TY - JOUR
T1 - Discovery of a new faint dwarf galaxy associated with NGC 253
AU - Sand, D. J.
AU - Crnojević, D.
AU - Strader, J.
AU - Toloba, E.
AU - Simon, J. D.
AU - Caldwell, N.
AU - Guhathakurta, P.
AU - McLeod, B.
AU - Seth, A. C.
N1 - Publisher Copyright:
© 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A.
PY - 2014/9/20
Y1 - 2014/9/20
N2 - We report the discovery of a new faint dwarf galaxy, which we dub Scl-MM-Dw1, at a projected distance of ∼65 kpc from the spiral galaxy NGC 253. The discovery results from the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), a program with the Magellan/Megacam imager to study faint substructure in resolved stellar light around massive galaxies outside of the Local Group. We measure a tip of the red giant branch distance to Scl-MM-Dw1 of D = 3.9 ± 0.5 Mpc, consistent with that of NGC 253, making their association likely. The new dwarf's stellar population is complex, with an old, metal-poor red giant branch (≳10 Gyr, [Fe/H] ∼ -2), and an asymptotic giant branch with an age of ∼500 Myr. Scl-MM-Dw1 has a half-light radius of rh = 340 ± 50 pc and an absolute magnitude of MV = -10.3 ± 0.6 mag, comparable to the Milky Way's satellites at the same luminosity. Once complete, our imaging survey of NGC 253 and other nearby massive galaxies will provide a census of faint substructure in halos beyond the Local Group, both to put our own environment into context and to confront models of hierarchical structure formation.
AB - We report the discovery of a new faint dwarf galaxy, which we dub Scl-MM-Dw1, at a projected distance of ∼65 kpc from the spiral galaxy NGC 253. The discovery results from the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), a program with the Magellan/Megacam imager to study faint substructure in resolved stellar light around massive galaxies outside of the Local Group. We measure a tip of the red giant branch distance to Scl-MM-Dw1 of D = 3.9 ± 0.5 Mpc, consistent with that of NGC 253, making their association likely. The new dwarf's stellar population is complex, with an old, metal-poor red giant branch (≳10 Gyr, [Fe/H] ∼ -2), and an asymptotic giant branch with an age of ∼500 Myr. Scl-MM-Dw1 has a half-light radius of rh = 340 ± 50 pc and an absolute magnitude of MV = -10.3 ± 0.6 mag, comparable to the Milky Way's satellites at the same luminosity. Once complete, our imaging survey of NGC 253 and other nearby massive galaxies will provide a census of faint substructure in halos beyond the Local Group, both to put our own environment into context and to confront models of hierarchical structure formation.
KW - Dark matter
KW - Galaxies: dwarf online-only material: color figures
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U2 - 10.1088/2041-8205/793/1/L7
DO - 10.1088/2041-8205/793/1/L7
M3 - Article
AN - SCOPUS:84924351360
SN - 2041-8205
VL - 793
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L7
ER -