TY - JOUR
T1 - Applying Noether's Theorem to Matter in the Milky Way
T2 - Evidence for External Perturbations and Non-steady-state Effects from Gaia Data Release 2
AU - Gardner, Susan
AU - Hinkel, Austin
AU - Yanny, Brian
N1 - Publisher Copyright:
© 2020. The American Astronomical Society. All rights reserved.
PY - 2020/2/20
Y1 - 2020/2/20
N2 - We apply Noether's theorem to observations of main-sequence stars from the Gaia Data Release 2 archive to probe the matter distribution function of the Galaxy. That is, we examine the axial symmetry of stars at vertical heights z, 0.2 ≤ |z| ≤ 3 kpc, to probe the quality of the angular momentum L z as an integral of motion. The failure of this symmetry test would speak to a Milky Way, in both its visible and dark matter, that is not isolated and/or not in steady state. The left-right symmetry-breaking pattern we have observed, north and south, reveals both effects, with a measured deviation from symmetry of typically 0.5%. We show that a prolate form of the gravitational distortion of the Milky Way by the Large Magellanic Cloud, determined from fits to the Orphan stream by Erkal et al., is compatible with the size and sign of the axial-symmetry-breaking effects we have discovered in our sample of up to 14.4 million main-sequence stars, speaking to a distortion of an emergent, rather than static, nature.
AB - We apply Noether's theorem to observations of main-sequence stars from the Gaia Data Release 2 archive to probe the matter distribution function of the Galaxy. That is, we examine the axial symmetry of stars at vertical heights z, 0.2 ≤ |z| ≤ 3 kpc, to probe the quality of the angular momentum L z as an integral of motion. The failure of this symmetry test would speak to a Milky Way, in both its visible and dark matter, that is not isolated and/or not in steady state. The left-right symmetry-breaking pattern we have observed, north and south, reveals both effects, with a measured deviation from symmetry of typically 0.5%. We show that a prolate form of the gravitational distortion of the Milky Way by the Large Magellanic Cloud, determined from fits to the Orphan stream by Erkal et al., is compatible with the size and sign of the axial-symmetry-breaking effects we have discovered in our sample of up to 14.4 million main-sequence stars, speaking to a distortion of an emergent, rather than static, nature.
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U2 - 10.3847/1538-4357/ab66c8
DO - 10.3847/1538-4357/ab66c8
M3 - Article
AN - SCOPUS:85081658701
SN - 0004-637X
VL - 890
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 110
ER -