MORGOTH: incorporating horizontal branch modelling into star formation history determinations

Abstract

We present a new method that incorporates the horizontal branch morphology into synthetic colour-magnitude diagram based star formation history determinations. This method, we call MORGOTH, self-consistently takes into account all the stellar evolution phases up to the early asymptothic giant branch, flexibly modelling red giant branch mass loss. We test MORGOTH on a range of synthetic populations, and find that the inclusion of the horizontal branch significantly increases the precision of the resulting star formation histories. When the main sequence turn-off is detected, MORGOTH can fit the star formation history and the red giant branch mass loss at the same time, efficiently breaking this degeneracy. As part of testing MORGOTH, we also model the observed colour-magnitude diagram of the well studied Sculptor dwarf spheroidal galaxy. We recover a new more detailed star formation history for this galaxy. Both the new star formation history and the red giant branch mass loss we determined for Sculptor with MORGOTH are in good agreement with previous analyses, thus demonstrating the power of this new approach.

12 pages, 11 figures, accepted for publication in MNRAS

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Cited by in corpus (12)

• VLT/FLAMES high-resolution chemical abundances in Sculptor: a textbook dwarf spheroidal galaxy
• The Hubble Space Telescope Survey of M31 Satellite Galaxies I. RR Lyrae-based Distances and Refined 3D Geometric Structure
• The age of the Milky Way inner stellar spheroid from RR Lyrae population synthesis
• RR Lyrae From Binary Evolution: Abundant, Young and Metal-Rich
• Simultaneous Constraints on the Star Formation History and Nucleosynthesis of Sculptor dSph
• Neutron-capture elements in dwarf galaxies II: Challenges for the s- and i-processes at low metallicity
• The HST/ACS star formation history of the Tucana dwarf spheroidal galaxy: clues from the horizontal branch
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• Measuring Resolved Star Formation Histories from High-Precision Color-Magnitude Diagrams with StarFormationHistories.jl
• The impact of rare events on the chemical enrichment in dwarf galaxies