On invisible plasma content in radio-loud AGNs: the case of TeV blazar Markarian 421 |
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| Authors: | M Kino F Takahara |
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| Institution: | ISAS/JAXA, 3-1-1 Yoshinodai, 229-8510 Sagamihara, Japan;Department of Science &Engineering, Waseda University, 169-8555 Tokyo, Japan;Department of Earth and Space Science, Osaka University, 560-0043 Toyonaka, Japan |
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| Abstract: | Invisible plasma content in blazar jets such as protons and/or thermal electron–positron ( e ±) pairs is explored through combined arguments of dynamical and radiative processes. By comparing physical quantities required by the internal shock model with those obtained through the observed broad-band spectra for Mrk 421, we obtain that the ratio of the Lorentz factors of a pair of cold shells resides in about 2 ～ 20, which implies that the shocks are at most mildly relativistic. Using the obtained Lorentz factors, the total mass density ρ in the shocked shells is investigated. The upper limit of ρ is obtained from the condition that thermal bremsstrahlung emission should not exceed the observed γ-ray luminosity, whilst the lower limit is constrained from the condition that the energy density of non-thermal electrons is smaller than that of the total plasma. Then, we find ρ is 102–103 times heavier than that of non-thermal electrons for pure e ± pairs, while 102–106 times heavier for pure electron–proton ( e / p ) content, implying the existence of a large amount of invisible plasma. The origin of the continuous blazar sequence is briefly discussed and we speculate that the total mass density and/or the blending ratio of e ± pairs and e / p plasma could be new key quantities for the origin of the sequence. |
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| Keywords: | radiation mechanisms: non-thermal galaxies: active BL Lacertae objects: general BL Lacertae objects: individual: Mrk 421 |
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