arXiv subjects

M. Kino

Publications and source records attributed to M. Kino.

58 records · Page 4Linked to original sources

arXiv2005

Estimate of the total kinetic power and age of extragalactic jet by its cocoon dynamics: The case of Cygnus A

We examine the constraints imposed on the total kinetic power ($L_{\rm j}$) and the age ($t_{\rm age}$) of relativistic jets in FR II radio sources in a new way. We solve the dynamical expansion of its cocoon embedded in the intra-cluster medium (ICM) and obtain the analytic solution of its physical quantities in terms of $L_{\rm j}$ and $t_{\rm age}$. The estimate of $L_{\rm j}$ and $t_{\rm age}$ is done by the comparison of the model and the observed shape of the cocoon. The analysis is focused on Cygnus A and we find that (i) the source age is $3 {\rm Myr} <t_{\rm age}<30 {\rm Myr}$ and (ii) the total kinetic power of the jet is estimated as $0.2\times 10^{46}{\rm erg s^{-1}} <L_{\rm j}<1\times 10^{48} {\rm erg s^{-1}}$ which is larger than 1% of the Eddington luminosity of Cygnus A.

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arXiv2005

Matter content in AGN jets: constraint from cocoon dynamics?

The matter content of jets in active galactic nuclei is examined in a new way. We model the dynamical expansion of its cocoon embedded in the intra-cluster medium (ICM). By comparing the observed shape of the cocoon with that expected from the theoretical model, we estimate the total pressure ($P_{\rm c}$) and electron temperature ($T_{e}$) of the cocoon. The number density of the total electrons ($n_{e^{-}}$) is constrained by using the non-thermal spectrum of the hot spot and the analysis of the momentum balance between the jet thrust and the rum pressure of ICM. Together with the obtained $P_{\rm c}$, $T_{e}$ and $n_{e^{-}}$, we constrain the matter content in the jets. We find that, in the case of Cygnus A, the ratio of number density of protons to that of electrons is of order of $10^{-3}$ . This implies the existence of a large number of positron in the jet.

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arXiv2004

Hydrodynamics of Internal Shocks in Relativistic Outflows

We study the hydrodynamical effects of two colliding shells, adopted to model internal shocks in various relativistic outflows such as gamma-ray bursts and blazars. We find that the density profiles are significantly affected by the propagation of rarefaction waves. A split-feature appears at the contact discontinuity of the two shells. The shell spreading with a few ten percent of the speed of light is also shown to be a notable aspect. The conversion efficiency of the bulk kinetic energy to internal one shows deviations from the widely-used inelastic two-point-mass-collision model. Observational implications are also shortly discussed.

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arXiv2003

Chandra Discovery of an X-ray Jet and Lobes in 3C 15

We report the Chandra detection of an X-ray jet in 3C 15. The peak of the X-ray emission in the jet is 4.1'' (a projected distance of 5.1 kpc) from the nucleus, and coincident with a component previously identified in the radio and optical jets. We examine four models for the X-ray jet emission: (I) weak synchrotron cooling in equip., (II) moderate synchrotron cooling in equip., (III) weak synchrotron plus SSC cooling, and (IV) moderate synchrotron plus SSC cooling. We argue that case (II) can most reasonably explain the overall emission from knot C. Case (III) is also possible, but requires a large departure from equipartition and for the jet power to be comparable to that of the brightest quasars. Diffuse X-ray emission has also been detected, distributed widely over the full extent (63kpc x 25kpc) of the radio lobes. We compare the total energy contained in the lobes with the jet power estimated from knot C, and discuss the energetic link between the jet and the lobes. We argue that the fueling time (t_fuel) and the source age (t_src) are comparable for case (II), whereas t_fuel << t_src is likely for case (III). The latter may imply that the jet has a very small filling factor, ~10^{-3}. We consider the pressure balance between the thermal galaxy halo and non-thermal relativistic electrons in the radio lobes. Finally, we show that the X-ray emission from the nucleus is not adequately fitted by a simple absorbed power-law model, but needs an additional power-law with heavy absorption intrinsic to the source. Such a high column density is consistent with the presence of a dense, dusty torus which obscures the quasar nucleus.

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