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arXiv · 0809.0890

E+A and Companion Galaxies - I : A Catalogue and Statistics

Chisato Yamauchi·Masafumi Yagi·Tomotsugu Goto
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Abstract

Based on our intensive spectroscopic campaign with the GoldCam spectrograph on the Kitt Peak National Observatory (KPNO) 2.1-m telescope, we have constructed the first catalogue of E+A galaxies with spectroscopic companion galaxies, and investigated a probability that an E+A galaxy have close companion galaxies. We selected 660 E+A galaxies with $4.0{\rm Å} < {\rm H}δ{\rm EW}$ at a redshift of $<0.167$ from the Data Release 5 of the Sloan Digital Sky Survey (SDSS). We selected their companion candidates from the SDSS imaging data, and classified them into true companions, fore/background galaxies and companion candidates using the SDSS and our KPNO spectra. We observed 26 companion candidates of E+A galaxies at the KPNO to measure their redshifts. Their spectra showed that 17 targets are true companion galaxies. The number of spectroscopically-confirmed E+A's companions are now 34. This becomes the first catalogue of E+A galaxies with spectroscopic companion systems. We found that E+A galaxies have an 54% larger probability of having companion galaxies (7.88%) compared to the comparison sample of normal galaxies (5.12%). A statistical test shows the probabilities are different with 99.7% significance. Our results based on spectroscopy tightens the connection between the dynamical merger/interaction and the origin of E+A galaxies.

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Chisato Yamauchi, Masafumi Yagi, Tomotsugu Goto. 2008-09-04. E+A and Companion Galaxies - I : A Catalogue and Statistics. https://doi.org/10.1111/j.1365-2966.2008.13756.x

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