天文学进展2017，Vol.35Issue(1)：16-34,19.DOI:10.3969/j.issn.1000-8349.2017.01.02
红移z≈2极亮红外星系的研究进展
Research Progress on Ultraluminous Infrared Galaxies at z≈2
摘要
Abstract
UltraLuminous InfraRed Galaxies (ULIRGs) are galaxies defined to have extremely high infrared (IR) luminosities (LIR ＞ 1012 L☉).Observations have shown that high-redshift ULIRGs are massive galaxies (M* ＞ 1011 M☉),with extremely high ratio of infrared to optical flux density (F24 μm/FR ＞ 1 000) and intensive star formation (100 ～ 1 000 M☉ · a-1).These objects are relatively rare at z ≈ 0,but their space density rapidly increase with look-back time and apparently peaks around z =2 ～ 3.Upon it's discovery,ULIRGs were suggested to be a feasible evolutionary phase towards the formation of local massive early-type galaxies.Their rest-frame optical morphologies show that high-redshift ULIRGs are a mixture of mergers or interacting systems,irregular galaxies,disks,and ellipticals.The morphological diversities of ULIRGs suggest that there are different formation processes for these galaxies.Merger processes between galaxies and disk instabilities play an important role in the formation and evolution of ULIRGs at high redshift.Mid-infrared (MIR) spectra of ULIRGs are observed with the Spitzer/IRS (InfraRed Spectrograph) instrument.For ULIRGs at z ≈ 2,major spectral features including the PAH (Polycyclic Aromatic Hydrocarbon) emission features at 7.7,8.6,and 11.3 μm and silicate absorption from 8 to 13 μm (peaking at 9.7 μm) fall in the observable wavelength range.ULIRGs can be divided into two types according to their MIR spectra.Objects with strong power-law continua are powered mainly by active galactic nuclei (AGNs),while those with a strong PAH emission are powered by intensive star formation.The clustering signal of ULIRGs roughly corresponds to a correlation length of r0 =7.40 h-1.Mpc for the full F24 μm ＞ 0.3 mJy sample.The clustering strength increases with luminosity,up to r0 =12.97 h-1.Mpc for F24 μm ＞ 0.6 mJy ULIRGs.Moreover,observations demonstrate that a median dust temperature is about 40 K for ULIRGs at z ≈ 2.关键词
高红移星系/星系观测/星系形态/星系光谱/星系成团性Key words
high-redshift/galaxy observation/galaxy morphology/galaxy spectroscopy/galaxy clustering分类
天文与地球科学引用本文复制引用
方官文,林泽森,孔旭..红移z≈2极亮红外星系的研究进展[J].天文学进展,2017,35(1):16-34,19.基金项目
国家自然科学基金(11303002,11225315,11320101002) （11303002,11225315,11320101002）
中国科学院战略性先导科技专项(XDB09000000) （XDB09000000）
云南省应用基础研究计划项目(2014FB155) （2014FB155）
