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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 421560.0, MPI für Astronomie / Publikationen_mpia
The ghost of a dwarf galaxy: fossils of the hierarchical formation of the nearby spiral galaxy NGC 5907
Authors:Martínez-Delgado, David; Peñarrubia, Jorge; Gabany, R. Jay; Trujillo, Ignacio; Majewski, Steven R.; Pohlen, M.
Language:English
Date of Publication (YYYY-MM-DD):2008
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Volume:689
Start Page:184
End Page:193
Review Status:not specified
Audience:Experts Only
Abstract / Description:We present an extragalactic perspective of an extended stellar tidal stream wrapping around the edge-on spiral galaxy NGC 5907. Our deep images reveal for the first time a large-scale complex of arcing loops that is an excellent example of how low-mass satellite accretion can produce an interwoven, rosette-like structure of debris dispersed in the halo of its host galaxy. The existence of this structure, which has probably formed and survived for several gigayears, confirms that halos of spiral galaxies in the local universe may still contain a significant number of galactic fossils from their hierarchical formation. To examine the validity of the external accretion scenario, we present N-body simulations of the tidal disruption of a dwarf galaxy-like system in a disk galaxy plus dark halo potential that demonstrate that most of the tidal features observed in NGC 5907 can be explained by a single accretion event. Unfortunately, with no kinematic data and only the projected geometry of the stream as a constraint, the parameters of our model are considerably degenerate and, for now, must be considered illustrative only. Interestingly, NGC 5907 has long been considered a prototypical example of a warped spiral in relative isolation. The presence of an extended tidal stream challenges this picture and suggests that the gravitational perturbations induced by the stream progenitor must be considered as a possible cause for the warp. The detection of an old, complex tidal stream in a nearby galaxy with rather modest instrumentation points to the viability of surveys to find extragalactic tidal substructures around spiral galaxies in the Local Volume (<15 Mpc), with the prospect of obtaining a census with enough statistical significance to be compared with cosmological simulations.
Free Keywords:Cosmology: Dark Matter; Galaxies: Dwarf; Galaxies: Evolution; Galaxies: Halos; Galaxies: Individual: NGC Number: NGC 5907; Galaxies: Interactions
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2008ApJ...689..184M [ID No:1]
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