Herschel Optimized Tau and Temperature (HOTT) Maps: Uncertainty Analysis and Robust Parameter Extraction

Abstract

Abstract We introduce the HOTT dust optical depth and temperature maps parameterizing thermal dust emission. Such maps have revolutionized studies of the distribution of matter in molecular clouds and processes relevant to star formation, including virial stability. HOTT maps for a suite of fields, including the Herschel Gould Belt Survey, are available online. The standardization of our robust pipeline for modified blackbody fitting of the spectral energy distribution (SED) of high-quality archival submillimeter data from the Herschel Space Observatory is based on a thorough analysis and quantification of the uncertainties of the data. This enables proper weighting in the SED fits. The uncertainties assessed fall into four main categories: instrument noise; the cosmic infrared background anisotropy, a contaminating sky signal; gradient-related noise arising because of dust signal morphology; and calibration uncertainty, scaling with the signal strength. Zero-level adjustments are important too. An analysis of residuals from the SED fits across many fields supports the overall appropriateness of the assumed modified blackbody model and points to where it breaks down. Finding χ 2 distributions close to the theoretical expectation boosts confidence in the pipeline and the optimized quality of the parameter maps and their estimated uncertainties. We compared our HOTT parameter maps to those from earlier studies to understand and quantify the potential for systematic differences.