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Resolving the Disk-Halo Degeneracy: A look at M74

Published online by Cambridge University Press:  21 March 2017

S. Aniyan ,
K. C. Freeman ,
M. Arnaboldi ,
O. Gerhard ,
L. Coccato ,
K. Kuijken  and
M. Merrifield
S. Aniyan
Affiliation:
Research School of Astronomy & Astrophysics, Australian National University email: suryashree.aniyan@anu.edu.au
K. C. Freeman
Affiliation:
Research School of Astronomy & Astrophysics, Australian National University email: suryashree.aniyan@anu.edu.au
M. Arnaboldi
Affiliation:
European Southern Observatory, Garching
O. Gerhard
Affiliation:
Max-Planck-Institut fur Extraterrestrische Physik, Garching
L. Coccato
Affiliation:
European Southern Observatory, Garching
K. Kuijken
Affiliation:
Leiden Observatory, Leiden University
M. Merrifield
Affiliation:
School of Physics and Astronomy, University of Nottingham
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Abstract

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The decomposition of the 21 cm rotation curve of galaxies into contribution from the disk and dark halo depends on the adopted mass to light ratio (M/L) of the disk. Given the vertical velocity dispersion (σz) of stars in the disk and its scale height (h), the disk surface density and hence the M/L can be estimated. Earlier works have used this technique to conclude that galaxy disks are submaximal. Here we address an important conceptual problem: σz and h must pertain to the same population. Our analysis concludes that previous studies underestimate the disk surface mass density by ~ 2, sufficient to make a maximal disk for M74 appear like a submaximal disk.

Keywords

galaxies: kinematics and dynamicsgalaxies: spiralgalaxies: halos
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S321: Formation and Evolution of Galaxy Outskirts , March 2016 , pp. 267
Copyright
Copyright © International Astronomical Union 2017 

References

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Aniyan, S., et al. 2016, MNRAS, 456, 1484 CrossRefGoogle Scholar