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Title: THE FOSSIL RECORD OF TWO-PHASE GALAXY ASSEMBLY: KINEMATICS AND METALLICITIES IN THE NEAREST S0 GALAXY

Abstract

We present a global analysis of kinematics and metallicity in the nearest S0 galaxy, NGC 3115, along with implications for its assembly history. The data include high-quality wide-field imaging from Suprime-Cam on the Subaru telescope, and multi-slit spectra of the field stars and globular clusters (GCs) obtained using Keck-DEIMOS/LRIS and Magellan-IMACS. Within two effective radii, the bulge (as traced by the stars and metal-rich GCs) is flattened and rotates rapidly (v/{sigma} {approx}> 1.5). At larger radii, the rotation declines dramatically to v/{sigma} {approx} 0.7, but remains well aligned with the inner regions. The radial decrease in characteristic metallicity of both the metal-rich and metal-poor GC subpopulations produces strong gradients with power-law slopes of -0.17 {+-} 0.04 and -0.38 {+-} 0.06 dex dex{sup -1}, respectively. We argue that this pattern is not naturally explained by a binary major merger, but instead by a two-phase assembly process where the inner regions have formed in an early violent, dissipative phase, followed by the protracted growth of the outer parts via minor mergers with typical mass ratios of {approx}15-20:1.

Authors:
; ;  [1]; ;  [2]; ;  [3];  [4]
  1. UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)
  3. Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia)
  4. California Institute of Technology, MS 105-24, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
21562508
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 736; Journal Issue: 2; Other Information: DOI: 10.1088/2041-8205/736/2/L26; Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; GALAXIES; GLOBAL ANALYSIS; METALS; ROTATION; STARS; ELEMENTS; MATHEMATICS; MOTION

Citation Formats

Arnold, Jacob A., Romanowsky, Aaron J., Brodie, Jean P., Chomiuk, Laura, Strader, Jay, Spitler, Lee R., Forbes, Duncan A., and Benson, Andrew J. THE FOSSIL RECORD OF TWO-PHASE GALAXY ASSEMBLY: KINEMATICS AND METALLICITIES IN THE NEAREST S0 GALAXY. United States: N. p., 2011. Web. doi:10.1088/2041-8205/736/2/L26.
Arnold, Jacob A., Romanowsky, Aaron J., Brodie, Jean P., Chomiuk, Laura, Strader, Jay, Spitler, Lee R., Forbes, Duncan A., & Benson, Andrew J. THE FOSSIL RECORD OF TWO-PHASE GALAXY ASSEMBLY: KINEMATICS AND METALLICITIES IN THE NEAREST S0 GALAXY. United States. doi:10.1088/2041-8205/736/2/L26.
Arnold, Jacob A., Romanowsky, Aaron J., Brodie, Jean P., Chomiuk, Laura, Strader, Jay, Spitler, Lee R., Forbes, Duncan A., and Benson, Andrew J. Mon . "THE FOSSIL RECORD OF TWO-PHASE GALAXY ASSEMBLY: KINEMATICS AND METALLICITIES IN THE NEAREST S0 GALAXY". United States. doi:10.1088/2041-8205/736/2/L26.
@article{osti_21562508,
title = {THE FOSSIL RECORD OF TWO-PHASE GALAXY ASSEMBLY: KINEMATICS AND METALLICITIES IN THE NEAREST S0 GALAXY},
author = {Arnold, Jacob A. and Romanowsky, Aaron J. and Brodie, Jean P. and Chomiuk, Laura and Strader, Jay and Spitler, Lee R. and Forbes, Duncan A. and Benson, Andrew J.},
abstractNote = {We present a global analysis of kinematics and metallicity in the nearest S0 galaxy, NGC 3115, along with implications for its assembly history. The data include high-quality wide-field imaging from Suprime-Cam on the Subaru telescope, and multi-slit spectra of the field stars and globular clusters (GCs) obtained using Keck-DEIMOS/LRIS and Magellan-IMACS. Within two effective radii, the bulge (as traced by the stars and metal-rich GCs) is flattened and rotates rapidly (v/{sigma} {approx}> 1.5). At larger radii, the rotation declines dramatically to v/{sigma} {approx} 0.7, but remains well aligned with the inner regions. The radial decrease in characteristic metallicity of both the metal-rich and metal-poor GC subpopulations produces strong gradients with power-law slopes of -0.17 {+-} 0.04 and -0.38 {+-} 0.06 dex dex{sup -1}, respectively. We argue that this pattern is not naturally explained by a binary major merger, but instead by a two-phase assembly process where the inner regions have formed in an early violent, dissipative phase, followed by the protracted growth of the outer parts via minor mergers with typical mass ratios of {approx}15-20:1.},
doi = {10.1088/2041-8205/736/2/L26},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 736,
place = {United States},
year = {2011},
month = {8}
}