluminal non-ballistic jet swing in the quasar NRAO 150 revealed by mm-VLBI

Author

Agudo, I., Bach, U., Krichbaum, T. P., Marscher, A. P., Gonidakis, I., Diamond, P. J., Perucho, M., Alef, W., Graham, D. A., Witzel, A., Zensus, J. A., Bremer, M., Acosta-Pulido, J. A., and Barrena, R.

Subjects
Astrophysics
Abstract

NRAO 150 -a compact and bright radio to mm source showing core/jet structure- has been recently identified as a quasar at redshift z=1.52 through a near-IR spectral observation. To study the jet kinematics on the smallest accessible scales and to compute the first estimates of its basic physical properties, we have analysed the ultra-high-resolution images from a new monitoring program at 86 GHz and 43 GHz with the GMVA and the VLBA, respectively. An additional archival and calibration VLBA data set, covering from 1997 to 2007, has been used. Our data shows an extreme projected counter-clock-wise jet position angle swing at an angular rate of up to ~11 deg./yr within the inner ~31 pc of the jet, which is associated with a non-ballistic superluminal motion of the jet within this region. The results suggest that the magnetic field could play an important role in the dynamics of the jet in NRAO 150, which is supported by the large values of the magnetic field strength obtained from our first estimates. The extreme characteristics of the jet swing make NRAO 150 a prime source to study the jet wobbling phenomenon., Comment: Accepted for publication in A&A Letters. 4 pages (including 3 figures) + 3 additional Tables

Published
2007
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126. Rapid and correlated variability of blazar S5 0716+71 from radio- to sub-mm bands

Author

Fuhrmann, L., Krichbaum, T. P., Witzel, A., Agudo, I., Britzen, S., Bernhart, S., Impellizzeri, V., Kraus, A., Angelakis, E., Bach, U., Gabányi, K., and Zensus, J. A.

Subjects
Astrophysics
Abstract

The BL Lac object S5 0716+71 was target of a coordinated and global multi-frequency campaign to search for rapid and correlated variability and signatures of the inverse-Compton catastrophe. Here we present first results obtained from a combined analysis of the cm- to sub-mm observations over a period of seven days aiming at a detailed study of the intra- to inter-day variability characteristics and to obtain constraints on the variability brightness temperatures and Doppler factors comparing the radio data with the high energy emission recorded by INTEGRAL. A more detailed description of the whole cm- to sub-mm observations and our analysis/results will be presented in a forthcoming paper. Our analysis reveals the source to be in a particular short-term variability phase when compared to the past with a correlated >~4 day time scale amplitude increase of up to 35%, which is systematically more pronounced towards higher frequencies. The obtained frequency dependent variability amplitudes and time lags contradict expectations from interstellar scintillation and strongly suggest a source intrinsic origin of this inter-day variability. A 7-day spectral evolution study indicate time-variable synchrotron self-absorption and expansion of the emission region, consistent with standard models. Assuming relativistic boosting, our different estimates of the Doppler factor yield robust lower limits of D_var,IC > 5-22 using the inverse-Compton limit and D_var,eq > 8-33 using the equipartition argument. Although high, these values are in good agreement with Doppler factors obtained from recent VLBI studies and from the inverse-Compton Doppler factors D_IC > 14-16 derived with the X-ray emission seen by INTEGRAL at 3-200 keV., Comment: 6 pages, 3 figures, to appear in the proceedings of the 8th EVN symposium held in Torun, Poland, September 2006

Published
2006

127. VLBI at the highest frequencies - AGN studied with micro-arcsecond resolution

Author

Krichbaum, T. P., Agudo, I., Bach, U., Witzel, A., and Zensus, J. A.

Subjects
Astrophysics
Abstract

Compact galactic and extragalactic radio sources can be imaged with an unsurpassed angular resolution of a few ten micro-arcseconds, adopting the observing technique of global millimeter VLBI. Here we present the Global Millimeter VLBI Array (GMVA) and discuss its present performance. For individual and partially archetypical radio sources with prominent VLBI jets (e.g. 3C120, Cygnus A, M87, 3C454.3, NRAO150),we show and discuss new results obtained with the GMVA. The variety of observed effects range from jet propagation and bending, partial fore-ground absorption in the nucleus, and jet component ejection after major flares to new and very small (15-20 Schwarzschild radii) upper limits to the jet base of M87. We also discuss the future development of mm-VLBI at 3mm and towards shorter wavelengths, and make suggestions for possible improvements., Comment: 15 pages, 9 figures, to appear in the proceedings of `The 8th European VLBI Network Symposium on New Developments in VLBI Science and Technology', ed. A. Marecki et al., held in Torun, Poland, on September 26-29, 2006 (invited Review)

Published
2006

128. 'Oscillating' components in the BL Lac object 0716+714?

Author

Britzen, S., Meyer, V., Witzel, A., Agudo, I., Aller, M. F., Aller, H. D., Eckart, A., and Zensus, J. A.

Subjects
Astrophysics
Abstract

15 VLBA observations of the BL Lac object 0716+714, performed between 1994.67 and 2006.40 at 15 GHz, have been analyzed. Part of the data (12 epochs) were obtained within the Mojave-survey project and reanalyzed by us. We present a new motion scenario for jet model component motion in this source which suggests that no longterm-outward motion but rather an oscillation of components around an average core separation is taking place. Although no significant outward motion in the core separation can be found, motion with regard to the position angle is observed. We give lower limits for the derived apparent motions and Doppler factors and compare them with values published in the literature. We find a relation between the total flux-density evolution at 14.5 GHz (UMRAO data) and the position angle changes observed for the jet component closest to the core. We suggest a significant geometric contribution to the longterm flux-density variability in 0716+714., Comment: 6 pages, 5 figures, to appear in the proceedings of the 8th European VLBI Network Symposium on New Developments in VLBI Science and Technology, Torun, Poland

Published
2006

129. Structure and flux variability in the VLBI jet of BL Lacertae during the WEBT campaigns (1995--2004)

Author

Bach, U., Villata, M., Raiteri, C. M., Agudo, I., Aller, H. D., Aller, M. F., Denn, G., Gomez, J. L., Jorstad, S., Marscher, A., Mutel, R. L., and Terasranta, H.

Subjects
Astrophysics
Abstract

BL Lacertae has been the target of several observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration and is one of the best studied blazars at all accessible wavelengths. A recent analysis of the optical and radio variability indicates that part of the radio variability is correlated with the optical light curve. Here we present an analysis of a huge VLBI data set including 108 images at 15, 22, and 43 GHz obtained between 1995 and 2004. The aim of this study is to identify the different components contributing to the single-dish radio light curves. We obtain separate radio light curves for the VLBI core and jet and show that the radio spectral index of single-dish observations can be used to trace the core variability. Cross-correlation of the radio spectral index with the optical light curve indicates that the optical variations lead the radio by about 100 days at 15 GHz. By fitting the radio time lags vs. frequency, we find that the power law is steeper than expected for a freely expanding conical jet in equipartition with energy density decreasing as the square of the distance down the jet as in the K\"onigl model. There is a section of the compact radio jet where the emission is weak such that flares propagating down the jet are bright first in the core region with a secondary increase in flux about 1.0 mas from the core. This illustrates the importance of direct imaging to the interpretation of multi-wavelength light curves that can be affected by several distinct components at any given time. We discuss how the complex behaviour of the light curves and correlations can be understood within the framework of a precessing helical jet model., Comment: 13(+5) pages, 12 figures, accepted for publication in A&A, replaced because of layout problems

Published
2006
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130. Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71: II. A search for intra-day variability at millimetre wavelengths with the IRAM 30 m telescope

Author

Agudo, I., Krichbaum, T. P., Ungerechts, H., Kraus, A., Witzel, A., Angelakis, E., Fuhrmann, L., Bach, U., Britzen, S., Zensus, J. A., Wagner, S. J., Ostorero, L., Ferrero, E., Gracia, J., and Grewing, M.

Subjects
Astrophysics
Abstract

We report on a densely time sampled polarimetric flux density monitoring of the BL Lac object S5 0716+71 at 86 GHz and 229 GHz with the IRAM 30 m telescope within a coordinated broad spectral band campaign, centred around an INTEGRAL observation during November 10 to 16, 2003. Our aim was to search for signatures of inverse-Compton "catastrophes". At 86 GHz, making use of a new calibration strategy, we reach a relative rms accuracy of the flux density measurements of 1.2%. At this frequency, S5 0716+71 showed no intra-day variability, but showed remarkable inter-day variability with a flux density increase of 34% during the first four observing days, which can not be explained by source extrinsic causes. The 86 GHz linear polarization fraction of S5 0716+71 was unusually large 15.0+-1.8%. Inter-day variability in linear polarization at 86 GHz, with significance level >~95%; sigma_P/=15% and sigma_chi=6 deg., was also observed. From the emission variations at the synchrotron turnover frequency (~86 GHz) we compute an apparent brightness temperature T_B,app>1.4x10^14K at a redshift of 0.3, which exceeds by two orders of magnitude the inverse-Compton limit. A relativistic correction for T_B,app with a Doppler factor delta > 7.8 brings the observed brightness temperature down to the inverse Compton limit. A more accurate lower limit of delta > 14.0, is obtained from the comparison of the 86 GHz synchrotron flux density and the upper limits for the synchrotron self-Compton flux density obtained from the INTEGRAL observations. The relativistic beaming of the emission by this high Doppler factor explains the non-detection of "catastrophic" inverse-Compton avalanches by INTEGRAL., Comment: Accepted for publication in A&A. 16 pages, 11 figures

Published
2006
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131. The milliarcsecond-scale jet of PKS 0735+178 during quiescence

Author

Agudo, I., Gomez, J. L., Gabuzda, D. C., Marscher, A. P., Jorstad, S. G., and Alberdi, A.

Subjects
Astrophysics
Abstract

We present polarimetric 5 GHz to 43 GHz VLBI observations of the BL Lacertae object PKS 0735+178, spanning March 1996 to May 2000. Comparison with previous and later observations suggests that the overall kinematic and structural properties of the jet are greatly influenced by its activity. Time intervals of enhanced activity, as reported before 1993 and after 2000 by other studies, are followed by highly superluminal motion along a rectilinear jet. In contrast the less active state in which we performed our observations, shows subluminal or slow superluminal jet features propagating through a twisted jet with two sharp bends of about 90 deg. within the innermost three-milliarcsecond jet structure. Proper motion estimates from the data presented here allow us to constrain the jet viewing angle to values < 9 deg., and the bulk Lorentz factor to be between 2 and 4., Comment: 11 pages, 12 figures. Accepted for publication in A&A

Published
2006
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132. Present and Future Millimeter VLBI Imaging of Jets in AGN: The Case of NRAO 150

Author

Agudo, I., Krichbaum, T. P., Bach, U., Pagels, A., Graham, D., Alef, W., Witzel, A., Zensus, J. A., Bremer, M., Grewing, M., and Teräsranta, H.

Subjects
Astrophysics
Abstract

The Global mm-VLBI Array is at present the most sensitive 3 mm-VLBI interferometer and provides images of up to 40 micro-arcsecond resolution. Using this array, we have monitored the rotation of the innermost jet in the quasar NRAO 150, which shows an angular speed of ~ 7 deg./yr. Future 3 mm arrays could include additional stations like ALMA, GBT, LMT, CARMA, SRT, Yebes, Nobeyama and Noto, which would allow to push VLBI at this wavelength to sensitivity and image quality levels comparable to those of present VLBI at centimeter wavelengths. This would improve our knowledge of the accretion systems and the magneto-hydrodynamics of the innermost jets in AGN and microquasars., Comment: 6 pages, 7 figures. Higher resolution figures can be requested to I. Agudo. To be published in Revista Mexicana de Astronomia y Astrofisica as a Proc. of the Conf. "Triggering Relativistic Jets", held in Cozumel (Mexico) from 28 March to 1 April 2005

Published
2005

133. The Innermost AGNs with Future mm-VLBI

Author

Agudo, I., Krichbaum, T. P., Bach, U., Pagels, A., Sohn, B. W., Graham, D. A., Witzel, A., Zensus, J. A., Gomez, J. L., Bremer, M., and Grewing, M.

Subjects
Astrophysics
Abstract

The capabilities of the Global mm-VLBI Array are summarized and demonstrated through actual images from our monitoring of extragalactic radio jets. This sensitive 3mm-VLBI interferometer is able to provide images of up to 50 microarcseconds resolution. For the near future, ALMA, the GBT, the LMT, CARMA, SRT, Yebes, Nobeyama and Noto are some of the most sensitive stations suitable to participate in mm-VLBI. This future array, together with the present Global mm-VLBI Array, would achieve 10 times better sensitivities than nowadays. Image fidelity would also largely increased. T he addition of ALMA would improve the (u,v)-coverage for sources with low declination (<20 deg.) and facilitate the VLBI imaging of the Galactic Centre source SgrA*., Comment: 2 pages, 1 figure, to appear in the Proc. of the Conf. "Exploring the Cosmic Frontier: Astrophysical Instruments for the XXI Century", in press

Published
2005
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134. 86 GHz polarimetry of OVV1633+382 after a major mm flare

Author

Sohn, B. W., Krichbaum, T. P., Agudo, I., Witzel, A., Zensus, J. A., Ungerechts, H., and Terasranta, H.

Subjects
Astrophysics
Abstract

The 18 mag QSO 1633+382 (4C38.41, z=1.807) showed a very pronounced outburst in 2001/2002. With a peak amplitude of more than 9 Jy at 90GHz, this flare was brighter than any known previous flare in this source (data available since 1980).During onset, the mm-flare was particulary fast, with an increase of more than 2 Jy at 230 GHz in less than 8 days. Since January 2002, the mm-flux of 1633+382 is decaying. During this decline, however, local flux variations with amplitudes of 1-3 Jy were seen, indicative of underlying and more rapid source activity on time scales of 1-2 months. After the main peak occurring in 2001.99, the 90 GHz flux showed secondary maxima at approximately half year intervals in 2002.3, 2002.7 and 2003.13. This kind of periodicity might be explained via the lighthouse model (Camenzind and Krockenberger 1992), which is based on the magnetic accelerator of Blanford and Payne (1982). At present the millimeter flux is nearly back to its quiescent level of 2-2.5 Jy, which the source had before the flare began. Our VLBA Polarimetry monitoring started June 2002 during the onset of the flare. At cm wavelength, the flare is only marginally detected which implies very high opacity of the source., Comment: 4 pages. 5 figures. Proceedings of the 7th European VLBI Network Symposium held in Toledo, Spain on October 12-15, 2004. Editors: R. Bachiller, F. Colomer, J.-F. Desmurs, P. de Vicente (Observatorio Astronomico Nacional), p. 85-88. Needs evn2004.cls

Published
2005

135. Real vs. simulated relativistic jets

Author

Gomez, J. L., Marti, J. M., Agudo, I., Marscher, A. P., Jorstad, S. G., and Aloy, M. A.

Subjects
Astrophysics
Abstract

Intensive VLBI monitoring programs of jets in AGN are showing the existence of intricate emission patterns, such as upstream motions or slow moving and quasi-stationary componentes trailing superluminal features. Relativistic hydrodynamic and emission simulations of jets are in very good agreement with these observations, proving as a powerful tool for the understanding of the physical processes taking place in the jets of AGN, microquasars and GRBs. These simulations show that the variability of the jet emission is the result of a complex combination of phase motions, viewing angle selection effects, and non-linear interactions between perturbations and the underlying jet and/or ambient medium. Both observations and simulations suggest that shock-in-jet models may be an overly simplistic idealization when interpreting the emission structure observed in actual jets., Comment: 6 pages. 4 figures. Proceedings of the 7th European VLBI Network Symposium held in Toledo, Spain on October 12-15, 2004. Editors: R. Bachiller, F. Colomer, J.-F. Desmurs, P. de Vicente (Observatorio Astronomico Nacional), p. 93-98. Needs evn2004.cls

Published
2005

136. Changes in the trajectory of the radio jet in 0735+178?

Author

Gomez, J. L., Guirado, J. C., Agudo, I., Marscher, A. P., Alberdi, A., Marcaide, J. M., and Gabuzda, D. C.

Subjects
Astrophysics
Abstract

We present multi-epoch 8.4 and 43 GHz Very Long Baseline Array images of the BL Lac object 0735+178. The images confirm the presence of a twisted jet with two sharp apparent bends of 90$^{\circ}$ within two milliarcseconds of the core, resembling a helix in projection. The observed twisted geometry could be the result of precession of the jet inlet, but is more likely produced by pressure gradients in the external medium through which the jet propagates. Quasi-stationary components are observed at the locations of the 90$^{\circ}$ bends, possibly produced by differential Doppler boosting. Identification of components across epochs, since the earliest VLBI observations of this source in 1979.2, proves difficult due to the sometimes large time gaps between observations. One possible identification suggests the existence of superluminal components following non--ballistic trajectories with velocities up to $11.6\pm 0.6 h_{65}^{-1} c$. However, in images obtained after mid-1995, components show a remarkable tendency to cluster near several jet positions, suggesting a different scenario in which components have remained nearly stationary in time at least since mid-1995. Comparison with the earlier published data, covering more than 19 years of observations, suggests a striking qualitative change in the jet trajectory sometime between mid-1992 and mid-1995, with the twisted jet structure with stationary components becoming apparent only at the later epochs. This would require a re-evaluation of the physical parameters estimated for 0735+178, such as the observing viewing angle, the plasma bulk Lorentz factor, and those deduced from these., Comment: 18 pages, 5 figures, accepted for publication in MNRAS

Published
2001
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137. Polarimetric VLBI observations of 0735+178

Author

Agudo, I., Gomez, J. L., Gabuzda, D. C., Guirado, J. C., Alberdi, A., Marscher, A. P., Aloy, M. A., and Marti, J. M.

Subjects
Astrophysics
Abstract

We present a new centimeter polarimetric VLBI image of the BL Lac object 0735+178. This source exhibits one of the most pronounced curvatures observed in jets of AGNs, with two sharp apparent bends of 90 degrees within the inner 2 milliarcseconds from the core. Through the analysis of the data gathered over the past decades we study whether this curvature is produced by precession of the jet with ejection of ballistic components, or a precession in such a way that components' velocity vector are always parallel to the jet axis. These possibilities are also studied by comparison with 3D hydrodynamic relativistic simulations of precessing jets., Comment: LaTeX, 4 pages, 4 PostScript figures. To be published in the Proceedings of the 5th EVN Symposium, eds. Conway, J., Polatidis, A. & Booth., R

Published
2001

138. Jet stability and the generation of superluminal and stationary components

Author

Agudo, I., Gomez, J. L., Marti, J. M., Ibanez, J. M, Marscher, A. P., Alberdi, A., Aloy, M. A., and Hardee, P. E.

Subjects
Astrophysics
Abstract

We present a numerical simulation of the response of an expanding relativistic jet to the ejection of a superluminal component. The simulation has been performed with a relativistic time-dependent hydrodynamical code from which simulated radio maps are computed by integrating the transfer equations for synchrotron radiation. The interaction of the superluminal component with the underlying jet results in the formation of multiple conical shocks behind the main perturbation. These trailing components can be easily distinguished because they appear to be released from the primary superluminal component, instead of being ejected from the core. Their oblique nature should also result in distinct polarization properties. Those appearing closer to the core show small apparent motions and a very slow secular decrease in brightness, and could be identified as stationary components. Those appearing farther downstream are weaker and can reach superluminal apparent motions. The existence of these trailing components indicates that not all observed components necessarily represent major perturbations at the jet inlet; rather, multiple emission components can be generated by a single disturbance in the jet. While the superluminal component associated with the primary perturbation exhibits a rather stable pattern speed, trailing components have velocities that increase with distance from the core but move at less than the jet speed. The trailing components exhibit motion and structure consistent with the triggering of pinch modes by the superluminal component., Comment: Accepted by ApJ Letters. LaTeX, 19 pages, 4 PostScript figures

Published
2001
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139. X-ray polarimetry and spectroscopy of the neutron star low-mass X-ray binary GX 9+9: An in-depth study with IXPE and NuSTAR

Author

Ursini, F., primary, Farinelli, R., additional, Gnarini, A., additional, Poutanen, J., additional, Bianchi, S., additional, Capitanio, F., additional, Di Marco, A., additional, Fabiani, S., additional, La Monaca, F., additional, Malacaria, C., additional, Matt, G., additional, Mikušincová, R., additional, Cocchi, M., additional, Kaaret, P., additional, Kajava, J. J. E., additional, Pilia, M., additional, Zhang, W., additional, Agudo, I., additional, Antonelli, L. A., additional, Bachetti, M., additional, Baldini, L., additional, Baumgartner, W. H., additional, Bellazzini, R., additional, Bongiorno, S. D., additional, Bonino, R., additional, Brez, A., additional, Bucciantini, N., additional, Castellano, S., additional, Cavazzuti, E., additional, Chen, C.-T., additional, Ciprini, S., additional, Costa, E., additional, De Rosa, A., additional, Del Monte, E., additional, Di Gesu, L., additional, Di Lalla, N., additional, Donnarumma, I., additional, Doroshenko, V., additional, Dovčiak, M., additional, Ehlert, S. R., additional, Enoto, T., additional, Evangelista, Y., additional, Ferrazzoli, R., additional, Garcia, J. A., additional, Gunji, S., additional, Hayashida, K., additional, Heyl, J., additional, Iwakiri, W., additional, Jorstad, S. G., additional, Karas, V., additional, Kislat, F., additional, Kitaguchi, T., additional, Kolodziejczak, J. J., additional, Krawczynski, H., additional, Latronico, L., additional, Liodakis, I., additional, Maldera, S., additional, Manfreda, A., additional, Marin, F., additional, Marinucci, A., additional, Marscher, A. P., additional, Marshall, H. L., additional, Massaro, F., additional, Mitsuishi, I., additional, Mizuno, T., additional, Muleri, F., additional, Negro, M., additional, Ng, C.-Y., additional, O’Dell, S. L., additional, Omodei, N., additional, Oppedisano, C., additional, Papitto, A., additional, Pavlov, G. G., additional, Peirson, A. L., additional, Perri, M., additional, Pesce-Rollins, M., additional, Petrucci, P.-O., additional, Possenti, A., additional, Puccetti, S., additional, Ramsey, B. D., additional, Rankin, J., additional, Ratheesh, A., additional, Roberts, O. J., additional, Romani, R. W., additional, Sgrò, C., additional, Slane, P., additional, Soffitta, P., additional, Spandre, G., additional, Swartz, D. A., additional, Tamagawa, T., additional, Tavecchio, F., additional, Taverna, R., additional, Tawara, Y., additional, Tennant, A. F., additional, Thomas, N. E., additional, Tombesi, F., additional, Trois, A., additional, Tsygankov, S. S., additional, Turolla, R., additional, Vink, J., additional, Weisskopf, M. C., additional, Wu, K., additional, Xie, F., additional, and Zane, S., additional

Published
2023
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140. Panning for gold, but finding helium: Discovery of the ultra-stripped supernova SN 2019wxt from gravitational-wave follow-up observations

Author

Agudo, I., primary, Amati, L., additional, An, T., additional, Bauer, F. E., additional, Benetti, S., additional, Bernardini, M. G., additional, Beswick, R., additional, Bhirombhakdi, K., additional, de Boer, T., additional, Branchesi, M., additional, Brennan, S. J., additional, Brocato, E., additional, Caballero-García, M. D., additional, Cappellaro, E., additional, Castro Rodríguez, N., additional, Castro-Tirado, A. J., additional, Chambers, K. C., additional, Chassande-Mottin, E., additional, Chaty, S., additional, Chen, T.-W., additional, Coleiro, A., additional, Covino, S., additional, D’Ammando, F., additional, D’Avanzo, P., additional, D’Elia, V., additional, Fiore, A., additional, Flörs, A., additional, Fraser, M., additional, Frey, S., additional, Frohmaier, C., additional, Fulton, M., additional, Galbany, L., additional, Gall, C., additional, Gao, H., additional, García-Rojas, J., additional, Ghirlanda, G., additional, Giarratana, S., additional, Gillanders, J. H., additional, Giroletti, M., additional, Gompertz, B. P., additional, Gromadzki, M., additional, Heintz, K. E., additional, Hjorth, J., additional, Hu, Y.-D., additional, Huber, M. E., additional, Inkenhaag, A., additional, Izzo, L., additional, Jin, Z. P., additional, Jonker, P. G., additional, Kann, D. A., additional, Kool, E. C., additional, Kotak, R., additional, Leloudas, G., additional, Levan, A. J., additional, Lin, C.-C., additional, Lyman, J. D., additional, Magnier, E. A., additional, Maguire, K., additional, Mandel, I., additional, Marcote, B., additional, Mata Sánchez, D., additional, Mattila, S., additional, Melandri, A., additional, Michałowski, M. J., additional, Moldon, J., additional, Nicholl, M., additional, Nicuesa Guelbenzu, A., additional, Oates, S. R., additional, Onori, F., additional, Orienti, M., additional, Paladino, R., additional, Paragi, Z., additional, Perez-Torres, M., additional, Pian, E., additional, Pignata, G., additional, Piranomonte, S., additional, Quirola-Vásquez, J., additional, Ragosta, F., additional, Rau, A., additional, Ronchini, S., additional, Rossi, A., additional, Sánchez-Ramírez, R., additional, Salafia, O. S., additional, Schulze, S., additional, Smartt, S. J., additional, Smith, K. W., additional, Sollerman, J., additional, Srivastav, S., additional, Starling, R. L. C., additional, Steeghs, D., additional, Stevance, H. F., additional, Tanvir, N. R., additional, Testa, V., additional, Torres, M. A. P., additional, Valeev, A., additional, Vergani, S. D., additional, Vescovi, D., additional, Wainscost, R., additional, Watson, D., additional, Wiersema, K., additional, Wyrzykowski, Ł., additional, Yang, J., additional, Yang, S., additional, and Young, D. R., additional

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2023
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141. X-ray polarimetry of X-ray pulsar X Persei: another orthogonal rotator?

Author

Mushtukov, A A, primary, Tsygankov, S S, additional, Poutanen, J, additional, Doroshenko, V, additional, Salganik, A, additional, Costa, E, additional, Marco, A Di, additional, Heyl, J, additional, Monaca, F La, additional, Lutovinov, A A, additional, Mereminsky, I A, additional, Papitto, A, additional, Semena, A N, additional, Shtykovsky, A E, additional, Suleimanov, V F, additional, Forsblom, S V, additional, González-Caniulef, D, additional, Malacaria, C, additional, Sunyaev, R A, additional, Agudo, I, additional, Antonelli, L A, additional, Bachetti, M, additional, Baldini, L, additional, Baumgartner, W H, additional, Bellazzini, R, additional, Bianchi, S, additional, Bongiorno, S D, additional, Bonino, R, additional, Brez, A, additional, Bucciantini, N, additional, Capitanio, F, additional, Castellano, S, additional, Cavazzuti, E, additional, Chen, C-T, additional, Ciprini, S, additional, De Rosa, A, additional, Del Monte, E, additional, Gesu, L Di, additional, Lalla, N Di, additional, Donnarumma, I, additional, Dovčiak, M, additional, Ehlert, S R, additional, Enoto, T, additional, Evangelista, Y, additional, Fabiani, S, additional, Ferrazzoli, R, additional, Garcia, J A, additional, Gunji, S, additional, Hayashida, K, additional, Iwakiri, W, additional, Jorstad, S G, additional, Kaaret, P, additional, Karas, V, additional, Kislat, F, additional, Kitaguchi, T, additional, Kolodziejczak, J J, additional, Krawczynski, H, additional, Latronico, L, additional, Liodakis, I, additional, Maldera, S, additional, Manfreda, A, additional, Marin, F, additional, Marscher, A P, additional, Marshall, H L, additional, Massaro, F, additional, Matt, G, additional, Mitsuishi, I, additional, Mizuno, T, additional, Muleri, F, additional, Negro, M, additional, Ng, C-Y, additional, O’Dell, S L, additional, Omodei, N, additional, Oppedisano, C, additional, Pavlov, G G, additional, Peirson, A L, additional, Perri, M, additional, Pesce-Rollins, M, additional, Petrucci, P-O, additional, Pilia, M, additional, Possenti, A, additional, Puccetti, S, additional, Ramsey, B D, additional, Rankin, J, additional, Ratheesh, A, additional, Roberts, O J, additional, Romani, R W, additional, Sgrò, C, additional, Slane, P, additional, Soffitta, P, additional, Spandre, G, additional, Swartz, D A, additional, Tamagawa, T, additional, Tavecchio, F, additional, Taverna, R, additional, Tawara, Y, additional, Tennant, A F, additional, Thomas, N E, additional, Tombesi, F, additional, Trois, A, additional, Turolla, R, additional, Vink, J, additional, Weisskopf, M C, additional, Wu, K, additional, Xie, F, additional, and Zane, S, additional

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2023
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142. Uncovering the geometry of the hot X-ray corona in the Seyfert galaxy NGC 4151 with IXPE

Author

Gianolli, V E, primary, Kim, D E, additional, Bianchi, S, additional, Agís-González, B, additional, Madejski, G, additional, Marin, F, additional, Marinucci, A, additional, Matt, G, additional, Middei, R, additional, Petrucci, P-O, additional, Soffitta, P, additional, Tagliacozzo, D, additional, Tombesi, F, additional, Ursini, F, additional, Barnouin, T, additional, De Rosa, A, additional, Di Gesu, L, additional, Ingram, A, additional, Loktev, V, additional, Panagiotou, C, additional, Podgorny, J, additional, Poutanen, J, additional, Puccetti, S, additional, Ratheesh, A, additional, Veledina, A, additional, Zhang, W, additional, Agudo, I, additional, Antonelli, L A, additional, Bachetti, M, additional, Baldini, L, additional, Baumgartner, W H, additional, Bellazzini, R, additional, Bongiorno, S D, additional, Bonino, R, additional, Brez, A, additional, Bucciantini, N, additional, Capitanio, F, additional, Castellano, S, additional, Cavazzuti, E, additional, Chen, C-T, additional, Ciprini, S, additional, Costa, E, additional, Del Monte, E, additional, Di Lalla, N, additional, Di Marco, A, additional, Donnarumma, I, additional, Doroshenko, V, additional, Dovčiak, M, additional, Ehlert, S R, additional, Enoto, T, additional, Evangelista, Y, additional, Fabiani, S, additional, Ferrazzoli, R, additional, García, J A, additional, Gunji, S, additional, Heyl, J, additional, Iwakiri, W, additional, Jorstad, S G, additional, Kaaret, P, additional, Karas, V, additional, Kislat, F, additional, Kitaguchi, T, additional, Kolodziejczak, J J, additional, Krawczynski, H, additional, La Monaca, F, additional, Latronico, L, additional, Liodakis, I, additional, Maldera, S, additional, Manfreda, A, additional, Marscher, A P, additional, Marshall, H L, additional, Massaro, F, additional, Mitsuishi, I, additional, Mizuno, T, additional, Muleri, F, additional, Negro, M, additional, Ng, C-Y, additional, O’Dell, S L, additional, Omodei, N, additional, Oppedisano, C, additional, Papitto, A, additional, Pavlov, G G, additional, Peirson, A L, additional, Perri, M, additional, Pesce-Rollins, M, additional, Pilia, M, additional, Possenti, A, additional, Ramsey, B D, additional, Rankin, J, additional, Roberts, O J, additional, Romani, R W, additional, Sgrò, C, additional, Slane, P, additional, Spandre, G, additional, Swartz, D A, additional, Tamagawa, T, additional, Tavecchio, F, additional, Taverna, R, additional, Tawara, Y, additional, Tennant, A F, additional, Thomas, N E, additional, Trois, A, additional, Tsygankov, S S, additional, Turolla, R, additional, Vink, J, additional, Weisskopf, M C, additional, Wu, K, additional, Xie, F, additional, and Zane, S, additional

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2023
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143. Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and γ-Ray Activity

Author

Abe, H., primary, Abe, S., additional, Acciari, V. A., additional, Agudo, I., additional, Aniello, T., additional, Ansoldi, S., additional, Antonelli, L. A., additional, Arbet-Engels, A., additional, Arcaro, C., additional, Artero, M., additional, Asano, K., additional, Baack, D., additional, Babić, A., additional, Baquero, A., additional, de Almeida, U. Barres, additional, Barrio, J. A., additional, Batković, I., additional, Baxter, J., additional, Becerra González, J., additional, Bednarek, W., additional, Bernardini, E., additional, Bernardos, M., additional, Berti, A., additional, Besenrieder, J., additional, Bhattacharyya, W., additional, Bigongiari, C., additional, Biland, A., additional, Blanch, O., additional, Bonnoli, G., additional, Bošnjak, Ž., additional, Burelli, I., additional, Busetto, G., additional, Carosi, R., additional, Carretero-Castrillo, M., additional, Castro-Tirado, A. J., additional, Ceribella, G., additional, Chai, Y., additional, Chilingarian, A., additional, Cikota, S., additional, Colombo, E., additional, Contreras, J. L., additional, Cortina, J., additional, Covino, S., additional, D’Amico, G., additional, D’Elia, V., additional, Da Vela, P., additional, Dazzi, F., additional, De Angelis, A., additional, De Lotto, B., additional, Del Popolo, A., additional, Delfino, M., additional, Delgado, J., additional, Delgado Mendez, C., additional, Depaoli, D., additional, Di Pierro, F., additional, Di Venere, L., additional, Souto Espiñeira, E. Do, additional, Dominis Prester, D., additional, Donini, A., additional, Dorner, D., additional, Doro, M., additional, Elsaesser, D., additional, Emery, G., additional, Escudero, J., additional, Fallah Ramazani, V., additional, Fariña, L., additional, Fattorini, A., additional, Foffano, L., additional, Font, L., additional, Fruck, C., additional, Fukami, S., additional, Fukazawa, Y., additional, García López, R. J., additional, Garczarczyk, M., additional, Gasparyan, S., additional, Gaug, M., additional, Giesbrecht Paiva, J. G., additional, Giglietto, N., additional, Giordano, F., additional, Gliwny, P., additional, Godinović, N., additional, Grau, R., additional, Green, D., additional, Green, J. G., additional, Hadasch, D., additional, Hahn, A., additional, Hassan, T., additional, Heckmann, L., additional, Herrera, J., additional, Hrupec, D., additional, Hütten, M., additional, Imazawa, R., additional, Inada, T., additional, Iotov, R., additional, Ishio, K., additional, Jiménez Martínez, I., additional, Jormanainen, J., additional, Kerszberg, D., additional, Kobayashi, Y., additional, Kubo, H., additional, Kushida, J., additional, Lamastra, A., additional, Lelas, D., additional, Leone, F., additional, Lindfors, E., additional, Linhoff, L., additional, Lombardi, S., additional, Longo, F., additional, López-Coto, R., additional, López-Moya, M., additional, López-Oramas, A., additional, Loporchio, S., additional, Lorini, A., additional, Lyard, E., additional, Machado de Oliveira Fraga, B., additional, Majumdar, P., additional, Makariev, M., additional, Maneva, G., additional, Mang, N., additional, Manganaro, M., additional, Mangano, S., additional, Mannheim, K., additional, Mariotti, M., additional, Martínez, M., additional, Mas-Aguilar, A., additional, Mazin, D., additional, Menchiari, S., additional, Mender, S., additional, Mićanović, S., additional, Miceli, D., additional, Miener, T., additional, Miranda, J. M., additional, Mirzoyan, R., additional, Molina, E., additional, Mondal, H. A., additional, Moralejo, A., additional, Morcuende, D., additional, Moreno, V., additional, Nakamori, T., additional, Nanci, C., additional, Nava, L., additional, Neustroev, V., additional, Nievas Rosillo, M., additional, Nigro, C., additional, Nilsson, K., additional, Nishijima, K., additional, Njoh Ekoume, T., additional, Noda, K., additional, Nozaki, S., additional, Ohtani, Y., additional, Oka, T., additional, Okumura, A., additional, Otero-Santos, J., additional, Paiano, S., additional, Palatiello, M., additional, Paneque, D., additional, Paoletti, R., additional, Paredes, J. M., additional, Pavletić, L., additional, Persic, M., additional, Pihet, M., additional, Pirola, G., additional, Podobnik, F., additional, Moroni, P. G. Prada, additional, Prandini, E., additional, Principe, G., additional, Priyadarshi, C., additional, Rhode, W., additional, Ribó, M., additional, Rico, J., additional, Righi, C., additional, Rugliancich, A., additional, Sahakyan, N., additional, Saito, T., additional, Sakurai, S., additional, Satalecka, K., additional, Saturni, F. G., additional, Schleicher, B., additional, Schmidt, K., additional, Schmuckermaier, F., additional, Schubert, J. L., additional, Schweizer, T., additional, Sitarek, J., additional, Sliusar, V., additional, Sobczynska, D., additional, Spolon, A., additional, Stamerra, A., additional, Strišković, J., additional, Strom, D., additional, Strzys, M., additional, Suda, Y., additional, Surić, T., additional, Tajima, H., additional, Takahashi, M., additional, Takeishi, R., additional, Tavecchio, F., additional, Temnikov, P., additional, Terauchi, K., additional, Terzić, T., additional, Teshima, M., additional, Tosti, L., additional, Truzzi, S., additional, Tutone, A., additional, Ubach, S., additional, van Scherpenberg, J., additional, Acosta, M. Vazquez, additional, Ventura, S., additional, Verguilov, V., additional, Viale, I., additional, Vigorito, C. F., additional, Vitale, V., additional, Vovk, I., additional, Walter, R., additional, Will, M., additional, Wunderlich, C., additional, Yamamoto, T., additional, Zarić, D., additional, Cerruti, M., additional, Acosta-Pulido, J. A., additional, Apolonio, G., additional, Bachev, R., additional, Baloković, M., additional, Benítez, E., additional, Björklund, I., additional, Bozhilov, V., additional, Brown, L. F., additional, Bugg, A., additional, Carbonell, W., additional, Carnerero, M. I., additional, Carosati, D., additional, Casadio, C., additional, Chamani, W., additional, Chen, W. P., additional, Chigladze, R. A., additional, Damljanovic, G., additional, Epps, K., additional, Erkenov, A., additional, Feige, M., additional, Finke, J., additional, Fuentes, A., additional, Gazeas, K., additional, Giroletti, M., additional, Grishina, T. S., additional, Gupta, A. C., additional, Gurwell,, M. A., additional, Heidemann, E., additional, Hiriart, D., additional, Hou, W. J., additional, Hovatta, T., additional, Ibryamov, S., additional, Joner, M. D., additional, Jorstad, S. G., additional, Kania, J., additional, Kiehlmann, S., additional, Kimeridze, G. N., additional, Kopatskaya, E. N., additional, Kopp, M., additional, Korte, M., additional, Kotas, B., additional, Koyama, S., additional, Kramer, J. A., additional, Kunkel, L., additional, Kurtanidze, S. O., additional, Kurtanidze, O. M., additional, Lähteenmäki, A., additional, López, J. M., additional, Larionov, V. M., additional, Larionova, E. G., additional, Larionova, L. V., additional, Leto, C., additional, Lorey, C., additional, Mújica, R., additional, Madejski, G. M., additional, Marchili, N., additional, Marscher, A. P., additional, Minev, M., additional, Modaressi, A., additional, Morozova, D. A., additional, Mufakharov, T., additional, Myserlis, I., additional, Nikiforova, A. A., additional, Nikolashvili, M. G., additional, Ovcharov, E., additional, Perri, M., additional, Raiteri, C. M., additional, Readhead, A. C. S., additional, Reimer, A., additional, Reinhart, D., additional, Righini, S., additional, Rosenlehner, K., additional, Sadun, A. C., additional, Savchenko, S. S., additional, Scherbantin, A., additional, Schneider, L., additional, Schoch, K., additional, Seifert, D., additional, Semkov, E., additional, Sigua, L. A., additional, Singh, C., additional, Sola, P., additional, Sotnikova, Y., additional, Spencer, M., additional, Steineke, R., additional, Stojanovic, M., additional, Strigachev, A., additional, Tornikoski, M., additional, Traianou, E., additional, Tramacere, A., additional, Troitskaya, Yu. V., additional, Troitskiy, I. S., additional, Trump, J. B., additional, Tsai, A., additional, Valcheva, A., additional, Vasilyev, A. A., additional, Verrecchia, F., additional, Villata, M., additional, Vince, O., additional, Vrontaki, K., additional, Weaver, Z. R., additional, Zaharieva, E., additional, and Zottmann, N., additional

Published
2023
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144. Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic Cloud

Author

Acharyya, A, primary, Adam, R, additional, Aguasca-Cabot, A, additional, Agudo, I, additional, Aguirre-Santaella, A, additional, Alfaro, J, additional, Aloisio, R, additional, Alves Batista, R, additional, Amato, E, additional, Angüner, E O, additional, Aramo, C, additional, Arcaro, C, additional, Asano, K, additional, Aschersleben, J, additional, Ashkar, H, additional, Backes, M, additional, Baktash, A, additional, Balazs, C, additional, Balbo, M, additional, Ballet, J, additional, Bamba, A, additional, Baquero Larriva, A, additional, Barbosa Martins, V, additional, Barres de Almeida, U, additional, Barrio, J A, additional, Bastieri, D, additional, Batista, P, additional, Batkovic, I, additional, Baxter, J R, additional, Becerra González, J, additional, Becker Tjus, J, additional, Benbow, W, additional, Bernardini, E, additional, Bernardos Martín, M I, additional, Bernete Medrano, J, additional, Berti, A, additional, Bertucci, B, additional, Beshley, V, additional, Bhattacharjee, P, additional, Bhattacharyya, S, additional, Bigongiari, C, additional, Biland, A, additional, Bissaldi, E, additional, Bocchino, F, additional, Bordas, P, additional, Borkowski, J, additional, Bottacini, E, additional, Böttcher, M, additional, Bradascio, F, additional, Brown, A M, additional, Bulgarelli, A, additional, Burmistrov, L, additional, Caroff, S, additional, Carosi, A, additional, Carquín, E, additional, Casanova, S, additional, Cascone, E, additional, Cassol, F, additional, Cerruti, M, additional, Chadwick, P, additional, Chaty, S, additional, Chen, A, additional, Chiavassa, A, additional, Chytka, L, additional, Conforti, V, additional, Cortina, J, additional, Costa, A, additional, Costantini, H, additional, Cotter, G, additional, Crestan, S, additional, Cristofari, P, additional, D’Ammando, F, additional, Dalchenko, M, additional, Dazzi, F, additional, De Angelis, A, additional, De Caprio, V, additional, de Gouveia Dal Pino, E M, additional, De Martino, D, additional, de Naurois, M, additional, de Souza, V, additional, del Valle, M V, additional, Delgado Giler, A G, additional, Delgado, C, additional, della Volpe, D, additional, Depaoli, D, additional, Di Girolamo, T, additional, Di Piano, A, additional, Di Pierro, F, additional, Di Tria, R, additional, Di Venere, L, additional, Diebold, S, additional, Doro, M, additional, Dumora, D, additional, Dwarkadas, V V, additional, Eckner, C, additional, Egberts, K, additional, Emery, G, additional, Escudero, J, additional, Falceta-Goncalves, D, additional, Fedorova, E, additional, Fegan, S, additional, Feng, Q, additional, Ferenc, D, additional, Ferrand, G, additional, Fiandrini, E, additional, Filipovic, M, additional, Fioretti, V, additional, Foffano, L, additional, Fontaine, G, additional, Fukui, Y, additional, Gaggero, D, additional, Galanti, G, additional, Galaz, G, additional, Gallozzi, S, additional, Gammaldi, V, additional, Garczarczyk, M, additional, Gasbarra, C, additional, Gasparrini, D, additional, Ghalumyan, A, additional, Giarrusso, M, additional, Giavitto, G, additional, Giglietto, N, additional, Giordano, F, additional, Giuliani, A, additional, Glicenstein, J -F, additional, Goldoni, P, additional, Goulart Coelho, J, additional, Granot, J, additional, Green, D, additional, Green, J G, additional, Grondin, M -H, additional, Gueta, O, additional, Hadasch, D, additional, Hamal, P, additional, Hassan, T, additional, Hayashi, K, additional, Heller, M, additional, Hernández Cadena, S, additional, Hiroshima, N, additional, Hnatyk, B, additional, Hnatyk, R, additional, Hofmann, W, additional, Holder, J, additional, Holler, M, additional, Horan, D, additional, Horvath, P, additional, Hrabovsky, M, additional, Hütten, M, additional, Iarlori, M, additional, Inada, T, additional, Incardona, F, additional, Inoue, S, additional, Iocco, F, additional, Jamrozy, M, additional, Jin, W, additional, Jung-Richardt, I, additional, Juryšek, J, additional, Kantzas, D, additional, Karas, V, additional, Katagiri, H, additional, Kerszberg, D, additional, Knödlseder, J, additional, Komin, N, additional, Kornecki, P, additional, Kosack, K, additional, Kowal, G, additional, Kubo, H, additional, Lamastra, A, additional, Lapington, J, additional, Lemoine-Goumard, M, additional, Lenain, J -P, additional, Leone, F, additional, Leto, G, additional, Leuschner, F, additional, Lindfors, E, additional, Lohse, T, additional, Lombardi, S, additional, Longo, F, additional, López-Coto, R, additional, López-Oramas, A, additional, Loporchio, S, additional, Luque-Escamilla, P L, additional, Macias, O, additional, Majumdar, P, additional, Mandat, D, additional, Mangano, S, additional, Manicò, G, additional, Mariotti, M, additional, Marquez, P, additional, Marsella, G, additional, Martí, J, additional, Martin, P, additional, Martínez, M, additional, Mazin, D, additional, Menchiari, S, additional, Meyer, D M -A, additional, Miceli, D, additional, Miceli, M, additional, Michałowski, J, additional, Mitchell, A, additional, Moderski, R, additional, Mohrmann, L, additional, Molero, M, additional, Molina, E, additional, Montaruli, T, additional, Moralejo, A, additional, Morcuende, D, additional, Morselli, A, additional, Moulin, E, additional, Moya, V, additional, Mukherjee, R, additional, Munari, K, additional, Muraczewski, A, additional, Nagataki, S, additional, Nakamori, T, additional, Nayak, A, additional, Niemiec, J, additional, Nievas, M, additional, Nikołajuk, M, additional, Nishijima, K, additional, Noda, K, additional, Nosek, D, additional, Novosyadlyj, B, additional, Nozaki, S, additional, Ohishi, M, additional, Ohm, S, additional, Okumura, A, additional, Olmi, B, additional, Ong, R A, additional, Orienti, M, additional, Orito, R, additional, Orlandini, M, additional, Orlando, E, additional, Orlando, S, additional, Ostrowski, M, additional, Oya, I, additional, Pagliaro, A, additional, Palatka, M, additional, Pantaleo, F R, additional, Paoletti, R, additional, Paredes, J M, additional, Parmiggiani, N, additional, Patricelli, B, additional, Pech, M, additional, Pecimotika, M, additional, Persic, M, additional, Petruk, O, additional, Pierre, E, additional, Pietropaolo, E, additional, Pirola, G, additional, Pohl, M, additional, Prandini, E, additional, Priyadarshi, C, additional, Pühlhofer, G, additional, Pumo, M L, additional, Punch, M, additional, Queiroz, F S, additional, Quirrenbach, A, additional, Rainò, S, additional, Rando, R, additional, Razzaque, S, additional, Reimer, A, additional, Reimer, O, additional, Reposeur, T, additional, Ribó, M, additional, Richtler, T, additional, Rico, J, additional, Rieger, F, additional, Rigoselli, M, additional, Rizi, V, additional, Roache, E, additional, Rodriguez Fernandez, G, additional, Romano, P, additional, Romeo, G, additional, Rosado, J, additional, Rosales de Leon, A, additional, Rudak, B, additional, Rulten, C, additional, Sadeh, I, additional, Saito, T, additional, Sánchez-Conde, M, additional, Sano, H, additional, Santangelo, A, additional, Santos-Lima, R, additional, Sarkar, S, additional, Saturni, F G, additional, Scherer, A, additional, Schovanek, P, additional, Schussler, F, additional, Schwanke, U, additional, Sergijenko, O, additional, Servillat, M, additional, Siejkowski, H, additional, Siqueira, C, additional, Spencer, S, additional, Stamerra, A, additional, Stanič, S, additional, Steppa, C, additional, Stolarczyk, T, additional, Suda, Y, additional, Tavernier, T, additional, Teshima, M, additional, Tibaldo, L, additional, Torres, D F, additional, Tothill, N, additional, Vacula, M, additional, Vallage, B, additional, Vallania, P, additional, van Eldik, C, additional, Vázquez Acosta, M, additional, Vecchi, M, additional, Ventura, S, additional, Vercellone, S, additional, Viana, A, additional, Vigorito, C F, additional, Vink, J, additional, Vitale, V, additional, Vodeb, V, additional, Vorobiov, S, additional, Vuillaume, T, additional, Wagner, S J, additional, Walter, R, additional, White, M, additional, Wierzcholska, A, additional, Will, M, additional, Yamazaki, R, additional, Yang, L, additional, Yoshikoshi, T, additional, Zacharias, M, additional, Zaharijas, G, additional, Zavrtanik, D, additional, Zavrtanik, M, additional, Zdziarski, A A, additional, Zhdanov, V I, additional, Ziętara, K, additional, and Živec, M, additional

Published
2023
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145. Multiwavelength study of the galactic PeVatron candidate LHAASO J2108+5157

Author

Abe, S., primary, Aguasca-Cabot, A., additional, Agudo, I., additional, Alvarez Crespo, N., additional, Antonelli, L. A., additional, Aramo, C., additional, Arbet-Engels, A., additional, Artero, M., additional, Asano, K., additional, Aubert, P., additional, Baktash, A., additional, Bamba, A., additional, Baquero Larriva, A., additional, Baroncelli, L., additional, Barres de Almeida, U., additional, Barrio, J. A., additional, Batkovic, I., additional, Baxter, J., additional, Becerra González, J., additional, Bernardini, E., additional, Bernardos, M. I., additional, Bernete Medrano, J., additional, Berti, A., additional, Bhattacharjee, P., additional, Biederbeck, N., additional, Bigongiari, C., additional, Bissaldi, E., additional, Blanch, O., additional, Bordas, P., additional, Buisson, C., additional, Bulgarelli, A., additional, Burelli, I., additional, Buscemi, M., additional, Cardillo, M., additional, Caroff, S., additional, Carosi, A., additional, Cassol, F., additional, Cauz, D., additional, Ceribella, G., additional, Chai, Y., additional, Cheng, K., additional, Chiavassa, A., additional, Chikawa, M., additional, Chytka, L., additional, Cifuentes, A., additional, Contreras, J. L., additional, Cortina, J., additional, Costantini, H., additional, D’Amico, G., additional, Dalchenko, M., additional, De Angelis, A., additional, de Bony de Lavergne, M., additional, De Lotto, B., additional, de Menezes, R., additional, Deleglise, G., additional, Delgado, C., additional, Delgado Mengual, J., additional, della Volpe, D., additional, Dellaiera, M., additional, Di Piano, A., additional, Di Pierro, F., additional, Di Tria, R., additional, Di Venere, L., additional, Díaz, C., additional, Dominik, R. M., additional, Dominis Prester, D., additional, Donini, A., additional, Dorner, D., additional, Doro, M., additional, Elsässer, D., additional, Emery, G., additional, Escudero, J., additional, Fallah Ramazani, V., additional, Ferrara, G., additional, Fiasson, A., additional, Freixas Coromina, L., additional, Fröse, S., additional, Fukami, S., additional, Fukazawa, Y., additional, Garcia, E., additional, Garcia López, R., additional, Gasparrini, D., additional, Geyer, D., additional, Giesbrecht Paiva, J., additional, Giglietto, N., additional, Giordano, F., additional, Giro, E., additional, Gliwny, P., additional, Godinovic, N., additional, Grau, R., additional, Green, D., additional, Green, J., additional, Gunji, S., additional, Hackfeld, J., additional, Hadasch, D., additional, Hahn, A., additional, Hashiyama, K., additional, Hassan, T., additional, Hayashi, K., additional, Heckmann, L., additional, Heller, M., additional, Herrera Llorente, J., additional, Hirotani, K., additional, Hoffmann, D., additional, Horns, D., additional, Houles, J., additional, Hrabovsky, M., additional, Hrupec, D., additional, Hui, D., additional, Hütten, M., additional, Imazawa, R., additional, Inada, T., additional, Inome, Y., additional, Ioka, K., additional, Iori, M., additional, Ishio, K., additional, Iwamura, Y., additional, Jacquemont, M., additional, Jimenez Martinez, I., additional, Jurysek, J., additional, Kagaya, M., additional, Karas, V., additional, Katagiri, H., additional, Kataoka, J., additional, Kerszberg, D., additional, Kobayashi, Y., additional, Kong, A., additional, Kubo, H., additional, Kushida, J., additional, Lainez, M., additional, Lamanna, G., additional, Lamastra, A., additional, Le Flour, T., additional, Linhoff, M., additional, Longo, F., additional, López-Coto, R., additional, López-Moya, M., additional, López-Oramas, A., additional, Loporchio, S., additional, Lorini, A., additional, Luque-Escamilla, P. L., additional, Majumdar, P., additional, Makariev, M., additional, Mandat, D., additional, Manganaro, M., additional, Manicò, G., additional, Mannheim, K., additional, Mariotti, M., additional, Marquez, P., additional, Marsella, G., additional, Martí, J., additional, Martinez, O., additional, Martínez, G., additional, Martínez, M., additional, Marusevec, P., additional, Mas-Aguilar, A., additional, Maurin, G., additional, Mazin, D., additional, Mestre Guillen, E., additional, Micanovic, S., additional, Miceli, D., additional, Miener, T., additional, Miranda, J. M., additional, Mirzoyan, R., additional, Mizuno, T., additional, Molero Gonzalez, M., additional, Molina, E., additional, Montaruli, T., additional, Monteiro, I., additional, Moralejo, A., additional, Morcuende, D., additional, Morselli, A., additional, Mrakovcic, K., additional, Murase, K., additional, Nagai, A., additional, Nakamori, T., additional, Nickel, L., additional, Nievas, M., additional, Nishijima, K., additional, Noda, K., additional, Nosek, D., additional, Nozaki, S., additional, Ohishi, M., additional, Ohtani, Y., additional, Okazaki, N., additional, Okumura, A., additional, Orito, R., additional, Otero-Santos, J., additional, Palatiello, M., additional, Paneque, D., additional, Pantaleo, F. R., additional, Paoletti, R., additional, Paredes, J. M., additional, Pavletić, L., additional, Pech, M., additional, Pecimotika, M., additional, Pietropaolo, E., additional, Pirola, G., additional, Podobnik, F., additional, Poireau, V., additional, Polo, M., additional, Pons, E., additional, Prandini, E., additional, Prast, J., additional, Priyadarshi, C., additional, Prouza, M., additional, Rando, R., additional, Rhode, W., additional, Ribó, M., additional, Rizi, V., additional, Rodriguez Fernandez, G., additional, Saito, T., additional, Sakurai, S., additional, Sanchez, D. A., additional, Šarić, T., additional, Saturni, F. G., additional, Scherpenberg, J., additional, Schleicher, B., additional, Schmuckermaier, F., additional, Schubert, J. L., additional, Schussler, F., additional, Schweizer, T., additional, Seglar Arroyo, M., additional, Sitarek, J., additional, Sliusar, V., additional, Spolon, A., additional, Strišković, J., additional, Strzys, M., additional, Suda, Y., additional, Sunada, Y., additional, Tajima, H., additional, Takahashi, M., additional, Takahashi, H., additional, Takata, J., additional, Takeishi, R., additional, Tam, P. H. T., additional, Tanaka, S. J., additional, Tateishi, D., additional, Temnikov, P., additional, Terada, Y., additional, Terauchi, K., additional, Terzic, T., additional, Teshima, M., additional, Tluczykont, M., additional, Tokanai, F., additional, Torres, D. F., additional, Travnicek, P., additional, Truzzi, S., additional, Tutone, A., additional, Uhlrich, G., additional, Vacula, M., additional, Vázquez Acosta, M., additional, Verguilov, V., additional, Viale, I., additional, Vigliano, A., additional, Vigorito, C. F., additional, Vitale, V., additional, Voutsinas, G., additional, Vovk, I., additional, Vuillaume, T., additional, Walter, R., additional, Will, M., additional, Yamamoto, T., additional, Yamazaki, R., additional, Yoshida, T., additional, Yoshikoshi, T., additional, Zywucka, N., additional, Balbo, M., additional, Eckert, D., additional, and Tramacere, A., additional

Published
2023
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146. MAGIC detection of GRB 201216C at z = 1.1.

Author

Abe, H, Abe, S, Acciari, V A, Agudo, I, Aniello, T, Ansoldi, S, Antonelli, L A, Engels, A Arbet, Arcaro, C, Artero, M, Asano, K, Baack, D, Babić, A, Baquero, A, de Almeida, U Barres, Barrio, J A, Batković, I, Baxter, J, González, J Becerra, and Bednarek, W

Subjects
ELECTROMAGNETIC radiation, ELECTROMAGNETIC waves, GAMMA ray bursts, COSMOLOGICAL distances, ENERGY bands, MAGIC
Abstract

Gamma-ray bursts (GRBs) are explosive transient events occurring at cosmological distances, releasing a large amount of energy as electromagnetic radiation over several energy bands. We report the detection of the long GRB 201216C by the MAGIC telescopes. The source is located at z  = 1.1 and thus it is the farthest one detected at very high energies. The emission above 70 GeV of GRB 201216C is modelled together with multiwavelength data within a synchrotron and synchrotron self-Compton (SSC) scenario. We find that SSC can explain the broad-band data well from the optical to the very-high-energy band. For the late-time radio data, a different component is needed to account for the observed emission. Differently from previous GRBs detected in the very-high-energy range, the model for GRB 201216C strongly favours a wind-like medium. The model parameters have values similar to those found in past studies of the afterglows of GRBs detected up to GeV energies. [ABSTRACT FROM AUTHOR]

Published
2024
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147. Repeating flaring activity of the blazar AO 0235+164.

Author

Escudero Pedrosa, J., Agudo, I., Tramacere, A., Marscher, A. P., Jorstad, S., Weaver, Z. R., Casadio, C., Thum, C., Myserlis, I., Fuentes, A., Traianou, E., Kim, J.-Y., Kramer, J., López-Coto, R., D'Ammando, F., Bernardos, M., Bonnoli, G., Blinov, D. A., Borman, G. A., and Grishina, T. S.

Subjects
*SPECTRAL energy distribution, *STATISTICAL correlation, *X-ray spectra, *IMAGE analysis
Abstract

Context. Blazar AO 0235+164, located at a redshift of z = 0.94, has undergone several sharp multi-spectral-range flaring episodes over recent decades. In particular, the episodes that peaked in 2008 and 2015, which were subject to extensive multi-wavelength coverage, exhibited an interesting behavior. Aims. We study the actual origin of these two observed flares by constraining the properties of the observed photo-polarimetric variability as well as of the broadband spectral energy distribution and the observed time-evolution behavior of the source. We use ultra-high-resolution total-flux and polarimetric very-long-baseline interferometry (VLBI) imaging. Methods. The analysis of VLBI images allowed us to constrain kinematic and geometrical parameters of the 7 mm jet. We used the discrete correlation function to compute the statistical correlation and the delays between emission at different spectral ranges. The multi-epoch modeling of the spectral energy distributions allowed us to propose specific models of the emission; in particular, with the aim to model the unusual spectral features observed in this source in the X-ray region of the spectrum during strong multi spectral-range flares. Results. We find that these X-ray spectral features can be explained by an emission component originating in a separate particle distribution than the one responsible for the two standard blazar bumps. This is in agreement with the results of our correlation analysis, where we did not find a strong correlation between the X-ray and the remaining spectral ranges. We find that both external Compton-dominated and synchrotron self-Compton-dominated models are able to explain the observed spectral energy distributions. However, the synchrotron self-Compton models are strongly favored by the delays and geometrical parameters inferred from the observations. [ABSTRACT FROM AUTHOR]

Published
2024
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148. Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES 2344+514.

Author

Abe, H., Abe, S., Acciari, V. A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Arcaro, C., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., Barres de Almeida, U., Batković, I., Baxter, J., Becerra González, J., Bernardini, E., and Bernete, J.

Subjects
SPECTRAL energy distribution, X-ray spectra, HARD X-rays, BL Lacertae objects
Abstract

Aims. The BL Lac 1ES 2344+514 is known for temporary extreme properties characterised by a shift of the synchrotron spectral energy distribution (SED) peak energy νsynch, p above 1 keV. While those extreme states have only been observed during high flux levels thus far, additional multi-year observing campaigns are required to achieve a coherent picture. Here, we report the longest investigation of the source from radio to very high energy (VHE) performed so far, focussing on a systematic characterisation of the intermittent extreme states. Methods. We organised a monitoring campaign covering a 3-year period from 2019 to 2021. More than ten instruments participated in the observations in order to cover the emission from radio to VHE. In particular, sensitive X-ray measurements by XMM-Newton, NuSTAR, and AstroSat took place simultaneously with multi-hour MAGIC observations, providing an unprecedented constraint of the two SED components for this blazar. Results. While our results confirm that 1ES 2344+514 typically exhibits νsynch, p > 1 keV during elevated flux periods, we also find periods where the extreme state coincides with low flux activity. A strong spectral variability thus happens in the quiescent state, and is likely caused by an increase in the electron acceleration efficiency without a change in the electron injection luminosity. On the other hand, we also report a strong X-ray flare (among the brightest for 1ES 2344+514) without a significant shift of νsynch, p. During this particular flare, the X-ray spectrum is among the softest of the campaign. It unveils complexity in the spectral evolution, where the common harder-when-brighter trend observed in BL Lacs is violated. By combining Swift-XRT and Swift-UVOT measurements during a low and hard X-ray state, we find an excess of the UV flux with respect to an extrapolation of the X-ray spectrum to lower energies. This UV excess implies that at least two regions significantly contribute to the infrared/optical/ultraviolet/X-ray emission. Using the simultaneous MAGIC, XMM-Newton, NuSTAR, and AstroSat observations, we argue that a region possibly associated with the 10 GHz radio core may explain such an excess. Finally, we investigate a VHE flare, showing an absence of simultaneous variability in the 0.3−2 keV band. Using time-dependent leptonic modelling, we show that this behaviour, in contradiction to single-zone scenarios, can instead be explained by a two-component model. [ABSTRACT FROM AUTHOR]

Published
2024
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149. Complex variations of X-ray polarization in the X-ray pulsar LS V +44 17/RX J0440.9+4431

Author

Doroshenko, V., Poutanen, J., Heyl, J., Tsygankov, S. S., Berdyugin, A. V., Caiazzo, I., Forsblom, S. V., Gonz\ález-Caniulef, D., Kravtsov, V., Loktev, V. V., Lutovinov, A. A., Malacaria, C., Mereminskiy, I. A., Molkov, S. V., Mushtukov, A., Nitindala, A. P., Salganik, A., Santangelo, A., Suleimanov, V. F., Turolla, R., Veledina, A., Agudo, I., Antonelli, L. A., Bachetti, M., Baldini, L., Baumgartner, W. H., Bellazzini, R., Bianchi, S., Bongiorno, S. D., Bonino, R., Brez, A., Bucciantini, N., Capitanio, F., Castellano, S., Cavazzuti, E., Chen, C., Ciprini, S., Costa, E., De Rosa, A., Del Monte, E., Di Gesu, L., Di Lalla, N., Di Marco, A., Donnarumma, I., Dovčiak, M., Ehlert, S. R., Enoto, T., Evangelista, Y., Fabiani, S., Ferrazzoli, R., Garcia, J. A., Gunji, S., Hayashida, K., Iwakiri, W., Jorstad, S. G., Kaaret, P., Karas, V., Kislat, F., Kitaguchi, T., Kolodziejczak, J. J., Krawczynski, H., La Monaca, F., Latronico, L., Liodakis, I., Maldera, S., Manfreda, A., Marin, F., Marinucci, A., Marscher, A. P., Marshall, H. L., Massaro, F., Matt, G., Mitsuishi, I., Mizuno, T., Muleri, F., Negro, M., Ng, C., O'Dell, S. L., Omodei, N., Oppedisano, C., Papitto, A., Pavlov, G. G., Peirson, A. L., Perri, M., Pesce-Rollins, M., Petrucci, P., Pilia, M., Possenti, A., Puccetti, S., Ramsey, B. D., Rankin, J., Ratheesh, A., Roberts, O. J., Romani, R. W., Sgrò, C., Slane, P., Soffitta, P., Spandre, G., Swartz, D. A., Tamagawa, T., Tavecchio, F., Taverna, R., Tawara, Y., Tent, A. F., Thomas, N. E., Tombesi, F., Trois, A., Vink, J., Weisskopf, M. C., Wu, K., Xie, F., and Zane, S.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on \ixpe observations of the Be-transient X-ray pulsar LS V +44 17/RX J0440.9+4431 at two luminosity levels during the giant outburst in January--February 2023. Considering the observed spectral variability and changes in the pulse profiles, the source was likely caught in super- and sub-critical states with significantly different emission region geometry, associated with the presence of accretion columns and hot spots, respectively. We focus here on the pulse-phase resolved polarimetric analysis and find that the observed dependencies of the polarization degree and polarization angle (PA) on pulse phase are indeed drastically different for the two observations. The observed differences, if interpreted within the framework of the rotating vector model (RVM), imply dramatic variations of the spin axis inclination and the position angle and the magnetic colatitude by tens of degrees within just a few days separating the observations. We suggest that the apparent changes in the observed PA phase dependence are predominantly related to the presence of a polarized unpulsed component in addition to the polarized radiation associated with the pulsar itself. We show that the observed PA phase dependence in both observations can then be explained with a single set of RVM parameters defining the pulsar's geometry. We also suggest that the additional polarized component is likely produced by scattering of the pulsar radiation off the equatorial disk wind., 9 pages, 5 figures, submitted to A&A

Published
2023

150. Discovery of strongly variable X-ray polarization in the neutron star low-mass X-ray binary transient XTE J1701$-$462

Author

Cocchi, M., Gnarini, A., Fabiani, S., Ursini, F., Poutanen, J., Capitanio, F., Bobrikova, A., Farinelli, R., Paizis, A., Sidoli, L., Veledina, A., Bianchi, S., Di Marco, A., Ingram, A., Kajava, J. J. E., La Monaca, F., Matt, G., Malacaria, C., Mikusincova, R., Rankin, J., Zane, S., Agudo, I., Antonelli, L. A., Bachetti, M., Baldini, L., Baumgartner, W. H., Bellazzini, R., Bongiorno, S. D., Bonino, R., Brez, A., Bucciantini, N., Castellano, S., Cavazzuti, E., Chen, C. -T., Ciprini, S., Costa, E., De Rosa, A., Del Monte, E., Di Gesu, L., Di Lalla, N., Donnarumma, I., Doroshenko, V., Dovciak, M., Ehlert, S. R., Enoto, T., Evangelista, Y., Ferrazzoli, R., Garcia, J. A., Gunji, S., Hayashida, K., Heyl, J., Iwakiri, W., Jorstad, S. G., Kaaret, P., Karas, V., Kislat, F., Kitaguchi, T., Kolodziejczak, J. J., Krawczynski, H., Latronico, L., Liodakis, I., Maldera, S., Manfreda, A., Marin, F., Marinucci, A., Marscher, A. P., Marshall, H. L., Massaro, F., Mitsuishi, I., Mizuno, T., Muleri, F., Negro, M., C. -Y., Ng, O'Dell, S. L., Omodei, N., Oppedisano, C., Papitto, A., Pavlov, G. G., Peirson, A. L., Perri, M., Pesce-Rollins, M., Petrucci, P. -O., Pilia, M., Possenti, A., Puccetti, S., Ramsey, B. D., Ratheesh, A., Roberts, O. J., Romani, R. W., Sgro, C., Slane, P., Soffitta, P., Spandre, G., Swartz, D. A., Tamagawa, T., Tavecchio, F., Taverna, R., Tawara, Y., Tennant, A. F., Thomas, N. E., Tombesi, F., Trois, A., Tsygankov, S. S., Turolla, R., Vink, J., Weisskopf, M. C., Wu, K., Xie, F., Cocchi, M., Gnarini, A., Fabiani, S., Ursini, F., Poutanen, J., Capitanio, F., Bobrikova, A., Farinelli, R., Paizis, A., Sidoli, L., Veledina, A., Bianchi, S., Di Marco, A., Ingram, A., Kajava, J. J. E., La Monaca, F., Matt, G., Malacaria, C., Mikusincova, R., Rankin, J., Zane, S., Agudo, I., Antonelli, L. A., Bachetti, M., Baldini, L., Baumgartner, W. H., Bellazzini, R., Bongiorno, S. D., Bonino, R., Brez, A., Bucciantini, N., Castellano, S., Cavazzuti, E., Chen, C. -T., Ciprini, S., Costa, E., De Rosa, A., Del Monte, E., Di Gesu, L., Di Lalla, N., Donnarumma, I., Doroshenko, V., Dovciak, M., Ehlert, S. R., Enoto, T., Evangelista, Y., Ferrazzoli, R., Garcia, J. A., Gunji, S., Hayashida, K., Heyl, J., Iwakiri, W., Jorstad, S. G., Kaaret, P., Karas, V., Kislat, F., Kitaguchi, T., Kolodziejczak, J. J., Krawczynski, H., Latronico, L., Liodakis, I., Maldera, S., Manfreda, A., Marin, F., Marinucci, A., Marscher, A. P., Marshall, H. L., Massaro, F., Mitsuishi, I., Mizuno, T., Muleri, F., Negro, M., Ng, C. -Y., O'Dell, S. L., Omodei, N., Oppedisano, C., Papitto, A., Pavlov, G. G., Peirson, A. L., Perri, M., Pesce-Rollins, M., Petrucci, P. -O., Pilia, M., Possenti, A., Puccetti, S., Ramsey, B. D., Ratheesh, A., Roberts, O. J., Romani, R. W., Sgro, C., Slane, P., Soffitta, P., Spandre, G., Swartz, D. A., Tamagawa, T., Tavecchio, F., Taverna, R., Tawara, Y., Tennant, A. F., Thomas, N. E., Tombesi, F., Trois, A., Tsygankov, S. S., Turolla, R., Vink, J., Weisskopf, M. C., Wu, K., and Xie, F.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

After about 16 years since its first outburst, the transient neutron star low-mass X-ray binary XTE J1701$-$462 turned on again in September 2022, allowing for the first study of its X-ray polarimetric characteristics by a dedicated observing program with the Imaging X-ray Polarimeter Explorer (IXPE). Polarimetric studies of XTE J1701$-$462 have been expected to improve our understanding of accreting weakly magnetized neutron stars, in particular, the physics and the geometry of the hot inner regions close to the compact object. The IXPE data of two triggered observations were analyzed using time-resolved spectroscopic and polarimetric techniques, following the source along its Z-track of the color-color diagram. During the first pointing on 2022 September 29, an average 2-8 keV polarization degree of 4.6$\pm$ 0.4\% was measured, the highest value found up to now for this class of sources. Conversely, only a $\sim$0.6\% average degree was obtained during the second pointing ten days later. The polarimetric signal appears to be strictly related to the higher energy blackbody component associated with the boundary layer (BL) emission and its reflection from the inner accretion disk, and it is as strong as 6.1\% and 1.2\% ($>95\%$ significant) above 3-4 keV for the two measurements, respectively. The variable polarimetric signal is apparently related to the spectral characteristics of XTE J1701$-$462, which is the strongest when the source was in the horizontal branch of its Z-track and the weakest in the normal branch. These IXPE results provide new important observational constraints on the physical models and geometry of the Z-sources. Here, we discuss the possible reasons for the presence of strong and variable polarization among these sources., 7 pages, 8 figures; published in A&A 674, L10 (2023)

Published
2023
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