S315p.57 — The nature of the extremely isolated galaxies

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Aug 4th at 6:00 PM until 6:00 PM

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Author(s): Oded Spector1, Noah Brosch1

Institution(s): 1. Tel Aviv University

We report results from a study of the most isolated galaxies (EIGs). The galaxies were selected to be about 4 Mpc away from any other object, based on optical and 21-cm redshifts. The meaning of “isolation” was tested with cosmological simulations of the nearby Universe; this showed that galaxies considered as isolated in other studies have companions with whom they could have interacted. The star formation properties of the sample galaxies were studied with optical, UV, nIR and HI data. We found that the EIGs have normal halos that evolved with no major events in the last 3 Gyr. The EIGs follow the “main sequence” of star-forming galaxies with those with stellar mass less than dex(10.6) solar masses being typical “blue cloud” objects. The most extreme EIGs tend to have less gas, and to be more “early-type” than the less extreme types. We speculate that the large-scale structure of the environment a galaxy finds itself in affects the HI mass and the morphology of a galaxy.