The sizes, masses and specific star formation rates of massive galaxies at 1.3 < z < 1.5: strong evidence in favour of evolution via minor mergers
The sizes, masses and specific star formation rates of massive galaxies at 1.3 < z < 1.5: strong evidence in favour of evolution via minor mergers
复制标题
DOI：
10.1093/mnras/sts092
复制
发表时间：
2012-05
影响因子：
4.8
通讯作者：
R. McLure;H. Pearce;J. Dunlop;M. Cirasuolo;E. Curtis-Lake;V. Bruce;K. Caputi;K. Caputi;
中科院分区：
文献类型：
--
作者：
R. McLure;H. Pearce;J. Dunlop;M. Cirasuolo;E. Curtis-Lake;V. Bruce;K. Caputi;K. Caputi;
利用UKIDSS超深巡天（UDS）的光谱样品，结合分光光度计获得的精确恒星质量测量值，对星系大小、恒星质量和特殊恒星形成率（sSFR）之间的关系进行了全面的研究。与此相反，我们发现，大质量的恒星形成星系在这个时代的谎言更接近当地晚型的大小质量关系，只有一个因子fg = 1：6 0：2比当地观察到的小。基于一个由被动天体和恒星形成天体组成的具有动力学质量估计的子样本，我们还导出了从z' 1：4到现在的半光半径典型增长的独立估计fg = 2：30：3。聚焦于被动子样本，我们得出结论，主要通过主要合并产生必要的演化将需要不可行的合并事件数量，并过度填充局部恒星质量函数的高质量端。相反，我们发现，一个方案中，质量吸积占主导地位的小合并可以舒适地产生必要的演变，从而在恒星质量的增加只有一个因素' 2，伴随着大小增长的一个因素' 3：5，是需要调和的大小-质量关系在z' 1：4与当地观察到的。最后，我们注意到，一个显着的分数（44%-12%）的被动星系在我们的样本中有一个盘状形态，提供额外的证据表明，单独的物理过程是负责淬火的恒星形成和大质量星系的形态转变。
We report the results of a comprehensive study of the relationship between galaxy size, stellar mass and specic star-formation rate (sSFR) at redshifts 1 :3 6 10 10 M ), spectroscopic sample from the UKIDSS Ultra- deep Survey (UDS), with accurate stellar-mass measurements derived from spectro- photometric tting, we nd no evidence that the o-set from the local size- mass relation is a function of stellar population age. In contrast, we nd that massive star-forming galaxies at this epoch lie closer to the local late-type size-mass relation and are only a factor fg = 1:6 0:2 smaller than observed locally. Based on a sub- sample with dynamical mass estimates, which consists of both passive and star-forming objects, we also derive an independent estimate of fg = 2:3 0:3 for the typical growth in half-light radius between z' 1:4 and the present day. Focusing on the passive sub- sample, we conclude that to produce the necessary evolution predominantly via major mergers would require an unfeasible number of merger events and over populate the high-mass end of the local stellar mass function. In contrast, we nd that a scenario in which mass accretion is dominated by minor mergers can comfortably produce the necessary evolution, whereby an increase in stellar mass of only a factor of' 2, accompanied by size growth of a factor of ' 3:5, is required to reconcile the size- mass relation at z' 1:4 with that observed locally. Finally, we note that a signicant fraction (44% 12%) of the passive galaxies in our sample have a disk-like morphology, providing additional evidence that separate physical processes are responsible for the quenching of star-formation and morphological transformation in massive galaxies.