X-ray spectral evolution of TeV BL Lacertae objects: eleven years of observations with BeppoSAX, XMM-Newton and Swift satellites

Massaro, F.; Tramacere, A.; Cavaliere, A.; Perri, M.; Giommi, P.

doi:10.1051/0004-6361:20078639

Cited by 127 publications

(169 citation statements)

References 34 publications

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“…These trends are relevant in understanding the physical mechanisms driving the evolution of the electron distribution under the effect of acceleration processes and may represent a common scenario for HBLs. Massaro et al (2008) confirmed that the E p − b relation holds for five of the TeV HBLs included in their analysis (PKS 0548-322, 1H 1426+418, Mrk 501, 1ES 1959+650, PKS 2155), and that, as for the S p − E p relation, the only exception to the previous list is PKS .…”

Section: Discussionsupporting

confidence: 64%

Swift observations of the very intense flaring activity of Mrk 421 during 2006. I. Phenomenological picture of electron acceleration and predictions for MeV/GeV emission

Tramacere¹,

Giommi

Perri

et al. 2009

A&A

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276

295

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Aims. We present the results of a deep spectral analysis of all Swift observations of Mrk 421 between April 2006 and July 2006, when it reached its highest X-ray flux recorded until the end of 2006. The peak flux was about 85 milli-Crab in the 2.0-10.0 keV band, and the peak energy (E p ) of the spectral energy distribution (SED) was often at energies higher than 10 keV. We study trends between the spectral parameters, and the physical insights the parameters provide into the underlying acceleration and emission mechanisms. Methods. We performed a spectral analysis of Swift observations to investigate trends between the spectral parameters. We searched for acceleration and energetic features phenomenologically linked to the SSC model parameters, by predicting their effects in the γ-ray band, and in particular, the spectral shape expected in the Fermi Gamma-ray Space Telescope-LAT band. Results. We confirm that the X-ray spectrum is described well by a log-parabolic distribution close to E p , that the peak flux of the SED (S p ) is correlated with E p , and that E p is anti-correlated with the curvature parameter (b). The spectral evolution in the Hardness-ratio-flux plane shows both clockwise and counter-clockwise patterns. During the most energetic flares, the UV-to-soft-X-ray spectral shape requires an electron distribution spectral index of s 2.3. Conclusions. We demonstrate that the UV-to-X-ray emission from Mrk 421 is probably generated by a population of electrons that is actually curved, and has a low energy power-law tail. The observed spectral curvature is consistent with both stochastic acceleration or energy-dependent acceleration probability mechanisms, whereas the power-law slope of XRT-UVOT data is close to that inferred from the GRBs X-ray afterglow and in agreement with the universal first-order relativistic shock acceleration models. This scenario implies that magnetic turbulence may play a twofold role: spatial diffusion relevant to the first order process and momentum diffusion relevant to the second order process.

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Section: Discussionsupporting

confidence: 64%

Swift observations of the very intense flaring activity of Mrk 421 during 2006. I. Phenomenological picture of electron acceleration and predictions for MeV/GeV emission

Tramacere¹,

Giommi

Perri

et al. 2009

A&A

Self Cite

276

295

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“…This is a trend often observed in HBL (see e.g. Massaro et al 2008;Tramacere et al 2007;Kataoka et al 1999), but quite rare for quasar-hosted blazars such as PKS 1510−089. For instance, 3C 454.3 shows approximately the same spectral slope in different brightness states (see e.g.…”

Section: Swift/xrt Datamentioning

confidence: 55%

AGILE detection of a rapid γ-ray flare from the blazar PKS 1510-089 during the GASP-WEBT monitoring

D’Ammando

Pucella²,

Raiteri

et al. 2009

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Aims. We report the detection by the AGILE satellite of a rapid γ-ray flare from the source 1AGL J1511−0908, associated with the powerful γ-ray quasar PKS 1510−089, during a pointing centered on the Galactic center region from 1 March to 30 March 2008. This source has been continuosly monitored in the radio-to-optical bands by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT). Moreover, the γ-ray flaring episode triggered three ToO observations by the Swi f t satellite in three consecutive days, starting from 20 March 2008. The quasisimultaneous radio-to-optical, UV, X-ray and γ-ray coverage allows us to make a detailed study of the multifrequency time evolution, the spectral energy distribution of this source, and its theoretical interpretation based on the synchrotron and inverse Compton (IC) emission mechanisms. Methods. During the radio-to-optical monitoring provided by the GASP-WEBT, AGILE observed the source with its two co-aligned imagers, the gamma-ray imaging detector (GRID) and the hard X-ray imager (SuperAGILE), which are sensitive in the 30 MeV-30 GeV and 18-60 keV energy bands, respectively. Results. In the period 1-16 March 2008, AGILE detected γ-ray emission from PKS 1510−089 at a significance level of 6.2-σ with an average flux over the entire period of (84 ± 17) × 10 −8 photons cm −2 s −1 for photon energies above 100 MeV. After a predefined satellite re-pointing, between 17 and 21 March 2008, AGILE detected the source at a significance level of 7.3-σ, with an average flux (E > 100 MeV) of (134 ± 29) × 10 −8 photons cm −2 s −1 and a peak level of (281 ± 68) × 10 −8 photons cm −2 s −1 with daily integration. During the observing period January-April 2008, the source also showed an intense and variable optical activity, with several flaring episodes and a significant increase in the flux was observed at millimetric frequencies. Moreover, in the X-ray band, the Swi f t/XRT observations seem to show a harder-when-brighter behavior of the source spectrum. Conclusions. The flat spectrum radio quasar PKS 1510−089 showed strong activity between January and April 2008, with episodes of rapid variability from radio to γ-ray energy bands, in particular with a rapid γ-ray flaring episode. The spectral energy distribution of mid-March 2008 is modeled with a homogeneous one-zone synchrotron self Compton (SSC) emission plus contributions from inverse Compton scattering of external photons from both the accretion disk and the broad line region. Indeed, some features in the optical-UV spectrum seem to indicate Seyfert-like components such as the little and the big blue bumps.

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“…Donato et al (2005) also found significant concave curvature after the break energy of ∼1.71 keV. Massaro et al (2008) also preferred log-parabolic model for the BeppoSAX observations of this source. Raiteri et al (2009) analyzed the XMM−Newton observations of this source during the period 2007-2008 in its low state and found significant concave curvature in all of the observations.…”

Section: S4 0954+65mentioning

confidence: 89%

“…One expects that FSRQs would have a flatter spectra (index Γ < 2), while the LSPs and ISPs would have intermediate slopes (with index Γ=1.5-1.8), or even concave X-ray continua (e.g. Donato et al 2005;Massaro et al 2008;Wierzcholska & Wagner 2016). In previous studies, it was inferred that the X-ray spectra of blazars is well described by a single power law or a broken power law (e.g.…”

Section: Introductionmentioning

confidence: 99%

Signature of inverse Compton emission from blazars

Gaur

Mohan

Wierzcholska

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Blazars are classified into high, intermediate and low energy peaked sources based on the location of their synchrotron peak. This lies in infra-red/optical to ultra-violet bands for low and intermediate peaked blazars. The transition from synchrotron to inverse Compton emission falls in the X-ray bands for such sources. We present the spectral and timing analysis of 14 low and intermediate energy peaked blazars observed with XMMNewton spanning 31 epochs. Parametric fits to X-ray spectra helps constrain the possible location of transition from the high energy end of the synchrotron to the low energy end of the inverse Compton emission. In seven sources in our sample, we infer such a transition and constrain the break energy in the range 0.6 10 keV. The Lomb-Scargle periodogram is used to estimate the power spectral density (PSD) shape. It is well described by a power law in a majority of light curves, the index being flatter compared to general expectation from AGN, ranging here between 0.01 and 1.12, possibly due to short observation durations resulting in an absence of long term trends. A toy model involving synchrotron self-Compton (SSC) and external Compton (EC; disk, broad line region, torus) mechanisms are used to estimate magnetic field strength 0.03 -0.88 G in sources displaying the energy break and infer a prominent EC contribution. The timescale for variability being shorter than synchrotron cooling implies steeper PSD slopes which are inferred in these sources.

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X-ray spectral evolution of TeV BL Lacertae objects: eleven years of observations with BeppoSAX, XMM-Newton and Swift satellites

Cited by 127 publications

References 34 publications

Swift observations of the very intense flaring activity of Mrk 421 during 2006. I. Phenomenological picture of electron acceleration and predictions for MeV/GeV emission

Swift observations of the very intense flaring activity of Mrk 421 during 2006. I. Phenomenological picture of electron acceleration and predictions for MeV/GeV emission

AGILE detection of a rapid γ-ray flare from the blazar PKS 1510-089 during the GASP-WEBT monitoring

Signature of inverse Compton emission from blazars

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