Overestimated inclinations of Milgromian disc galaxies: the case of the ultradiffuse galaxy AGC 114905. Issue 3 (19th April 2022)

• Record Type: Journal Article
• Authors: Banik, Indranil; Nagesh, Srikanth T; Haghi, Hosein; Kroupa, Pavel; Zhao, Hongsheng
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 513:Issue 3(2022)
• Page Start: 3541
• Page End: 3548
• Publication Date: 2022-04-19
• Subjects: gravitation -- galaxies: dwarf -- galaxies: fundamental parameters -- galaxies: individual: AGC 114905 -- galaxies: kinematics and dynamics; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac1073
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present two hydrodynamical star-forming simulations in the Milgromian dynamics (MOND) framework of a gas-rich disc galaxy with properties similar to AGC 114905, which has recently been argued to have a rotation curve (RC) that is inconsistent with the MOND prediction. Our first model considers the galaxy in isolation, while our second model includes an external field of $0.05 \, a_{_0}$, the estimated gravitational field from large-scale structure. We show that isophotes in the face-on view can differ from circular at the 50 per cent level. This could mislead observers into overestimating the inclination i between disc and sky planes. Because RCs require a correction factor of 1/sin i, the actual RC could be much higher than that reported by observers. This plausibly reconciles AGC 114905 with MOND expectations.