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Title: EVOLUTIONARY TRACKS OF TIDALLY STIRRED DISKY DWARF GALAXIES

Abstract

Using collisionless N-body simulations, we investigate the tidal evolution of late-type, rotationally supported dwarfs inside Milky Way sized host galaxies. Our study focuses on a wide variety of dwarf orbital configurations and initial structures. During the evolution, the disky dwarfs undergo strong mass loss, the stellar disks are transformed into spheroids, and rotation is replaced by random motions of the stars. Thus, the late-type progenitors are transformed into early-type dwarfs as envisioned by the tidal stirring model for the formation of dwarf spheroidal (dSph) galaxies in the Local Group. We determine the photometric properties of the dwarfs, including the total visual magnitude, the half-light radius, and the central surface brightness as they would be measured by an observer near the galactic center. Special emphasis is also placed on studying their kinematics and shapes. We demonstrate that the measured values are biased by a number of observational effects including the increasing angle of the observation cone near the orbital pericenter, the fact that away from the pericenter the tidal tails are typically oriented along the line of sight, and the fact that for most of the evolution the stellar components of the dwarfs are triaxial ellipsoids whose major axis tumbles withmore » respect to the line of sight. Finally, we compare the measured properties of the simulated dwarfs to those of dwarf galaxies in the Local Group. The evolutionary tracks of the dwarfs in different parameter planes and the correlations between their different properties, especially the total magnitude and the surface brightness, strongly suggest that present-day dSph galaxies may have indeed formed from late-type progenitors as proposed by the tidal stirring scenario.« less

Authors:
 [1];  [2];  [3]
  1. Nicolaus Copernicus Astronomical Center, 00-716 Warsaw (Poland)
  2. Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States)
  3. Institute for Theoretical Physics, University of Zuerich, CH-8057 Zuerich (Switzerland)
Publication Date:
OSTI Identifier:
21587507
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 739; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/739/1/46; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; GALAXIES; SIMULATION; STARS

Citation Formats

Lokas, Ewa L., Kazantzidis, Stelios, and Mayer, Lucio, E-mail: lokas@camk.edu.pl, E-mail: stelios@mps.ohio-state.edu, E-mail: lucio@phys.ethz.ch. EVOLUTIONARY TRACKS OF TIDALLY STIRRED DISKY DWARF GALAXIES. United States: N. p., 2011. Web. doi:10.1088/0004-637X/739/1/46; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Lokas, Ewa L., Kazantzidis, Stelios, & Mayer, Lucio, E-mail: lokas@camk.edu.pl, E-mail: stelios@mps.ohio-state.edu, E-mail: lucio@phys.ethz.ch. EVOLUTIONARY TRACKS OF TIDALLY STIRRED DISKY DWARF GALAXIES. United States. doi:10.1088/0004-637X/739/1/46; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Lokas, Ewa L., Kazantzidis, Stelios, and Mayer, Lucio, E-mail: lokas@camk.edu.pl, E-mail: stelios@mps.ohio-state.edu, E-mail: lucio@phys.ethz.ch. Tue . "EVOLUTIONARY TRACKS OF TIDALLY STIRRED DISKY DWARF GALAXIES". United States. doi:10.1088/0004-637X/739/1/46; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21587507,
title = {EVOLUTIONARY TRACKS OF TIDALLY STIRRED DISKY DWARF GALAXIES},
author = {Lokas, Ewa L. and Kazantzidis, Stelios and Mayer, Lucio, E-mail: lokas@camk.edu.pl, E-mail: stelios@mps.ohio-state.edu, E-mail: lucio@phys.ethz.ch},
abstractNote = {Using collisionless N-body simulations, we investigate the tidal evolution of late-type, rotationally supported dwarfs inside Milky Way sized host galaxies. Our study focuses on a wide variety of dwarf orbital configurations and initial structures. During the evolution, the disky dwarfs undergo strong mass loss, the stellar disks are transformed into spheroids, and rotation is replaced by random motions of the stars. Thus, the late-type progenitors are transformed into early-type dwarfs as envisioned by the tidal stirring model for the formation of dwarf spheroidal (dSph) galaxies in the Local Group. We determine the photometric properties of the dwarfs, including the total visual magnitude, the half-light radius, and the central surface brightness as they would be measured by an observer near the galactic center. Special emphasis is also placed on studying their kinematics and shapes. We demonstrate that the measured values are biased by a number of observational effects including the increasing angle of the observation cone near the orbital pericenter, the fact that away from the pericenter the tidal tails are typically oriented along the line of sight, and the fact that for most of the evolution the stellar components of the dwarfs are triaxial ellipsoids whose major axis tumbles with respect to the line of sight. Finally, we compare the measured properties of the simulated dwarfs to those of dwarf galaxies in the Local Group. The evolutionary tracks of the dwarfs in different parameter planes and the correlations between their different properties, especially the total magnitude and the surface brightness, strongly suggest that present-day dSph galaxies may have indeed formed from late-type progenitors as proposed by the tidal stirring scenario.},
doi = {10.1088/0004-637X/739/1/46; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 739,
place = {United States},
year = {2011},
month = {9}
}