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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/5976

    Title: 后髮座星系團內相對論性電子能譜的數值計算;Numerical Calculations Of The Energy Spectrum Of Relativistic Electrons In The Coma Galaxy Cluster
    Authors: 蔡明燕;Ming-Yann Tsay
    Contributors: 天文研究所
    Keywords: 后髮座星系團;相對論性電子;Coma galaxy cluster;Relativistic electrons
    Date: 2001-06-22
    Issue Date: 2009-09-22 10:11:19 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 我們利用數值方式,去模擬后髮座星系團內相對論性電子在能量上可能的分佈,並藉此結果,加以推論這些相對論性電子是在何種物理狀態下累積而成。 由EUVE及BeppoSAX衛星對后髮座星系團的觀測發現,在65-245 eV波段(EUV波段)及20-80 keV波段(hard X-ray波段),有餘值輻射(excess emission)的出現。一般認為,於后髮座星系團內所偵測到的X-ray輻射,是由溫度約8 keV的氣體熱輻射而來。所謂的餘值輻射,以疊加在熱X-ray輻射上多餘輻射的形式出現。在EUV波段的餘值輻射,通常被認為是由能量幾百MeV的電子,經逆康普頓散射微波背景輻射光子後的結果,而在hard X-ray波段的餘值輻射來源目前仍有爭議。如果在EUV波段的餘值輻射是由逆康普頓散射而成,則我們可以藉此給定電子在能譜上能量γ約等於400附近的數量分布。同樣的,無線電輻射可以給定電子在能譜上能量γ約從700到4×104附近的數量分布。磁場強度將決定由無線電輻射資料導出的電子能量範圍。 我們提出連續注入電子模型,並計算在此模型下相對論性電子的可能能譜。我們進一步依照有無初始的強電子注入事件,將此模型分成二種亞型。在做模擬計算時,我們分別計算磁場為5μG及0.2μG下的相對論性電子能譜。由我們的模擬結果發現,餘值輻射在連續注入電子模型且有初始強電子注入事件的狀態下,無論在磁場為5μG或0.2μG,都能獲得很好的擬和。相對的,在連續注入電子模型且無初始強電子注入事件的狀況下,只有在磁場為0.2μG的狀況下,能獲得餘值輻射良好的擬和。 We calculate the possible energy spectra of relativistic electrons in the Coma galaxy cluster using numerical methods and discuss some possible scenarios for production of these electrons. Observations carried out by Extreme Ultraviolet Explorer (EUVE) and the BeppoSAX on the Coma cluster detect excess emission, which is an extra emission superposed on what expected of a thermal X-ray emission and lies at both ends of this thermal X-ray emission. At the low-energy end between 65-245 eV (the EUV excess), the excess is usually explained as inverse Compton emission by a few-hundred-MeV electrons up scattering the cosmic microwave background photons while the origin of the excess at the high-energy end between 20-80 keV is still in debate. The assumption of an inverse Compton scattering origin for the EUV excess can give a constraint on the electron spectrum at ˘ 400 while synchrotron radio emission will give a constraint on electron spectra in the energy range of ˘ 700 to ˘ 40000 depending on the strength of the magnetic field. We propose models of continuous electron injections either with or without a major first event and carry out the modeling electron spectra by adopting two different magnetic fields, 5 and 0.2 G, which are as suggested by Faraday rotation measurements and as required for the inverse Compton interpretation of the observed hard X-ray excess emission. We nd that the observed excess emission can be perfectly explained by models of continuous electron injections with a major first event in both magnetic fields and models of continuous electron injections without a major first event in low magnetic field.
    Appears in Collections:[天文研究所] 博碩士論文

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