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arXiv 1704.02192astro-ph.GA
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去混合深赫歇尔巡天:多波长方法

De-blending Deep Herschel Surveys: A Multi-wavelength Approach

W. J. Pearson, L. Wang, F. F. S. van der Tak, P. D. Hurley, D. Burgarella, S. J. Oliver

摘要:

远红外线宇宙学调查是众所周知的遭受混乱。贝叶斯去混合工具,XID+,目前提供了一个最好的方法去混淆深赫歇尔SPIRE图像,使用一个平坦的通量密度先验。这项工作是为了证明,现有的多波长数据集可以被利用来改善XID+提供一个知情的先验,从而导致更准确和精确的提取通量密度。在COSMOS领域的星系测光数据被用来约束光谱能量分布(SED),使用拟合工具CIGALE。这些SED用于在XID+的SPIRE波段中创建高斯先验估计。多波长光度法和提取的SPIRE通量密度再次通过CIGALE运行,以使我们能够比较两种先验的性能。将来自第二次CIGALE运行的最佳拟合SED的870 $μ$ m和1250 $μ$ m处的推断ALMA通量密度(F $^i$)与测量的ALMA通量密度(F $^m$)进行比较,作为独立的性能验证。使用SED建模和拟合工具MAGPHYS和修改的黑体函数进行了类似的验证,以测试模型依赖性。我们证明了一个明显的改善与XID+和现有的数据在其他波长提取的通量密度之间的协议时,使用新的知情高斯先验在原来的不知情的先验。计算F $^m$和F $^i$之间的残差。对于高斯先验,这些残差(表示为ALMA误差的倍数($σ$))具有较小的标准差,高斯先验为7.95 $σ$,而平坦先验为12.21 $σ$,平均值降低,$σ$为1.83,而$σ$为3.44,并且具有降低的偏正值,7.97与11.50。确定这些结果不具有显著的模型依赖性。这导致统计上更可靠的SPIRE通量密度。

英文摘要:

Cosmological surveys in the far infrared are known to suffer from confusion. The Bayesian de-blending tool, XID+, currently provides one of the best ways to de-confuse deep Herschel SPIRE images, using a flat flux density prior. This work is to demonstrate that existing multi-wavelength data sets can be exploited to improve XID+ by providing an informed prior, resulting in more accurate and precise extracted flux densities. Photometric data for galaxies in the COSMOS field were used to constrain spectral energy distributions (SEDs) using the fitting tool CIGALE. These SEDs were used to create Gaussian prior estimates in the SPIRE bands for XID+. The multi-wavelength photometry and the extracted SPIRE flux densities were run through CIGALE again to allow us to compare the performance of the two priors. Inferred ALMA flux densities (F$^i$), at 870$μ$m and 1250$μ$m, from the best fitting SEDs from the second CIGALE run were compared with measured ALMA flux densities (F$^m$) as an independent performance validation. Similar validations were conducted with the SED modelling and fitting tool MAGPHYS and modified black body functions to test for model dependency. We demonstrate a clear improvement in agreement between the flux densities extracted with XID+ and existing data at other wavelengths when using the new informed Gaussian prior over the original uninformed prior. The residuals between F$^m$ and F$^i$ were calculated. For the Gaussian prior, these residuals, expressed as a multiple of the ALMA error ($σ$), have a smaller standard deviation, 7.95$σ$ for the Gaussian prior compared to 12.21$σ$ for the flat prior, reduced mean, 1.83$σ$ compared to 3.44$σ$, and have reduced skew to positive values, 7.97 compared to 11.50. These results were determined to not be significantly model dependent. This results in statistically more reliable SPIRE flux densities.

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