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Title: Type I Shell Galaxies as a Test of Gravity Models

Abstract

Shell galaxies are understood to form through the collision of a dwarf galaxy with an elliptical galaxy. Shell structures and kinematics have been noted to be independent tools to measure the gravitational potential of the shell galaxies. We compare theoretically the formation of shells in Type I shell galaxies in different gravity theories in this work because this is so far missing in the literature. We include Newtonian plus dark halo gravity, and two non-Newtonian gravity models, MOG and MOND, in identical initial systems. We investigate the effect of dynamical friction, which by slowing down the dwarf galaxy in the dark halo models limits the range of shell radii to low values. Under the same initial conditions, shells appear on a shorter timescale and over a smaller range of distances in the presence of dark matter than in the corresponding non-Newtonian gravity models. If galaxies are embedded in a dark matter halo, then the merging time may be too rapid to allow multi-generation shell formation as required by observed systems because of the large dynamical friction effect. Starting from the same initial state, the observation of small bright shells in the dark halo model should be accompanied by large faintmore » ones, while for the case of MOG, the next shell generation patterns iterate with a specific time delay. The first shell generation pattern shows a degeneracy with the age of the shells and in different theories, but the relative distance of the shells and the shell expansion velocity can break this degeneracy.« less

Authors:
;  [1];  [2]
  1. Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)
  2. Helmholtz-Institut für Strahlen-und Kernphysik, Universität Bonn, Nussallee 14-16, D-53115 Bonn (Germany)
Publication Date:
OSTI Identifier:
22679767
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 848; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COLLISIONS; COMPARATIVE EVALUATIONS; COSMOLOGY; EXPANSION; GALAXIES; GRAVITATION; INTERACTIONS; NONLUMINOUS MATTER; SHELLS; SIMULATION; SLOWING-DOWN; TIME DELAY; VELOCITY

Citation Formats

Vakili, Hajar, Rahvar, Sohrab, and Kroupa, Pavel, E-mail: vakili@physics.sharif.edu. Type I Shell Galaxies as a Test of Gravity Models. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8DFD.
Vakili, Hajar, Rahvar, Sohrab, & Kroupa, Pavel, E-mail: vakili@physics.sharif.edu. Type I Shell Galaxies as a Test of Gravity Models. United States. doi:10.3847/1538-4357/AA8DFD.
Vakili, Hajar, Rahvar, Sohrab, and Kroupa, Pavel, E-mail: vakili@physics.sharif.edu. Tue . "Type I Shell Galaxies as a Test of Gravity Models". United States. doi:10.3847/1538-4357/AA8DFD.
@article{osti_22679767,
title = {Type I Shell Galaxies as a Test of Gravity Models},
author = {Vakili, Hajar and Rahvar, Sohrab and Kroupa, Pavel, E-mail: vakili@physics.sharif.edu},
abstractNote = {Shell galaxies are understood to form through the collision of a dwarf galaxy with an elliptical galaxy. Shell structures and kinematics have been noted to be independent tools to measure the gravitational potential of the shell galaxies. We compare theoretically the formation of shells in Type I shell galaxies in different gravity theories in this work because this is so far missing in the literature. We include Newtonian plus dark halo gravity, and two non-Newtonian gravity models, MOG and MOND, in identical initial systems. We investigate the effect of dynamical friction, which by slowing down the dwarf galaxy in the dark halo models limits the range of shell radii to low values. Under the same initial conditions, shells appear on a shorter timescale and over a smaller range of distances in the presence of dark matter than in the corresponding non-Newtonian gravity models. If galaxies are embedded in a dark matter halo, then the merging time may be too rapid to allow multi-generation shell formation as required by observed systems because of the large dynamical friction effect. Starting from the same initial state, the observation of small bright shells in the dark halo model should be accompanied by large faint ones, while for the case of MOG, the next shell generation patterns iterate with a specific time delay. The first shell generation pattern shows a degeneracy with the age of the shells and in different theories, but the relative distance of the shells and the shell expansion velocity can break this degeneracy.},
doi = {10.3847/1538-4357/AA8DFD},
journal = {Astrophysical Journal},
number = 1,
volume = 848,
place = {United States},
year = {Tue Oct 10 00:00:00 EDT 2017},
month = {Tue Oct 10 00:00:00 EDT 2017}
}