arXiv 2302.002622023-02-01astro-ph.GA

根据尘埃质量和恒星形成活动的尘埃温度的Kpc尺度特性

Kpc-scale properties of dust temperature in terms of dust mass and star formation activity

I-Da Chiang, Hiroyuki Hirashita, Jeremy Chastenet, Eric W. Koch, Adam K. Leroy, Erik Rosolowsky, Karin M. Sandstrom, Amy Sardone, Jiayi Sun, Thomas G. Williams

备注：: 16 pages, 8 figures, accepted for publication in MNRAS
DOI：: 10.1093/mnras/stad373

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摘要：

研究了尘埃表面密度（$Σ_\mathrm{dust}$）、尘埃与气体的比值（D/G）和星际辐射场等环境参量对尘埃温度的影响。我们在46个邻近星系中编译多波长观测，用$2~$ kpc的共同物理分辨率统一处理。利用物理尘埃模型拟合了WISE和Herschel观测到的红外尘埃辐射光谱能量分布。用经WISE红外校正的GALEX紫外数据跟踪恒星形成率。我们发现尘埃温度与SFR面密度（$Σ_{\rm SFR}$）有很好的相关性，它可以追踪年轻恒星的辐射。当$Σ_\mathrm{SFR}$高于$\sim 2\times 10^{-3}~\rm M_\odot~yr^{-1}~kpc^{-2}$时，在固定的$Σ_{\rm SFR}$下，灰尘温度随着D/G的增加而降低，这与在高D/G下更强的灰尘屏蔽所预期的一样。这些测量结果与我们提出的分析模型预测的尘埃温度吻合得很好。在$Σ_\mathrm{SFR}$范围以下，观测到的尘埃温度比模型预测的要高，并且对D/G的依赖性很弱，这可能是由于老恒星星族的尘埃加热或过去$10^{10}~$年SFR的变化造成的。总的来说，尘埃温度作为$Σ_\mathrm{SFR}$和$Σ_\mathrm{dust}$的函数，我们的分析模型预测与观测是一致的。我们还注意到，在固定的气体表面密度下，$Σ_{\rm SFR}$倾向于随着D/G而增加，即我们可以根据经验修改Kennicutt-Schmidt定律与D/G的依赖关系，以更好地匹配观察结果。

英文摘要：

We investigate how the dust temperature is affected by local environmental quantities, especially dust surface density ($Σ_\mathrm{dust}$), dust-to-gas ratio (D/G) and interstellar radiation field. We compile multi-wavelength observations in 46 nearby galaxies, uniformly processed with a common physical resolution of $2~$kpc. A physical dust model is used to fit the infrared dust emission spectral energy distribution (SED) observed with WISE and Herschel. The star formation rate (SFR) is traced with GALEX ultraviolet data corrected by WISE infrared. We find that the dust temperature correlates well with the SFR surface density ($Σ_{\rm SFR}$), which traces the radiation from young stars. The dust temperature decreases with increasing D/G at fixed $Σ_{\rm SFR}$ as expected from stronger dust shielding at high D/G, when $Σ_\mathrm{SFR}$ is higher than $\sim 2\times 10^{-3}~\rm M_\odot~yr^{-1}~kpc^{-2}$. These measurements are in good agreement with the dust temperature predicted by our proposed analytical model. Below this range of $Σ_\mathrm{SFR}$, the observed dust temperature is higher than the model prediction and is only weakly dependent on D/G, which is possibly due to the dust heating from old stellar population or the variation of SFR within the past $10^{10}~$yr. Overall, the dust temperature as a function of $Σ_\mathrm{SFR}$ and $Σ_\mathrm{dust}$ predicted by our analytical model is consistent with observations. We also notice that at fixed gas surface density, $Σ_{\rm SFR}$ tends to increase with D/G, i.e. we can empirically modify the Kennicutt-Schmidt law with a dependence on D/G to better match observations.

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