arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1808.05929astro-ph.GA
收藏

连接低红移的致密恒星形成星系和扩展恒星形成星系:星系压缩和淬火的含义

Connecting Compact Star-forming and Extended Star-forming Galaxies at Low-redshift: Implications for Galaxy Compaction and Quenching

Enci Wang, Xu Kong, Zhizheng Pan

摘要:

以前的研究结果表明,致密的核心或凸起的存在是淬火星系的先决条件,导致提出了两步淬火方案:压缩和淬火。在这种情况下,星系首先将其核心增长到恒星质量表面密度阈值,随后发生淬火,这表明星系从扩展的恒星形成星系(eSFGs),通过紧凑的恒星形成星系(cSFGs),到淬火人口。在这项工作中,我们的目标是通过确定恒星形成率(SFR),气相金属丰度和HI含量的趋势来研究eSFGs和cSFGs之间可能的演化联系,因为人们自然会期望星系沿着冷气消耗和金属增强的轨道演化。我们选择了一个体积有限的样本,15,933个星系的恒星质量以上$10^{9.5}M_{\odot}$和红移为0.02 < z < 0.05的NASA-Sloan-Atlas星表内的ALMAFA足迹。cSFG平均表现出类似或略高的SFR $\sim$ 0.06 dex和显着更高的气相金属丰度(低质量时高达0.2 dex)相对于eSFG,而cSFG占主导地位的星系人口最激烈的恒星形成活动。更重要的是,总体上cSFG的中值HI含量和气体耗尽时间约为eSFG的一半。我们的研究结果支持星系的压缩和淬火的方案,沿着冷气消耗和金属增强的轨道演化和增长的核心。eSFG和cSFG的环境是不可区分的,这表明压缩过程至少对于低红移宇宙来说是独立于任何环境影响的。

英文摘要:

Previous findings show that the existence of dense cores or bulges is the prerequisite for quenching a galaxy, leading to a proposed two-step quenching scenario: compaction and quenching. In this scenario, galaxies first grow their cores to a stellar mass surface density threshold and subsequently quenching occurs, suggesting that galaxies evolve from extended star-forming galaxies (eSFGs), through compact star-forming galaxies (cSFGs), to quenched population. In this work, we aim at examining the possible evolutionary link between eSFGs and cSFGs by identifying the trends in star formation rate (SFR), gas-phase metallicity and HI content, since one would naturally expect that galaxies evolve along the track of cold gas consumption and metal enhancement. We select a volume-limited sample of 15,933 galaxies with stellar mass above $10^{9.5}M_{\odot}$ and redshift of 0.02 < z < 0.05 from the NASA-Sloan-Atlas catalog within the ALFALFA footprint. The cSFGs on average exhibit similar or slightly higher SFRs of $\sim$0.06 dex and significantly higher gas-phase metallicity (up to 0.2 dex at low mass) with respect to the eSFGs, while the cSFGs dominate the galaxy population of the most intense star formation activities. More importantly, overall the median HI content and gas depletion time of cSFGs are about half of eSFGs. Our result supports the compaction and quenching scenario that galaxies evolve and grow their cores along the track of cold gas consumption and metal enhancement. The environments of eSFGs and cSFGs are indistinguishable, suggesting that the compaction process is independent of any environmental effects at least for low-redshift universe.

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。

↑