Obscured by clouds: Deep tomography of the Galactic bulge with 4MOST and infrared dwarfs

Obscured by thick interstellar dust clouds, 24000 light years away, the central bulge region of our Milky Way galaxy has emerged as the most enigmatic of the Galactic stellar populations.

From being a simple classical bulge population, new data points toward a bulge that formed out of existing disk material.

However, the observations are both contradictory and inconclusive, and there is a debate about the existence of young bulge stars, the number of subpopulations present, and whether there is a classical bulge component at all?

A severe shortcoming, due to the extinction, is that our global view of the bulge is largely based on observations of the outer bulge.

The inner bulge is therefore unexplored, hampering our understanding of how it connects to the surrounding bar and disk populations.1. What is the age and abundance structure of the stars in the inner obscured bulge?2. How is the bulge connect to the other Galactic populations, and is there a classical bulge?3.

Are there relics from ancient merger events in the bulge?To answer these questions, a campaign to observe microlensed bulge dwarf stars, now at infrared wavelengths, will for the first time, measure stellar ages and abundances in inner bulge.

Adding elemental abundances for 4 million stars from the upcoming 4MOST bulge and disk high-resolution survey we have a goldmine of unprecedented scale and quality that will aid us in our goal to understand the origin and evolution of our home galaxy, the Milky Way.