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Full-Text Articles in Physical Sciences and Mathematics
The Hi Content Of Isolated Ultra-Diffuse Galaxies: A Sign Of Multiple Formation Mechanisms?, E. Papastergis, E. Adams, Aaron Romanowsky
The Hi Content Of Isolated Ultra-Diffuse Galaxies: A Sign Of Multiple Formation Mechanisms?, E. Papastergis, E. Adams, Aaron Romanowsky
Faculty Publications
We report on the results of radio observations in the 21 cm emission line of atomic hydrogen (HI) of four relatively isolated ultra-diffuse galaxies (UDGs): DGSAT I, R-127-1, M-161-1, and SECCO-dI-2. Our Effelsberg observations resulted in non-detections for the first three UDGs, and a clear detection for the last. DGSAT I, R-127-1, and M-161-1 are quiescent galaxies with gas fractions that are much lower than those of typical field galaxies of the same stellar mass. On the other hand, SECCO-dI-2 is a star forming gas-rich dwarf, similar to two other field UDGs that have literature HI data: SECCO-dI-1 and UGC …
The Sluggs Survey: Stellar Masses And Effective Radii Of Early-Type Galaxies From Spitzer Space Telescope 3.6 Μm Imaging, Duncan Forbes, Luciana Sinpetru, Giulia Savorgnan, Aaron Romanowsky, Christopher Usher, Jean Brodie
The Sluggs Survey: Stellar Masses And Effective Radii Of Early-Type Galaxies From Spitzer Space Telescope 3.6 Μm Imaging, Duncan Forbes, Luciana Sinpetru, Giulia Savorgnan, Aaron Romanowsky, Christopher Usher, Jean Brodie
Faculty Publications
Galaxy starlight at 3.6 μm is an excellent tracer of stellar mass. Here we use the latest 3.6 μm imaging from the Spitzer Space Telescope to measure the total stellar mass and effective radii in a homogeneous way for a sample of galaxies from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey. These galaxies are representative of nearby early-type galaxies in the stellar mass range of 10 < log M*/M⊙ < 11.7 and our methodology can be applied to other samples of early-type galaxies. We model each galaxy in 2D and estimate its total asymptotic magnitude from a 1D curve-of-growth. Magnitudes are converted into stellar masses using a 3.6 μm mass-to-light ratio from the latest stellar population models of Röck et al., assuming a Kroupa initial mass function. We apply a ratio based on each galaxy's mean mass-weighted stellar age within one effective radius (the mass-to-light ratio is insensitive to galaxy metallicity for the generally old stellar ages and high metallicities found in massive early-type galaxies). Our 3.6 μm stellar masses agree well with masses derived from 2.2 μm data. From the 1D surface brightness profile, we fit a single Sérsic law, excluding the very central regions. We measure the effective radius, Sérsic n parameter and effective surface brightness for each galaxy. We find that galaxy sizes derived from shallow optical imaging and the 2MASS survey tend to underestimate the true size of the largest, most massive galaxies in our sample. We adopt the 3.6 μm stellar masses and effective radii for the SLUGGS survey galaxies.