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The Gaia inertial reference frame and the tilting of the Milky Way disk

Perryman, Michael; Spergel, David N. and Lindegren, Lennart LU (2014) In Astrophysical Journal 789(2).
Abstract
While the precise relationship between the Milky Way disk and the symmetry planes of the dark matter halo remains somewhat uncertain, a time-varying disk orientation with respect to an inertial reference frame seems probable. Hierarchical structure formation models predict that the dark matter halo is triaxial and tumbles with a characteristic rate of similar to 2 rad H-0(-1) (similar to 30 mu as yr(-1)). These models also predict a time-dependent accretion of gas, such that the angular momentum vector of the disk should be misaligned with that of the halo. These effects, as well as tidal effects of the LMC, will result in the rotation of the angular momentum vector of the disk population with respect to the quasar reference frame. We... (More)
While the precise relationship between the Milky Way disk and the symmetry planes of the dark matter halo remains somewhat uncertain, a time-varying disk orientation with respect to an inertial reference frame seems probable. Hierarchical structure formation models predict that the dark matter halo is triaxial and tumbles with a characteristic rate of similar to 2 rad H-0(-1) (similar to 30 mu as yr(-1)). These models also predict a time-dependent accretion of gas, such that the angular momentum vector of the disk should be misaligned with that of the halo. These effects, as well as tidal effects of the LMC, will result in the rotation of the angular momentum vector of the disk population with respect to the quasar reference frame. We assess the accuracy with which the positions and proper motions from Gaia can be referred to a kinematically non-rotating system, and show that the spin vector of the transformation from any rigid self-consistent catalog frame to the quasi-inertial system defined by quasars should be defined to better than 1 mu as yr(-1). Determination of this inertial frame by Gaia will reveal any signature of the disk orientation varying with time, improve models of the potential and dynamics of the Milky Way, test theories of gravity, and provide new insights into the orbital evolution of the Sagittarius dwarf galaxy and the Magellanic Clouds. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
astrometry, cosmology: observations, Galaxy: disk, Galaxy: formation, reference systems, space vehicles: instruments
in
Astrophysical Journal
volume
789
issue
2
publisher
University of Chicago Press
external identifiers
  • wos:000338674900075
  • scopus:84903271010
ISSN
0004-637X
DOI
10.1088/0004-637X/789/2/166
language
English
LU publication?
yes
id
5ed2605a-c5bc-4d0a-aa0d-aeb21e3c6707 (old id 4598952)
date added to LUP
2014-09-05 09:11:10
date last changed
2017-07-02 03:48:59
@article{5ed2605a-c5bc-4d0a-aa0d-aeb21e3c6707,
  abstract     = {While the precise relationship between the Milky Way disk and the symmetry planes of the dark matter halo remains somewhat uncertain, a time-varying disk orientation with respect to an inertial reference frame seems probable. Hierarchical structure formation models predict that the dark matter halo is triaxial and tumbles with a characteristic rate of similar to 2 rad H-0(-1) (similar to 30 mu as yr(-1)). These models also predict a time-dependent accretion of gas, such that the angular momentum vector of the disk should be misaligned with that of the halo. These effects, as well as tidal effects of the LMC, will result in the rotation of the angular momentum vector of the disk population with respect to the quasar reference frame. We assess the accuracy with which the positions and proper motions from Gaia can be referred to a kinematically non-rotating system, and show that the spin vector of the transformation from any rigid self-consistent catalog frame to the quasi-inertial system defined by quasars should be defined to better than 1 mu as yr(-1). Determination of this inertial frame by Gaia will reveal any signature of the disk orientation varying with time, improve models of the potential and dynamics of the Milky Way, test theories of gravity, and provide new insights into the orbital evolution of the Sagittarius dwarf galaxy and the Magellanic Clouds.},
  articleno    = {166},
  author       = {Perryman, Michael and Spergel, David N. and Lindegren, Lennart},
  issn         = {0004-637X},
  keyword      = {astrometry,cosmology: observations,Galaxy: disk,Galaxy: formation,reference systems,space vehicles: instruments},
  language     = {eng},
  number       = {2},
  publisher    = {University of Chicago Press},
  series       = {Astrophysical Journal},
  title        = {The Gaia inertial reference frame and the tilting of the Milky Way disk},
  url          = {http://dx.doi.org/10.1088/0004-637X/789/2/166},
  volume       = {789},
  year         = {2014},
}