Exploring the collisionless shocks by suing multi-wavelength spectra of AGN fossil shell emission

2015 Fiscal Year Final Research Report

• Project/Area Number: 25800099
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Astronomy
• Research Institution: Kure National College of Technology
• Principal Investigator: KAWAKATU NOZOMU 呉工業高等専門学校, 自然科学系分野, 准教授 (30450183)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 理論天文学 / 無衝突衝撃波

Outline of Final Research Achievements

We theoretically evaluate the evolution of the emission from both the lobe and the shell, which are composed of shocked jet matter (i.e., cocoon) and a shocked ambient medium (i.e., shell). Based on a simple dynamical model of expanding lobe and shell, we clarify how the broadband spectrum of each component evolves before and after the cessation of the jet activity. (i) As a result, overall emission from the shell overwhelms that from the lobe at a wide range of frequencies from radio up to gamma-ray soon after the jet activity has ceased. Our result predicts a new class of dead radio sources that are dominated by shell emission. (ii) We examine the plasma composition of relativistic jets in four Fanaroff-Riley type II (FRII) radio galaxies by analysing the total cocoon pressure in terms of partial pressures of thermal and non-thermal electrons/positrons and protons. We find that the positron-free plasma comprising protons and electrons is ruled out.

Free Research Field

数物系科学