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Are we observing an NSC in course of formation in the NGC 4654 galaxy?

Schiavi, R. ; Capuzzo-Dolcetta, R. ; Georgiev, I. Y. ; Arca-Sedda, M. and Mastrobuono-Battisti, A. LU (2021) In Monthly Notices of the Royal Astronomical Society 503(1). p.594-602
Abstract

We use direct N-body simulations to explore some possible scenarios for the future evolution of two massive clusters observed towards the centre of NGC 4654, a spiral galaxy with mass similar to that of the Milky Way. Using archival HST data, we obtain the photometric masses of the two clusters, M = 3 × 105 M= and M = 1.7 × 106 M=, their half-light radii, Reff ∼4 pc and Reff ∼6 pc, and their projected distances from the photometric centre of the galaxy (both <22 pc). The knowledge of the structure and separation of these two clusters (∼24 pc) provides a unique view for studying the dynamics of a galactic central zone hosting massive clusters. Varying some of the unknown cluster orbital parameters, we carry out several N-body... (More)

We use direct N-body simulations to explore some possible scenarios for the future evolution of two massive clusters observed towards the centre of NGC 4654, a spiral galaxy with mass similar to that of the Milky Way. Using archival HST data, we obtain the photometric masses of the two clusters, M = 3 × 105 M= and M = 1.7 × 106 M=, their half-light radii, Reff ∼4 pc and Reff ∼6 pc, and their projected distances from the photometric centre of the galaxy (both <22 pc). The knowledge of the structure and separation of these two clusters (∼24 pc) provides a unique view for studying the dynamics of a galactic central zone hosting massive clusters. Varying some of the unknown cluster orbital parameters, we carry out several N-body simulations showing that the future evolution of these clusters will inevitably result in their merger. We find that, mainly depending on the shape of their relative orbit, they will merge into the galactic centre in less than 82 Myr. In addition to the tidal interaction, a proper consideration of the dynamical friction braking would shorten the merging times up to few Myr. We also investigate the possibility to form a massive nuclear star cluster (NSC) in the centre of the galaxy by this process. Our analysis suggests that for low-eccentricity orbits, and relatively long merger times, the final merged cluster is spherical in shape, with an effective radius of few parsecs and a mass within the effective radius of the order of 105,M⊙. Because the central density of such a cluster is higher than that of the host galaxy, it is likely that this merger remnant could be the likely embryo of a future NSC.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
galaxies: nuclei, galaxies: star clusters
in
Monthly Notices of the Royal Astronomical Society
volume
503
issue
1
pages
9 pages
publisher
Oxford University Press
external identifiers
  • scopus:85105217140
ISSN
0035-8711
DOI
10.1093/mnras/stab458
language
English
LU publication?
yes
id
cbd15e6f-f2e9-41bd-a16d-a2d2e0bcfb1c
date added to LUP
2021-05-19 12:09:32
date last changed
2023-01-01 06:14:38
@article{cbd15e6f-f2e9-41bd-a16d-a2d2e0bcfb1c,
  abstract     = {{<p>We use direct N-body simulations to explore some possible scenarios for the future evolution of two massive clusters observed towards the centre of NGC 4654, a spiral galaxy with mass similar to that of the Milky Way. Using archival HST data, we obtain the photometric masses of the two clusters, M = 3 × 105 M= and M = 1.7 × 106 M=, their half-light radii, Reff ∼4 pc and Reff ∼6 pc, and their projected distances from the photometric centre of the galaxy (both &lt;22 pc). The knowledge of the structure and separation of these two clusters (∼24 pc) provides a unique view for studying the dynamics of a galactic central zone hosting massive clusters. Varying some of the unknown cluster orbital parameters, we carry out several N-body simulations showing that the future evolution of these clusters will inevitably result in their merger. We find that, mainly depending on the shape of their relative orbit, they will merge into the galactic centre in less than 82 Myr. In addition to the tidal interaction, a proper consideration of the dynamical friction braking would shorten the merging times up to few Myr. We also investigate the possibility to form a massive nuclear star cluster (NSC) in the centre of the galaxy by this process. Our analysis suggests that for low-eccentricity orbits, and relatively long merger times, the final merged cluster is spherical in shape, with an effective radius of few parsecs and a mass within the effective radius of the order of 105,M⊙. Because the central density of such a cluster is higher than that of the host galaxy, it is likely that this merger remnant could be the likely embryo of a future NSC. </p>}},
  author       = {{Schiavi, R. and Capuzzo-Dolcetta, R. and Georgiev, I. Y. and Arca-Sedda, M. and Mastrobuono-Battisti, A.}},
  issn         = {{0035-8711}},
  keywords     = {{galaxies: nuclei; galaxies: star clusters}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{1}},
  pages        = {{594--602}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{Are we observing an NSC in course of formation in the NGC 4654 galaxy?}},
  url          = {{http://dx.doi.org/10.1093/mnras/stab458}},
  doi          = {{10.1093/mnras/stab458}},
  volume       = {{503}},
  year         = {{2021}},
}