Testing gravity with motion of satellites around galaxies: Newtonian gravity against Modified Newtonian Dynamics
| dc.creator | Klypin, A. | |
| dc.creator | Prada, F. | |
| dc.date | 2007-06-25 | |
| dc.date | 2008-09-01 | |
| dc.date.accessioned | 2026-07-07T12:29:50Z | |
| dc.date.available | 2026-07-07T12:29:50Z | |
| dc.description | The motion of satellite galaxies around normal galaxies at distances 50-500 kpc provides a sensitive test for the theories. We study the surface density and the velocities of satellites around isolated galaxies in the Sloan Digital Sky Survey. We find that the surface number-density of satellites declines with the projected distance as a power law with the slope -1.5-2. The rms velocities gradually decline: observations exclude constant velocities at a 10 sigma level. We show that observational data strongly favor the standard model: all three major statistics of satellites - the number-density profile, the line-of-sight velocity dispersion, and the distribution function of the velocities -- agree remarkably well with the predictions of the standard cosmological model. Thus, that the success of the standard model extends to scales (50-500) kpc, much lower than what was previously considered. MOND fails on these scales for models which assume any single power-law number-density profile of satellites and any constant velocity anisotropy by predicting nearly constant rms velocities of satellites. Satellite data can be fit by fine-tuned models, which require (1) specific non-power-law density profile, (2) very radial orbits at large distances (velocity anisotropy beta =0.6-0.7 at 200-300 kpc), and (3) 2-2.5 times more stellar mass than what is found in the galaxies. The external gravity force - a necessary component for MOND -- makes the situation even worse. We argue that a combination of satellite data and observational constraints on stellar masses make these models very problematic. | |
| dc.description | 14 pages, 7 figures. Accepted for publication in ApJ | |
| dc.identifier | https://arxiv.org/abs/0706.3554 | |
| dc.identifier | http://arxiv.org/abs/0706.3554 | |
| dc.identifier | Astrophys.J.690:1488-1496,2009 | |
| dc.identifier | doi:10.1088/0004-637X/690/2/1488 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/215964 | |
| dc.subject | Astrophysics | |
| dc.title | Testing gravity with motion of satellites around galaxies: Newtonian gravity against Modified Newtonian Dynamics | |
| dc.type | text |