Bar-driven Dark Halo Evolution: A Resolution of the Cusp-Core Controversy

By M. Weinberg, Neal Katz. 2001

187 citations recorded by the source corpus.

Simulations predict that the dark matter halos of galaxies should have central cusps, while those inferred from observed galaxies do not have cusps. We demonstrate, using both linear perturbation theory and n-body simulations, that a disk bar, which should be ubiquitous in forming galaxies, can produce cores in cuspy cold dark matter profiles within five bar orbital times. Simulations of forming galaxies suggest that one of Milky Way size could have a 10 kpc primordial bar; this bar will remove the cusp out to ~2.5 kpc in ~1.5 Gyr, while the disk would lose only ~8% of its original angular momentum. Larger bars would remove the cusp out to correspondingly larger radii. An inner Lindblad-like resonance couples the rotating bar to orbits at all radii through the cusp, transferring the bar-pattern angular momentum to the dark matter cusp, rapidly flattening it. This resonance disappears for profiles with cores and is responsible for a qualitative difference in bar-driven halo evolution with and without a cusp. This bar-induced evolution will have a profound effect on the structure and evolution of almost all galaxies. Hence, both to understand galaxy formation and evolution and to make predictions from theory, it is necessary to resolve these dynamical processes. Unfortunately, correctly resolving these important dynamical processes in ab initio calculations of galaxy formation is a daunting task, requiring at least 4,000,000 halo particles using our SCF code and probably requiring many times more particles when using noisier tree, direct summation, or grid-based techniques—the usual methods employed in such calculations.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/364002734e75e227c339d34456af5f3d7632ca89

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Citations in the corpus

The Formation of a Realistic Disk Galaxy in Λ-dominated Cosmologies (2002, background): “…evolution; suppression of disk self-gravity by a softening larger than the disk scale length would inhibit processes like bar formation that are essential ingredients n disk formation and evolution (Romeo 1991, 1994; Weinberg & Katz 2002; Valenzuela & Klypin 2003; Mayer & Wadsley 2004).”
How Large Are the Bars in Barred Galaxies (2005, background): “In addition to c© 0000 RAS the well-known effects of bars on gas flow, Weinberg & Katz (2002) and Holley-Bockelmann et al. (2005) argued that bars can also restructure dark-matter halos, flattening out the steep central cusps which are produced in cosmological simulations but apparently not seen in…”
Ejection of Supermassive Black Holes from Galaxy Cores (2007, background): “A number of other authors have reported low effective values of the dynamical friction force as it acs on massive objects that inspiral into constant-density cores (Bontekoe 1988; Bertin et al. 2003; Read et al. 2006) or on rotating bars (Weinberg & Katz 2002; Valenzuela & Klypin 2003).”
The Core-Cusp Problem (2009, methodology): “An alternative way to achieve the removal of the cusp was proposed byWeinberg and Katz [108].”
Empirical Models for Dark Matter Halos. II. Inner Profile Slopes, Dynamical Profiles, and ρ/σ3 (2006, background): “Baryonic processes (Weinberg & Katz 2002) might therefore be important here, especially if fractionally more HI gas exists in LSB galaxies.”
How supernova feedback turns dark matter cusps into cores (2011, background): “…Mo & Mao 2004; Read & Gilmore 2005; Mashchenko et al. 2006, 2008), and dynamical friction from infalling baryonic clumps or disk instablities (El-Zant et al. 2001; Weinberg & Katz 2002; Tonini et al. 2006; Romano-Dı́az et al. 2008, 2009; Pasetto et al. 2010; Goerdt et al. 2010; Cole et al. 2011).”
NGC 3741: the dark halo profile from the most extended rotation curve (2006, background): “However, there is no general agreement yet as to whether realistic bars can significantly flatten the cusp (Weinberg & Katz 2002; Sellwood 2006).”
Gamma Ray Signals from Dark Matter: Concepts, Status and Prospects (2012, background): “bservation was certainly unexpected, it might possibly be explained by the interplay between baryons forming a bar and DM [101]. The same bar would however also likely destroy a DM cusp in the center [268]; tidal disruption by the central supermassive black hole may be a further issue to worry about”
High-Resolution Measurements of the Halos of Four Dark Matter-Dominated Galaxies: Deviations from a Universal Density Profile (2004, background): “Baryonic processes, however, probably can (e.g., Weinberg & Katz 2002).”
Dynamical modelling of the galactic bulge and bar: the Milky Way's pattern speed, stellar and dark matter mass distribution (2016, background): “Such processes are the resonance effects of a large primordial stellar bar (Weinberg & Katz 2002; but see Dubinski et al. 2009), supernova feedback (Pontzen & Governato 2012) and stellar feedback (Chan et al. 2015; Schaller et al. 2015; but see Marinacci et al. 2014).”
Numerical simulations of the dark universe: State of the art and the next decade (2012, background): “Examples of such cusp-to-core conversion processes are resonant interactions of the DM halo with a stellar bar6 [382–384], the decay of a supermassive black hole binary [385], dynamical friction”
Dark halo response and the stellar initial mass function in early-type and late-type galaxies (2010, background): “In addition other processes such as rapid ejection of baryons c© 2011 RAS, MNRAS 000, 1–27 from the disk through supernova driven winds (e.g., Navarro et al. 1996b), and galactic bars (Weinberg & Katz 2002) may also contribute to expanding the halo.”