Astron. J., 157, 158-158 (2019/April-0)
The neutral gas properties of extremely isolated early-type galaxies III.
ASHLEY T., MARCUM P.M., ALPASLAN M., FANELLI M.N. and FROST J.D.
Abstract (from CDS):
We report on the neutral hydrogen gas content (21 cm emission) of eight extremely isolated early-type galaxies (IEGs) using the Green Bank Telescope. Emission is detected in seven of the eight objects. This paper is the third in a series that collectively present new H I observations for 20 IEGs. Among the 14 H I detections in our observations, eight exhibit a Gaussian-like H I line profile shape, four are double-peaked, one is triple-peaked, and another has a plateaued rectangular shape. Five additional IEGs observed in previous surveys were added to our analysis, bringing the total number of IEGs with H I observations to 25. Of these objects, emission is detected in 19 (76%). The 25 IEGs in our combined study have gas masses that are systematically larger than their luminosity-matched comparison galaxy counterparts. The IEGs presented here follow a trend of increasing gas-richness with bluer B - V colors. This correlation is also observed in a comparison sample drawn from the literature composed of loose group and field early-type galaxies. Two IEGs, KIG 164 and KIG 870, exhibit properties highly anomalous for spheroidal systems: luminous (MB = -20.5, -20.1) and blue (B - V = 0.47, 0.48), respectively, with substantial neutral gas, M_H I_ = 4.1 and 5.5 x 109 M☉. Other IEG systems may represent early-type galaxies continuing to assemble via quiescent H I accretion from the cosmic web or relaxed merged systems.
© 2019. The American Astronomical Society. All rights reserved.
galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: ISM - galaxies: star formation
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