3C 66B as a TeV radio galaxy

Tavecchio, F.; Ghisellini, G.

doi:10.1111/j.1745-3933.2009.00629.x

Cited by 18 publications

(16 citation statements)

References 46 publications

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“…There are also other possible two-zone model setups, such as a spine-sheath model (Ghisellini et al 2005), where a slower sheath of the jet surrounds a faster spine. For the previous VHE γ-ray flaring epoch, a spine-sheath model (Ghisellini et al 2005) was shown to provide a reasonable fit to the SED data (Anderhub et al 2009;Tavecchio & Ghisellini 2009). We tested the spine-sheath model for the SEDs shown here and found acceptable agreement with the SED data.…”

Section: Broadband Sedmentioning

confidence: 51%

“…The analysis of multi-wavelength data suggested a correlation between the VHE γ-ray and optical emission. A structured jet model, composed of a fast spine surrounded by a slower-moving layer (Ghisellini et al 2005;Tavecchio & Ghisellini 2009) better described the data compared to a simple one-zone SSC model. This source is also among the bright blazars in the Fermi-LAT (Large Area Telescope) bright active galactic nuclei (AGNs) sample (LBAS; Abdo et al 2010a) and in the Fermi third catalog (Acero et al 2015) it is one of the blazars with the highest variability index.…”

Section: Introductionmentioning

confidence: 96%

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Multi-wavelength characterization of the blazar S5 0716+714 during an unprecedented outburst phase

Ahnen¹,

Ansoldi²,

Antonelli³

et al. 2018

A&A

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Context. The BL Lac object S5 0716+714, a highly variable blazar, underwent an impressive outburst in January 2015 (Phase A), followed by minor activity in February (Phase B). The MAGIC observations were triggered by the optical flux observed in Phase A, corresponding to the brightest ever reported state of the source in the R-band. Aims.The comprehensive dataset collected is investigated in order to shed light on the mechanism of the broadband emission. Methods. Multi-wavelength light curves have been studied together with the broadband spectral energy distributions (SEDs). The sample includes data from Effelsberg, OVRO, Metsähovi, VLBI, CARMA, IRAM, SMA, Swift-UVOT, KVA, Tuorla, Steward, RINGO3, KANATA, AZT-8+ST7, Perkins, LX-200, Swift-XRT, NuSTAR, Fermi-LAT and MAGIC. Results. The flaring state of Phase A was detected in all the energy bands, providing for the first time a multi-wavelength sample of simultaneous data from the radio band to the very-high-energy (VHE, E > 100 GeV). In the constructed SED, the Swift-XRT+NuSTAR data constrain the transition between the synchrotron and inverse Compton components very accurately, while the second peak is constrained from 0.1 GeV to 600 GeV by Fermi+MAGIC data. The broadband SED cannot be described with a one-zone synchrotron self-Compton model as it severely underestimates the optical flux in order to reproduce the X-ray to γ-ray data. Instead we use a two-zone model. The electric vector position angle (EVPA) shows an unprecedented fast rotation. An estimation of the redshift of the source by combined high-energy (HE, 0.1 GeV < E < 100 GeV) and VHE data provides a value of z = 0.31 ± 0.02stats ± 0.05sys, confirming the literature value. Conclusions. The data show the VHE emission originating in the entrance and exit of a superluminal knot in and out of a recollimation shock in the inner jet. A shock–shock interaction in the jet seems responsible for the observed flares and EVPA swing. This scenario is also consistent with the SED modeling.

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Section: Broadband Sedmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 96%

Multi-wavelength characterization of the blazar S5 0716+714 during an unprecedented outburst phase

Ahnen¹,

Ansoldi²,

Antonelli³

et al. 2018

A&A

View full text Add to dashboard Cite

show abstract

“…PKS 1424+240 and PG 1553+113 have been detected at TeV energies [see Ong et al (2009) and Teshima et al (2009) for 1424+240, and Aharonian et al (2006) and Albert et al (2007) for PG 1553+113; see also Prandini et al (2010)], and very likely also 3C 66A (Acciari et al 2009), although there can be a contamination from the nearby 3C 66B radio‐galaxy (see the discussion in Tavecchio & Ghisellini 2009). The redshift of 3C 66A is uncertain, even if a value of z = 0.444 is commonly used.…”

Section: The Fermi Blazars’ Divide One Year Aftermentioning

confidence: 99%

The transition between BL Lac objects and flat spectrum radio quasars

Ghisellini

Tavecchio

Foschini

et al. 2011

Monthly Notices of the Royal Astronomical Society

349

344

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We study the BL Lac objects detected in the 1‐year all‐sky survey of the Fermi satellite, with an energy spectral slope αγ in the 0.1–100 GeV band greater than 1.2. In the αγ versus γ‐ray luminosity plane, these BL Lacs occupy the region populated by flat spectrum radio quasars (FSRQs). Studying the properties of their spectral energy distributions (SEDs) and of their emitting lines, we find that several of these BL Lacs have an SED similar to FSRQs and that they do have broad lines of large equivalent width (EW), and should be reclassified as FSRQs even adopting the current phenomenological definition (i.e. EW of the emitting line greater than 5 Å). In other cases, even if the EW is small, the emitting lines can be as luminous as in quasars, and again their SED is similar to the SED of FSRQs. Sources classified as BL Lacs with an SED appearing as intermediate between BL Lacs and FSRQs also have relatively weak broad emission lines and small EW, and can be considered as transition sources. These properties are confirmed also by model fitting that allows us to derive the relevant intrinsic jet parameters and the jet power. This study leads us to propose a physical distinction between the two classes of blazars, based on the luminosity of the broad‐line region measured in Eddington units. The dividing line is of the order of LBLR/LEdd∼ 5 × 10−4, in good agreement with the idea that the presence of strong emitting lines is related to a transition in the accretion regime, becoming radiatively inefficient below a disc luminosity of the order of 1 per cent of the Eddington one.

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“…Although the SSC model reproduces the SED well when only the LAT data are considered, the fit of the TeV emission observed in 2008 April by MAGIC is difficult, although feasible (Anderhub et al 2009), requiring a rather broad high‐energy component extending above 300 GeV. Also in this case a viable solution invokes the emission from a structured jet (Tavecchio & Ghisellini 2009; Anderhub et al 2009).…”

Section: Modelling Of the Spectral Energy Distributionsmentioning

confidence: 99%

TeV BL Lac objects at the dawn of theFermiera

Tavecchio

Ghisellini

Ghirlanda

et al. 2010

Monthly Notices of the Royal Astronomical Society

266

282

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We reconsider the emission properties of BL Lac objects emitting in the high‐energy γ‐ray band, by exploiting the information in the MeV–GeV band obtained by the Large Area Telescope (LAT) on board the Fermi Gamma‐Ray Space Telescope in its first three months of operation. To this aim we construct the spectral energy distribution of all the BL Lacs revealed by LAT and of the known TeV BL Lacs not detected by LAT, also including data from the Swift satellite, and model them with a simple one‐zone leptonic model. The analysis shows that the BL Lacs detected by LAT (whether or not already detected in the TeV band) share similar physical parameters. While some of the TeV BL Lacs not revealed by LAT have spectral energy distributions and physical parameters very similar to the LAT BL Lacs, one group of objects displays peculiar properties (larger electron energies and smaller magnetic fields), suggesting different physical conditions in the emission region. Finally, we discuss possible criteria to select in an effective manner good new candidates for the Cherenkov telescopes among the LAT sources, presenting a list of predicted fluxes in the very high‐energy band calculated including the effects of absorption by extragalactic background light.

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3C 66B as a TeV radio galaxy

Cited by 18 publications

References 46 publications

Multi-wavelength characterization of the blazar S5 0716+714 during an unprecedented outburst phase

Multi-wavelength characterization of the blazar S5 0716+714 during an unprecedented outburst phase

The transition between BL Lac objects and flat spectrum radio quasars

TeV BL Lac objects at the dawn of theFermiera

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