Star Formation Histories of Ultra-Faint Dwarf Galaxies: environmental differences between Magellanic and non-Magellanic satellites?
Authors: Elena Sacchi, Hannah Richstein, Nitya Kallivayalil, Roeland van der Marel, Mattia Libralato, Paul Zivick, Gurtina Besla, Thomas M. Brown, Yumi Choi, Alis Deason, Tobias Fritz, Marla Geha, Puragra Guhathakurta, Myoungwon Jeon, Evan Kirby, Steven R. Majewski, Ekta Patel, Joshua D. Simon, Sangmo Tony Sohn, Erik Tollerud, Andrew Wetzel
Abstract
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 $z\sim6$. 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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The Hubble Space Telescope Survey of M31 Satellite Galaxies. II. The Star Formation Histories of Ultrafaint Dwarf GalaxiesA. Savino, D. Weisz, E. Skillman et al. · 2023 · Astrophysical Journal · cited 32 times · Not summarized yet
Abstract
We present the lifetime star formation histories (SFHs) for six ultrafaint dwarf (UFD; M V > − 7.0, 4.9<log10(M*(z=0)/M⊙)<5.5 ) satellite galaxies of M31 based on deep color–magnitude diagrams constructed from Hubble Space Telescope imaging. These are the first SFHs obtained from the oldest main-sequence turnoff of UFDs outside the halo of the Milky Way (MW). We find that five UFDs formed at least 50% of their stellar mass by z = 5 (12.6 Gyr ago), similar to known UFDs around the MW, but that 10%–40% of their stellar mass formed at later times. We uncover one remarkable UFD, And xiii, which formed only 10% of its stellar mass by z = 5, and 75% in a rapid burst at z ∼ 2–3, a result that is ro…
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Comparing the Quenching Times of Faint M31 and Milky Way Satellite GalaxiesD. Weisz, Nicolas F. Martin, A. Dolphin et al. · 2019 · Astrophysical Journal · cited 34 times · Not summarized yet
Abstract
We present the star formation histories (SFHs) of 20 faint M31 satellites (−12 ≲ MV ≲ −6) that were measured by modeling sub-horizontal branch depth color–magnitude diagrams constructed from Hubble Space Telescope (HST) imaging. Reinforcing previous results, we find that virtually all galaxies quenched between 3 and 9 Gyr ago, independent of luminosity, with a notable concentration 3–6 Gyr ago. This is in contrast to the Milky Way (MW) satellites, which are generally either faint with ancient quenching times or luminous with recent (<3 Gyr) quenching times. We suggest that systematic differences in the quenching times of M31 and MW satellites may be a reflection of the varying accretion hist…
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THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. III. CHARACTERIZING QUENCHING IN LOW-MASS GALAXIESD. Weisz, A. Dolphin, E. Skillman et al. · 2015 · The Astrophysical Journal · cited 63 times · Not summarized yet
Abstract
We explore the quenching of low-mass galaxies (10 4 ≲ M ⋆ ≲ ?> 108 M ⊙ ?> ) as a function of lookback time using the star formation histories (SFHs) of 38 Local Group dwarf galaxies. The SFHs were derived by analyzing color–magnitude diagrams of resolved stellar populations in archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. We find: (1) lower-mass galaxies quench earlier than higher-mass galaxies; (2) inside of R virial ?> there is no correlation between a satellite’s current proximity to a massive host and its quenching epoch; and (3) there are hints of systematic differences in the quenching times of M31 and Milky Way (MW) satellites, although the sample size and unc…
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The cumulative star formation histories of dwarf galaxies with TNG50. I: environment-driven diversity and connection to quenchingGandhali D Joshi, A. Pillepich, D. Nelson et al. · 2021 · Monthly notices of the Royal Astronomical Society · cited 26 times · Not summarized yet
Abstract
We present the cumulative star formation histories (SFHs) of >15 000 dwarf galaxies ($M_{\rm *}=10^{7-10}\, {\rm M}_{\odot }$) simulated with the TNG50 run of the IllustrisTNG suite across a vast range of environments. The key factors that determine the dwarfs’ SFHs are their central/satellite status and stellar mass, with centrals and more massive dwarfs assembling their stellar mass at later times, on average, compared to satellites and lower mass dwarfs. Satellites (in hosts of mass $M_{\rm 200c, host}=10^{12-14.3}\, {\rm M}_{\odot }$) assembled 90 per cent of their stellar mass ${\sim}7.0_{-5.5}^{+3.3}$ Gyr ago, on average and within the 10th to 90th percentiles, while the centrals did s…
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PRE-REIONIZATION FOSSILS, ULTRA-FAINT DWARFS, AND THE MISSING GALACTIC SATELLITE PROBLEMM. Bovill, M. Ricotti · 2008 · The Astrophysical Journal · cited 145 times · Not summarized yet
Abstract
We argue that, at least a fraction of the newly discovered population of ultra-faint dwarf spheroidal galaxies in the Local Group constitute the fossil relic of a once ubiquitous population of dwarf galaxies formed before reionization with circular velocities smaller than vcrc ∼ 20 km s−1. We present several arguments in support of this model. The number of luminous Milky Way satellites inferred from observations is larger than the estimated number of dark halos in the Galaxy that have, or had in the past, a circular velocity greater than vcrc, as predicted by the “Via Lactea” simulation. This implies that some ultra-faint dwarfs are fossils. However, this argument is weakened by recent resu…
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THE QUENCHING OF THE ULTRA-FAINT DWARF GALAXIES IN THE REIONIZATION ERAT. Brown, J. Tumlinson, M. Geha et al. · 2014 · The Astrophysical Journal · cited 205 times · Not summarized yet
Abstract
We present new constraints on the star formation histories of six ultra-faint dwarf galaxies: Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I. Our analysis employs a combination of high-precision photometry obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, medium-resolution spectroscopy obtained with the DEep Imaging Multi-Object Spectrograph on the W. M. Keck Observatory, and updated Victoria-Regina isochrones tailored to the abundance patterns appropriate for these galaxies. The data for five of these Milky Way satellites are best fit by a star formation history where at least 75% of the stars formed by z ∼ 10 (13.3 Gyr ago). All o…
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Stars, gas, and star formation of distant post-starburst galaxiesPo-Feng Wu, Rachel Bezanson, Francesco D'Eugenio et al. · 2023 · Astrophysics of Galaxies · cited 11 times · AI summary available
Abstract
We present a comprehensive multi-wavelength study of 5 poststarburst galaxies with $M_\ast > 10^{11} M_\odot$ at $z\sim 0.7$, examining their stars, gas, and current and past star-formation activities. Using optical images from the Subaru telescope and Hubble Space Telescope, we observe a high incidence of companion galaxies and low surface brightness tidal features, indicating that quenching is closely related to interactions between galaxies. From optical spectra provided by the LEGA-C survey, we model the stellar continuum to derive the star-formation histories and show that the stellar masses of progenitors ranging from $2\times10^9 M_\odot$ to $10^{11} M_\odot$, undergoing a burst of st…
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The HST Legacy Archival Uniform Reduction of Local Group Imaging (LAURELIN). I. Photometry and Star Formation Histories for 36 Ultra-faint Dwarf GalaxiesM. Durbin, Yu-Mi Choi, A. Savino et al. · 2025 · Astrophysical Journal · cited 16 times · Not summarized yet
Abstract
We present uniformly measured resolved stellar photometry and star formation histories (SFHs) for 36 nearby (≲400 kpc) ultra-faint dwarf galaxies (UFDs; −7.1 ≤ MV ≤ +0.0) from new and archival Hubble Space Telescope (HST) imaging. We measure homogeneous distances to all systems via isochrone fitting and find good agreement (≤2%) for the 18 UFDs that have literature RR Lyrae distances. From the ensemble of SFHs, we find (i) an average quenching time (here defined as the lookback time by which 80% of the stellar mass formed, τ80) of 12.48 ± 0.18 Gyr ago ( z=4.6−0.5+0.6 ), which is compatible with reionization-based quenching scenarios; and (ii) modest evidence of a delay (≲800 Myr) in quenchin…
Prior work it builds on
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The Missing Satellites of the Magellanic Clouds? Gaia Proper Motions of the Recently Discovered Ultra-faint GalaxiesN. Kallivayalil, L. Sales, Paul Zivick et al. · 2018 · Astrophysical Journal · cited 118 times · Not summarized yet
Abstract
According to LCDM theory, hierarchical evolution occurs on all mass scales, implying that satellites of the Milky Way should also have companions. The recent discovery of ultra-faint dwarf galaxy candidates in close proximity to the Magellanic Clouds provides an opportunity to test this theory. We present proper motion (PM) measurements for 13 of the 32 new dwarf galaxy candidates using Gaia data release 2. All 13 also have radial velocity measurements. We compare the measured 3D velocities of these dwarfs to those expected at the corresponding distance and location for the debris of a Large Magellanic Cloud (LMC) analog in a cosmological numerical simulation. We conclude that four of these …
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Dark and luminous satellites of LMC-mass galaxies in the FIRE simulationsEthan D. Jahn, L. V. Sales, A. Wetzel et al. · 2019 · Monthly notices of the Royal Astronomical Society · cited 31 times · Not summarized yet
Abstract
Within lambda cold dark matter ($\Lambda$CDM), dwarf galaxies like the Large Magellanic Cloud (LMC) are expected to host numerous dark matter subhaloes, several of which should host faint dwarf companions. Recent Gaia proper motions confirm new members of the LMC system in addition to the previously known SMC, including two classical dwarf galaxies ($M_\ast$$\gt 10^5$ M$_{\odot }$; Carina and Fornax) as well as several ultrafaint dwarfs (Car2, Car3, Hor1, and Hyd1). We use the Feedback In Realistic Environments (FIRE) simulations to study the dark and luminous (down to ultrafaint masses, $M_\ast$$\sim$6$\times 10^ {3}$ M$_{\odot }$) substructure population of isolated LMC-mass hosts ($M_{\te…
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THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. II. SEARCHING FOR SIGNATURES OF REIONIZATIOND. Weisz, A. Dolphin, E. Skillman et al. · 2014 · The Astrophysical Journal · cited 97 times · Not summarized yet
Abstract
We search for signatures of reionization in the star formation histories (SFHs) of 38 Local Group dwarf galaxies (104 < M⋆ < 109 M☉). The SFHs are derived from color–magnitude diagrams using archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. Only five quenched galaxies (And V, And VI, And XIII, Leo IV, and Hercules) are consistent with forming the bulk of their stars before reionization, when full uncertainties are considered. Observations of 13 of the predicted “true fossils” identified by Bovill & Ricotti show that only two (Hercules and Leo IV) indicate star formation quenched by reionization. However, both are within the virial radius of the Milky Way and evidence of …
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The predicted luminous satellite populations around SMC and LMC-mass galaxies - A missing satellite problem around the LMC?Gregory A. Dooley, A. Peter, J. Carlin et al. · 2017 · Monthly Notices of the Royal Astronomical Society · cited 63 times · Not summarized yet
Abstract
Recent discovery of many dwarf satellite galaxies in the direction of the Small and Large Magellanic Clouds (SMC and LMC) provokes questions of their origins, and what they can reveal about galaxy evolution theory. Here, we predict the satellite stellar mass function of Magellanic Cloud-mass host galaxies using abundance matching and reionization models applied to the \textit{Caterpillar} simulations. Specifically focusing on the volume within $50$~kpc of the LMC, we predict a mean of 4-8 satellites with stellar mass $M_* > 10^4\, \mathrm{M_\odot}$, and 3-4 satellites with $80 10^5\, \mathrm{M_\odot}$ ($M_* > 10^4\, \mathrm{M_\odot}$) within the virial volume of each, and 1-3 (1-7) within a …
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Identifying true satellites of the Magellanic Clouds.L. Sales, J. Navarro, N. Kallivayalil et al. · 2016 · Monthly Notices of the Royal Astronomical Society · cited 80 times · Not summarized yet
Abstract
The hierarchical nature of ΛCDM suggests that the Magellanic Clouds must have been surrounded by a number of satellites before their infall into the Milky Way halo. Many of those satellites should still be in close proximity to the Clouds, but some could have dispersed ahead/behind the Clouds along their Galactic orbit. Either way, prior association with the Clouds constrains the present-day positions and velocities of candidate Magellanic satellites: they must lie close to the nearly polar orbital plane of the Magellanic Stream, and their distances and radial velocities must follow the latitude dependence expected for a tidal stream with the Clouds near pericentre. We use a cosmological num…
Papers that cite it
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Timing the r-process Enrichment of the Ultra-faint Dwarf Galaxy Reticulum IIJ. Simon, T. Brown, B. Mutlu-Pakdİl et al. · 2022 · Astrophysical Journal · cited 21 times · Not summarized yet
Abstract
The ultra-faint dwarf galaxy Reticulum II (Ret II) exhibits a unique chemical evolution history, with 72−12+10 % of its stars strongly enhanced in r-process elements. We present deep Hubble Space Telescope photometry of Ret II and analyze its star formation history. As in other ultra-faint dwarfs, the color–magnitude diagram is best fit by a model consisting of two bursts of star formation. If we assume that the bursts were instantaneous, then the older burst occurred around the epoch of reionization, forming ∼80% of the stars in the galaxy, while the remainder of the stars formed ∼3 Gyr later. When the bursts are allowed to have nonzero durations, we obtain slightly better fits. The best-fi…
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The Hubble Space Telescope Survey of M31 Satellite Galaxies. IV. Survey Overview and Lifetime Star Formation HistoriesA. Savino, D. Weisz, A. Dolphin et al. · 2025 · Astrophysical Journal · cited 17 times · Not summarized yet
Abstract
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Abstract
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Abstract
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Abstract
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