2009A&A...501..879T


Query : 2009A&A...501..879T

2009A&A...501..879T - Astronomy and Astrophysics, volume 501, 879-898 (2009/7-3)

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.

TRAMACERE A., GIOMMI P., PERRI M., VERRECCHIA F. and TOSTI G.

Abstract (from CDS):

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 2.0-10.0keV band, and the peak energy (Ep) of the spectral energy distribution (SED) was often at energies higher than 10keV. We study trends between the spectral parameters, and the physical insights the parameters provide into the underlying acceleration and emission mechanisms. 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. We confirm that the X-ray spectrum is described well by a log-parabolic distribution close to Ep, that the peak flux of the SED (Sp) is correlated with Ep, and that Ep 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. 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.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: BL Lacertae objects: individual: Mrk 421 - X-rays: individual: Mrk 421 - radiation mechanisms: non-thermal - acceleration of particles

CDS comments: Paragraph.10 1ES 128-304 is a misprint for 1ES 1218+30.4

Simbad objects: 11

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Number of rows : 11
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 QSO B0548-322 BLL 05 50 40.5706739558 -32 16 16.488658537   16.07 15.5     ~ 381 1
2 2A 1058-226 BLL 11 03 37.6150843895 -23 29 31.202114088   17.00 16.55 16.61   ~ 336 2
3 Mrk 421 BLL 11 04 27.3139210166 +38 12 31.798324828   13.50 12.90 8.31   ~ 2478 1
4 * 51 UMa PM* 11 04 31.2214215951 +38 14 28.919071134   6.18 6.02 7.39 5.86 A3III-IV 73 0
5 QSO B1218+304 BLL 12 21 21.9427463316 +30 10 37.161573795   16.50 15.85 15.7   ~ 416 1
6 QSO B1426+428 BLL 14 28 32.6090831425 +42 40 21.050020627   16.95 16.45 14.4   ~ 471 2
7 4C 39.49 BLL 16 53 52.21668494 +39 45 36.6089458 14.09 14.15 13.29 8.26   ~ 1992 2
8 QSO B1959+650 BLL 19 59 59.8525497024 +65 08 54.651170114     12.8 11.21   ~ 539 2
9 QSO B2155-304 BLL 21 58 52.0651817803 -30 13 32.120657891   13.36 13.09 12.62   ~ 1624 1
10 NAME BL Lac BLL 22 02 43.2913773726 +42 16 39.978417860   15.66 14.72     ~ 2084 1
11 QSO B2356-309 BLL 23 59 07.9032684889 -30 37 40.667900741   18.414 16.44 16.795   ~ 263 1

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2021.12.03-18:52:09

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