Tracing satellite planes in the Sculptor group: II. Discovery of five faint dwarf galaxies in the DESI Legacy Survey
arxiv(2024)
摘要
The problem of missing satellites still remains one of the well-known
problems of the Lambda-CDM cosmological theory. Despite significant progress in
cosmological modeling achieved in recent years, the search for new dwarf
galaxies-satellites of nearby giant galaxies remains extremely important. In
this series of papers we report the first results of an on-going systematic
survey of faint dwarf spheroidal galaxies in the vicinity of the bright
late-type spiral NGC 253 galaxy, the brightest member of the Sculptor filament
located at a distance of 3.7 Mpc. We performed a new NGC 253 satellite search
by means of visual inspection using co-added image cutouts reprocessed in the
DESI Legacy image surveys, reaching a very low surface brightness regime
(28.0–29.0 mag arcsec-2). Five new dwarf galaxies have been discovered in the
vicinity of NGC 253, that we named them Do V, Do VI, Do VII, Do VIII and Do IX.
Assuming they are associated to NGC 253, their total absolute V-magnitudes fall
in the -7 to -9 mag range, which is typical for dwarf satellites in the local
Universe. The central surface brightness tend to be extremely low for all the
discovered dwarfs and fall roughly in the range of 25–26 mag arcsec-2 in
g-band. We present a new list of galaxies located around the giant spiral NGC
253. With the inclusion of these additional satellites, the overall spatial
distribution of the system becomes less flattened and is now broadly consistent
with analogs drawn from Lambda-CDM expectations. Interestingly, the
distribution appears to be rather lopsided. Yet, firm conclusions on the
presence of absence of a correlated satellite structure are hampered since
distance information is lacking, the census of observed dwarfs in the system
remains far from complete, and spectroscopic velocities are not even available
for most known satellites.
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