Evidence of wind signatures in the gas velocity profiles of Red Geysers

Abstract

Spatially resolved spectroscopy from SDSS-IV MaNGA survey has revealed a class of quiescent, relatively common early-type galaxies, termed "red geysers", that possibly host large scale active galactic nuclei driven winds. Given their potential importance in maintaining low level of star formation at late times, additional evidence confirming that winds are responsible for the red geyser phenomenon is critical. In this work, we present follow-up observations with the Echellette Spectrograph and Imager (ESI) at the Keck telescope of two red geysers (z<0.1) using multiple long slit positions to sample different regions of each galaxy. Our ESI data with a spectral resolution (R) ∼ 8000 improves upon MaNGA's resolution by a factor of four, allowing us to resolve the ionized gas velocity profiles along the putative wind cone with an instrumental resolution of σ = 16 km s −1 . The line profiles of Hα and [NII]λ6584 show asymmetric shapes that depend systematically on location − extended blue wings on the red-shifted side of the galaxy and red wings on the opposite side. We construct a simple wind model and show that our results are consistent with geometric projections through an outflowing conical wind oriented at an angle towards the line of sight. An alternative hypothesis that assigns the asymmetric pattern to "beam-smearing" of a rotating, ionized gas disk does a poor job matching the line asymmetry profiles. While our study features just two sources, it lends further support to the notion that red geysers are the result of galaxy-scale winds.