Catching Tidal Dwarf Galaxies at a Later Evolutionary Stage with ALFALFA
Catching Tidal Dwarf Galaxies at a Later Evolutionary Stage with ALFALFA
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DOI：
10.3847/1538-3881/acc4c6
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发表时间：
2023-04
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通讯作者：
Laurin Gray;K. Rhode;L. Leisman;Pavel E. Mancera Piña;J. Cannon;J. Salzer;Lexi Gault;John H. Fuson;G. Józsa;Elizabeth A. K. Adams;Nicholas J. Smith;M. Haynes;S. Janowiecki;Hannah J. Pagel
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作者：
Laurin Gray;K. Rhode;L. Leisman;Pavel E. Mancera Piña;J. Cannon;J. Salzer;Lexi Gault;John H. Fuson;G. Józsa;Elizabeth A. K. Adams;Nicholas J. Smith;M. Haynes;S. Janowiecki;Hannah J. Pagel
我们提出了深光学成像和测光的四个对象被归类为“几乎黑暗”的星系在阿雷西博遗产快速阿雷西博L波段饲料阵列（ALCAFA）的调查，因为他们的气体丰富的性质和极其微弱或失踪的光学发射在现有的目录。它们的H i质量为107-109 M，距离为109 -100 Mpc。WIYN 3.5米望远镜和一度成像仪的观测揭示了在g波段中心表面亮度为24-25 magarcsec−2的微弱恒星成分。我们还介绍了韦斯特博克综合射电望远镜的H i综合观测结果。这些几乎黑暗的星系已经被确定为可能的潮汐矮星系（TDG），基于它们与一个或多个大质量星系的接近程度。我们证明了AGC 229398和AGC 333576可能具有代表TDG的低暗物质含量和大有效半径。它们比以前研究的TDG离它们的祖先更远，这表明它们更古老，更进化。AGC 219369可能是暗物质占主导地位，而AGC 123216的暗物质含量对于TDG来说异常高，但对于正常的矮星系来说很低。我们认为可能的机制，如传统的主要合并方案和气体喷射从高速飞越的TDG候选人的形成。盲H i调查，如ALOCHFA，能够检测到在其他调查中可能被忽视的富含气体的光学昏暗的TDG，从而提供了一个更完整的低质量星系人口普查，并有机会在其生命周期的更高级阶段研究TDG。
We present deep optical imaging and photometry of four objects classified as “Almost-Dark” galaxies in the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey because of their gas-rich nature and extremely faint or missing optical emission in existing catalogs. They have H i masses of 107–109 M ⊙ and distances of ∼9–100 Mpc. Observations with the WIYN 3.5 m telescope and One Degree Imager reveal faint stellar components with central surface brightnesses of ∼24–25 magarcsec−2 in the g band. We also present the results of H i synthesis observations with the Westerbork Synthesis Radio Telescope. These Almost-Dark galaxies have been identified as possible tidal dwarf galaxies (TDGs) based on their proximity to one or more massive galaxies. We demonstrate that AGC 229398 and AGC 333576 likely have the low dark matter content and large effective radii representative of TDGs. They are located much farther from their progenitors than previously studied TDGs, suggesting they are older and more evolved. AGC 219369 is likely dark matter dominated, while AGC 123216 has a dark matter content that is unusually high for a TDG, but low for a normal dwarf galaxy. We consider possible mechanisms for the formation of the TDG candidates such as a traditional major merger scenario and gas ejection from a high-velocity flyby. Blind H i surveys like ALFALFA enable the detection of gas-rich, optically faint TDGs that can be overlooked in other surveys, thereby providing a more complete census of the low-mass galaxy population and an opportunity to study TDGs at a more advanced stage of their life cycle.