arXiv 1707.093582017-07-28astro-ph.GA

$z<0.2$恒星形成星系中多环芳烃特征与星系合并的关系

A Relationship of Polycyclic Aromatic Hydrocarbon Features with Galaxy Merger in Star-forming Galaxies at $z<0.2$

Katsuhiro L. Murata, Rika Yamada, Shinki Oyabu, Hidehiro Kaneda, Daisuke Ishihara, Mitsuyoshi Yamagishi, Takuma Kokusho, Tsutomu T. Takeuchi

备注：: 14 pages, 13 figures, Accepted for publication in MNRAS
DOI：: 10.1093/mnras/stx1902

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摘要：

利用AKARI、WISE、IRAS、SDSS和HST等卫星观测数据，研究了大气中多环芳烃（PAH）的质量与大气温度的关系（$M_{\rm PAH}$），非常小的颗粒质量本文计算了55个恒星形成星系在$z<0.2$红移下的质量（$M_{\rm VSG}$）、大颗粒质量（$M_{\rm BG}$）和恒星质量（$M_{\rm star}$）。利用$z<0.1$上的SDSS图像和$z>0.1$上的HST图像，利用形态参数不对称度$A$将星系分为合并星系和非合并星系，并根据形态指标、最亮20个$\%$区域的二阶动量$M_{20}$和Gini系数对星系的合并阶段进行了量化。发现并合星系的$M_{\rm PAH}/M_{\rm BG}$有低于非并合星系的趋势，并且并合星系和非并合星系的$M_{\rm VSG}/M_{\rm BG}$和$M_{\rm BG}/M_{\rm star}$没有系统的差异。我们发现，具有非常低的$M_{\rm PAH}/M_{\rm BG}$的星系似乎是合并星系的后期阶段。这些结果表明，多环芳烃部分被破坏的后期阶段的合并过程。此外，我们还研究了$M_{\rm PAH}/M_{\rm BG}$随辐射场强$G_0$和碰撞星系激波示踪剂$[{\rm O\,{\scriptsize I}}]λ6300/{\rm H}α$的发射线比的变化，发现$M_{\rm PAH}/M_{\rm BG}$随$G_0$和$[{\rm O\,{\scriptsize I}}]/{\rm H}α$的增大而减小。PAH的破坏可能是由两个过程引起的：强辐射场和星系合并过程中的大尺度冲击。

英文摘要：

Using the AKARI, Wide-field Infrared Survey Explorer (WISE), Infrared Astronomical Satellite (IRAS), Sloan Digital Sky Survey (SDSS) and Hubble Space Telescope (HST) data, we investigated the relation of polycyclic aromatic hydrocarbon (PAH) mass ($M_{\rm PAH}$), very small grain mass ($M_{\rm VSG}$), big grain mass ($M_{\rm BG}$) and stellar mass ($M_{\rm star}$) with galaxy merger for 55 star-forming galaxies at redshift $z<0.2$. Using the SDSS image at $z<0.1$ and the HST image at $z>0.1$, we divided the galaxies into merger galaxies and non-merger galaxies with the morphological parameter asymmetry $A$, and quantified merging stages of galaxies based on the morphological indicators, the second-order momentum of the brightest 20$\%$ region $M_{20}$ and the Gini coefficient. We find that $M_{\rm PAH}/M_{\rm BG}$ of merger galaxies tend to be lower than that of non-merger galaxies and there are no systematic differences of $M_{\rm VSG}/M_{\rm BG}$ and $M_{\rm BG}/M_{\rm star}$ between merger galaxies and non-merger galaxies. We find that galaxies with very low $M_{\rm PAH}/M_{\rm BG}$ seem to be merger galaxies at late stages. These results suggest that PAHs are partly destroyed at late stages of merging processes. Furthermore, we investigated $M_{\rm PAH}/M_{\rm BG}$ variations in radiation field intensity strength $G_0$ and the emission line ratio of $[{\rm O\,{\scriptsize I}}]λ6300/{\rm H}α$ which is a shock tracer for merger galaxies and find that $M_{\rm PAH}/M_{\rm BG}$ decreases with increasing both $G_0$ and $[{\rm O\,{\scriptsize I}}]/{\rm H}α$. PAH destruction is likely to be caused by two processes; strong radiation fields and large-scale shocks during merging processes of galaxies.

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