arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1505.04567astro-ph.GA
收藏

在Herschel-ATLAS巡天中对两个边对旋涡星系的尘埃能量平衡研究

Dust energy balance study of two edge-on spiral galaxies in the Herschel-ATLAS survey

Gert De Geyter, Maarten Baes, Ilse De Looze, George J. Bendo, Nathan Bourne, Peter Camps, Asantha Cooray, Gianfranco De Zotti, Loretta Dunne, Simon Dye, Steve A… 展开作者

Gert De Geyter, Maarten Baes, Ilse De Looze, George J. Bendo, Nathan Bourne, Peter Camps, Asantha Cooray, Gianfranco De Zotti, Loretta Dunne, Simon Dye, Steve A. Eales, Jacopo Fritz, Cristina Furlanetto, Gianfranco Gentile, Thomas M. Hughes, Rob J. Ivison, Steve J. Maddox, Michał J. Michałowski, Matthew W. L. Smith, Elisabetta Valiante, Sébastien Viaene

摘要:

星系中的星际尘埃可以通过其对恒星光的消光效应或通过其红外波长的热发射来追踪。最近对附近几个边缘星系的辐射转移研究发现,尘埃能量平衡存在明显的不一致性:成功解释消光现象的辐射转移模型平均低估了观测到的通量三倍。本文研究了Herschel空间天文台在H-ATLAS巡天框架下观测到的两个边缘螺旋星系IC 4225和NGC 5166的尘埃能量平衡。我们从模型开始,从光学数据的约束,并将其扩展到构建我们的星系的整个光谱能量分布。这些预测值随后进行比较,观察到的远红外通量。我们发现,包括一个年轻的恒星星族的建模是必要的,因为它在尘埃颗粒的加热中起着不可忽视的作用。虽然两个星系的建模方法几乎相同,但我们发现了两个非常不同的结果。正如在其他边缘螺旋星系中经常看到的那样,我们的IC 4225辐射转移模型的远红外发射将观测到的通量低估了约三倍。另一方面,对于NGC 5166,我们发现预测的光谱能量分布以及模拟图像与观测结果非常匹配。我们探讨了这种差异的可能原因,并得出结论,这是不可能的,一个单一的机制是在螺旋星系的尘埃能量平衡问题的原因。我们讨论了不同的方法,可以考虑,以得到一个结论性的答案,这种差异的起源。

英文摘要:

Interstellar dust in galaxies can be traced either through its extinction effects on the star light, or through its thermal emission at infrared wavelengths. Recent radiative transfer studies of several nearby edge-on galaxies have found an apparent inconsistency in the dust energy balance: the radiative transfer models that successfully explain the optical extinction underestimate the observed fluxes by an average factor of three. We investigate the dust energy balance for IC4225 and NGC5166, two edge-on spiral galaxies observed by the Herschel Space Observatory in the frame of the H-ATLAS survey. We start from models which were constrained from optical data and extend them to construct the entire spectral energy distribution of our galaxies. These predicted values are subsequently compared to the observed far-infrared fluxes. We find that including a young stellar population in the modelling is necessary as it plays a non-negligible part in the heating of the dust grains. While the modelling approach for both galaxies is nearly identical, we find two very different results. As is often seen in other edge-on spiral galaxies, the far-infrared emission of our radiative transfer model of IC4225 underestimates the observed fluxes by a factor of about three. For NGC5166 on the other hand, we find that both the predicted spectral energy distribution as well as the simulated images match the observations particularly well. We explore possible reasons for this difference and conclude that it is unlikely that one single mechanism is the cause of the dust energy balance problem in spiral galaxies. We discuss the different approaches that can be considered in order to get a conclusive answer on the origin this discrepancy.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑