透過積分視場光譜解析本地宇宙中星系淬熄過程的早期階段

Abstract

後星爆星系（Post-starburst galaxies, PSBs）被認為是星系從恆星形成階段過渡到靜止階段的中間階段，並且通常具有快速的恆星形成淬熄特徵。在MaNGA積分視場單元（IFU）巡天資料的幫助下，我們研究了六個具有延伸發射線區域（EELRs）的星系的恆星族群性質，而這些區域被認為是近期AGN活動的指標。年齡敏感的吸收線指標Hδ_A顯示，這六個PSB星系的中心皆由A型恆星主導。我們對這六個PSB星系的不同區域進行了SED擬合，以取得它們的恆星形成歷史（SFH），擬合使用Python套件piXedfit。擬合結果顯示，所有六個星系的中心區域都擁有較年輕的恆星族群；此外，四個星系在約20億年前有顯著的恆星形成活動。AGN反饋被認為是導致PSB星系快速淬熄的機制之一。然而，在我們的分析中，並未發現有證據支持AGN反饋與這六個PSB星系淬熄之間存在相關性。此外，我們發現目前用於SED擬合的SFH模型無法良好地重現短波段的光度資料，顯示SFH的模型仍需更進一步的改進。

Post-starburst galaxies (PSBs) are considered as a transition phase for a galaxy to move from star-forming to quiescent, and they usually have rapid star formation quenching. With the data of MaNGA IFU survey, we investigated the stellar population of six galaxies that have extended emission line regions (EELRs), which indicate recent AGN activity. The age-sensitive absorption line indices HδA show that the centers of all six PSB galaxies are dominant by the A-type stars. We perform the SED fitting to the different local areas of six PSB galaxy to obtain their star formation history (SFH) with the Python package piXedfit. The fitting results suggest that all six galaxy have a younger stellar population in their central region. Beside that, four galaxies show a strong star formation at 2 Gyrs ago. AGN feedback is one of the mechanisms that is considered to be responsible for the rapid quenching of PSB galaxy. However, in our analysis, we did not find evidence supporting the correlation between the AGN feedback and the quenching of six PSB galaxies. In addition, we found that the SFH model used for the SED fitting can not well reproduce the short-wavelength photometry, which underscores the need for more detailed SFH.