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7 results on '"Krichbaum, T. P."'

1. MOMO – V. Effelsberg, Swift, and Fermi study of the blazar and supermassive binary black hole candidate OJ 287 in a period of high activity.

Author

Komossa, S, Grupe, D, Kraus, A, Gonzalez, A, Gallo, L C, Valtonen, M J, Laine, S, Krichbaum, T P, Gurwell, M A, Gómez, J L, Ciprini, S, Myserlis, I, and Bach, U

Subjects
BL Lacertae objects, SUPERMASSIVE black holes, BINARY black holes, SOLAR flares, CORONAL mass ejections, ACTIVE galaxies
Abstract

We report results from our ongoing project MOMO (Multiwavelength Observations and Modelling of OJ 287). In this latest publication of a sequence, we combine our Swift UVOT–XRT and Effelsberg radio data (2.6–44 GHz) between 2019 and 2022.04 with public SMA data and gamma-ray data from the Fermi satellite. The observational epoch covers OJ 287 in a high state of activity from radio to X-rays. The epoch also covers two major events predicted by the binary supermassive black hole (SMBH) model of OJ 287. Spectral and timing analyses clearly establish: a new UV–optical minimum state in 2021 December at an epoch where the secondary SMBH is predicted to cross the disc surrounding the primary SMBH; an overall low level of gamma-ray activity in comparison to pre-2017 epochs; the presence of a remarkable, long-lasting UV–optical flare event of intermediate amplitude in 2020–2021; a high level of activity in the radio band with multiple flares; and particularly a bright, ongoing radio flare peaking in 2021 November that may be associated with a gamma-ray flare, the strongest in 6 yr. Several explanations for the UV–optical minimum state are explored, including the possibility that a secondary SMBH launches a temporary jet, but the observations are best explained by variability associated with the main jet. [ABSTRACT FROM AUTHOR]

Published
2022
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2. Connection between inner jet kinematics and broadband flux variability in the BL Lacertae object S5 0716+714.

Author

Rani, B., Krichbaum, T. P., Marscher, A. P., Hodgson, J. A., Fuhrmann, L., Angelakis, E., Britzen, S., and Zensus, J. A.

Subjects
*BL Lacertae objects, *EXTRAGALACTIC jets (Astrophysics), *ACTIVE galaxies, *GAMMA ray astronomy, *SHOCK waves
Abstract

We present a high-frequency very long baseline interferometry (VLBI) kinematical study of the BL Lac object S5 0716+714 over the time period of September 2008 to October 2010. The aim of the study is to investigate the relation of the jet kinematics to the observed broadband flux variability. We find significant non-radial motions in the jet outflow of the source. In the radial direction, the highest measured apparent speed is ~37 c, which is exceptionally high, especially for a BL Lac object. Patterns in the jet flow reveal a roughly stationary feature ~0.15 mas downstream of the core. The long-term fits to the component trajectories reveal acceleration in the sub-mas region of the jet. The measured brightness temperature, TB, follows a continuous trend of decline with distance, TB ∝ rjet-(2.36 ± 0.41), which suggests that there is a gradient in Doppler factor along the jet axis. Our analysis favors that a moving disturbance (or a shock wave) from the base of the jet produces the high-energy (optical to γ-ray) variations upstream of the 7 mm core and then later causes an outburst in the core. Repetitive optical/γ-ray flares and the curved trajectories of the associated components suggest that the shock front propagates along a bent trajectory or helical path. Sharper γ-ray flares could be related to the passage of moving disturbances through the stationary feature. Our analysis indicates that the γ-ray and radio emission regions have different Doppler factors. [ABSTRACT FROM AUTHOR]

Published
2015
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3. Very Long Baseline polarimetry and the γ-ray connection in Markarian 421 during the broadband campaign in 2011.

Author

Giroletti, M., Lico, R., Orienti, M., D'Ammando, F., Blasi, M. G., Kino, M., Sokolovsky, K. V., Kovalev, Y. Y., Paneque, D., Piner, B. G., Gómez, J. L., Casadio, C., Cotton, W., Edwards, P. G., Fuhrmann, L., Krichbaum, T. P., Marscher, A. P., and Jorstad, S.

Subjects
LIGHT curves, TOPOLOGY, ACTIVE galaxies, ASTROPHYSICS, ASTRONOMY
Abstract

Conte×t. This is the third paper in a series devoted to the analysis of the multiwavelength data from a campaign on the nearby (z = 0.03) TeV blazar Mrk 421 during 2011. Aims. We investigate the structure of the high angular resolution polarization, the magnetic topology, the total intensity light curve, the γ-ray flu×, and the photon inde×. We describe how they evolve and how they are connected. Methods. We analyzed data in polarized intensity obtained with the Very Long Baseline Array (VLBA) at twelve epochs (one observation per month from January to December 2011) at 15, 24, and 43 GHz. For the absolute orientation of the electric vector position angles (EVPA) we used the D-terms method; we also confirm its accuracy. We also used γ-ray data from the Fermi Large Area Telescope on weekly time bins throughout 2011. Results. The source shows polarized emission, and its properties vary with time, frequency, and location along the jet. The core mean polarization fraction is generally between 1% and 2%, with a 4% peak at 43 GHz in March; the polarization angle is variable, mainly at 15 GHz, where it changes frequently, and less so at 43 GHz, where it oscillates in the range 114°-173°∘. The jet polarization properties are more stable, with a fractional polarization of around 16% and a polarization angle nearly perpendicular to the jet a×is. The average flu× and photon inde× at γ-ray energies are (17.4 ± 0.5) ×10-8 ph cm-2 s-1 and Γ = 1.77 ± 0.02. The γ-ray light curve shows variability, with a main peak of (38 ± 11) × 10-8 ph cm-2 s-1 at the beginning of March and two later peaks centered on September 8 and November 13. The first γ-ray peak appears to be associated with the peak in the core polarized emission at 43 GHz, as well as with the total intensity light curve. A discrete correlation function analysis yields a correlation coefficient of 0.54 at zero delay, with a significance level >99.7%. Conclusions. With this multifrequency study, we accurately determine the polarization properties of Mrk 421, both in the core and in the jet region. The radio and γ-ray light curves are correlated. The observed EVPA variability at 15 GHz is partly due to opacity and partly to a variable Faraday rotation effect. To e×plain the residual variability of the intrinsic polarization angle and the low degree of polarization in the core region, we invoke a blend of variable cross-polarized subcomponents with different polarization properties within the beam. [ABSTRACT FROM AUTHOR]

Published
2014
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4. Multiwavelength intraday variability of the BL Lacertae S5 0716+714.

Author

Gupta, Alok C., Krichbaum, T. P., Wiita, P. J., Rani, B., Sokolovsky, K. V., Mohan, P., Mangalam, A., Marchili, N., Fuhrmann, L., Agudo, I., Bach, U., Bachev, R., Böttcher, M., Gabanyi, K. E., Gaur, H., Hawkins, K., Kimeridze, G. N., Kurtanidze, O. M., Kurtanidze, S. O., and Lee, C.-U.

Subjects
*WAVELENGTHS, *BL Lacertae objects, *TELESCOPES, *ACQUISITION of data, *ASTRONOMICAL observations, *SCINTILLATION spectrometry, *ACTIVE galaxies
Abstract

ABSTRACT We report results from a one-week multiwavelength campaign to monitor the BL Lacertae object (BL Lac) S5 0716+714 (on 2009 December 9-16). Nine ground-based telescopes at widely separated longitudes and one space-based telescope aboard the Swift satellite collected optical data. Radio data were obtained from the Effelsberg and Urumqi observatories and X-ray data from Swift. In the radio bands, the source shows rapid [∼(0.5-1.5) d] intraday variability with peak amplitudes of up to ∼10 per cent. The variability at 2.8 cm leads by about 1 d the variability at 6 and 11 cm. This time lag and more rapid variations suggest an intrinsic contribution to the source's intraday variability at 2.8 cm, while at 6 and 11 cm, interstellar scintillation (ISS) seems to predominate. Large and quasi-sinusoidal variations of ∼0.8 mag were detected in the V, R and I bands. The X-ray data (0.2-10 keV) do not reveal significant variability on a 4 d time-scale, favouring reprocessed inverse Compton over synchrotron radiation in this band. The characteristic variability time-scales in radio and optical bands are similar. A quasi-periodic variation of 0.9-1.1 d in the optical data may be present, but if so it is marginal and limited to 2.2 cycles. Cross-correlations between radio and optical bands are discussed. The lack of a strong radio-optical correlation indicates different physical causes of variability (ISS at long radio wavelengths, source intrinsic origin in the optical) and is consistent with a high jet opacity and a compact synchrotron component peaking at ≃100 GHz in an ongoing very prominent flux-density outburst. For the campaign period, we construct a quasi-simultaneous spectral energy distribution, including γ-ray data from the Fermi satellite. We obtain lower limits for the relativistic Doppler boosting of δ ≥ 12-26, which for a BL Lac-type object is remarkably high. [ABSTRACT FROM AUTHOR]

Published
2012
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5. 3mm POLARIZATION PROPERTIES OF OPTICAL AND γ-RAY CLASSES OF BLAZARS.

Author

AGUDO, I., THUM, C., WIESEMEYER, H., and KRICHBAUM, T. P.

Subjects
BL Lacertae objects, ACTIVE galaxies, RADIO sources (Astronomy), ACTIVE galactic nuclei, QUASARS
Abstract

We have performed the first 3.5 mm polarimetric survey of radio loud active galactic nuclei (AGN) with the IRAM 30 m Telescope. Unlike radio wavelengths, millimeter observations allow us to measure the intrinsic linearly polarized emission from AGN, thanks to the marginal effect of Faraday rotation and depolarization at mm wavelengths. The sample contains 145 sources, and it essentially consists of all flat-spectrum AGN with declinations accessible to the 30 m Telescope (Dec. (J2000.0) > -30°), and with 3 mm flux density ≳ 1 Jy, as measured from 1978 to 1994. LBAS quasars in our sample show larger luminosity than non-LBAS ones, which is consistent with previous work claiming larger Doppler factors for brighter γ-ray blazars. This effect cannot be claimed for BL Lacertae objects in our sample, which suggests that only quasars contribute to distribute LBAS blazars towards larger luminosities. We find a systematic 3.5 mm linear polarization degree excess by a factor of ~ 2 with regard to the one at 2 cm for all optical and γ-ray classes of sources considered here. Our sample shows a significant trend to increase the luminosity of their jets for decreasing linear polarization fraction. Unlike previous studies in the radio spectral range, we do not find a clear relation between the linear polarization angle and the jet structural position angle of any source class in our sample. This is interpreted as a markedly non-axisymmetric character of the 3 mm emitting region of radio loud AGN jets. [ABSTRACT FROM AUTHOR]

Published
2010
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6. Simultaneous Radio to (Sub-) mm-Monitoring of Variability and Spectral Shape Evolution of potential GLAST Blazars.

Author

Fuhrmann, L., Zensus, J. A., Krichbaum, T. P., Angelakis, E., and Readhead, A. C. S.

Subjects
BL Lacertae objects, ACTIVE galaxies, RADIO telescopes, SPECTRAL energy distribution, SPECTRUM analysis, SYNCHROTRON radiation, ELECTROMAGNETIC waves
Abstract

The Large Area Telescope (LAT) instrument onboard GLAST offers a tremendous opportunity for future blazar studies. In order to fully benefit from its capabilities and to maximize the scientific return from the LAT, it is of great importance to conduct dedicated multi-frequency monitoring campaigns that will result comprehensive observations. Consequently, we initiated an effort to conduct a GLAST-dedicated, quasi-simultaneous, broad-band flux-density (and polarization) monitoring of potential GLAST blazars with the Effelsberg and OVRO radio telescopes (11 cm to 7 mm wavelength). Here, we present a short overview of these activities which will complement the multi-wavelengths activities of the GLAST/LAT collaboration towards the ‘low-energy’ radio bands. Further we will give a brief outlook including the extension of this coordinated campaign towards higher frequencies and future scientific aims. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2007
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7. The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

Author

MAGIC Collaboration, J. Aleksić(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), S. Ansoldi(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), L. A. Antonelli(INAF National Institute for Astrophysics, I-00136 Rome, Italy), P. Antoranz(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), A. Babic(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), P. Bangale(Max-Planck-Institut für Physik, D-80805 München, Germany), U. Barres de Almeida(Max-Planck-Institut für Physik, D-80805 München, Germany), J. A. Barrio(Universidad Complutense, E-28040 Madrid, Spain), J. Becerra González(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), W. Bednarek(University of Lodz, PL-90236 Lodz, Poland), K. Berger(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), E. Bernardini(Deutsches Elektronen-Synchrotron), A. Biland(ETH Zurich, CH-8093 Zurich, Switzerland), O. Blanch(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), R. K. Bock(Max-Planck-Institut für Physik, D-80805 München, Germany), S. Bonnefoy(Universidad Complutense, E-28040 Madrid, Spain), G. Bonnoli(INAF National Institute for Astrophysics, I-00136 Rome, Italy), F. Borracci(Max-Planck-Institut für Physik, D-80805 München, Germany), T. Bretz(Universität Würzburg, D-97074 Würzburg, Germany), E. Carmona(Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, E-28040 Madrid, Spain), A. Carosi(INAF National Institute for Astrophysics, I-00136 Rome, Italy), D. Carreto Fidalgo(Universität Würzburg, D-97074 Würzburg, Germany), P. Colin(Max-Planck-Institut für Physik, D-80805 München, Germany), E. Colombo(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), J. L. Contreras(Universidad Complutense, E-28040 Madrid, Spain), J. Cortina(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), S. Covino(INAF National Institute for Astrophysics, I-00136 Rome, Italy), P. Da Vela(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), F. Dazzi(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), A. De Angelis(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), G. De Caneva(Deutsches Elektronen-Synchrotron), B. De Lotto(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), C. Delgado Mendez(Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, E-28040 Madrid, Spain), M. Doert(Technische Universität Dortmund, D-44221 Dortmund, Germany), A. Domínguez(Inst. de Astrofísica de Andalucía), D. Dominis Prester(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), D. Dorner(Universität Würzburg, D-97074 Würzburg, Germany), M. Doro(Università di Padova and INFN, I-35131 Padova, Italy), S. Einecke(Technische Universität Dortmund, D-44221 Dortmund, Germany), D. Eisenacher(Universität Würzburg, D-97074 Würzburg, Germany), D. Elsaesser(Universität Würzburg, D-97074 Würzburg, Germany), E. Farina(Università dell'Insubria, Como, I-22100 Como, Italy), D. Ferenc(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), M. V. Fonseca(Universidad Complutense, E-28040 Madrid, Spain), L. Font(Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain), K. Frantzen(Technische Universität Dortmund, D-44221 Dortmund, Germany), C. Fruck(Max-Planck-Institut für Physik, D-80805 München, Germany), R. J. García López(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), M. Garczarczyk(Deutsches Elektronen-Synchrotron), D. Garrido Terrats(Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain), M. Gaug(Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain), G. Giavitto(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), N. Godinović(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), A. González Mu\ noz(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), S. R. Gozzini(Deutsches Elektronen-Synchrotron), A. Hadamek(Technische Universität Dortmund, D-44221 Dortmund, Germany), D. Hadasch(Institut de Ciències de l'Espai), A. Herrero(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), D. Hildebrand(ETH Zurich, CH-8093 Zurich, Switzerland), J. Hose(Max-Planck-Institut für Physik, D-80805 München, Germany), D. Hrupec(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), W. Idec(University of Lodz, PL-90236 Lodz, Poland), V. Kadenius(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), H. Kellermann(Max-Planck-Institut für Physik, D-80805 München, Germany), M. L. Knoetig(ETH Zurich, CH-8093 Zurich, Switzerland), J. Krause(Max-Planck-Institut für Physik, D-80805 München, Germany), J. Kushida(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), A. La Barbera(INAF National Institute for Astrophysics, I-00136 Rome, Italy), D. Lelas(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), N. Lewandowska(Universität Würzburg, D-97074 Würzburg, Germany), E. Lindfors(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), F. Longo(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), S. Lombardi(INAF National Institute for Astrophysics, I-00136 Rome, Italy), M. López(Universidad Complutense, E-28040 Madrid, Spain), R. López-Coto(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), A. López-Oramas(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), E. Lorenz(Max-Planck-Institut für Physik, D-80805 München, Germany), I. Lozano(Universidad Complutense, E-28040 Madrid, Spain), M. Makariev(Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria), K. Mallot(Deutsches Elektronen-Synchrotron), G. Maneva(Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria), N. Mankuzhiyil(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), K. Mannheim(Universität Würzburg, D-97074 Würzburg, Germany), L. Maraschi(INAF National Institute for Astrophysics, I-00136 Rome, Italy), B. Marcote(Universitat de Barcelona), M. Mariotti(Università di Padova and INFN, I-35131 Padova, Italy), M. Martínez(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), D. Mazin(Max-Planck-Institut für Physik, D-80805 München, Germany), U. Menzel(Max-Planck-Institut für Physik, D-80805 München, Germany), M. Meucci(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), J. M. Miranda(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), R. Mirzoyan(Max-Planck-Institut für Physik, D-80805 München, Germany), A. Moralejo(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), P. Munar-Adrover(Universitat de Barcelona), D. Nakajima(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), A. Niedzwiecki(University of Lodz, PL-90236 Lodz, Poland), K. Nilsson(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), N. Nowak(6,32,*), R. Orito(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), A. Overkemping(Technische Universität Dortmund, D-44221 Dortmund, Germany), S. Paiano(Università di Padova and INFN, I-35131 Padova, Italy), M. Palatiello(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), D. Paneque(6,*), R. Paoletti(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), J. M. Paredes(Universitat de Barcelona), X. Paredes-Fortuny(Universitat de Barcelona), S. Partini(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), M. Persic(Università di Udine, and INFN Trieste, I-33100 Udine, Italy), F. Prada(Inst. de Astrofísica de Andalucía), P. G. Prada Moroni(Università di Pisa, and INFN Pisa, I-56126 Pisa, Italy), E. Prandini(Università di Padova and INFN, I-35131 Padova, Italy), S. Preziuso(Università di Siena, and INFN Pisa, I-53100 Siena, Italy), I. Puljak(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), R. Reinthal(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), W. Rhode(Technische Universität Dortmund, D-44221 Dortmund, Germany), M. Ribó(Universitat de Barcelona), J. Rico(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), J. Rodriguez Garcia(Max-Planck-Institut für Physik, D-80805 München, Germany), S. Rügamer(Universität Würzburg, D-97074 Würzburg, Germany), A. Saggion(Università di Padova and INFN, I-35131 Padova, Italy), K. Saito(Japanese MAGIC Consortium, Division of Physics and Astronomy, Kyoto University, Japan), M. Salvati(INAF National Institute for Astrophysics, I-00136 Rome, Italy), K. Satalecka(Universidad Complutense, E-28040 Madrid, Spain), V. Scalzotto(Università di Padova and INFN, I-35131 Padova, Italy), V. Scapin(Universidad Complutense, E-28040 Madrid, Spain), C. Schultz(Università di Padova and INFN, I-35131 Padova, Italy), T. Schweizer(Max-Planck-Institut für Physik, D-80805 München, Germany), S. N. Shore(Università di Pisa, and INFN Pisa, I-56126 Pisa, Italy), A. Sillanpää(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), J. Sitarek(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), I. Snidaric(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), D. Sobczynska(University of Lodz, PL-90236 Lodz, Poland), F. Spanier(Universität Würzburg, D-97074 Würzburg, Germany), V. Stamatescu(IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra, Spain), A. Stamerra(INAF National Institute for Astrophysics, I-00136 Rome, Italy), T. Steinbring(Universität Würzburg, D-97074 Würzburg, Germany), J. Storz(Universität Würzburg, D-97074 Würzburg, Germany), S. Sun(Max-Planck-Institut für Physik, D-80805 München, Germany), T. Surić(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), L. Takalo(Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Department of Physics, University of Oulu, Finland), F. Tavecchio(INAF National Institute for Astrophysics, I-00136 Rome, Italy), P. Temnikov(Inst. for Nucl. Research and Nucl. Energy, BG-1784 Sofia, Bulgaria), T. Terzić(Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka and University of Split, HR-10000 Zagreb, Croatia), D. Tescaro(Inst. de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain), M. Teshima(Max-Planck-Institut für Physik, D-80805 München, Germany), J. Thaele(Technische Universität Dortmund, D-44221 Dortmund, Germany), O. Tibolla(Universität Würzburg, D-97074 Würzburg, Germany), D. F. Torres(Institut de Ciències de l'Espai), T. Toyama(Max-Planck-Institut für Physik, D-80805 München, Germany), A. Treves(Università dell'Insubria, Como, I-22100 Como, Italy), M. Uellenbeck(Technische Universität Dortmund, D-44221 Dortmund, Germany), P. Vogler(ETH Zurich, CH-8093 Zurich, Switzerland), R. M. Wagner(Max-Planck-Institut für Physik, D-80805 München, Germany), F. Zandanel(Inst. de Astrofísica de Andalucía), R. Zanin(Universitat de Barcelona), VERITAS collaboration(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), (Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), S. Archambault(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), B. Behera(Deutsches Elektronen-Synchrotron), M. Beilicke(Department of Physics, Washington University, St. Louis, MO 63130, USA), W. Benbow(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), R. Bird(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), J. H. Buckley(Department of Physics, Washington University, St. Louis, MO 63130, USA), V. Bugaev(Department of Physics, Washington University, St. Louis, MO 63130, USA), M. Cerruti(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), X. Chen(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), L. Ciupik(Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605, USA), E. Collins-Hughes(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), W. Cui(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. Dumm(School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA), J. D. Eisch(Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA), A. Falcone(Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802, USA), S. Federici(DESY, Platanenallee 6, 15738 Zeuthen, Germany), Q. Feng(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. P. Finley(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), H. Fleischhack(Deutsches Elektronen-Synchrotron), P. Fortin(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA), L. Fortson(School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA), A. Furniss(Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064, USA), S. Griffin(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), S. T. Griffiths(Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242, USA), J. Grube(Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605, USA), G. Gyuk(Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605, USA), D. Hanna(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), J. Holder(Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716, USA), G. Hughes(Deutsches Elektronen-Synchrotron), T. B. Humensky(Physics Department, Columbia University, New York, NY 10027, USA), C. A. Johnson(Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064, USA), P. Kaaret(Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242, USA), M. Kertzman(Department of Physics and Astronomy, DePauw University, Greencastle, IN 46135-0037, USA), Y. Khassen(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), D. Kieda(Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA), H. Krawczynski(Department of Physics, Washington University, St. Louis, MO 63130, USA), F. Krennrich(Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA), S. Kumar(Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716, USA), M. J. Lang(School of Physics, National University of Ireland Galway, University Road, Galway, Ireland), G. Maier(Deutsches Elektronen-Synchrotron), S. McArthur(Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA), K. Meagher(School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332-0430), P. Moriarty(Department of Life and Physical Sciences, Galway-Mayo Institute of Technology, Dublin Road, Galway, Ireland), R. Mukherjee(Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027, USA), R. A. Ong(Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA), A. N. Otte(School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332-0430), N. Park(Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA), A. Pichel(Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67 - Sucursal 28), M. Pohl(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), A. Popkow(Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA), H. Prokoph(Deutsches Elektronen-Synchrotron), J. Quinn(School of Physics, University College Dublin, Belfield, Dublin 4, Ireland), K. Ragan(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), J. Rajotte(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), P. T. Reynolds(Department of Applied Physics and Instrumentation, Cork Institute of Technology, Bishopstown, Cork, Ireland), G. T. Richards(School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332-0430), E. Roache(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), A. C. Rovero(Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67 - Sucursal 28), G. H. Sembroski(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), K. Shahinyan(School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA), D. Staszak(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), I. Telezhinsky(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), M. Theiling(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. V. Tucci(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), J. Tyler(Physics Department, McGill University, Montreal, QC H3A 2T8, Canada), A. Varlotta(Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA), S. P. Wakely(Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA), T. C. Weekes(Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA), A. Weinstein(Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA), R. Welsing(Deutsches Elektronen-Synchrotron), A. Wilhelm(Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany), D. A. Williams(Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064, USA), B. Zitzer(Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA), External collaborators(INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), (INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), M. Villata(INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), C. Raiteri(INAF, Osservatorio Astronomico di Torino, I-10025 Pino Torinese), H. D. Aller(Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1042, USA), M. F. Aller(Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1042, USA), W. P. Chen(Graduate Institute of Astronomy, National Central University, Jhongli 32054, Taiwan), B. Jordan(School of Cosmic Physics, Dublin Institute for Advanced Studies, Dublin, 2, Ireland), E. Koptelova(Graduate Institute of Astronomy, National Central University, Jhongli 32054, Taiwan), O. M. Kurtanidze(Abastumani Observatory, Mt. Kanobili, 0301 Abastumani, Georgia), A. Lähteenmäki(Aalto University Metsähovi Radio Observatory Metsähovintie 114 FIN-02540 Kylmälä Finland), B. McBreen(University College Dublin, Belfield, Dublin 4, Ireland), V. M. Larionov(Isaac Newton Institute of Chile, St. Petersburg Branch, St. Petersburg, Russia), C. S. Lin(Graduate Institute of Astronomy, National Central University, Jhongli 32054, Taiwan), M. G. Nikolashvili(Abastumani Observatory, Mt. Kanobili, 0301 Abastumani, Georgia), E. Angelakis(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), M. Capalbi(ASI-Science Data Center, Via del Politecnico, I-00133 Rome, Italy), A. Carrami\ nana(Instituto Nacional de Astrofísica, Óptica y Electrónica, Tonantzintla, Puebla 72840, Mexico), L. Carrasco(Instituto Nacional de Astrofísica, Óptica y Electrónica, Tonantzintla, Puebla 72840, Mexico), P. Cassaro(INAF Istituto di Radioastronomia, Sezione di Noto, Contrada Renna Bassa, 96017 Noto), A. Cesarini(Department of Physics, University of Trento, I38050, Povo, Trento, Italy), L. Fuhrmann(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), M. Giroletti(INAF Istituto di Radioastronomia, 40129 Bologna, Italy), T. Hovatta(Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125), T. P. Krichbaum(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), H. A. Krimm(Astro Space Center of the Lebedev Physical Institute, 117997 Moscow, Russia), W. Max-Moerbeck(Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125), J. W. Moody(Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA), G. Maccaferri(INAF Istituto di Radioastronomia, Stazione Radioastronomica di Medicina, I-40059 Medicina), Y. Mori(Department of Physics, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551, Japan), I. Nestoras(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), A. Orlati(INAF Istituto di Radioastronomia, Stazione Radioastronomica di Medicina, I-40059 Medicina), C. Pace(Indiana University, Department of Astronomy, Swain Hall West 319, Bloomington, IN 47405-7105, USA), R. Pearson(Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA), M. Perri(INAF National Institute for Astrophysics, I-00136 Rome, Italy), A. C. S. Readhead(Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125), J. L. Richards(Department of Physics, Purdue University, 525 Northwestern Ave, West Lafayette, IN 47907), A. C. Sadun(Department of Physics, University of Colorado, Denver, CO 80220, USA), T. Sakamoto(Department of Physics and Mathematics, College of Science and 952 Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuoku, Sagamihara-shi Kanagawa 252-5258, Japan), J. Tammi(Aalto University Metsähovi Radio Observatory Metsähovintie 114 FIN-02540 Kylmälä Finland), M. Tornikoski(Aalto University Metsähovi Radio Observatory Metsähovintie 114 FIN-02540 Kylmälä Finland), Y. Yatsu(Department of Physics, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551, Japan), A. Zook(Department of Physics and Astronomy, Pomona College, Claremont CA 91711-6312, USA), Aleksić, J, Ansoldi, Stefano, Antonelli, L. A., Antoranz, P., Babic, A., Bangale, P., Barres De Almeida, U., Barrio, J. A., Becerra González, J., Bednarek, W., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Carreto Fidalgo, D., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Delgado Mendez, C., Doert, M., Domínguez, A., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Eisenacher, D., Elsaesser, D., Farina, E., Ferenc, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., García López, R. J., Garczarczyk, M., Garrido Terrats, D., Gaug, M., Giavitto, G., Godinović, N., González Muñoz, A., Gozzini, S. R., Hadamek, A., Hadasch, D., Herrero, A., Hildebrand, D., Hose, J., Hrupec, D., Idec, W., Kadenius, V., Kellermann, H., Knoetig, M. L., Krause, J., Kushida, J., La Barbera, A., Lelas, D., Lewandowska, N., Lindfors, E., Longo, Francesco, Lombardi, S., López, M., López Coto, R., López Oramas, A., Lorenz, E., Lozano, I., Makariev, M., Mallot, K., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Meucci, M., Miranda, J. M., Mirzoyan, R., Moralejo, A., Munar Adrover, P., Nakajima, D., Niedzwiecki, A., Nilsson, K., Nowak, N., Orito, R., Overkemping, A., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes Fortuny, X., Partini, S., Persic, M., Prada, F., Prada Moroni, P. G., Prandini, E., Preziuso, S., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rodriguezgarcia, J., Rügamer, S., Saggion, A., Saito, K., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Spanier, F., Stamatescu, V., Stamerra, A., Steinbring, T., Storz, J., Sun, S., Surić, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Tibolla, O., Torres, D. F., Toyama, T., Treves, A., Uellenbeck, M., Vogler, P., Wagner, R. M., Zandanel, F., Zanin, R., Archambault, S., Behera, B., Beilicke, M., Benbow, W., Bird, R., Buckley, J. H., Bugaev, V., Cerruti, M., Chen, X., Ciupik, L., Collins Hughes, E., Cui, W., Dumm, J., Eisch, J. D., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Fleischhack, H., Fortin, P., Fortson, L., Furniss, A., Griffin, S., Griffiths, S. T., Grube, J., Gyuk, G., Hanna, D., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Kumar, S., Lang, M. J., Maier, G., Mcarthur, S., Meagher, K., Moriarty, P., Mukherjee, R., Ong, R. A., Otte, A. N., Park, N., Pichel, A., Pohl, M., Popkow, A., Prokoph, H., Quinn, J., Ragan, K., Rajotte, J., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Sembroski, G. H., Shahinyan, K., Staszak, D., Telezhinsky, I., Theiling, M., Tucci, J. V., Tyler, J., Varlotta, A., Wakely, S. P., Weekes, T. C., Weinstein, A., Welsing, R., Wilhelm, A., Williams, D. A., Zitzer, B., Villata, M., Raiteri, C., Aller, H. D., Aller, M. F., Chen, W. P., Jordan, B., Koptelova, E., Kurtanidze, O. M., Lähteenmäki, A., Mcbreen, B., Larionov, V. M., Lin, C. S., Nikolashvili, M. G., Angelakis, E., Capalbi, M., Carramiñana, A., Carrasco, L., Cassaro, P., Cesarini, A., Fuhrmann, L., Giroletti, M., Hovatta, T., Krichbaum, T. P., Krimm, H. A., Max Moerbeck, W., Moody, J. W., Maccaferri, G., Mori, Y., Nestoras, I., Orlati, A., Pace, C., Pearson, R., Perri, M., Readhead, A. C. S., Richards, J. L., Sadun, A. C., Sakamoto, T., Tammi, J., Tornikoski, M., Yatsu, Y., Zook, A., Department of Radio Science and Engineering, Aalto-yliopisto, Aalto University, and Universitat de Barcelona

Subjects
Astrofísica, Brightness, Ciencias Físicas, blazars, Astrophysics, telescope, x-ray variability, 01 natural sciences, Spectral line, BL Lacertae objects, individual, Mrk 421, purl.org/becyt/ford/1 [https], Raigs gamma, emission, MAGIC (telescope), 010303 astronomy & astrophysics, Physics, astro-ph.HE, High Energy Astrophysical Phenomena (astro-ph.HE), individual: Mrk 421 [BL Lacertae objects], Galaxies: BL Lacertae objects: individual: Markarian 421, Spectral energy distribution, Electrónica, Electricidad, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, power spectra, BL Lacertae object, tev photons, 0103 physical sciences, Nucli galàctic actiu, bl lacertae objects: individual: mrk 421, Blazar, Astronomy and Astrophysics, Space and Planetary Science, Active galactic nuclei, 010308 nuclear & particles physics, light curves, Gamma rays, Institut für Physik und Astronomie, purl.org/becyt/ford/1.3 [https], Light curve, Galaxies, Galàxies, Astronomía, Crab Nebula, optical variability, active galactic nuclei, Galàxies actives, Active galaxies, markarian-421, ddc:520
Abstract

We performed a 4.5-month multi-instrument campaign (from radio to VHE gamma rays) on Mrk421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-correlation between optical/UV and X-rays extending over the duration of the campaign. The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multi-wavelength campaign suggests that the physical processes dominating the emission during non-flaring states have similarities with those occurring during flaring activity. In particular, this observation supports leptonic scenarios as being responsible for the emission of Mrk421 during non-flaring activity. Such a temporally extended X-ray/VHE correlation is not driven by any single flaring event, and hence is difficult to explain within the standard hadronic scenarios. The highest variability is observed in the X-ray band, which, within the one-zone synchrotron self-Compton scenario, indicates that the electron energy distribution is most variable at the highest energies., Comment: Accepted for publication in A&A, 18 pages, 14 figures (v2 has a small modification in the acknowledgments, and also corrects a typo in the field "author" in the metadata)

Published
2015
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