Off the Baryonic Tully-Fisher Relation: A Population of Baryon-dominated Ultra-diffuse Galaxies

We study the gas kinematics traced by the 21 cm emission of a sample of six H i-rich low surface brightness galaxies classified as ultra-diffuse galaxies (UDGs). Using the 3D kinematic modeling code 3DBarolo we derive robust circular velocities, revealing a startling feature: H i-rich UDGs are clear...

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Published inAstrophysical journal. Letters Vol. 883; no. 2; p. L33
Main Authors Mancera Piña, Pavel E., Fraternali, Filippo, Adams, Elizabeth A. K., Marasco, Antonino, Oosterloo, Tom, Oman, Kyle A., Leisman, Lukas, di Teodoro, Enrico M., Posti, Lorenzo, Battipaglia, Michael, Cannon, John M., Gault, Lexi, Haynes, Martha P., Janowiecki, Steven, McAllan, Elizabeth, Pagel, Hannah J., Reiter, Kameron, Rhode, Katherine L., Salzer, John J., Smith, Nicholas J.
Format Journal Article
LanguageEnglish
Published Austin The American Astronomical Society 01.10.2019
IOP Publishing
Bristol : IOP Publishing
Subjects
Astronomical models
Astrophysics
Baryons
Circularity
Dark matter
Dwarf galaxies
Emission analysis
Fish populations
Galactic rotation
Galaxies
Galaxy dynamics
Galaxy evolution
Galaxy formation
Galaxy kinematics
Galaxy rotation curves
Kinematics
Low surface brightness galaxies
Outliers (statistics)
Physics
Surface brightness
Three dimensional models
Tully-Fisher relation
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Summary:We study the gas kinematics traced by the 21 cm emission of a sample of six H i-rich low surface brightness galaxies classified as ultra-diffuse galaxies (UDGs). Using the 3D kinematic modeling code 3DBarolo we derive robust circular velocities, revealing a startling feature: H i-rich UDGs are clear outliers from the baryonic Tully-Fisher relation, with circular velocities much lower than galaxies with similar baryonic mass. Notably, the baryon fraction of our UDG sample is consistent with the cosmological value: these UDGs are compatible with having no "missing baryons" within their virial radii. Moreover, the gravitational potential provided by the baryons is sufficient to account for the amplitude of the rotation curve out to the outermost measured point, contrary to other galaxies with similar circular velocities. We speculate that any formation scenario for these objects will require very inefficient feedback and a broad diversity in their inner dark matter content.
Bibliography:AAS18772
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/ab40c7