Spectroscopy of ultra-diffuse galaxies in the coma cluster

Jennifer Kadowaki, Dennis Zaritsky, R. L. Donnerstein

Research output: Contribution to journalArticlepeer-review

Abstract

We present spectra of 5 ultra-diffuse galaxies (UDGs) in the vicinity of the Coma Cluster obtained with the Multi-Object Double Spectrograph on the Large Binocular Telescope. We confirm 4 of these as members of the cluster, quintupling the number of spectroscopically confirmed systems. Like the previously confirmed large (projected half light radius > 4.6 kpc) UDG, DF44, the systems we targeted all have projected half light radii > 2.9 kpc. As such, we spectroscopically confirm a population of physically large UDGs in the Coma cluster. The remaining UDG is located in the field, about 45 Mpc behind the cluster. We observe Balmer and Ca II H & K absorption lines in all of our UDG spectra. By comparing the stacked UDG spectrum against stellar population synthesis models, we conclude that, on average, these UDGs are composed of metal-poor stars ([Fe/H]. −1.5). We also discover the first UDG with [OII] and [OIII] emission lines within a clustered environment, demonstrating that not all cluster UDGs are devoid of gas and sources of ionizing radiation.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Mar 6 2017

Keywords

  • Galaxies: distances and redshifts
  • Galaxies: general
  • Galaxies: stellar content

ASJC Scopus subject areas

  • General

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