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Robust H i kinematics of gas-rich ultra-diffuse galaxies: hints of a weak-feedback formation scenario

Mancera Piña, Pavel E.; Fraternali, Filippo; Oman, Kyle A.; Adams, Elizabeth AK; Bacchini, Cecilia; Marasco, Antonino; Oosterloo, Tom; Pezzulli, Gabriele; Posti, Lorenzo; Leisman, Lukas; Cannon, John M.; di Teodoro, Enrico M.; Gault, Lexi; Haynes, Martha P.; Reiter, Kameron; Rhode, Katherine L.; Salzer, John J.; Smith, Nicholas J.

Robust H i kinematics of gas-rich ultra-diffuse galaxies: hints of a weak-feedback formation scenario Thumbnail


Pavel E. Mancera Piña

Filippo Fraternali

Elizabeth AK Adams

Cecilia Bacchini

Antonino Marasco

Tom Oosterloo

Gabriele Pezzulli

Lorenzo Posti

Lukas Leisman

John M. Cannon

Enrico M. di Teodoro

Lexi Gault

Martha P. Haynes

Kameron Reiter

Katherine L. Rhode

John J. Salzer

Nicholas J. Smith


We study the gas kinematics of a sample of six isolated gas-rich low surface brightness galaxies, of the class called ultra-diffuse galaxies (UDGs). These galaxies have recently been shown to be outliers from the baryonic Tully–Fisher relation (BTFR), as they rotate much slower than expected given their baryonic mass, and to have a baryon fraction similar to the cosmological mean. By means of a 3D kinematic modelling fitting technique, we show that the H I in our UDGs is distributed in ‘thin’ regularly rotating discs and we determine their rotation velocity and gas velocity dispersion. We revisit the BTFR adding galaxies from other studies. We find a previously unknown trend between the deviation from the BTFR and the exponential disc scale length valid for dwarf galaxies with circular speeds ≲ 45 km s−1, with our UDGs being at the extreme end. Based on our findings, we suggest that the high baryon fractions of our UDGs may originate due to the fact that they have experienced weak stellar feedback, likely due to their low star formation rate surface densities, and as a result they did not eject significant amounts of gas out of their discs. At the same time, we find indications that our UDGs may have higher-than-average stellar specific angular momentum, which can explain their large optical scale lengths.


Mancera Piña, P. E., Fraternali, F., Oman, K. A., Adams, E. A., Bacchini, C., Marasco, A., …Smith, N. J. (2020). Robust H i kinematics of gas-rich ultra-diffuse galaxies: hints of a weak-feedback formation scenario. Monthly Notices of the Royal Astronomical Society, 495(4), 3636-3655.

Journal Article Type Article
Acceptance Date Apr 29, 2020
Online Publication Date May 7, 2020
Publication Date 2020-07
Deposit Date Jul 31, 2020
Publicly Available Date Jul 31, 2020
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 495
Issue 4
Pages 3636-3655


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Copyright Statement
© The Author(s) 2020. Published by Oxford University Press on behalf of The Royal Astronomical Society.<br /> This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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