2019/08/31 by Tousif Islam, Koushik Dutta · 13 citations
Physics and Astronomy · #Astronomy #Astrophysics #Conformal gravity #Conformal map #Conformal symmetry #Context (archaeology) #Cosmology and Gravitation Theories #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Galaxy rotation curve #General relativity #Geometry #Gravitation #Mathematical physics #Modified Newtonian dynamics #Physics #Solar and Space Plasma Dynamics #Velocity dispersion #astro-ph.CO #astro-ph.GA #gr-qc
paper · pdf · doi:10.1103/physrevd.100.104049
published in Physical review. D/Physical review. D. 100(10) (American Physical Society) · 7 pages, 6 figures; matches the published version
openalex created_date 2019/08/29 · openalex publication_date 2019/11/25 · arxiv created 2019/12/07 · arxiv updated 2019/12/10 · openalex updated_date 2026/08/06
Recent observations of ultradwarf galaxy NGC1052-DF2 started an interesting discussion between dark matter hypothesis and modified gravity theories. Reported low-velocity dispersion (less than 10.5 km/s at 90% confidence level) derived from the kinematic data of ten globular clusters in the galaxy points toward an extraordinarily low dynamical mass (approximately 3.4\ifmmode×\else\texttimes\fi108 M_\ensuremath\bigodot), which is of the same order of the luminous mass (approximately 2.0\ifmmode×\else\texttimes\fi108 M_\ensuremath\bigodot) in the galaxy. This has been interpreted as the first evidence of a galaxy ``without dark matter.'' It has been argued that dark matter is not necessarily coupled to the baryonic mass on the galactic scale and poses a challenge to modified gravity theories. We explore the dynamics of NGC1052-DF2 within the context of four popular alternative theories of gravity [modified Newtonian dynamics (MOND), Weyl conformal gravity, modified gravity (MOG)/scalar-tensor-vector gravity (STVG), and Verlinde's emergent gravity] and present the analysis of detailed radial variation of the velocity dispersion. We demonstrate that the dispersion data of NGC1052-DF2 are fully consistent with the modified gravity paradigm (as well as with general relativity without dark matter). We reach a similar conclusion for the ultradwarf NGC1052-DF4, which has been claimed to be the second candidate for galaxies without dark matter.