We travelled to Nagoya Univervity in Nagoya, Japan for the 38th International Cosmic Ray Conference (ICRC 2023). For two days, I presented a poster about ongoing work on a common inference scheme for inferring atomic Hydrogen (HI), molecular Hydrogen (H2) and corrections to the Galactic velocity field.
Title: Bayesian inference of 3D densities of galactic HI and H2.
Abstract: Due to our vantage point in the disk of the Galaxy, its 3D structure is not directly accessible. However, knowing the spatial distribution, e.g. of gas is of great importance for interpreting and modelling cosmic ray data and diffuse emission. Using novel Bayesian inference techniques, we independently reconstruct the 3D densities of atomic and molecular hydrogen within the Galaxy. In order to regularise the infinite number of degrees of freedom and obtain information in regions with missing or insufficient data, we incorporate the correlation structure of the gas fields into our prior. Basis for these reconstructions are the datasets from the HI4PI-survey on the 21-cm emission line and the CO line survey by Dame et al. (2001) together with two different gas flow models. Reconstructing mock data, we can show that systematic uncertainties of the method are well under control. We present the estimated mean densities as well as uncertainty estimates and characterise the statistical properties of the gas density fields. In the future, we plan to relax assumptions on the optical thickness and also reconstruct the velocity field together with the gas densities by incorporating additional datasets into our reconstruction algorithm.
Authors: Laurin Söding, Philipp Mertsch, Vo Hong Minh Phan
When: 27th and 28th of July 2023
Where: Nagoya University in Nagoya, Japan
This is a link to “PoS” about my accompanying conference proceedings and 2309.14075 is the corresponding arXiv link. Below, you can find my poster contribution in pdf format: