Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010-猫眼课题宝

DOI：

10.1051/0004-6361/201424811

发表时间：

2014-12

期刊：

Astronomy and Astrophysics

影响因子：

6.5

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

T. M. C. J. Aleksi'c;S. Ansoldi;L. A. Antonelli;P. Antoranz;A. Babić;P. Bangale;U. D. Almeida;J. Barrio;J. Gonz'alez;W. Bednarek;E. Bernardini;B. Biasuzzi;A. Biland;O. Blanch;A. Boller;S. Bonnefoy;G. Bonnoli;F. Borracci;T. Bretz;E. Carmona;A. Carosi;P. Colin;E. Colombo;J. Contreras;J. Cortina;S. Covino;P. D. Vela;F. Dazzi;A. Angelis;G. Caneva;B. Lotto;E. O. Wilhelmi;C. Mendez;D. D. Prester-D.;D. Dorner;M. Doro;S. Einecke;D. Eisenacher;D. Elsaesser;M. V. Fonseca;L. Font;K. Frantzen;C. Fruck;D. Galindo;R. L'opez;M. Garczarczyk;D. G. Terrats;M. Gaug;N. Godinovi'c;A. G. Muñoz;S. Gozzini;D. Hadasch;Y. Hanabata;M. Hayashida;J. Herrera;D. Hildebrand;J. Hose;D. Hrupec;G. Hughes;W. Idec;V. Kadenius;H. Kellermann;M. Knoetig;K. Kodani;Y. Konno;J. Krause;H. Kubo;J. Kushida;A. Barbera;D. Lelas;N. Lewandowska;E. Lindfors;S. Lombardi;M. L'opez;R. L'opez-Coto;A. L'opez-Oramas;E. Lorenz;I. Lozano;M. Makariev;K. Mallot;G. Maneva;N. Mankuzhiyil;K. Mannheim;L. Maraschi;B. Marcote;M. Mariotti;M. Mart'inez;D. Mazin;U. Menzel;J. Miranda;R. Mirzoyan;A. Moralejo;P. Munar-Adrover;D. Nakajima;A. Niedźwiecki;K. Nilsson;K. Nishijima;K. Noda;R. Orito;A. Overkemping;S. Paiano;M. Palatiello;D. Paneque;R. Paoletti;J. Paredes;X. Paredes-Fortuny;M. Persic;P. Moroni;E. Prandini;I. Puljak;R. Reinthal;W. Rhode;M. Rib'o;J. Rico;J. Garcia;S. Rugamer;T. Saito;K. Saito;K. Satalecka;V. Scalzotto;V. Scapin;C. Schultz;T. Schweizer;S. Sun;S. Shore;A. Sillanpaa;J. Sitarek;I. Šnidarić;D. Sobczynska;F. Spanier;V. Stamatescu;A. Stamerra;T. Steinbring;B. Steinke;J. Storz;M. Strzys;L. Takalo;H. Takami;F. Tavecchio;P. Temnikov;T. Terzi'c;D. Tescaro;M. Teshima;J. Thaele;O. Tibolla;D. Torres;T. Toyama;A. Treves;M. Uellenbeck;P. Vogler;R. Zanin;T. V. C. S. Archambault;A. Archer;M. Beilicke;W. Benbow;K. Berger;R. Bird;J. Biteau;J. Buckley;V. Bugaev;M. Cerruti;X. Chen;L. Ciupik;E. Collins-Hughes;W. Cui;J. Eisch;A. Falcone;Q. Feng;J. Finley;P. Fortin;L. Fortson;A. Furniss;N. Galante;G. Gillanders;S. Griffin;G. Gyuk;N. Haakansson;J. Holder;C. Johnson;P. Kaaret;P. Kar;M. Kertzman;D. Kieda;M. Lang;S. McArthur;A. McCann;K. Meagher;J. Millis;P. Moriarty;R. Ong;A. Otte;J. Perkins;A. Pichel;M. Pohl;A. Popkow;H. Prokoph;E. Pueschel;K. Ragan;L. Reyes;P. Reynolds;G. Richards;E. Roache;A. Rovero;G. Sembroski;K. Shahinyan;D. Staszak;I. Telezhinsky;J. Tucci;J. Tyler;A. Varlotta;S. Wakely;R. Welsing;A. Wilhelm;D. Williams;External Collaborators S. Buson;J. Finke;M. Villata;C. Raiteri;H. Aller;M. Aller;A. Cesarini;W. P. Chen;M. Gurwell;S. Jorstad;G. Kimeridze;E. Koptelova;O. Kurtanidze;S. O. Kurtanidze;A. Lahteenmaki;V. Larionov;E. Larionova;H. C. Lin;B. Mcbreen;J. Moody;D. Morozova;A. Marscher;W. Max-Moerbeck;M. Nikolashvili;M. Perri;A. Readhead;J. Richards;J. A. Ros;A. Sadun;T. Sakamoto;L. Sigua;P. Smith;M. Tornikoski;I. Troitsky;A. Wehrle;B. Ifae;Campus Uab;Bellaterra;Spain.;U. Udine;I. Trieste;Udine;Italy.;I. I. F. Astrophysics-I.;Romé;U. Siena;I. Pisa;Siena;Croatian Magic Consortium;Rudjer Boskovic Institute;University of Rijeka;University of Split;Zagreb;Croatia.;M. F. Physik;Munchen;H Germany;U. Complutense;Madrid;Instituto de Astrof'isica de Canarias-Instituto-de-Astrof'isica-de-Canarias-102997450;Tenerife;University of L'od;Lodz;Poland;D. Elektronen-Synchrotron;Zeuthen;E. Zurich;Zurich;Switzerland.;U. Wurzburg;Wurzburg;Centro de Investigaciones Energ'eticas;Medioambientales y Tecnol'ogicas;Institute for Space Sciences;Barcelona;U. Padova;Infn;Padova;Technische Universitat Dortmund;Dortmund;Unitat de F'isica de les Radiacions-Unitat-de-F'isica-de-les-Radiacions-1381421020;D. D. F'isica-D.;CERES-IEEC;U. Barcelona;U. Barcelona;Icc;IEEC-UB;Japanese Magic Consortium;D. Physics;Astronomy;Kyoto University;Japan.;Finnish Magic Consortium;T. Observatory;U. Turku;D. Physics;U. Oulu;Finland.;Inst. for Nucl. Research;Nucl. Energy;Sofía;Bulgaria.;U. Pisa;Pisa;Icrea;Universita' dell'Insubria;Infn Milano Bicocca;Como;Now at Centro Brasileiro de Pesquisas F'isicas;R. Janeiro;Brazil.;Nasa Goddard Space Flight Center;Greenbelt;Usa;D. Astronomy;U. Maryland;College Park;N. C. E. P. F. D. Lausanne;Lausanne;Now at Institut fur Astro- und Teilchenphysik;L. Innsbruck;Innsbruck;Austria;N. Eso;Turku;N. Division;Bhabha Atomic Research Centre;Mumbai;India.;also at INAF-Trieste;now at School of ChemistryPhysics;U. Adelaide;Australia.;P. Department;M. University;Montreal.;Canada.;W. University;S. Louis;Fred Lawrence Whipple Observatory;H. C. F. Astrophysics;Amado;the Bartol Research Institute;U. Delaware;Newark;S. O. Physics;University College Dublin;Dublin.;Ireland;Santa Cruz Institute for Particle Physics;U. California;Santa Cruz;I. Physics;U. Potsdam;Potsdam-Golm;A. Department;Adler Planetarium;Astronomy Museum;Chicago.;P. University;W. Lafayette;I. S. University;Ames;Astrophysics;P. S. University;U. Park;U. 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语境。由于距离较近，Mrk 421 是研究 BL Lac 天体性质的最佳来源之一。它的邻近性使我们能够表征其宽带光谱能量分布（SED）。目标。目标是更好地了解 Mrk 421 的宽带发射和时间演化的机制。这些机制也可能适用于无法以相同详细程度研究的更遥远的耀变体。方法。使用 MAGIC、VERITAS、Whipple、Fermi-LAT、MAXI、RXTE、Swift、GASP-WEBT 和数台光学和射电望远镜连续 13 天观测到 2010 年 3 月发生的耀斑（从 MJD 55 265 到 MJD 55 277），其波长覆盖范围从射电到极高能（VHE；E> 100 GeV）γ 射线。我们使用一区和两区同步加速器自康普顿 (SSC) 模型对日尺度 SED 进行了建模，研究了物理参数，并评估了观察到的宽带 SED 变化是否与相对论粒子群的变化相关。结果。 Mrk 421的活性最初很高，然后在13天内缓慢下降。 X 射线和 VHE 波段的通量变化非常显着，但其他波段的通量变化较小或不显着。光学偏振的变化也很小。这些观测结果表明，2-10 keV 波段的 X 射线通量与 200 GeV 以上的 VHE γ 射线通量之间几乎呈线性相关，这与 SSC 模型框架中克莱因-仁科体系中逆康普顿散射产生的 γ 射线一致。单区 SSC 模型可以相当好地描述连续 13 天每天的 SED，这再次显示了这种标准理论场景在描述 VHE BL Lacs（例如 Mrk 421）的 SED 方面的成功。两区 SSC 模型也很好地描述了这种燃烧活动，其中一个区域负责静态排放，而与第一个区域在空间上分离的另一个较小区域则有助于每日变量 X 射线和 VHE γ 射线发生发射。假设第二个斑点具有较小的体积和较窄的电子能量分布，其中 3 × 10^4<γ< 6 × 10^5，其中 γ 是电子的洛伦兹因子。这种两区场景自然会导致 X 射线和 VHE 波段的相关变化，而光学/紫外波段没有变化，以及 X 射线和 VHE 波段的变化相对于其他波段的变化的时间尺度更短。结论。一区和两区 SSC 模型都可以通过仅四到五个模型参数的变化来描述每日 SED，假设变化主要与底层粒子群相关。这表明产生辐射粒子的粒子加速和冷却机制可能是耀变体耀斑期间宽带 SED 变化的主要机制。尽管除了与粒子群相关的参数之外，还可以通过改变与发射区域本身相关的参数（δ、B 和 R）来进一步改进所报道的一区 SSC 模型，但两区 SSC 模型与在最高活动期间低能和高能凸块窄峰处观察到的 SED 提供了更好的一致性。

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) γ-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 γ-ray flux above 200 GeV, consistent with the γ-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 γ-rays. The second blob is assumed to have a smaller volume and a narrow electron energy distribution with 3 × 10^4<γ< 6 × 10^5, where γ 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 (δ, B and R), in addition to the parameters related to the particle population.

Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010

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