TY - JOUR
T1 - Star Formation Histories of Ultra-faint Dwarf Galaxies
T2 - Environmental Differences between Magellanic and Non-Magellanic Satellites?
AU - Sacchi, Elena
AU - Richstein, Hannah
AU - Kallivayalil, Nitya
AU - Van Der Marel, Roeland
AU - Libralato, Mattia
AU - Zivick, Paul
AU - Besla, Gurtina
AU - Brown, Thomas M.
AU - Choi, Yumi
AU - Deason, Alis
AU - Fritz, Tobias
AU - Geha, Marla
AU - Guhathakurta, Puragra
AU - Jeon, Myoungwon
AU - Kirby, Evan
AU - Majewski, Steven R.
AU - Patel, Ekta
AU - Simon, Joshua D.
AU - Tony Sohn, Sangmo
AU - Tollerud, Erik
AU - Wetzel, Andrew
N1 - Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.
PY - 2021/10/10
Y1 - 2021/10/10
N2 - We present the color-magnitude diagrams and star formation histories (SFHs) of seven ultra-faint dwarf galaxies: Horologium 1, Hydra 2, Phoenix 2, Reticulum 2, Sagittarius 2, Triangulum 2, and Tucana 2, derived from high-precision Hubble Space Telescope photometry. We find that the SFH of each galaxy is consistent with them having created at least 80% of the stellar mass by z ~ 6. For all galaxies, we find quenching times older than 11.5 Gyr ago, compatible with the scenario in which reionization suppresses the star formation of small dark matter halos. However, our analysis also reveals some differences in the SFHs of candidate Magellanic Cloud satellites, i.e., galaxies that are likely satellites of the Large Magellanic Cloud and that entered the Milky Way potential only recently. Indeed, Magellanic satellites show quenching times about 600 Myr more recent with respect to those of other Milky Way satellites, on average, even though the respective timings are still compatible within the errors. This finding is consistent with theoretical models that suggest that satellites' SFHs may depend on their host environment at early times, although we caution that within the error bars all galaxies in our sample are consistent with being quenched at a single epoch.
AB - We present the color-magnitude diagrams and star formation histories (SFHs) of seven ultra-faint dwarf galaxies: Horologium 1, Hydra 2, Phoenix 2, Reticulum 2, Sagittarius 2, Triangulum 2, and Tucana 2, derived from high-precision Hubble Space Telescope photometry. We find that the SFH of each galaxy is consistent with them having created at least 80% of the stellar mass by z ~ 6. For all galaxies, we find quenching times older than 11.5 Gyr ago, compatible with the scenario in which reionization suppresses the star formation of small dark matter halos. However, our analysis also reveals some differences in the SFHs of candidate Magellanic Cloud satellites, i.e., galaxies that are likely satellites of the Large Magellanic Cloud and that entered the Milky Way potential only recently. Indeed, Magellanic satellites show quenching times about 600 Myr more recent with respect to those of other Milky Way satellites, on average, even though the respective timings are still compatible within the errors. This finding is consistent with theoretical models that suggest that satellites' SFHs may depend on their host environment at early times, although we caution that within the error bars all galaxies in our sample are consistent with being quenched at a single epoch.
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U2 - 10.3847/2041-8213/ac2aa3
DO - 10.3847/2041-8213/ac2aa3
M3 - Article
AN - SCOPUS:85117184023
SN - 2041-8205
VL - 920
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L19
ER -