Bibcode
Martínez-Delgado, David; Romanowsky, Aaron J.; Gabany, R. Jay; Annibali, Francesca; Arnold, Jacob A.; Fliri, Jürgen; Zibetti, Stefano; van der Marel, Roeland P.; Rix, Hans-Walter; Chonis, Taylor S.; Carballo-Bello, J. A.; Aloisi, Alessandra; Macciò, Andrea V.; Gallego-Laborda, J.; Brodie, Jean P.; Merrifield, Michael R.
Referencia bibliográfica
The Astrophysical Journal Letters, Volume 748, Issue 2, article id. L24 (2012).
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4
2012
Número de citas
141
Número de citas referidas
128
Descripción
A candidate diffuse stellar substructure was previously reported in the
halo of the nearby dwarf starburst galaxy NGC 4449 by Karachentsev et
al. We map and analyze this feature using a unique combination of deep
integrated-light images from the BlackBird 0.5 m telescope, and
high-resolution wide-field images from the 8 m Subaru Telescope, which
resolve the nebulosity into a stream of red giant branch stars, and
confirm its physical association with NGC 4449. The properties of the
stream imply a massive dwarf spheroidal progenitor, which after complete
disruption will deposit an amount of stellar mass that is comparable to
the existing stellar halo of the main galaxy. The stellar mass ratio
between the two galaxies is ~1:50, while the indirectly measured
dynamical mass ratio, when including dark matter, may be ~1:10-1:5. This
system may thus represent a "stealth" merger, where an infalling
satellite galaxy is nearly undetectable by conventional means, yet has a
substantial dynamical influence on its host galaxy. This singular
discovery also suggests that satellite accretion can play a significant
role in building up the stellar halos of low-mass galaxies, and possibly
in triggering their starbursts.
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