活動詳細資訊 Event Information
活動詳細資訊 Event Information
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活動訊息最後更新時間 : 2017-06-19 15:14:52
開始日期 Starting Date:2017-06-28  14:00
結束日期 Ending Date:2017-06-28  15:30
會議狀態 State:確定 Definitive
主/協辦單位 Organizer:天文及天文物理研究所 Institute of Astronomy and Astrophysics
活動地點 Venue:R1203 of the Astronomy-Mathematics Building, National Taiwan University
活動備忘 Event Memo:

Abstract

The Interferometric Monitoring of Gamma-ray Bright AGNs (iMOGABA) is a monitoring program for about 30 gamma-ray bright AGNs using the Korean VLBI Network (KVN) at simultaneous frequency bands (22, 43, 86 and 129 GHz) aimed at studying the origins of the gamma-ray flares of AGNs. Here We present observations of the flat spectrum radio quasar 4C 38.41 as part of the iMOGABA program combined with additional observations in radio, optical, X-rays and gamma-rays carried out between the period 2012 March - 2015 August. The monitoring of this source reveals a significant increase in its activity in the radio bands, which correlates with other bands from sub-millimeter to gamma-rays. The epochs of the maxima for the two largest gamma ray flares seem to coincide with the ejection of two respective new VLBI components. The evolution of the flares probes the adiabatic losses in agreement with the shock-in-jet model. Derived synchrotron self absorption magnetic fields, of the order of 0.1 mG, do not seem to dramatically change during the flares, and are much smaller than the estimated equipartition magnetic fields, indicating that the source of the flare may be associated with a particle dominated emitting region. This is consistent with considerations suggesting that this region may be located near but downstream the acceleration and collimation region.