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Abstract We analyze the first cosmological baryonic zoom-in simulations of galaxies in dissipative self-interacting dark matter (dSIDM). The simulations utilize the FIRE-2 galaxy formation physics with the inclusion of dissipative dark matter self-interactions modeled as a constant fractional energy dissipation (fdiss= 0.75). In this paper, we examine the properties of dwarf galaxies withM*∼ 105–109M⊙in both isolation and within Milky Way–mass hosts. For isolated dwarfs, we find more compact galaxy sizes and promotion of disk formation in dSIDM with (σ/m) ≤ 1 cm2g−1. On the contrary, models with (σ/m) = 10 cm2g−1produce puffier stellar distributions that are in tension with the observed size–mass relation. In addition, owing to the steeper central density profiles, the subkiloparsec circular velocities of isolated dwarfs when (σ/m) ≥ 0.1 cm2g−1are enhanced by about a factor of 2, which are still consistent with the kinematic measurements of Local Group dwarfs but in tension with the Hirotation curves of more massive field dwarfs. Meanwhile, for satellites of Milky Way–mass hosts, the median circular velocity profiles are marginally affected by dSIDM physics, but dSIDM may help promote the structural diversity of dwarf satellites. The number of satellites is slightly enhanced in dSIDM, but the differences are small compared with the large host-to-host variations. In conclusion, the dSIDM models with (σ/m) ≳ 0.1 cm2g−1,fdiss= 0.75 are in tension in massive dwarfs (Mhalo∼ 1011M⊙) due to circular velocity constraints. However, models with lower effective cross sections (at this halo mass/velocity scale) are still viable and can produce nontrivial observable signatures.
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This content will become publicly available on August 28, 2026
A Constraint on the Density of Jupiter’s Moon Thebe from Primordial Dynamics
Abstract Of the 97 known satellites in the Jovian system, the individual masses and densities of each moon have only been determined for six of them: the four Galileans, Amalthea, and Himalia. In this Letter, we derive a prediction for the mean density (and mass) of Thebe, Jupiter’s sixth-largest regular moon, obtaining a lower limit ofρT≳ 1.0 g cm–3(mT≳ 5 × 1020g). In particular, this value emerges as a key constraint within the context of the resonant transport model for the origins of Jupiter’s interior satellites. Expanding on this theory, here we carry out simulations of the simultaneous gravitational shepherding of Amalthea and Thebe via the resonant influence of inward-migrating Io during Jupiter’s disk-bearing epoch. We find that owing to overstability of resonant dynamics facilitated by the circumjovian disk’s aerodynamic drag, Thebe’s smaller radius (compared to that of Amalthea) requires a higher density to ensure its terminal orbital distance exceeds that of Amalthea, as it does today. With multiple current and upcoming space missions devoted to in situ exploration of the Jovian system, a proper measurement of Thebe’s mass provides an avenue toward empirical falsification or confirmation of our theoretical model for the dynamical evolution of Jupiter’s inner moons.
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- Award ID(s):
- 2408867
- PAR ID:
- 10634580
- Publisher / Repository:
- AAS Journals
- Date Published:
- Journal Name:
- The Astrophysical Journal Letters
- Volume:
- 990
- Issue:
- 1
- ISSN:
- 2041-8205
- Page Range / eLocation ID:
- L11
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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