An Improved Method for Far Infrared Galaxy SED Fitting

Citation:

Scott S, et al. An Improved Method for Far Infrared Galaxy SED Fitting. Astronomical Society Meeting Abstracts #233. 2019;233 :245.18.
An Improved Method for Far Infrared Galaxy SED Fitting

Abstract:

In this work, we examine spectral energy distribution (SED) fitting techniques commonly used to measure the dust temperatures of galaxies. Using toy models, we show that current far infrared (FIR) fitting techniques do not accurately recover the temperature of the dust within a galaxy. Instead, current fitting techniques recover temperatures which are higher than the actual mean of the dust temperature due to fact that hotter blackbodies are brighter than cooler blackbodies at all wavelengths. We demonstrate a method for FIR SED fitting which uses Markov Chain Monte Carlo (MCMC) methods to recover a distribution of dust temperatures given a galaxy's SED. We show that the mean dust temperature of the distribution recovered using MCMC methods on generated data is significantly different from the temperature recovered from conventional curve fitting techniques. We then demonstrate the power of our our fitting method on synthetic SEDs generated using cosmological galaxy formation simulations coupled with 3D dust radiative transfer models. Using this simulated data, we also establish a temperature distribution shape to use for this MCMC method based on the temperature of the CMB at a given redshift. Code to implement MCMC curve fitting will be made publicly available.