The first Fermi multifrequency campaign on BL Lacertae: characterizing the low-activity state of the eponymous blazar

A. A. Abdo; M. Ackermann; M. Ajello; E. Antolini; L. Baldini; Jean Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. Bonamente; A. W. Borgland; J. Bregeon; A. Brez; M. Brigida; Pascal Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; A. Cannon; P. A. Caraveo; S. Carrigan; J. M. Casandjian; C. Cecchi; Ö. Çelik; E. Charles; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; L. Costamante; S. Cutini; C. D. Dermer; F. de Palma; D. Donato; E. Do Couto E Silva; P. S. Drell; R. Dubois; L. Escande; C. Favuzzi; S. J. Fegan; J. Finke; W. B. Focke; P. Fortin; M. Frailis; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; N. Giglietto; F. Giordano; M. Giroletti; T. Glanzman; G. Godfrey; I. A. Grenier; S. Guiriec; D. Hadasch; M. Hayashida; E. Hays; R. E. Hughes; R. Itoh; G. Jóhannesson; A. S. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; Jürgen Knödlseder; M. Kuss; J. Lande; S. Larsson; L. Latronico; S.-H. Lee; M. Llena Garde; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; A. Makeev; M. N. Mazziotta; J. E. Mcenery; J. Mehault; P. F. Michelson; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; T. Nakamori; M. Naumann-Godo; S. Nishino; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; A. Okumura; N. Omodei; E. Orlando; J. F. Ormes; M. Ozaki; D. Paneque; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Reimer; O. Reimer; S. Ritz; M. Roth; H. F.-W. Sadrozinski; D. Sanchez; A. Sander; F. K. Schinzel; C. Sgrò; E. J. Siskind; P. D. Smith; K. V. Sokolovsky; G. Spandre; P. Spinelli; M. S. Strickman; D. J. Suson; H. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; T. Uehara; T. L. Usher; J. Vandenbroucke; V. Vasileiou; N. Vilchez; V. Vitale; A. P. Waite; E. Wallace; P. Wang; B. L. Winer; K. S. Wood; Z. Yang; T. Ylinen; M. Ziegler; A. Berdyugin; M. Boettcher; A. Carramiñana; L. Carrasco; E. de La Fuente; C. Diltz; T. Hovatta; V. Kadenius; Y. Y. Kovalev; A. Lähteenmäki; E. Lindfors; A. P. Marscher; K. Nilsson; D. Pereira; R. Reinthal; P. Roustazadeh; T. Savolainen; A. Sillanpää; L. O. Takalo; M. Tornikoski

doi:10.1088/0004-637X/730/2/101

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The first Fermi multifrequency campaign on BL Lacertae: characterizing the low-activity state of the eponymous blazar

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The first Fermi multifrequency campaign on BL Lacertae: characterizing the low-activity state of the eponymous blazar

A. A. Abdo, M. Ackermann, M. Ajello, E. Antolini, L. Baldini, Jean Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, …

The Astrophysical Journal, Vol.730

01/04/2011

DOI: https://doi.org/10.1088/0004-637X/730/2/101

Abstract

BL Lacertae objects: general

BL Lacertae objects: individual (BL Lacertae)

galaxies: jets

gamma rays: galaxies

radiation mechanisms: non-thermal

X-rays: galaxies

98.54.Cm Active and peculiar galaxies and related systems (including BL Lacertae objects, blazars, Seyfert galaxies, Markarian galaxies, and active galactic nuclei) 95.85.Pw &ggr;-ray 95.30.Gv Radiation mechanisms; polarization 98.62.En

We report on observations of BL Lacertae during the first 18 months of Fermi-LAT science operations and present results from a 48-day multifrequency coordinated campaign from 2008 August 19 to 2008 October 7. The radio to gamma-ray behavior of BL Lac is unveiled during a low activity state thanks to the coordinated observations of radio-band (Metsahovi and VLBA), near-IR/optical (Tuorla, Steward, OAGH and MDM) and X-ray (RXTE and Swift) observatories. No variability was resolved in gamma-rays during the campaign, and the brightness level was 15 times lower than the level of the 1997 EGRET outburst. Moderate and uncorrelated variability has been detected in UV and X-rays. The X-ray spectrum is found to be concave indicating the transition region between the low and high energy component of the spectral energy distribution (SED). VLBA observation detected a synchrotron spectrum self-absorption turnover in the innermost part of the radio jet appearing to be elongated and inhomogeneous, and constrained the average magnetic field there to be less than 3 G. Over the following months BL Lac appeared variable in gamma-rays, showing flares (in 2009 April and 2010 January). There is no evidence for correlation of the gamma-rays with the optical flux monitored from the ground in 18 months. The SED may be described by a single zone or two zone synchrotron self-Compton (SSC) model, but a hybrid SSC plus external radiation Compton (ERC) model seems preferred based on the observed variability and the fact that it provides a fit closest to equipartition.

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Title: The first Fermi multifrequency campaign on BL Lacertae: characterizing the low-activity state of the eponymous blazar
Creators - without role: A. A. Abdo - National Academy of Sciences
M. Ackermann - Kavli Institute for Particle Astrophysics and Cosmology
M. Ajello - Kavli Institute for Particle Astrophysics and Cosmology
E. Antolini - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
L. Baldini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
Jean Ballet - Astrophysique, Instrumentation et Modélisation
G. Barbiellini - University of Trieste
D. Bastieri - University of Padua
K. Bechtol - Kavli Institute for Particle Astrophysics and Cosmology
R. Bellazzini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
B. Berenji - Kavli Institute for Particle Astrophysics and Cosmology
R. D. Blandford - Kavli Institute for Particle Astrophysics and Cosmology
E. Bonamente - University of Perugia
A. W. Borgland - Stanford University
J. Bregeon - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
A. Brez - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
M. Brigida - Polytechnic University of Bari
Pascal Bruel - École Polytechnique
R. Buehler - Kavli Institute for Particle Astrophysics and Cosmology
S. Buson - University of Padua
G. A. Caliandro - Institute of Space Sciences
R. A. Cameron - Kavli Institute for Particle Astrophysics and Cosmology
A. Cannon - Goddard Space Flight Center
P. A. Caraveo - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
S. Carrigan - University of Padua
J. M. Casandjian - Université Paris Cité
C. Cecchi - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
Ö. Çelik - Goddard Space Flight Center
E. Charles - Kavli Institute for Particle Astrophysics and Cosmology
A. Chekhtman - United States Naval Research Laboratory
C. C. Cheung - United States Naval Research Laboratory
J. Chiang - Kavli Institute for Particle Astrophysics and Cosmology
S. Ciprini - University of Perugia
R. Claus - Kavli Institute for Particle Astrophysics and Cosmology
J. Cohen-Tanugi - Université de Montpellier
J. Conrad - Stockholm University
L. Costamante - Kavli Institute for Particle Astrophysics and Cosmology
S. Cutini - Agenzia Spaziale Italiana
C. D. Dermer - United States Naval Research Laboratory
F. de Palma - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
D. Donato - University of Maryland, College Park
E. Do Couto E Silva
P. S. Drell - Kavli Institute for Particle Astrophysics and Cosmology
R. Dubois - Kavli Institute for Particle Astrophysics and Cosmology
L. Escande - Laboratoire de Physique des deux infinis Bordeaux
C. Favuzzi - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
S. J. Fegan - Laboratoire Leprince-Ringuet
J. Finke - National Academy of Sciences
W. B. Focke - Stanford University
P. Fortin - Centre National de la Recherche Scientifique
M. Frailis - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
Y. Fukazawa - Hiroshima University
S. Funk - Kavli Institute for Particle Astrophysics and Cosmology
P. Fusco - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
F. Gargano - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
D. Gasparrini - Agenzia Spaziale Italiana
N. Gehrels - Goddard Space Flight Center
S. Germani - University of Perugia
N. Giglietto - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
F. Giordano - Polytechnic University of Bari
M. Giroletti - Istituto di Radioastronomia di Bologna
T. Glanzman - Kavli Institute for Particle Astrophysics and Cosmology
G. Godfrey - Kavli Institute for Particle Astrophysics and Cosmology
I. A. Grenier - CEA Paris-Saclay
S. Guiriec - University of Alabama in Huntsville
D. Hadasch - Institute of Space Sciences
M. Hayashida - Kavli Institute for Particle Astrophysics and Cosmology
E. Hays - Goddard Space Flight Center
R. E. Hughes - The Ohio State University
R. Itoh - Hiroshima University
G. Jóhannesson - University of Iceland
A. S. Johnson - Stanford University
W. N. Johnson - United States Naval Research Laboratory
T. Kamae - Kavli Institute for Particle Astrophysics and Cosmology
H. Katagiri - Hiroshima University
J. Kataoka - Waseda University
Jürgen Knödlseder - Centre National d'Études Spatiales
M. Kuss - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
J. Lande - Kavli Institute for Particle Astrophysics and Cosmology
S. Larsson - Fraunhofer Chalmers Research Centre for Industrial Mathematics
L. Latronico - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
S.-H. Lee - Kavli Institute for Particle Astrophysics and Cosmology
M. Llena Garde
F. Longo - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
F. Loparco - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
B. Lott - Laboratoire de Physique des deux infinis Bordeaux
M. N. Lovellette - United States Naval Research Laboratory
P. Lubrano - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
A. Makeev - United States Naval Research Laboratory
M. N. Mazziotta - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
J. E. Mcenery - University of Maryland, College Park
J. Mehault - Institut National de Physique Nucléaire et de Physique des Particules
P. F. Michelson - Kavli Institute for Particle Astrophysics and Cosmology
T. Mizuno - Hiroshima University
C. Monte - Polytechnic University of Bari
M. E. Monzani - Kavli Institute for Particle Astrophysics and Cosmology
A. Morselli - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
I. V. Moskalenko - Stanford University
S. Murgia - Kavli Institute for Particle Astrophysics and Cosmology
T. Nakamori - Waseda University
M. Naumann-Godo - CEA Paris-Saclay
S. Nishino - Hiroshima University
P. L. Nolan - Kavli Institute for Particle Astrophysics and Cosmology
J. P. Norris - University of Denver
E. Nuss - Institut National de Physique Nucléaire et de Physique des Particules
T. Ohsugi - Hiroshima University
A. Okumura - Institute of Space and Astronautical Science
N. Omodei - Kavli Institute for Particle Astrophysics and Cosmology
E. Orlando - Max Planck Institute for Extraterrestrial Physics
J. F. Ormes - University of Denver
M. Ozaki - Institute of Space and Astronautical Science
D. Paneque - Kavli Institute for Particle Astrophysics and Cosmology
J. H. Panetta - Kavli Institute for Particle Astrophysics and Cosmology
D. Parent - George Mason University
V. Pelassa - Institut National de Physique Nucléaire et de Physique des Particules
M. Pepe - University of Perugia
M. Pesce-Rollins - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
F. Piron - Laboratoire de Physique Théorique
T. A. Porter - Kavli Institute for Particle Astrophysics and Cosmology
S. Rainò - Polytechnic University of Bari
R. Rando - Istituto Nazionale di Fisica Nucleare, Sezione di Padova
M. Razzano - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
A. Reimer - Kavli Institute for Particle Astrophysics and Cosmology
O. Reimer - Stanford University
S. Ritz - University of California, Santa Cruz
M. Roth - University of Washington
H. F.-W. Sadrozinski - University of California, Santa Cruz
D. Sanchez - École Polytechnique
A. Sander - The Ohio State University
F. K. Schinzel - Max Planck Institute for Radio Astronomy
C. Sgrò - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
E. J. Siskind - Real Time Tomography
P. D. Smith - The Ohio State University
K. V. Sokolovsky - Max Planck Institute for Radio Astronomy
G. Spandre - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
P. Spinelli - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
M. S. Strickman - United States Naval Research Laboratory
D. J. Suson - Purdue University Northwest
H. Takahashi - Hiroshima University
T. Tanaka - Kavli Institute for Particle Astrophysics and Cosmology
J. B. Thayer - Kavli Institute for Particle Astrophysics and Cosmology
J. G. Thayer - Kavli Institute for Particle Astrophysics and Cosmology
D. J. Thompson - Goddard Space Flight Center
L. Tibaldo - Astrophysique, Instrumentation et Modélisation
D. F. Torres - Institució Catalana de Recerca i Estudis Avançats
G. Tosti - University of Perugia
A. Tramacere - Kavli Institute for Particle Astrophysics and Cosmology
T. Uehara - Hiroshima University
T. L. Usher - Kavli Institute for Particle Astrophysics and Cosmology
J. Vandenbroucke - Kavli Institute for Particle Astrophysics and Cosmology
V. Vasileiou - Goddard Space Flight Center
N. Vilchez - Université Toulouse III - Paul Sabatier
V. Vitale - University of Rome Tor Vergata
A. P. Waite - Kavli Institute for Particle Astrophysics and Cosmology
E. Wallace - University of Washington
P. Wang - SLAC National Accelerator Laboratory
B. L. Winer - The Ohio State University
K. S. Wood - United States Naval Research Laboratory
Z. Yang - Fraunhofer Chalmers Research Centre for Industrial Mathematics
T. Ylinen - Fraunhofer Chalmers Research Centre for Industrial Mathematics
M. Ziegler - University of California, Santa Cruz
A. Berdyugin - University of Turku
M. Boettcher - Ohio University
A. Carramiñana - National Institute of Astrophysics, Optics and Electronics
L. Carrasco - National Institute of Astrophysics, Optics and Electronics
E. de La Fuente - Universidad de Guadalajara
C. Diltz - Ohio University
T. Hovatta - Aalto University
V. Kadenius - University of Turku
Y. Y. Kovalev - Max Planck Institute for Radio Astronomy
A. Lähteenmäki - Aalto University
E. Lindfors - University of Turku
A. P. Marscher - Boston University
K. Nilsson - Turku Centre for Computer Science
D. Pereira - Goddard Space Flight Center
R. Reinthal - University of Turku
P. Roustazadeh - Ohio University
T. Savolainen - Max Planck Institute for Radio Astronomy
A. Sillanpää - University of Turku
L. O. Takalo - University of Turku
M. Tornikoski - Aalto University
Publication Details: The Astrophysical Journal, Vol.730
Identifiers: 9934372609311
Academic Unit: Université de Montpellier
Language: English
Resource Type: Journal article
Local Fields: in2p3-00587827