The Imprint of Clump Formation at High Redshift. II. The Chemistry of the Bulge
Abstract
In Paper I, we showed that clumps in high-redshift galaxies, having a high star formation rate density (ΣSFR), produce disks with two tracks in the [Fe/H]-[α/Fe] chemical space, similar to that of the Milky Way's (MW's) thin+thick disks. Here we investigate the effect of clumps on the bulge's chemistry. The chemistry of the MW's bulge is comprised of a single track with two density peaks separated by a trough. We show that the bulge chemistry of an N-body + smoothed particle hydrodynamics clumpy simulation also has a single track. Star formation within the bulge is itself in the high-ΣSFR clumpy mode, which ensures that the bulge's chemical track follows that of the thick disk at low [Fe/H] and then extends to high [Fe/H], where it peaks. The peak at low metallicity instead is comprised of a mixture of in situ stars and stars accreted via clumps. As a result, the trough between the peaks occurs at the end of the thick disk track. We find that the high-metallicity peak dominates near the mid-plane and declines in relative importance with height, as in the MW. The bulge is already rapidly rotating by the end of the clump epoch, with higher rotation at low [α/Fe]. Thus clumpy star formation is able to simultaneously explain the chemodynamic trends of the MW's bulge, thin+thick disks, and the splash.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2023
- DOI:
- 10.3847/1538-4357/acbb00
- arXiv:
- arXiv:2303.08265
- Bibcode:
- 2023ApJ...946..118D
- Keywords:
-
- Galactic bulge;
- Milky Way formation;
- Milky Way evolution;
- Milky Way dynamics;
- Galaxy bulges;
- 2041;
- 1053;
- 1052;
- 1051;
- 578;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 25 pages, in press at ApJ