The star formation histories of dwarf galaxies in Local Group cosmological simulations

Digby, Ruth; Navarro, Julio F; Fattahi, Azadeh; Simpson, Christine M; Oman, Kyle A; Gomez, Facundo A; Frenk, Carlos S; Grand, Robert JJ; Pakmor, Ruediger

Abstract

We use the apostle and Auriga cosmological simulations to study the star formation histories (SFHs) of field and satellite dwarf galaxies. Despite sizeable galaxy-to-galaxy scatter, the SFHs of apostle and Auriga dwarfs exhibit robust average trends with galaxy stellar mass: faint field dwarfs (105 < Mstar/M⊙ < 106) have, on average, steadily declining SFHs, whereas brighter dwarfs (107 < Mstar/M⊙ < 109) show the opposite trend. Intermediate-mass dwarfs have roughly constant SFHs. Satellites exhibit similar average trends, but with substantially suppressed star formation in the most recent ∼5 Gyr, likely as a result of gas loss due to tidal and ram-pressure stripping after entering the haloes of their primaries. These simple mass and environmental trends are in good agreement with the derived SFHs of Local Group (LG) dwarfs whose photometry reaches the oldest main-sequence turn-off. SFHs of galaxies with less deep data show deviations from these trends, but this may be explained, at least in part, by the large galaxy-to-galaxy scatter, the limited sample size, and the large uncertainties of the inferred SFHs. Confirming the predicted mass and environmental trends will require deeper photometric data than currently available, especially for isolated dwarfs.

Citation

Digby, R., Navarro, J. F., Fattahi, A., Simpson, C. M., Oman, K., Gomez, F. A., Frenk, C. S., Grand, R. J., & Pakmor, R. (2019). The star formation histories of dwarf galaxies in Local Group cosmological simulations. Monthly Notices of the Royal Astronomical Society, 485(4), 5423-5437. https://doi.org/10.1093/mnras/stz745

• Journal Article Type: Article
• Acceptance Date: Mar 11, 2019
• Online Publication Date: Mar 13, 2019
• Publication Date: Mar 13, 2019
• Deposit Date: Jun 26, 2019
• Publicly Available Date: Jun 27, 2019
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 485
• Issue: 4
• Pages: 5423-5437
• DOI: https://doi.org/10.1093/mnras/stz745
• Public URL: https://durham-repository.worktribe.com/output/1298637