我们结合了近红外积分场光谱学和宽带光度学获得的Halpha发射的二维运动学和形态学信息,研究了10个晚型星系样本在1.0 < z < 1.5时的动力学结构和物理性质。样本显示了一系列的运动学类型,其中包括一个合并,一个面对星系,和八个物体显示旋转的证据。在这八个天体中,有一半是旋转主导的星系,而其余的则是分散主导的星系。我们还发现,两个星系的旋转主导的星系是纯旋转支持的磁盘。它们在0.5-1千秒差距内达到最大速度约180-290公里/秒,类似于具有薄盘的局部螺旋。我们样本中的星系具有相对年轻的恒星星族(< 1.5 Gyr),恒星质量范围为0.6-5 × 10^10 Msun。此外,它们中的大多数还没有将大部分气体转化为恒星(6个星系的气体比例> 50%)。因此,那些已经有稳定盘的星系,其最终的恒星质量可能与现在的螺旋星系相似,这些旋转系统可以被看作是螺旋星系的前身。我们通过研究1.2 < z < 1.5时的恒星质量Tully-Fisher关系来结束我们的研究。
英文摘要:
We combined two-dimensional kinematic and morphology information on the Halpha emission, obtained using near-infrared integral field spectroscopy, with broad-band photometry to investigate the dynamical structure and the physical properties of a sample of ten late-type galaxies at 1.0 < z < 1.5. The sample displays a range of kinematical types which include one merger, one face-on galaxy, and eight objects showing evidence of rotation. Among these eight objects, half are rotation-dominated galaxies, while the rest are dispersion-dominated. We found also that two galaxies out of the rotation-dominated galaxies are pure rotationally supported disks. They achieve a maximum velocity of ~180-290 km/s within ~0.5-1 kpc, similar to local spirals with thin disks. The galaxies of our sample have relatively young stellar populations (< 1.5 Gyr) and possess a range of stellar mass of 0.6-5 X10^10 Msun. In addition, most of them have not yet converted the majority of their gas into stars (six galaxies have their gas fraction >50 per cent). Therefore, those of them which already have a stable disk will probably have their final stellar mass similar to the present-day spirals, to which these rotating systems can be seen as precursors. We conclude our study by investigating the stellar mass Tully-Fisher relation at 1.2 < z < 1.5.
We study the kinematics of galaxies within massive clusters, as a probe of the physics of star-formation quenching within clusters. Using N-body simulations, we argue that satellite kinematics provide information about galaxy infall that is complementary to the (instantaneous) spatial distribution of satellites. Comparing the simulation results with measurements of real cluster galaxies, we find evidence that the kinematics of red (quiescent) satellite galaxies are consistent with earlier infall times than that of blue (star-forming) satellites.
We present bivariate luminosity and stellar mass functions of H$α$ star forming galaxies drawn from the Galaxy And Mass Assembly (GAMA) survey. While optically deep spectroscopic observations of GAMA over a wide sky area enable the detection of a large number of $0.001<{SFR}_{Hα}$ (M$_{\odot}$ yr$^{-1}$)$<100$ galaxies, the requirement for an H$α$ detection in targets selected from an $r$-band magnitude limited survey leads to an incompleteness due to missing optically faint star forming galaxies. Using $z<0.1$ bivariate distributions as a reference we model the higher-$z$ distributions, there…
On the Last 10 Billion Years of Stellar Mass Growth in Star-Forming Galaxies
恒星形成率-恒星质量关系(SFR-M*)及其演化(即,SFR主序)描述了给定恒星质量和给定红移的星系的增长率。假设现在的恒星形成星系在过去总是恒星形成的,这些增长率观测可以被整合来计算平均恒星形成历史(SFH)。使用这种主序列积分(MSI)方法,我们可以追溯到现在的大质量恒星形成星系,当它们是当前恒星质量的10-20%时。在这些时期的整合是强大的:支持我们的计算的SFR数据是一致的恒星质量密度在这个政权的演变。这些SFH的分析近似。基于积分的结果重申了以前的建议,即目前的恒星形成星系形成几乎所有的恒星质量在z <2. It follows that massive galaxies observed at z>2不是典型的祖先恒星形成星系今天。我们还检查基于MSI的SFH对那些从化石记录的分析推断-从光谱能量分布(SED)的恒星形成星系在斯隆数字巡天,和色星等图(CMD)的矮不规则星系解决恒星。一旦考虑到恒星星族年龄的不确定性,主序列与基于SED的SFH(来自VESPA)非常一致。外推SFR主序星观测到矮星系,我们发现的ACS附近的星系巡天金库和本星系群星系的CMD分析的MSI结果和SFH之间的差异。解析出的矮星系似乎比主序列趋势所暗示的要慢得多,也比质量稍高的SED分析星系慢。这种差异可能标志着SFH测定的问题,但它也可能标志着在最低恒星质量下恒星形成趋势的转变。
The kinematics of galaxies provide valuable insights in their physics and assembly history. Kinematics are governed not only by the gravitational potential, but also by merger events and stellar feedback processes such as stellar winds and supernova explosions. Aims. We aim at identifying what governs the kinematics in a sample of SDSS selected nearby starburst galaxies, by obtaining spatially resolved measurements of the gas and stellar kinematics. We obtain near-infrared integral field K-band spectroscopy with VLT/SINFONI of 15 compact starburst galaxies. We derive the integrated as well as …
We use a robust analytical model together with a high-resolution hydrodynamical cosmological simulation to demonstrate that in a $Λ$ cold dark matter ($Λ$CDM) universe, a small fraction of dwarf galaxies inhabiting dark matter (DM) halos in the mass range $3\times 10^{9} \lesssim M_{200} / M_{\odot} \lesssim 10^{10}$ form unusually late ($z<3$) compared to the bulk population of galaxies. These galaxies originate from the interplay between the stochastic growth of DM halos and the existence of a time-dependent DM halo mass below which galaxies do not form. The formation epoch of the simulated …
Galaxy surveys targeting emission lines are characterising the evolution of star-forming galaxies, but there is still little theoretical progress in modelling their physical properties. We predict nebular emission from star-forming galaxies within a cosmological galaxy formation model. Emission lines are computed by combining the semi-analytical model \sag\ with the photoionisation code \mapp. We characterise the interstellar medium (ISM) of galaxies by relating the ionisation parameter of gas in galaxies to their cold gas metallicity, obtaining a reasonable agreement with the observed \ha, \o…
A majority of the $γ$-ray emission from star-forming galaxies is generated by the interaction of high-energy cosmic rays with the interstellar gas and radiation fields. Star-forming galaxies are expected to contribute to both the extragalactic $γ$-ray background and the IceCube astrophysical neutrino flux. Using roughly 10\,years of $γ$-ray data taken by the {\it Fermi} Large Area Telescope, in this study we constrain the $γ$-ray properties of star-forming galaxies. We report the detection of 11 bona-fide $γ$-ray emitting galaxies and 2 candidates. Moreover, we show that the cumulative $γ$-ray…
Strongly star forming galaxies in the local Universe with nebular He II 4686 emission
我们提出了一个样本的2865强星云He II 4686发射线星系斯隆数字巡天数据发布7,并使用这个样本来调查这条线在恒星形成星系的起源。我们证明了恒星形成星系和由活动星系核控制的星系在He II 4686/Hβ与[N II] 6584/Hα诊断图中形成了明显分离的分支,并导出了分离这两类星系的经验分类方案。我们还提出了一个分析的物理性质的189个恒星形成的星系与强大的He II 4686的排放。这些恒星形成星系提供了对大质量恒星的硬电离连续体的限制。为了与观测结果进行定量比较,我们使用光电离模型,并研究不同的恒星星族模型如何影响预测的He II 4686发射。我们证实了以前的研究结果,模型可以预测He II 4686发射只有20%的太阳金属丰度或更高的瞬时爆发,只有4 - 5万年的年龄,当极紫外线连续的时期是由沃尔夫-拉叶星的发射为主。然而,我们发现,83的恒星形成星系(40%)在我们的样本中没有沃尔夫-拉叶特征的光谱,尽管显示出强大的星云He II 4686发射。我们讨论了可能的原因,这和可能的机制,在这些星系中的He II 4686发射。