arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1012.5859astro-ph.COastro-ph.GA
收藏

早型和晚型星系的暗晕响应和恒星初始质量函数

Dark halo response and the stellar initial mass function in early-type and late-type galaxies

Aaron A. Dutton, Charlie Conroy, Frank C. van den Bosch, Luc Simard, J. Trevor Mendel, Stephane Courteau, Avishai Dekel, Surhud More, Francisco Prada

摘要:

本文研究了早型星系(ETG)和晚型星系(LTG)中恒星质量与光学圆速度关系--Faber-Jackson(FJ)和Tully-Fisher(TF)关系的起源。我们结合暗晕质量的测量(从卫星运动学和弱透镜),和星系中重子的分布(从星系标度关系的新汇编),从宇宙学模拟暗晕结构的约束。主要的未知数是晕对星系形成的响应和恒星初始质量函数(IMF)。TF和FJ关系的斜率自然地再现了大范围的晕圈响应和IMF。然而,具有通用IMF和通用晕轮响应的模型不能同时再现TF和FJ关系的零点。对于具有通用Chabrier IMF的模型,LTG需要晕扩张,而ETG需要晕收缩。Salpeter IMF允许用于高质量(sigma > 180 km/s)ETG,但对于中等质量不一致,除非V_circ(R_e)/sigma_e > 1.6。如果国际货币基金组织是普遍的,接近Chabrier,我们推测,一个重大的合并的存在可能是负责收缩的ETGs,而clueroscopic增生流和/或反馈导致扩张的LTG。另一方面,最近提出的IMF的变化不利于晕收缩在这两种类型的星系。最后,我们表明,我们的模型自然地再现平坦的和无特征的圆形速度轮廓内的光学区域的星系没有微调。

英文摘要:

We investigate the origin of the relations between stellar mass and optical circular velocity for early-type (ETG) and late-type (LTG) galaxies --- the Faber-Jackson (FJ) and Tully-Fisher (TF) relations. We combine measurements of dark halo masses (from satellite kinematics and weak lensing), and the distribution of baryons in galaxies (from a new compilation of galaxy scaling relations), with constraints on dark halo structure from cosmological simulations. The principle unknowns are the halo response to galaxy formation and the stellar initial mass function (IMF). The slopes of the TF and FJ relations are naturally reproduced for a wide range of halo response and IMFs. However, models with a universal IMF and universal halo response cannot simultaneously reproduce the zero points of both the TF and FJ relations. For a model with a universal Chabrier IMF, LTGs require halo expansion, while ETGs require halo contraction. A Salpeter IMF is permitted for high mass (sigma > 180 km/s) ETGs, but is inconsistent for intermediate masses, unless V_circ(R_e)/sigma_e > 1.6. If the IMF is universal and close to Chabrier, we speculate that the presence of a major merger may be responsible for the contraction in ETGs while clumpy accreting streams and/or feedback leads to expansion in LTGs. Alternatively, a recently proposed variation in the IMF disfavors halo contraction in both types of galaxies. Finally we show that our models naturally reproduce flat and featureless circular velocity profiles within the optical regions of galaxies without fine-tuning.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑