论文标题
选择最模糊的星系核的技术
A technique to select the most obscured galaxy nuclei
论文作者
论文摘要
紧凑的遮盖核（CONS）主要在局部U/LIRG中发现。在本地宇宙中，通常通过检测亚毫升波长的HCN-VIB（3-2）发射线选择这些来源。在这项工作中，我们提出了一种诊断方法，可以选择基于中红外（MID-IR）多环芳烃（PAHS）和连续性比例深入掩埋核。使用局部Ulirgs代表性样本的Spitzer/IRS光谱（Z <0.27），我们检查了它们的PAH和基础连续发射比。对于深层嵌入的来源，我们发现9.7微米硅酸盐吸收带对11.3 micron PAH特征具有特别明显的影响。与其他PAH特征相比，核硅酸盐吸收带中的低通量水平增强了11.3微米PAH特征对比度（高PAH当量宽度）。该技术已扩展到包括连续比的使用。但是，后者受到宿主星系和核区域的灭绝影响，而在使用PAH当量宽度比时，前景灭绝被取消。我们将我们的方法应用于HEUS和目标样本，并将其分类为候选14个Ulirgs和10个LIRG，对应于30％的Ulirgs和7％的LIRGS。我们发现，可以通过假设具有锥形磁盘几何形状和光滑的灰尘分布的圆环模型来解释观察到的连续源的连续比。这表明缺点的核尘土结构具有极高的灰尘覆盖率。我们还证明，使用中红外颜色图是在不同红移下选择连接源的有效方法。特别是，JWST/MIRI的过滤器的组合将使Z〜1.5的缺点选择。这将允许将缺席的选择扩展到U/LIRG越来越多的高红移。
Compact obscured nuclei (CONs) are mainly found in local U/LIRGs. In the local Universe, these sources are generally selected through the detection of the HCN-vib (3-2) emission line at submillimetre wavelengths. In this work, we present a diagnostic method to select deeply buried nuclei based on mid-infrared (mid-IR) polycyclic aromatic hydrocarbons (PAHs) and continuum ratios. Using Spitzer/IRS spectra of a representative sample of local ULIRGs (z<0.27), we examine their PAH and underlying continuum emission ratios. For deeply embedded sources, we find that the 9.7 micron silicate absorption band has a particularly pronounced effect on the 11.3 micron PAH feature. The low flux level in the nuclear silicate absorption band enhances the 11.3 micron PAH feature contrast (high PAH equivalent width) compared to that of the other PAH features. The technique has been extended to include the use of the continuum ratios. However, the latter are affected both by the extinction coming from the host galaxy as well as the nuclear region, whereas the foreground extinction is cancelled out when using the PAH equivalent width ratios. We apply our method to the HERUS and GOALS samples and classify as CON candidates 14 ULIRGs and 10 LIRGs, corresponding to 30% of ULIRGs and 7% of LIRGs from these samples. We find that the observed continuum ratios of CON-dominated sources can be explained by assuming torus models with a tapered disk geometry and a smooth dust distribution. This suggests that the nuclear dusty structure of CONs has an extremely high dust coverage. We also demonstrate that the use of mid-IR color-color diagrams is an effective way to select CON-dominated sources at different redshifts. In particular, the combination of filters of the JWST/MIRI will enable the selection of CONs out to z~1.5. This will allow extending the selection of CONs to high redshifts where U/LIRGs are more numerous.
