论文标题
一种从Spitzer Spectra提取空间分辨的多环芳烃发射的方法：应用于M51
A Method to Extract Spatially Resolved Polycyclic Aromatic Hydrocarbon Emission from Spitzer Spectra: Application to M51
论文作者
论文摘要
中红外光谱包含丰富的诊断，以探测星系的物理特性，其中多环芳族烃（PAHS）的普遍发射特征提供了一种有希望的方法来估计恒星形成速率（SFR）相对免于粉尘的免疫力。本文通过研究附近大型设计螺旋星系M51的Spitzer/IRS映射模式观测值来研究PAH发射作为SFR指标在子KPC量表上的有效性。我们提出了一种分析光谱数据库的空间元素的新方法，该方法同时最大程度地提高了空间分辨率和空间覆盖范围，同时产生了总计$ 5-20 \，μ$ M PAH的可靠测量值。我们设计了一种仅具有部分光谱覆盖率的光谱来提取稳健的PAH排放的策略，以适当组合的中红外光度法补充缺失的光谱区域。 We find that in M51 the PAH emission correlates tightly with the extinction-corrected far-ultraviolet, near-ultraviolet, and H$α$ emission, from scales$\sim 0.4$ kpc close to the nucleus to 6 kpc out in the disk of the galaxy, indicating that PAH serves as an excellent tracer of SFR over a wide range of galactic environments.但是存在区域差异。接近M51的活性核6.2 $μ$ M的特征较弱，并且PAH发射的整体水平被抑制。银河系的螺旋臂和中央恒星形成区域比臂间区域更强的7.7和8.6 $ m $ m pAH。
The mid-infrared spectrum contains rich diagnostics to probe the physical properties of galaxies, among which the pervasive emission features from polycyclic aromatic hydrocarbons (PAHs) offer a promising means of estimating the star formation rate (SFR) relatively immune from dust extinction. This paper investigates the effectiveness of PAH emission as a SFR indicator on sub-kpc scales by studying the Spitzer/IRS mapping-mode observations of the nearby grand-design spiral galaxy M51. We present a new approach of analyzing the spatial elements of the spectral datacube that simultaneously maximizes spatial resolution and spatial coverage, while yielding reliable measurements of the total, integrated $5-20\,μ$m PAH emission. We devise a strategy of extracting robust PAH emission using spectra with only partial spectral coverage, complementing missing spectral regions with properly combined mid-infrared photometry. We find that in M51 the PAH emission correlates tightly with the extinction-corrected far-ultraviolet, near-ultraviolet, and H$α$ emission, from scales$\sim 0.4$ kpc close to the nucleus to 6 kpc out in the disk of the galaxy, indicating that PAH serves as an excellent tracer of SFR over a wide range of galactic environments. But regional differences exist. Close to the active nucleus of M51 the 6.2 $μ$m feature is weaker, and the overall level of PAH emission is suppressed. The spiral arms and the central star-forming region of the galaxy emit stronger 7.7 and 8.6 $μ$m PAH features than the inter-arm regions.
