利用可見光挑出來的很紅的星系的紅外光性質; Infrared Properties of Optically-Selected Very Red Galaxies

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/48031

Title:	利用可見光挑出來的很紅的星系的紅外光性質;Infrared Properties of Optically-Selected Very Red Galaxies
Authors:	劉瑋芳;Wei-Fang Liu
Contributors:	天文研究所
Keywords:	星系;紅外光;infrared;galaxy
Date:	2011-08-20
Issue Date:	2012-01-05 14:27:42 (UTC+8)
Abstract:	本研究是探討大約3000個可見光部分很紅的星系（optically-selected very red galaxies，簡稱OVRGs）的紅外性質，這些星系是從一平方度的紅序列星系團巡天二號計畫（Red Sequence Cluster Survey 2）的天區中挑選出來的。我們挑選這些很紅的星系的標準，是利用可見光的顏色指數：r’波段比g’波段亮2.2個星等，或是z’波段比r’波段亮1.8個星等。我們利用各種不同的巡天資料，包括可見光以及紅外光，來研究這些很紅的星系的性質。我們的分析顯示了這些很紅的星系，有一群是可以觀測到它們的24微米波段的輻射，這群星系和其他一般的星系比較起來，有著特別弱的8微米波段輻射。有一個可能的解釋是，因為這些星系的星際物質較年輕，還沒有被太多的多環芳香烴（PAH）汙染，而且位在離我們銀河系較近的地方。另一種可能性是，這些星系其實是有著很多的恆星形成，而且是高紅移的星系。 We study the infrared properties of ∼ 3000 optically-selected very red galaxies (OVRGs) selected from one square-degree ﬁeld of the Red Sequence Cluster Survey 2 (RCS2) using the Canada-France-Hawaii Telescope (CFHT). We use the selecting criteria g' − r' ≥ 2.2 or r' − z' ≥ 1.8 mag in optical bands to choose the OVRGs. We investigate the properties of these OVRGs using the data from the Sloan Digital Sky Survey (SDSS) optical data, the UKIRT Infrared Deep Sky Survey (UKIDSS) data, and the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) data. Our analyses show that the OVRGs with detectable 24 μm emission have lower 8 μm emission than normal spiral-like galaxies with similar 24 μm emission. A possible explanation is that these star-forming OVRGs have very young ISM, which contain little or no PAH molecules at local. Another possibility is very luminous star forming galaxies at high redshifts.
Appears in Collections:	[Graduate Institute of Astronomy] Electronic Thesis & Dissertation

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