Constraining the thick disc formation scenario of the Milky Way

Understand

We study the shape of the thick disc using photometric data at high and intermediate latitudes from SDSS and 2MASS surveys.

• We use the population synthesis approach using an ABC-MCMC method to characterize the thick disc shape, scale height, scale length, local density and flare, and we investigate the extend of the thick disc formation period by simulating several formation episodes.
• We find that the vertical variation in density is not exponential, but much closer to an hyperbolic secant squared.
• Assuming a single formation epoch, the thick disc is better fitted with a sech2 scale height of 470 pc and a scale length of 2.3 kpc.