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Title: Unusual flaring activity in the blazar PKS 1424-418 during 2008-2011

Context. Blazars are a subset of active galactic nuclei (AGN) with jets that are oriented along our line of sight. Variability and spectral energy distribution (SED) studies are crucial tools for understanding the physical processes responsible for observed AGN emission. Aims. We report peculiar behaviour in the bright γ-ray blazar PKS 1424-418 and use its strong variability to reveal information about the particle acceleration and interactions in the jet. Methods. Correlation analysis of the extensive optical coverage by the ATOM telescope and nearly continuous γ-ray coverage by the Fermi Large Area Telescope is combined with broadband, time-dependent modeling of the SED incorporating supplemental information from radio and X-ray observations of this blazar. Results. We analyse in detail four bright phases at optical-GeV energies. These flares of PKS 1424-418 show high correlation between these energy ranges, with the exception of one large optical flare that coincides with relatively low γ-ray activity. Although the optical/ γ-ray behaviour of PKS 1424-418 shows variety, the multiwavelength modeling indicates that these differences can largely be explained by changes in the flux and energy spectrum of the electrons in the jet that are radiating. We find that for all flares the SED is adequately represented bymore » a leptonic model that includes inverse Compton emission from external radiation fields with similar parameters. Conclusions. Detailed studies of individual blazars like PKS 1424-418 during periods of enhanced activity in different wavebands are helping us identify underlying patterns in the physical parameters in this class of AGN.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [4] ;  [6] ;  [7] ;  [8] ;  [6] ;  [9] ;  [1] ;  [10] ;  [10] ;  [11] ;  [12] ;  [13] ;  [14] ;  [11] ;  [11] more »;  [15] ;  [16] ;  [17] ;  [16] ;  [18] ;  [19] ;  [20] « less
  1. Istituto Nazionale di Fisica Nucleare (INFN), Padova (Italy).; Univ. of Padova (Italy)
  2. Univ. of Trieste (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Triest (Italy)
  3. Stockholm Univ. (Sweden); AlbaNova, Stockholm (Sweden)
  4. Agenzia Spaziale Italiana (ASI) Science Data Center, Rome (Italy); Osservatorio Astronomico di Roma, Rome (Italy)
  5. Naval Research Lab. (NRL), Washington, DC (United States)
  6. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  7. Istituto Nazionale di Astrofisica (INAF), Bologna (Italy). Istituto di Radioastronomia
  8. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
  9. Univ. of Trieste (Italy)
  10. Univ. of Heidelberg (Germany)
  11. Max Planck Inst. for Radioastronomy, Bonn (Germany)
  12. The Catholic Univ. of America, Washington, DC (United States)
  13. Univ. of Wurzburg (Germany); Dr. Remeis-Sternwarte Bamberg (Germany)
  14. Univ. of Wurzburg (Germany); Dr. Remeis-Sternwarte Bamberg (Germany); Istituto Nazionale di Astrofisica (INAF), Bologna (Italy). Istituto di Radioastronomia; Erlangen Centre for Astroparticle Physics (Germany); Universities Space Research Association (USRA), Columbia, MD (United States)
  15. Commonwealth Scientific and Industrial Research Organization (CSIRO), Narrabri, NSW (Australia)
  16. Univ. of Tasmania, Hobart, TAS (Australia)
  17. Commonwealth Scientific and Industrial Research Organization (CSIRO), Epping, NSW (Australia)
  18. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  19. Space Science Inst., Boulder, CO (United States)
  20. California Inst. of Technology (CalTech), La Canada Flintridge, CA (United States). Jet Propulsion Lab.
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 569; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
OSTI Identifier:
1356445

Buson, S., Longo, F., Larsson, S., Cutini, S., Finke, J., Ciprini, S., Ojha, R., D’Ammando, F., Donato, D., Thompson, D. J., Desiante, R., Bastieri, D., Wagner, S., Hauser, M., Fuhrmann, L., Dutka, M., Müller, C., Kadler, M., Angelakis, E., Zensus, J. A., Stevens, J., Blanchard, J. M., Edwards, P. G., Lovell, J. E. J., Gurwell, M. A., Wehrle, A. E., and Zook, A.. Unusual flaring activity in the blazar PKS 1424-418 during 2008-2011. United States: N. p., Web. doi:10.1051/0004-6361/201423367.
Buson, S., Longo, F., Larsson, S., Cutini, S., Finke, J., Ciprini, S., Ojha, R., D’Ammando, F., Donato, D., Thompson, D. J., Desiante, R., Bastieri, D., Wagner, S., Hauser, M., Fuhrmann, L., Dutka, M., Müller, C., Kadler, M., Angelakis, E., Zensus, J. A., Stevens, J., Blanchard, J. M., Edwards, P. G., Lovell, J. E. J., Gurwell, M. A., Wehrle, A. E., & Zook, A.. Unusual flaring activity in the blazar PKS 1424-418 during 2008-2011. United States. doi:10.1051/0004-6361/201423367.
Buson, S., Longo, F., Larsson, S., Cutini, S., Finke, J., Ciprini, S., Ojha, R., D’Ammando, F., Donato, D., Thompson, D. J., Desiante, R., Bastieri, D., Wagner, S., Hauser, M., Fuhrmann, L., Dutka, M., Müller, C., Kadler, M., Angelakis, E., Zensus, J. A., Stevens, J., Blanchard, J. M., Edwards, P. G., Lovell, J. E. J., Gurwell, M. A., Wehrle, A. E., and Zook, A.. 2014. "Unusual flaring activity in the blazar PKS 1424-418 during 2008-2011". United States. doi:10.1051/0004-6361/201423367. https://www.osti.gov/servlets/purl/1356445.
@article{osti_1356445,
title = {Unusual flaring activity in the blazar PKS 1424-418 during 2008-2011},
author = {Buson, S. and Longo, F. and Larsson, S. and Cutini, S. and Finke, J. and Ciprini, S. and Ojha, R. and D’Ammando, F. and Donato, D. and Thompson, D. J. and Desiante, R. and Bastieri, D. and Wagner, S. and Hauser, M. and Fuhrmann, L. and Dutka, M. and Müller, C. and Kadler, M. and Angelakis, E. and Zensus, J. A. and Stevens, J. and Blanchard, J. M. and Edwards, P. G. and Lovell, J. E. J. and Gurwell, M. A. and Wehrle, A. E. and Zook, A.},
abstractNote = {Context. Blazars are a subset of active galactic nuclei (AGN) with jets that are oriented along our line of sight. Variability and spectral energy distribution (SED) studies are crucial tools for understanding the physical processes responsible for observed AGN emission. Aims. We report peculiar behaviour in the bright γ-ray blazar PKS 1424-418 and use its strong variability to reveal information about the particle acceleration and interactions in the jet. Methods. Correlation analysis of the extensive optical coverage by the ATOM telescope and nearly continuous γ-ray coverage by the Fermi Large Area Telescope is combined with broadband, time-dependent modeling of the SED incorporating supplemental information from radio and X-ray observations of this blazar. Results. We analyse in detail four bright phases at optical-GeV energies. These flares of PKS 1424-418 show high correlation between these energy ranges, with the exception of one large optical flare that coincides with relatively low γ-ray activity. Although the optical/ γ-ray behaviour of PKS 1424-418 shows variety, the multiwavelength modeling indicates that these differences can largely be explained by changes in the flux and energy spectrum of the electrons in the jet that are radiating. We find that for all flares the SED is adequately represented by a leptonic model that includes inverse Compton emission from external radiation fields with similar parameters. Conclusions. Detailed studies of individual blazars like PKS 1424-418 during periods of enhanced activity in different wavebands are helping us identify underlying patterns in the physical parameters in this class of AGN.},
doi = {10.1051/0004-6361/201423367},
journal = {Astronomy and Astrophysics},
number = ,
volume = 569,
place = {United States},
year = {2014},
month = {9}
}