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ABSTRACT The tension between the diverging density profiles in Lambda cold dark matter simulations and the constant-density inner regions of observed galaxies is a long-standing challenge known as the ‘core–cusp’ problem. We demonstrate that the SMUGGLE galaxy formation model implemented in the arepo moving mesh code forms constant-density cores in idealized dwarf galaxies of M⋆ ≈ 8 × 107 Msun with initially cuspy dark matter (DM) haloes of M200 ≈ 1010 Msun. Identical initial conditions run with an effective equation of state interstellar medium model preserve cuspiness. Literature on the subject has pointed to the low density threshold for star formation, ρth, in such effective models as an obstacle to baryon-induced core formation. Using a SMUGGLE run with equal ρth, we demonstrate that core formation can proceed at low density thresholds, indicating that ρth is insufficient on its own to determine whether a galaxy develops a core. We reaffirm that the ability to resolve a multiphase interstellar medium at sufficiently high densities is a more reliable indicator of core formation than any individual model parameter. In SMUGGLE, core formation is accompanied by large degrees of non-circular motion, with gas rotational velocity profiles that consistently fall below the circular velocity $$v_\text{circ} = \sqrt{GM/R}$$ out to ∼2 kpc. Asymmetric drift corrections help recover the average underlying DM potential for some of our less efficient feedback runs, but time-variations in the instantaneous azimuthal gas velocity component are substantial, highlighting the need for careful modelling in the inner regions of dwarfs to infer the true distribution of DM.
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Estimating Loadability Region of Natural Gas System via Monotone Inner Polytope Sequence
Natural gas network is important for residential heating, industrial manufacturing, and electricity generation. Although it is reliable and resilient to local disruptions, extreme situations such as natural disasters and political conflicts can degenerate its capability of gas transportation and delivery, influencing other social activities. Evaluating loadability regions of natural gas networks is hard due to nonlinear constraints. This paper proposes a fast computational tool for feasibility screening of natural gas load profiles. It first establishes the theoretical results on the convexity of loadability regions with sufficient conditions. Then, an asymptotic algorithm is applied to compute a sequence of inner polytopes that converges to the convex loadability region. Each polytope in the sequence can serve as a certificate for feasibility. The conservativeness of this inner estimation will decline along the monotone sequence. The algorithm is testified on a modified realistic Belgian natural gas system with multi-dimensional load profiles.
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- Award ID(s):
- 1638331
- PAR ID:
- 10131340
- Date Published:
- Journal Name:
- IEEE Transactions on Control of Network Systems
- ISSN:
- 2372-2533
- Page Range / eLocation ID:
- 1 to 1
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/TCNS.2019.2937212
