We investigate the far-infrared (IR) dust emission for 20 local star forming galaxies from the Key Insights on Nearby Galaxies: A Far-IR Survey with Herschel (KINGFISH) sample. We model the far-IR/submillimeter spectral energy distribution (SED) using images from Spitzer Space Telescope and Herschel Space Observatory. We calculate the cold dust temperature (Tc ) and emissivity (β) on a pixel by pixel basis (where each pixel ranges from 0.1 to 3 kpc2) using a two-temperature modified blackbody fitting routine. Our fitting method allows us to investigate the resolved nature of temperature and emissivity variations by modeling from the galaxy centers to the outskirts (physical scales of ~15-50 kpc, depending on the size of the galaxy). We fit each SED in two ways: (1) fit Tc and β simultaneously, (2) hold β constant and fit Tc . We compare Tc and β with star formation rates (calculated from L Hα and L 24 μm), the luminosity of the old stellar population (traced through L 3.6 μm), and the dust mass surface density (traced by 500 μm luminosity, L 500). We find a significant trend between SFR/L 500 and Tc , implying that the flux of hard UV photons relative to the amount of dust is significantly contributing to the heating of the cold, or diffuse, dust component. We also see a trend between L 3.6/L 500 and β, indicating that the old stellar population contributes to the heating at far-IR/submillimeter wavelengths. Finally, we find that when β is held constant, Tc exhibits a strongly decreasing radial trend, illustrating that the shape of the far-IR SED is changing radially through a galaxy, thus confirming on a sample almost double in size the trends observed in Galametz et?al.
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机译：我们从“邻近星系的关键见解：利用赫歇尔（KINGFISH）进行的远红外调查”中调查了20个本地恒星形成星系的远红外（IR）尘埃排放。我们使用Spitzer空间望远镜和Herschel空间天文台的图像对远红外/亚毫米波频谱能量分布（SED）进行建模。我们使用经过两次温度修正的黑体拟合程序，逐个像素（每个像素的范围从0.1到3 kpc2）计算冷尘温度（Tc）和发射率（β）。我们的拟合方法使我们能够通过对从银河中心到郊区（物理尺度约为15-50 kpc，取决于银河的大小）进行建模来研究温度和发射率变化的分辨特性。我们通过两种方式拟合每个SED：（1）同时拟合Tc和β，（2）保持β恒定并拟合Tc。我们将Tc和β与恒星形成率（从LHα和L 24μm计算），旧恒星群体的光度（通过L 3.6μm跟踪）以及尘埃质量表面密度（由500μm的发光度跟踪，L 500）进行比较。 ）。我们发现SFR / L 500和Tc之间存在显着趋势，这意味着硬UV光子的通量相对于粉尘量显着促进了冷粉尘或扩散粉尘成分的加热。我们还看到L 3.6 / L 500和β之间的趋势，表明旧的恒星种群在远红外/亚毫米波长下对加热有贡献。最后，我们发现当β保持恒定时，Tc呈现出急剧下降的径向趋势，这说明远红外SED的形状通过一个星系沿径向变化，从而在样本上确认了在Galametz中观察到的趋势几乎翻了一番。等？
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