MaNGA巡天中低表面亮度盘星系的由内向外增长与千秒差距尺度恒星形成主序
Inside-out growth and the kiloparsec-scale star formation main sequence for low-surface-brightness disk galaxies in MaNGA
- National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
- University of Chinese Academy of Sciences（中国科学院大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
该研究以MaNGA巡天的38个LSBGs和216个HSBGs为样本，发现LSBGs呈由内向外增长，SFMS在千秒差距尺度成立，且仅用恒星形成区域研究SFMS更合适。
中文摘要 AI 辅助
低表面亮度星系（LSBGs）是宇宙中非常暗弱的天体，其形成与演化长期以来都是未解决的问题。我们从MaNGA巡天中选取了一个晚型、正面朝向、以盘为主的星系样本，采用中心表面亮度阈值μ₀(g)=22.0 mag arcsec⁻²，该样本包含38个LSBGs和216个高表面亮度星系（HSBGs）。基于星系中恒星形成区域的pipe3D产品衍生出的图，我们研究了全局和分辨的恒星形成主序（SFMS和rSFMS）以及恒星质量密度（Σ₊）、恒星形成率密度（Σ_{SFR}）和比恒星形成率（Σ_{sSFR}）的径向分布。Σ₊和Σ_{SFR}的径向分布呈现负梯度，而Σ_{sSFR}的径向分布呈现正梯度。与HSBGs相比，LSBGs的Σ₊、Σ_{SFR}和Σ_{sSFR}梯度分别表现出相似、更平缓、更陡峭的斜率。LSBGs的Σ_{SFR}梯度非常平缓，其斜率范围为-0.1至-0.2，这表明整个星系中存在均匀的恒星形成；而正的Σ_{sSFR}梯度则反映了它们的“由内向外”增长。我们的LSBGs和HSBGs与全样本遵循相同的全局和分辨SFMS，且μ₀对SFMS和rSFMS均无影响。对于我们的全样本及两个子样本（HSBGs和LSBGs），全局SFMS和rSFMS的斜率一致，这表明SFMS在千秒差距尺度上仍然成立，且恒星形成活动受局部事件调控。星系中不同激发源的处理会影响SFMS和rSFMS的斜率，仅使用恒星形成区域更为可取。
英文摘要
Low surface brightness galaxies (LSBGs) are very faint objects in the universe whose formation and evolution have long remained an unresolved problem. We selected a late-type, face-on, and disk-dominated galaxy sample from the MaNGA survey, composed of 38 LSBGs and 216 high surface brightness galaxies (HSBGs) by adopting a central surface brightness threshold $μ_{0}(g) = {\rm 22.0\ mag\ arcsec^{-2}}$. Based on maps derived from pipe3D products of star-forming areas in galaxies, we investigated the global and resolved star formation main sequence (SFMS and rSFMS) and radial profiles of the stellar mass density ($\mathrm{Σ_{*}}$), star formation rate density ($\mathrm{Σ_{SFR}}$), and specific star formation rate ($\mathrm{Σ_{sSFR}}$). The radial profiles of $\mathrm{Σ_{*}}$ and $\mathrm{Σ_{SFR}}$ present negative gradients, while those of $\mathrm{Σ_{sSFR}}$ present positive gradients. Compared to HSBGs, the LSBGs show similar, flatter, and steeper slopes in $\mathrm{Σ_{*}}$, $\mathrm{Σ_{SFR}}$, and $\mathrm{Σ_{sSFR}}$ gradients, respectively. The very flat $\mathrm{Σ_{SFR}}$ gradients of LSBGs, whose slopes range from -0.1 to -0.2, indicates uniform star formation throughout the whole galaxy, and the positive $\mathrm{Σ_{sSFR}}$ gradients reflects their ``inside-out'' growth. Our LSBGs and HSBGs follow the same global and resolved SFMS as the full sample, and $μ_{0}$ shows no influence on both SFMS and rSFMS. For our full sample and two subsamples (HSBGs and LSBGs), the slopes of global SFMS and rSFMS are consistent, which indicates that the SFMS still hold on a kiloparsec scale and the star formation activities are regulated by local events. The treatment of different excitation sources in galaxies affects the slope of the SFMS and rSFMS, and using star-forming areas only is more advisable.
