论文标题

Starburst矮人星系CGCG007-025的解析化学组成:直接方法与光电离心模型拟合

The resolved chemical composition of the starburst dwarf galaxy CGCG007-025: Direct method versus photoionization model fitting

论文作者

Fernández, Vital, Amorín, Ricardo, Sanchez-Janssen, Rubén, del Valle-Espinosa, Macarena Garcia, Papaderos, Polychronis

论文摘要

这项工作着重于CGCG007-025的气体化学成分。这个紧凑的矮人正在经历一个星系宽的恒星形成爆发,VLT/Muse已经观察到了空间行为。我们提出了一个新的线测量库,以处理近7800次体素。直接方法化学分析仅限于484个体素,对$ [SIII] $ 6312 $ \ MATHRING {\ MATHRM {a}} $温度诊断线。通过种群合成,校正了重组通量,以获得恒星吸收。此外,我们讨论了一种新算法,以通过神经网络拟合光电离心模型。分析的8个离子丰度显示出一个空间正态分布,其$σ\ sim0.1 \ dex $,其中只能通过测量中的不确定性来解释该值的一半。氧丰度分布为$ 12+日志(O/H)= 7.88 \ PM0.11 $。 $ t_ {e} [siii] $和$ ne [sii] $也正态分布。但是,在中央和最明亮的地区,$ NE [SII] $几乎是平均星系值的三次。这也反映在灭绝测量中。电离参数的分布为$ log(u)= -2.52^{0.17} _ {0.19} $。参数空间行为与$ s^{2+}/s^{+} $ map一致。最后,讨论了直接方法与光电离模型拟合之间的差异。在后一种技术中,我们发现具有不平衡不确定性幅度的混合线会影响结果的准确性。在这些配件中,我们建议高估最小通量不确定性的最小通量不确定性。这提供了与直接方法更好的匹配。

This work focuses on the gas chemical composition of CGCG007-025. This compact dwarf is undergoing a galaxy wide star forming burst, whose spatial behaviour has been observed by VLT/MUSE. We present a new line measurement library to treat almost 7800 voxels. The direct method chemical analysis is limited to 484 voxels with good detection of the $[SIII]$6312$\mathring{\mathrm{A}}$ temperature diagnostic line. The recombination fluxes are corrected for stellar absorption via a population synthesis. Additionally, we discuss a new algorithm to fit photoionization models via neural networks. The 8 ionic abundances analyzed show a spatial normal distribution with a $σ\sim0.1\,dex$, where only half this value can be explained by the uncertainty in the measurements. The oxygen abundance distribution is $12+log(O/H)=7.88\pm0.11$. The $T_{e}[SIII]$ and $ne[SII]$ are also normally distributed. However, in the central and brightest region, the $ne[SII]$ is almost thrice the mean galaxy value. This is also reflected in the extinction measurements. The ionization parameter has a distribution of $log(U) = -2.52^{0.17}_{0.19}$. The parameter spatial behaviour agrees with the $S^{2+}/S^{+}$ map. Finally, the discrepancies between the direct method and the photoionization model fitting are discussed. In the latter technique, we find that mixing lines with uneven uncertainty magnitudes can impact the accuracy of the results. In these fittings, we recommend overestimating the minimum flux uncertainty one order below the maximum line flux uncertainty. This provides a better match with the direct method.

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