THE FIRST<i>FERMI</i>MULTIFREQUENCY CAMPAIGN ON BL LACERTAE: CHARACTERIZING THE LOW-ACTIVITY STATE OF THE EPONYMOUS BLAZAR

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

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

Cited by 62 publications

(54 citation statements)

References 56 publications

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“…There was no apparent activity in the soft X-ray either, but changes in flux may have occurred at UV and optical wavelengths (although there was no UVOT coverage during the TeV gamma-ray flare). The XRT spectrum was relatively hard, with a photon index of ∼1.8, compared to that obtained during the Fermi-LAT campaign during a low state in 2008 (Abdo et al 2011). There was no apparent variation in the radio flux from the source at the time of the TeV gamma-ray flare.…”

Section: Gamma-ray Propertiesmentioning

confidence: 79%

“…Interestingly, according to Raiteri et al (2009), the IR flux of BL Lacertae did not vary significantly (within a factor two) during their long-term monitoring (for over 150 days) in 2007-2008 (see also Abdo et al 2011). It is also worth noting that the synchrotron SED peak of BL Lacertae lies in the near-IR band, and the archival SEDs between the near-IR and the X-ray can be roughly described by a power law (e.g., Böttcher et al 2003;Raiteri et al 2010;Abdo et al 2011). The spectral index (α) varied in the range 1.34-1.40 in the frequency range 7 × 10 13 -10 17 Hz.…”

Section: Discussionmentioning

confidence: 92%

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RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

Arlen¹,

Aune²,

Beilicke³

et al. 2012

ApJ

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100

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We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6 minute exposure, when the integral flux above 200 GeV reached (3.4 ± 0.6) × 10 −6 photons m −2 s −1 , roughly 125% of the Crab Nebula flux measured by VERITAS. The light curve indicates that the observations missed the rising phase of the flare but covered a significant portion of the decaying phase. The exponential decay time was determined to be 13 ± 4 minutes, making it one of the most rapid gamma-ray flares seen from a TeV blazar. The gamma-ray spectrum of BL Lacertae during the flare was soft, with a photon index of 3.6 ± 0.4, which is in agreement with the measurement made previously by MAGIC in a lower flaring state. component from the core around the time of the TeV gamma-ray flare, accompanied by changes in the optical polarization angle. Changes in flux also appear to have occurred at optical, UV, and GeV gamma-ray wavelengths at the time of the flare, although they are difficult to quantify precisely due to sparse coverage. A strong flare was seen at radio wavelengths roughly four months later, which might be related to the gamma-ray flaring activities. We discuss the implications of these multiwavelength results.

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Section: Gamma-ray Propertiesmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 92%

RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

Arlen¹,

Aune²,

Beilicke³

et al. 2012

ApJ

Self Cite

100

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show abstract

“…For each time bin, the integrated flux values were computed using the maximum-likelihood algorithm implemented in the science tool gtlike to estimate significance of the results. We used a detection criteria which corresponds to a maximumlikelihood test statistic TS > 4 or the number of model predicted photons is higher than 10 ( Abdo et al 2011). Otherwise a 2σ upper limit of the flux was computed.…”

Section: Gamma-ray Fermi /Lat Datamentioning

confidence: 99%

Multiwavelength observations of the γ-ray flaring quasar S4 1030+61 in 2009–2014

Kravchenko

Kovalev

Hovatta

2016

Mon. Not. R. Astron. Soc.

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We present a study of the parsec-scale multi-frequency properties of the quasar S4 1030+61 during a prolonged radio and γ-ray activity. Observations were performed within Fermi γ-ray telescope, OVRO 40-m telescope and MOJAVE VLBA monitoring programs, covering five years from 2009. The data are supplemented by four-epoch VLBA observations at 5, 8, 15, 24, and 43 GHz, which were triggered by the bright γ-ray flare, registered in the quasar in 2010. The S4 1030+61 jet exhibits an apparent superluminal velocity of (6.4±0.4)c and does not show ejections of new components in the observed period, while decomposition of the radio light curve reveals nine prominent flares. The measured variability parameters of the source show values typical for Fermi-detected quasars. Combined analysis of radio and γ-ray emission implies a spatial separation between emitting regions at these bands of about 12 pc and locates the γ-ray emission within a parsec from the central engine. We detected changes in the value and direction of the linear polarization and the Faraday rotation measure. The value of the intrinsic brightness temperature of the core is above the equipartition state, while its value as a function of distance from the core is well approximated by the power-law. Altogether these results show that the radio flaring activity of the quasar is accompanied by injection of relativistic particles and energy losses at the jet base, while S4 1030+61 has a stable, straight jet well described by standard conical jet theories.

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“…Abdo et al (2011) completed a pre-planned multiwavelength campaign that caught BL Lac in a low, relatively quiescent state. Most recently, Raiteri et al (2013) reported on Fermi, Swift, Submillimeter Array (SMA) and Whole Earth Blazar Telescope 11 observations beginning in 2008, through an episode of strong activity in [2011][2012], and continuing to 2012 October 31.…”

Section: Introductionmentioning

confidence: 99%

“…We processed the data as described by Marscher et al (2008), fitting the photon count spectrum with a single power law plus photoelectric absorption corresponding to a neutral hydrogen column density of 2.7 × 10 21 cm −2 (Madejski et al 1999). We note that Abdo et al (2011) found that changing the absorbing column density from N H = 2.0 × 10 21 cm −2 to 3.6 × 10 21 cm −2 changes the energy index by less than 0.02. We estimate that a similar increase from N H = 2.7 × 10 21 cm −2 to 3.4 × 10 21 cm −2 changes the flux by 5%; since the RXTE data are shown primarily for historical context and to demonstrate changes of the energy index with brightness, we have not re-reduced the data with the larger, more current value of the hydrogen column density, N H = 3.4 × 10 21 cm −2 ).…”

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confidence: 99%

Erratic Flaring of Bl Lac in 2012–2013: Multiwavelength Observations

Wehrle

Grupe

Jorstad

et al. 2016

ApJ

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BL Lac, the eponymous blazar, flared to historically high levels at millimeter, infrared, X-ray, and gamma-ray wavelengths in 2012. We present observations made with Herschel, Swift, NuSTAR, Fermi, the Submillimeter Array, CARMA, and the VLBA in 2012-2013, including three months with nearly daily sampling at several wavebands. We have also conducted an intensive campaign of 30 hr with every-orbit observations by Swift and NuSTAR, accompanied by Herschel, and Fermi observations. The source was highly variable at all bands. Time lags, correlations between bands, and the changing shapes of the spectral energy distributions can be explained by synchrotron radiation and inverse Compton emission from nonthermal seed photons originating from within the jet. The passage of four new superluminal very long baseline interferometry knots through the core and two stationary knots about 4 pc downstream accompanied the high flaring in 2012-2013. The seed photons for inverse Compton scattering may arise from the stationary knots and from a Mach disk near the core where relatively slowmoving plasma generates intense nonthermal radiation. The 95 spectral energy distributions obtained on consecutive days form the most densely sampled, broad wavelength coverage for any blazar. The observed spectral energy distributions and multi-waveband light curves are similar to simulated spectral energy distributions and light curves generated with a model in which turbulent plasma crosses a conical shock with a Mach disk.

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THE FIRSTFERMIMULTIFREQUENCY CAMPAIGN ON BL LACERTAE: CHARACTERIZING THE LOW-ACTIVITY STATE OF THE EPONYMOUS BLAZAR

Cited by 62 publications

References 56 publications

RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

Multiwavelength observations of the γ-ray flaring quasar S4 1030+61 in 2009–2014

Erratic Flaring of Bl Lac in 2012–2013: Multiwavelength Observations

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