類星體-星系對 0248+430 中的原子與分子氣體;Atomic and Molecular Gas in the QSO-Galaxy Pair 0248+430

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题名:	類星體-星系對 0248+430 中的原子與分子氣體;Atomic and Molecular Gas in the QSO-Galaxy Pair 0248+430
作者:	邱淑慧;Shwu-Huey Chiou
贡献者:	天文研究所
关键词:	類星體;交互作用星系;分子氣體;原子氣體;吸收譜線;QSO absorption lines;interacting galaxies;atomic gas;molecular gas;QSO-galaxy pair
日期:	2002-06-26
上传时间:	2009-09-22 10:11:29 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	「類星體-星系對」為在投影平面上距離很接近（約數萬秒差距）的類星體和星系，但兩者間紅位移相距甚大。藉由兩者在視線方向上的相近，星系的外圍通過類星體的前景位置，吸收了來自類星體連續譜的特定波長而在類星體的光譜上形成吸收譜線，藉由對類星體吸收譜線的研究，我們可以了解星系外圍氣體的性質。我們利用分析VLA對「類星體-星系對」0248+430在氫原子21公分譜線波段的觀測資料，並和BIMA在一氧化碳CO(1-0)的觀測結果比較，研究前景的交互作用星系G0248+430中，氫原子和氫分子氣體的分布情形。分析結果顯示，在G0248+430中，星系交互作用形成的潮汐尾中的氣體，含有較一般星系氣體高比例的金屬豐度，推論原因為在星系交互作用過程中，外圍氣體因溫度達到塵埃的昇華溫度，造成潮汐尾中塵埃大量的被破壞，使得原本在塵埃中的金屬（鈣、鈉等）被釋放到氣體中，使氣體中金屬比例增加，此可由我們推導出的溫度得到佐證。另一方面，我們發現在交互作用過程中，氫原子氣體並不像氫分子一樣被大量帶往星系中心約數百秒差距的小區域集中，而是仍有許多氫原子留在星系外圍區域或被帶往更外圍的潮汐尾中。中心大量集中的氫分子氣體，主要是由原本存在於星系中心約數千秒差距範圍內的氫分子聚集而成，在此高密度的環境下，氫分子不是以如同銀河系中氫分子般，以受重力束縛的巨型分子雲型態存在，而是形成連續性的雲氣間介質。 We present the results of HI observations of Q0248+430 with the Very Large Array (VLA). The quasar Q0248+430 (z = 1.313, Mv = 17.65) is a variable radio source with a foreground object, G0248+430 (z ~ 0.051), which consists of two galaxies in a merging process. The two nuclei are separated by 3.8", and the tidal tail lies in the direction of Q0248+430. Absorption lines of CaII and NaI with redshifts very close to the redshifts of the merging galaxies have been detected in the optical spectra of Q0248+430. It has been accepted that the class of narrow, metal absorption lines (with redshift z_abs<< z_em) seen in the spectra of QSOs are due to gas associated with intervening galaxies.We find distinct HI absorption near the redshifts of the stronger optical absorption lines and calculate the spin temperatures of discrete clouds in the tidal tail of the merging system. Comparing with gas associated with normal galaxies, the clouds in the tidal tail show relatively higher ratio of N(CaII)/N(HI) and N(NaI)/N(HI). Dusts in the tidal tail have been destroyed during strong tidal interaction and metals associated with the dusts have been released into the gas. Because the spin temperatures of these clouds are higher than the sublimation temperature of dusts, we suggest that the mechanism involved in dust destroying is thermal evaporation. Besides, G0248+430 shows no HI emission in the central region as H_2 does. Our results indicate that the properties of gas in tidal tail is quite different from gas associated with normal galaxies and the atomic gas which is in the outer part of the galaxy before merging has not been forced to the central region in the merging process
显示于类别:	[天文研究所] 博碩士論文

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