Spectroscopy of Ultra-diffuse Galaxies in the Coma Cluster

We present spectra of five 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 four of these as members of the cluster, quintupling the number of spectroscopically confirmed systems. Like th...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2017-04, Vol.838 (2), p.L21-L21
Main Authors: Kadowaki, Jennifer, Zaritsky, Dennis, Donnerstein, R. L.
Format: Article
Language:English
Subjects:
ABSORPTION SPECTRA
Astronomical models
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
BALMER LINES
CALCIUM
Clusters
Coma
DISTANCE
Galactic clusters
GALAXIES
galaxies: distances and redshifts
galaxies: general
galaxies: stellar content
HYDROGEN
IONIZING RADIATIONS
Pollution sources
POTASSIUM
Spectra
Spectrographs
SPECTROSCOPY
STARS
TELESCOPES
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Summary:We present spectra of five 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 four 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 . 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 and 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 [O ii] and [O iii] emission lines within a clustered environment, demonstrating that not all cluster UDGs are devoid of gas and sources of ionizing radiation.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/aa653d