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Title: NGC 7457: evidence for merger-driven cylindrical rotation in disc galaxies

Abstract

ABSTRACT We construct Schwarzschild orbit-based models of NGC 7457, known as a peculiar low-mass lenticular galaxy. Our best-fitting model successfully retrieves most of the unusual kinematics behaviours of this galaxy, in which, the orbital distribution of stars is dominated by warm and hot orbits. The reconstructed surface brightness of the hot component matches fairly well the photometric bulge and the reconstructed LOSVD map of this component shows clear rotation around the major photometric axis of the galaxy. In the absence of a dominant cold component, the outer part of our model is dominated by warm orbits, representing an exponential thick disc. Our orbital analysis also confirms the existence of a counter-rotating orbital substructure in the very centre, reported in previous observational studies. By comparing our model with a variety of simulation studies, and considering the stellar kinematics and populations properties of this galaxy, we suggest that the thick disc is most likely a dynamically heated structure, formed through the interactions and accretion of satellite(s) with near-polar initial inclination. We also suggest a merger-driven process as the most plausible scenario to explain the observed and dynamically modelled properties of the bulge of NGC 7457. We conclude that both the high levelmore » of cylindrical rotation and unusually low velocity dispersion reported for the NGC 7457 have most likely external origins. Therefore, NGC 7457 could be considered as a candidate for merger-driven cylindrical rotation in the absence of a strong bar in disc galaxies.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [1]; ORCiD logo [3]; ORCiD logo [1];  [4];  [1]; ORCiD logo [1];  [5]; ORCiD logo [6]
  1. Instituto de Astrofísica de Canarias, E-38200 La Laguna, Spain, Depto. Astrofísica, Universidad de La Laguna (ULL), E-38206 La Laguna, Tenerife, Spain
  2. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China
  3. Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
  4. Instituto de Astrofísica de Canarias, E-38200 La Laguna, Spain, Isaac Newton Group of Telescopes, Apartado 321, E-38700 Santa Cruz de La Palma, Canary Islands, Spain
  5. School of Astronomy, Institute for Research in Fundamental Sciences (IPM), PO Box 19395-5746, Tehran, Iran
  6. Kapteyn Astronomical Institute, University of Groningen, Postbus 800, NL-9700 AV Groningen, the Netherlands
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1542513
Resource Type:
Published Article
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 488 Journal Issue: 1; Journal ID: ISSN 0035-8711
Publisher:
Oxford University Press
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Molaeinezhad, A., Zhu, L., Falcón-Barroso, J., van de Ven, G., Méndez-Abreu, J., Balcells, M., Aguerri, J. A. L., Vazdekis, A., Khosroshahi, H. G., and Peletier, R. F. NGC 7457: evidence for merger-driven cylindrical rotation in disc galaxies. United Kingdom: N. p., 2019. Web. doi:10.1093/mnras/stz1776.
Molaeinezhad, A., Zhu, L., Falcón-Barroso, J., van de Ven, G., Méndez-Abreu, J., Balcells, M., Aguerri, J. A. L., Vazdekis, A., Khosroshahi, H. G., & Peletier, R. F. NGC 7457: evidence for merger-driven cylindrical rotation in disc galaxies. United Kingdom. doi:10.1093/mnras/stz1776.
Molaeinezhad, A., Zhu, L., Falcón-Barroso, J., van de Ven, G., Méndez-Abreu, J., Balcells, M., Aguerri, J. A. L., Vazdekis, A., Khosroshahi, H. G., and Peletier, R. F. Fri . "NGC 7457: evidence for merger-driven cylindrical rotation in disc galaxies". United Kingdom. doi:10.1093/mnras/stz1776.
@article{osti_1542513,
title = {NGC 7457: evidence for merger-driven cylindrical rotation in disc galaxies},
author = {Molaeinezhad, A. and Zhu, L. and Falcón-Barroso, J. and van de Ven, G. and Méndez-Abreu, J. and Balcells, M. and Aguerri, J. A. L. and Vazdekis, A. and Khosroshahi, H. G. and Peletier, R. F.},
abstractNote = {ABSTRACT We construct Schwarzschild orbit-based models of NGC 7457, known as a peculiar low-mass lenticular galaxy. Our best-fitting model successfully retrieves most of the unusual kinematics behaviours of this galaxy, in which, the orbital distribution of stars is dominated by warm and hot orbits. The reconstructed surface brightness of the hot component matches fairly well the photometric bulge and the reconstructed LOSVD map of this component shows clear rotation around the major photometric axis of the galaxy. In the absence of a dominant cold component, the outer part of our model is dominated by warm orbits, representing an exponential thick disc. Our orbital analysis also confirms the existence of a counter-rotating orbital substructure in the very centre, reported in previous observational studies. By comparing our model with a variety of simulation studies, and considering the stellar kinematics and populations properties of this galaxy, we suggest that the thick disc is most likely a dynamically heated structure, formed through the interactions and accretion of satellite(s) with near-polar initial inclination. We also suggest a merger-driven process as the most plausible scenario to explain the observed and dynamically modelled properties of the bulge of NGC 7457. We conclude that both the high level of cylindrical rotation and unusually low velocity dispersion reported for the NGC 7457 have most likely external origins. Therefore, NGC 7457 could be considered as a candidate for merger-driven cylindrical rotation in the absence of a strong bar in disc galaxies.},
doi = {10.1093/mnras/stz1776},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 1,
volume = 488,
place = {United Kingdom},
year = {2019},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1093/mnras/stz1776

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