Off the baryonic Tully-Fisher relation: a population of baryon-dominated ultra-diffuse galaxies
Abstract
We study the gas kinematics traced by the 21-cm emission of a sample of six HIrich low surface brightness galaxies classified as ultra-diffuse galaxies (UDGs). Using the 3D kinematic modelling code Barolo we derive robust circular velocities, revealing a startling feature: HIrich 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.
Keywords
Cite
@article{arxiv.1909.01363,
title = {Off the baryonic Tully-Fisher relation: a population of baryon-dominated ultra-diffuse galaxies},
author = {Pavel E. Mancera Piña and Filippo Fraternali and Elizabeth A. K. Adams and Antonino Marasco and Tom Oosterloo and Kyle A. Oman and Lukas Leisman and Enrico M. di Teodoro and Lorenzo Posti and Michael Battipaglia and John M. Cannon and Lexi Gault and Martha P. Haynes and Steven Janowiecki and Elizabeth McAllan and Hannah J. Pagel and Kameron Reiter and Katherine L. Rhode and John J. Salzer and Nicholas J. Smith},
journal= {arXiv preprint arXiv:1909.01363},
year = {2019}
}
Comments
Accepted for publication by The Astrophysical Journal Letters (ApJL). V2: Acknowledgments have been updated, and a typo has been corrected