Diffuse Interstellar Models in the inner Galaxy

Gamma rays provide fundamental insights on the high-energy processes in the Galactic center. Unfortunately, most analyses and interpretations of current high-quality data from the Fermi Large Area Telescope, especially in the Galactic center, highly rely on large-scale interstellar models of the diffuse emission, which are very uncertain. This interstellar emission is produced by Galactic cosmic-rays propagating and interacting in the interstellar medium. To complicate the picture, most of the current models officially used to analyze Fermi-LAT diffuse data usually do not take advantage of important constraints coming from radio and microwave available foreground data.

We present our approach and updates of our effort in coherently modeling the interstellar emission in the entire Galaxy by accounting for multifrequency observations from radio to gamma rays and for the latest accurate cosmic-ray direct measurements. This has clear implications for studies of the Galactic Center. For example, we found that models based on synchrotron observations in radio produce a more peaked inverse-Compton gamma-ray emission in the inner Galaxy with respect to the standard models used to analyze Fermi LAT data.

This contribution is mainly based on our results from Orlando (2019) Physical Review D 99, 043007 and Orlando (2018) MNRAS 475, 2724.