Dynamical Friction in Cuspy Galaxies

Sedda, Manuel Arca; Capuzzo–Dolcetta, R.

doi:10.1088/0004-637x/785/1/51

Cited by 73 publications

(69 citation statements)

References 44 publications

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“…In our model both bmax and bmin vary along the orbit as a function of the local background and satellite properties. Arca-Sedda & Capuzzo-Dolcetta (2014) state that the local approximation overestimates the effects of dynamical friction in the innermost cuspy regions of galaxies, however in our approach the maximum impact parameter tends to zero at small radii for cuspy distributions, reducing the range at which the local approximation acts over. For distributions with γ > 1 this local scale length is smaller than the distance semi-analytic Gadget Figure 21.…”

Section: Comparison With Arca-sedda and Capuzzo-dolcetta (2014)mentioning

confidence: 55%

“…This frictional force is likely responsible for galactic mergers (Gan et al 2010;Peirani et al 2010), the accretion of satellites and globular clusters onto the Galaxy (Gan et al 2010;Arca-Sedda & Capuzzo-Dolcetta 2014), and even (in part) the coalescence of supermassive black holes (Begelman et al 1980). Numerical simulations using both direct summation codes and collisionless codes have shown that Chandrasekhar's formula (equation 1) works remarkably well, despite the fact that it likely misses important physics like res-E-mail: j.petts@surrey.ac.uk onant interactions between the infalling body and the background (Tremaine & Weinberg 1984;Inoue 2009;Weinberg 1986).…”

Section: Introductionmentioning

confidence: 99%

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A semi-analytic dynamical friction model that reproduces core stalling

Petts¹,

Gualandris²,

Read³

2015

Mon. Not. R. Astron. Soc.

105

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We present a new semi-analytic model for dynamical friction based on Chandrasekhar's formalism. The key novelty is the introduction of physically motivated, radially varying, maximum and minimum impact parameters. With these, our model gives an excellent match to full N-body simulations for isotropic background density distributions, both cuspy and shallow, without any fine-tuning of the model parameters. In particular, we are able to reproduce the dramatic core-stalling effect that occurs in shallow/constant density cores, for the first time. This gives us new physical insight into the core-stalling phenomenon. We show that core stalling occurs in the limit in which the product of the Coulomb logarithm and the local fraction of stars with velocity lower than the infalling body tends to zero. For cuspy backgrounds, this occurs when the infalling mass approaches the enclosed background mass. For cored backgrounds, it occurs at larger distances from the centre, due to a combination of a rapidly increasing minimum impact parameter and a lack of slow moving stars in the core. This demonstrates that the physics of core-stalling is likely the same for both massive infalling objects and low-mass objects moving in shallow density backgrounds. We implement our prescription for dynamical friction in the direct summation code NBODY6 as an analytic correction for stars that remain within the Roche volume of the infalling object. This approach is computationally efficient, since only stars in the inspiralling system need to be evolved with direct summation. Our method can be applied to study a variety of astrophysical systems, including young star clusters orbiting near the Galactic Centre; globular clusters moving within the Galaxy; and dwarf galaxies orbiting within dark matter halos.

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Section: Comparison With Arca-sedda and Capuzzo-dolcetta (2014)mentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

A semi-analytic dynamical friction model that reproduces core stalling

Petts¹,

Gualandris²,

Read³

2015

Mon. Not. R. Astron. Soc.

105

View full text Add to dashboard Cite

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“…In this scenario, the NSC forms by accreting gas-free GCs that spiral into the galaxy's centre due to dynamical friction (e.g. Tremaine et al 1975;Arca-Sedda & Capuzzo-Dolcetta 2014). Consequently, the formed NSC should reflect the properties of the accreted GCs that are typically more metal-poor than their hosts (e.g.…”

Section: Insights On Nuclear Star Cluster Formationmentioning

confidence: 99%

Metal-poor nuclear star clusters in two dwarf galaxies near Centaurus A suggesting formation from the in-spiraling of globular clusters

Fahrion

Müller

Rejkuba

et al. 2020

A&A

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Studies of nucleated dwarf galaxies can constrain the scenarios for the formation and evolution of nuclear star clusters (NSC) in low-mass galaxies and give us insights on the origin of ultra compact dwarf galaxies (UCDs). We report the discovery of a NSC in the dwarf galaxy KKs58 and investigate its properties together with those of another NSC in KK197. Both NSCs are hosted by dwarf elliptical galaxies of the Centaurus group. Combining ESO VLT MUSE data with photometry from VLT FORS2, CTIO Blanco DECam, and HST ACS, as well as high-resolution spectroscopy from VLT UVES, we analyse the photometric, kinematic and stellar population properties of the NSCs and their host galaxies. We confirm membership of the NSCs based on their radial velocities and location close to the galaxy centres. We also confirm the membership of two globular clusters (GCs) and detect oblate rotation in the main body of KK197. Based on high signal-to-noise spectra taken with MUSE of the NSCs of both KKs58 and KK197 we measure low metallicities, [Fe/H] = −1.75 ± 0.06 dex and [Fe/H] = −1.84 ± 0.05 dex, and stellar masses of 7.3 × 10 5 M and 1.0 × 10 6 M , respectively. Both NSCs are more metal-poor than their hosts that have metallicities of −1.35 ± 0.23 dex (KKs58) and −0.84 ± 0.12 dex (KK197). This can be interpreted as NSC formation via the in-spiral of GCs. The masses, sizes and metallicities of the two NSCs place them among other NSCs, but also among the known UCDs of the Centaurus group. This indicates that NSCs might constitute the progenitors of a part of the low-mass UCDs, although their properties are almost indistinguishable from typical GCs.

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“…Different mechanisms for funnelling gas to the centre have been studied, such as magnetorotational instability, gas cloud mergers or instabilities from bar structures (Milosavljević 2004;Bekki 2007;Schinnerer et al 2008). On the other hand, NSC formation might happen through gas-free accretion of GCs that have formed at larger galactic radii and migrate inwards due to dynamical friction (Tremaine et al 1975;Capuzzo-Dolcetta 1993;Capuzzo-Dolcetta & Miocchi 2008;Agarwal & Milosavljević 2011;Arca-Sedda & Capuzzo-Dolcetta 2014). Also, the formation of nuclear stellar disks via this channel has been explored (Portaluri et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Constraining nuclear star cluster formation using MUSE-AO observations of the early-type galaxy FCC 47

Fahrion

Lyubenova

Ven

et al. 2019

A&A

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Context. Nuclear star clusters (NSCs) are found in at least 70% of all galaxies, but their formation path is still unclear. In the most common scenarios, NSCs form in-situ from the galaxy's central gas reservoir, through merging of globular clusters (GCs), or through a combination of the two. Aims. As the scenarios pose different expectations for angular momentum and stellar population properties of the NSC in comparison to the host galaxy and the GC system, it is necessary to characterise the stellar light, NSC and GCs simultaneously. The large NSC (r eff = 66 pc) and rich GC system of the early-type Fornax cluster galaxy FCC 47 (NGC 1336) render this galaxy an ideal laboratory to constrain NSC formation. Methods. Using MUSE science verification data assisted by adaptive optics, we obtained maps for the stellar kinematics and for stellar-population properties of FCC 47. We extracted the spectra of the central NSC and determined line-of-sight velocities of 24 GCs and metallicities of five. Results. FCC 47 shows two decoupled components (KDCs): a rotating disk and the NSC. Our orbit-based dynamical Schwarzschild model revealed that the NSC is a distinct kinematic feature and it constitutes the peak of metallicity and old ages in the galaxy. The main body consists of two counter-rotating populations and is dominated by a more metal-poor population. The GC system is bimodal with a dominant metal-poor population and the total GC system mass is ∼ 17% of the NSC mass (∼ 7 × 10 8 M ). Conclusions. The rotation, high metallicity and high mass of the NSC cannot be uniquely explained by GC-inspiral and most likely requires additional, but quickly quenched, in-situ formation. The presence of two KDCs most probably are evidence of a major merger that has altered the structure of FCC 47 significantly, indicating the important role of galaxy mergers in forming the complex kinematics in the galaxy-NSC system.

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Dynamical Friction in Cuspy Galaxies

Cited by 73 publications

References 44 publications

A semi-analytic dynamical friction model that reproduces core stalling

A semi-analytic dynamical friction model that reproduces core stalling

Metal-poor nuclear star clusters in two dwarf galaxies near Centaurus A suggesting formation from the in-spiraling of globular clusters

Constraining nuclear star cluster formation using MUSE-AO observations of the early-type galaxy FCC 47

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