TY - JOUR
A1 - Aleksic, J.
A1 - Ansoldi, S.
A1 - Antonelli, L. A.
A1 - Antoranz, P.
A1 - Babic, A.
A1 - Bangale, P.
A1 - de Almeida, U. Barres
A1 - Barrio, J. A.
A1 - Gonzalez, J. Becerra
A1 - Bednarek, W.
A1 - Bernardini, E.
A1 - Biasuzzi, B.
A1 - Biland, A.
A1 - Blanch, O.
A1 - Boller, A.
A1 - Bonnefoy, S.
A1 - Bonnoli, G.
A1 - Borracci, F.
A1 - Bretz, T.
A1 - Carmona, E.
A1 - Carosi, A.
A1 - Colin, P.
A1 - Colombo, E.
A1 - Contreras, J. L.
A1 - Cortina, J.
A1 - Covino, S.
A1 - Da Vela, P.
A1 - Dazzi, F.
A1 - De Angelis, A.
A1 - De Caneva, G.
A1 - De Lotto, B.
A1 - Wilhelmi, E. de Ona
A1 - Mendez, C. Delgado
A1 - Prester, Dijana Dominis
A1 - Dorner, D.
A1 - Doro, M.
A1 - Einecke, S.
A1 - Eisenacher, D.
A1 - Elsaesser, D.
A1 - Fonseca, M. V.
A1 - Font, L.
A1 - Frantzen, K.
A1 - Fruck, C.
A1 - Galindo, D.
A1 - Lopez, R. J. Garcia
A1 - Garczarczyk, M.
A1 - Terrats, D. Garrido
A1 - Gaug, M.
A1 - Godinovic, N.
A1 - Munoz, A. Gonzalez
A1 - Gozzini, S. R.
A1 - Hadasch, D.
A1 - Hanabata, Y.
A1 - Hayashida, M.
A1 - Herrera, J.
A1 - Hildebrand, D.
A1 - Hose, J.
A1 - Hrupec, D.
A1 - Hughes, G.
A1 - Idec, W.
A1 - Kadenius, V.
A1 - Kellermann, H.
A1 - Knoetig, M. L.
A1 - Kodani, K.
A1 - Konno, Y.
A1 - Krause, J.
A1 - Kubo, H.
A1 - Kushida, J.
A1 - La Barbera, A.
A1 - Lelas, D.
A1 - Lewandowska, N.
A1 - Lindfors, E.
A1 - Lombardi, S.
A1 - Lopez, M.
A1 - Lopez-Coto, R.
A1 - Lopez-Oramas, A.
A1 - Lorenz, E.
A1 - Lozano, I.
A1 - Makariev, M.
A1 - Mallot, K.
A1 - Maneva, G.
A1 - Mankuzhiyil, N.
A1 - Mannheim, K.
A1 - Maraschi, L.
A1 - Marcote, B.
A1 - Mariotti, M.
A1 - Martinez, M.
A1 - Mazin, D.
A1 - Menzel, U.
A1 - Miranda, J. M.
A1 - Mirzoyan, R.
A1 - Moralejo, A.
A1 - Munar-Adrover, P.
A1 - Nakajima, D.
A1 - Niedzwiecki, A.
A1 - Nilsson, K.
A1 - Nishijima, K.
A1 - Noda, K.
A1 - Orito, R.
A1 - Overkemping, A.
A1 - Paiano, S.
A1 - Palatiello, M.
A1 - Paneque, D.
A1 - Paoletti, R.
A1 - Paredes, J. M.
A1 - Paredes-Fortuny, X.
A1 - Persic, M.
A1 - Moroni, P. G. Prada
A1 - Prandini, E.
A1 - Puljak, I.
A1 - Reinthal, R.
A1 - Rhode, W.
A1 - Ribo, M.
A1 - Rico, J.
A1 - Garcia, J. Rodriguez
A1 - Rugamer, S.
A1 - Saito, T.
A1 - Saito, K.
A1 - Satalecka, K.
A1 - Scalzotto, V.
A1 - Scapin, V.
A1 - Schultz, C.
A1 - Schweizer, T.
A1 - Sun, S.
A1 - Shore, S. N.
A1 - Sillanpaa, A.
A1 - Sitarek, J.
A1 - Snidaric, I.
A1 - Sobczynska, D.
A1 - Spanier, F.
A1 - Stamatescu, V.
A1 - Stamerra, A.
A1 - Steinbring, T.
A1 - Steinke, B.
A1 - Storz, J.
A1 - Strzys, M.
A1 - Takalo, L.
A1 - Takami, H.
A1 - Tavecchio, F.
A1 - Temnikov, P.
A1 - Terzic, T.
A1 - Tescaro, D.
A1 - Teshima, M.
A1 - Thaele, J.
A1 - Tibolla, O.
A1 - Torres, D. F.
A1 - Toyama, T.
A1 - Treves, A.
A1 - Uellenbeck, M.
A1 - Vogler, P.
A1 - Zanin, R.
A1 - Archambault, S.
A1 - Archer, A.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Berger, K.
A1 - Bird, R.
A1 - Biteau, J.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Cerruti, M.
A1 - Chen, Xiaoming
A1 - Ciupik, L.
A1 - Collins-Hughes, E.
A1 - Cui, W.
A1 - Eisch, J. D.
A1 - Falcone, A.
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fortin, P.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Galante, N.
A1 - Gillanders, G. H.
A1 - Griffin, S.
A1 - Gyuk, G.
A1 - Hakansson, Nils
A1 - Holder, J.
A1 - Johnson, C. A.
A1 - Kaaret, P.
A1 - Kar, P.
A1 - Kertzman, M.
A1 - Kieda, D.
A1 - Lang, M. J.
A1 - McArthur, S.
A1 - McCann, A.
A1 - Meagher, K.
A1 - Millis, J.
A1 - Moriarty, P.
A1 - Ong, R. A.
A1 - Otte, A. N.
A1 - Perkins, J. S.
A1 - Pichel, A.
A1 - Pohl, Manuela
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Pueschel, E.
A1 - Ragan, K.
A1 - Reyes, L. C.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Rovero, A. C.
A1 - Sembroski, G. H.
A1 - Shahinyan, K.
A1 - Staszak, D.
A1 - Telezhinsky, Igor
A1 - Tucci, J. V.
A1 - Tyler, J.
A1 - Varlotta, A.
A1 - Wakely, S. P.
A1 - Welsing, R.
A1 - Wilhelm, Alina
A1 - Williams, D. A.
A1 - Buson, S.
A1 - Finke, J.
A1 - Villata, M.
A1 - Raiteri, C.
A1 - Aller, H. D.
A1 - Aller, M. F.
A1 - Cesarini, A.
A1 - Chen, W. P.
A1 - Gurwell, M. A.
A1 - Jorstad, S. G.
A1 - Kimeridze, G. N.
A1 - Koptelova, E.
A1 - Kurtanidze, O. M.
A1 - Kurtanidze, S. O.
A1 - Lahteenmaki, A.
A1 - Larionov, V. M.
A1 - Larionova, E. G.
A1 - Lin, H. C.
A1 - McBreen, B.
A1 - Moody, J. W.
A1 - Morozova, D. A.
A1 - Marscher, A. P.
A1 - Max-Moerbeck, W.
A1 - Nikolashvili, M. G.
A1 - Perri, M.
A1 - Readhead, A. C. S.
A1 - Richards, J. L.
A1 - Ros, J. A.
A1 - Sadun, A. C.
A1 - Sakamoto, T.
A1 - Sigua, L. A.
A1 - Smith, P. S.
A1 - Tornikoski, M.
A1 - Troitsky, I. S.
A1 - Wehrle, A. E.
A1 - Jordan, B.
T1 - Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010
JF - Astronomy and astrophysics : an international weekly journal
N2 - Context. Because of its proximity, Mrk 421 is one of the best sources on which to study the nature of BL Lac objects. Its proximity allows us to characterize its broadband spectral energy distribution (SED).
Aims. The goal is to better understand the mechanisms responsible for the broadband emission and the temporal evolution of Mrk 421. These mechanisms may also apply to more distant blazars that cannot be studied with the same level of detail.
Methods. A flare occurring in March 2010 was observed for 13 consecutive days (from MJD 55 265 to MJD 55 277) with unprecedented wavelength coverage from radio to very high energy (VHE; E > 100 GeV) gamma-rays with MAGIC, VERITAS, Whipple, Fermi-LAT, MAXI, RXTE, Swift, GASP-WEBT, and several optical and radio telescopes. We modeled the day-scale SEDs with one-zone and two-zone synchrotron self-Compton (SSC) models, investigated the physical parameters, and evaluated whether the observed broadband SED variability can be associated with variations in the relativistic particle population.
Results. The activity of Mrk 421 initially was high and then slowly decreased during the 13-day period. The flux variability was remarkable at the X-ray and VHE bands, but it was minor or not significant at the other bands. The variability in optical polarization was also minor. These observations revealed an almost linear correlation between the X-ray flux at the 2-10 keV band and the VHE gamma-ray flux above 200 GeV, consistent with the gamma-rays being produced by inverse-Compton scattering in the Klein-Nishina regime in the framework of SSC models. The one-zone SSC model can describe the SED of each day for the 13 consecutive days reasonably well, which once more shows the success of this standard theoretical scenario to describe the SEDs of VHE BL Lacs such as Mrk 421. This flaring activity is also very well described by a two-zone SSC model, where one zone is responsible for the quiescent emission, while the other smaller zone, which is spatially separated from the first, contributes to the daily variable emission occurring at X-rays and VHE gamma-rays. The second blob is assumed to have a smaller volume and a narrow electron energy distribution with 3 x 10(4) < gamma < 6 x 10(5), where. is the Lorentz factor of the electrons. Such a two-zone scenario would naturally lead to the correlated variability at the X-ray and VHE bands without variability at the optical/UV band, as well as to shorter timescales for the variability at the X-ray and VHE bands with respect to the variability at the other bands.
Conclusions. Both the one-zone and the two-zone SSC models can describe the daily SEDs via the variation of only four or five model parameters, under the hypothesis that the variability is associated mostly with the underlying particle population. This shows that the particle acceleration and cooling mechanism that produces the radiating particles might be the main mechanism responsible for the broadband SED variations during the flaring episodes in blazars. The two-zone SSC model provides a better agreement with the observed SED at the narrow peaks of the low-and high-energy bumps during the highest activity, although the reported one-zone SSC model could be further improved by varying the parameters related to the emitting region itself (delta, B and R), in addition to the parameters related to the particle population.
KW - radiation mechanisms: non-thermal
KW - galaxies: active
KW - BL Lacertae objects: individual: Mrk 421
KW - gamma rays: galaxies
Y1 - 2015
U6 - http://dx.doi.org/10.1051/0004-6361/201424811
SN - 0004-6361 (print)
SN - 1432-0746 (online)
VL - 578
PB - EDP Sciences
CY - Les Ulis
ER -
TY - JOUR
A1 - Aleksic, J.
A1 - Ansoldi, S.
A1 - Antonelli, L. A.
A1 - Antoranz, P.
A1 - Babic, A.
A1 - Bangale, P.
A1 - de Almeida, U. Barres
A1 - Barrio, J. A.
A1 - Gonzalez, J. Becerra
A1 - Bednarek, W.
A1 - Berger, K.
A1 - Bernardini, E.
A1 - Bilandli, A.
A1 - Bianch, O.
A1 - Bock, R. K.
A1 - Bonnefoy, S.
A1 - Bonnoli, G.
A1 - Borracci, F.
A1 - Bretz, T.
A1 - Carmona, E.
A1 - Carosi, A.
A1 - Fidalgo, D. Carreto
A1 - Colin, P.
A1 - Colombo, E.
A1 - Contreras, J. L.
A1 - Cortina, J.
A1 - Covino, S.
A1 - Da Vela, P.
A1 - Dazzi, F.
A1 - De Angelis, A.
A1 - De Caneva, G.
A1 - De Lotto, B.
A1 - Delgado Mendez, C.
A1 - Doert, M.
A1 - Dominguez, A.
A1 - Prester, Dijana Dominis
A1 - Dorner, D.
A1 - Doro, M.
A1 - Einecke, S.
A1 - Eisenacher, D.
A1 - Elsaesser, D.
A1 - Farina, E.
A1 - Ferenc, D.
A1 - Fonseca, M. V.
A1 - Font, L.
A1 - Frantzen, K.
A1 - Fruck, C.
A1 - Garcia Lopez, R. J.
A1 - Garczarczyki, M.
A1 - Garrido Terrats, D.
A1 - Gaug, M.
A1 - Giavitto, G.
A1 - Godinovic, N.
A1 - Gonzalez Munoz, A.
A1 - Gozzini, S. R.
A1 - Hadamek, A.
A1 - Hadasch, D.
A1 - Herrero, A.
A1 - Hildebrand, D.
A1 - Hose, J.
A1 - Hrupec, D.
A1 - Idec, W.
A1 - Kadenius, V.
A1 - Kellermann, H.
A1 - Knoetig, M. L.
A1 - Krause, J.
A1 - Kushida, J.
A1 - La Barbera, A.
A1 - Lelas, D.
A1 - Lewandowska, N.
A1 - Lindfors, E.
A1 - Longo, F.
A1 - Lombardi, S.
A1 - Lopez, M.
A1 - Lopez-Coto, R.
A1 - Lopez-Oramas, A.
A1 - Lorenz, E.
A1 - Lozano, I.
A1 - Makariev, M.
A1 - Mallot, K.
A1 - Maneva, G.
A1 - Mankuzhiyil, N.
A1 - Mannheim, K.
A1 - Maraschi, L.
A1 - Marcote, B.
A1 - Mariotti, M.
A1 - Martinez, M.
A1 - Mazin, D.
A1 - Menzel, U.
A1 - Meucci, M.
A1 - Miranda, J. M.
A1 - Mirzoyan, R.
A1 - Moralejo, A.
A1 - Munar-Adrover, P.
A1 - Nakajima, D.
A1 - Niedzwiecki, A.
A1 - Nilsson, K.
A1 - Nowak, N.
A1 - Orito, R.
A1 - Overkemping, A.
A1 - Paiano, S.
A1 - Palatiello, M.
A1 - Paneque, D.
A1 - Paoletti, R.
A1 - Paredes, J. M.
A1 - Paredes-Fortuny, X.
A1 - Partini, S.
A1 - Persic, M.
A1 - Prada, F.
A1 - Moroni, P. G. Prada
A1 - Prandini, E.
A1 - Preziuso, S.
A1 - Puljak, I.
A1 - Reinthal, R.
A1 - Rhode, W.
A1 - Ribo, M.
A1 - Rico, J.
A1 - Garcia, J. Rodriguez
A1 - Ruegamer, S.
A1 - Saggion, A.
A1 - Saito, K.
A1 - Salvati, M.
A1 - Satalecka, K.
A1 - Scalzotto, V.
A1 - Scapin, V.
A1 - Schuliz, C.
A1 - Schweizer, T.
A1 - Shore, S. N.
A1 - Sillanpaa, A.
A1 - Sitarek, J.
A1 - Snidaric, I.
A1 - Sobczynska, D.
A1 - Spanier, F.
A1 - Stamatescu, V.
A1 - Stamerra, A.
A1 - Steinbring, T.
A1 - Storz, J.
A1 - Sun, S.
A1 - Suric, T.
A1 - Takalo, L.
A1 - Tavecchio, F.
A1 - Temnikov, P.
A1 - Terzic, T.
A1 - Tescaro, D.
A1 - Teshima, M.
A1 - Thaele, J.
A1 - Tibolla, O.
A1 - Torres, D. F.
A1 - Toyama, T.
A1 - Treves, A.
A1 - Uellenbeck, M.
A1 - Vogler, P.
A1 - Wagner, R. M.
A1 - Zandanel, F.
A1 - Zanin, R.
A1 - Archambault, S.
A1 - Behera, B.
A1 - Beilicke, M.
A1 - Benbow, W.
A1 - Bird, R.
A1 - Buckley, J. H.
A1 - Bugaev, V.
A1 - Cerruti, M.
A1 - Chen, X.
A1 - Ciupik, L.
A1 - Collins-Hughes, E.
A1 - Cui, W.
A1 - Dumm, J.
A1 - Eisch, J. D.
A1 - Falcone, A.
A1 - Federici, S.
A1 - Feng, Q.
A1 - Finley, J. P.
A1 - Fleischhack, H.
A1 - Fortin, P.
A1 - Fortson, L.
A1 - Furniss, A.
A1 - Griffin, S.
A1 - Griffiths, S. T.
A1 - Grube, J.
A1 - Gyuk, G.
A1 - Hanna, D.
A1 - Holder, J.
A1 - Hughes, G.
A1 - Humensky, T. B.
A1 - Johnson, C. A.
A1 - Kaaret, P.
A1 - Kertzman, M.
A1 - Khassen, Y.
A1 - Kieda, D.
A1 - Krawczynski, H.
A1 - Krennrich, F.
A1 - Kumar, S.
A1 - Lang, M. J.
A1 - Maier, G.
A1 - McArthur, S.
A1 - Meagher, K.
A1 - Moriarty, P.
A1 - Mukherjee, R.
A1 - Ong, R. A.
A1 - Otte, A. N.
A1 - Park, N.
A1 - Pichel, A.
A1 - Pohl, M.
A1 - Popkow, A.
A1 - Prokoph, H.
A1 - Quinn, M. J.
A1 - Ragan, K.
A1 - Rajotte, J.
A1 - Reynolds, P. T.
A1 - Richards, G. T.
A1 - Roache, E.
A1 - Rovero, A. C.
A1 - Sembroski, G. H.
A1 - Shahinyan, K.
A1 - Staszak, D.
A1 - Telezhinsky, I.
A1 - Theiling, M.
A1 - Tucci, J. V.
A1 - Tyler, J.
A1 - Varlotta, A.
A1 - Wakely, S. P.
A1 - Weekes, T. C.
A1 - Weinstein, A.
A1 - Welsing, R.
A1 - Wilhelm, A.
A1 - Williams, D. A.
A1 - Zitzer, B.
A1 - Villata, M.
A1 - Raiteri, C.
A1 - Aller, H. D.
A1 - Aller, M. F.
A1 - Chen, W. P.
A1 - Jordan, B.
A1 - Koptelova, E.
A1 - Kurtanidze, O. M.
A1 - Lahteenmaki, A.
A1 - McBreen, B.
A1 - Larionov, V. M.
A1 - Lin, C. S.
A1 - Nikolashvili, M. G.
A1 - Angelakis, E.
A1 - Capalbi, M.
A1 - Carraminana, A.
A1 - Carrasco, L.
A1 - Cassaro, P.
A1 - Cesarini, A.
A1 - Fuhrmann, L.
A1 - Giroletti, M.
A1 - Hovatta, T.
A1 - Krichbaum, T. P.
A1 - Krimm, H. A.
A1 - Max-Moerbeck, W.
A1 - Moody, J. W.
A1 - Maccaferri, G.
A1 - Mori, Y.
A1 - Nestoras, I.
A1 - Orlati, A.
A1 - Pace, C.
A1 - Pearson, R.
A1 - Perri, M.
A1 - Readhead, A. C. S.
A1 - Richards, J. L.
A1 - Sadun, A. C.
A1 - Sakamoto, T.
A1 - Tammi, J.
A1 - Tornikoski, M.
A1 - Yatsu, Y.
A1 - Zook, A.
T1 - The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies
JF - Astronomy and astrophysics : an international weekly journal
N2 - Aims. We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z = 0.031) of Mrk 421 make it an excellent laboratory to study blazar emission. The goal is to learn about the physical processes responsible for the typical emission of Mrk 421, which might also be extended to other blazars that are located farther away and hence are more difficult to study.
Methods. We performed a 4.5-month multi-instrument campaign on Mrk 421 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. This extensive radio to very-high-energy (VHE; E > 100 GeV) gamma-ray dataset provides excellent temporal and energy coverage, which allows detailed studies of the evolution of the broadband spectral energy distribution.
Results. 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.
Conclusions. The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multiwavelength 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 Mrk 421 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.
KW - BL Lacertae objects: individual: Mrk 421
Y1 - 2015
U6 - http://dx.doi.org/10.1051/0004-6361/201424216
SN - 0004-6361 (print)
SN - 1432-0746 (online)
VL - 576
PB - EDP Sciences
CY - Les Ulis
ER -