期刊
ASTROPHYSICAL JOURNAL
卷 760, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/760/1/2
关键词
dark matter; Galaxy: kinematics and dynamics; Galaxy: structure; methods: statistical
资金
- Ramon y Cajal Program
- Ministerio of Economia y Competitividad
- NASA through Hubble Fellowship [HST-HF-51283.01-A]
- Space Telescope Science Institute
- Association of Universities for Research in Astronomy, Inc., for NASA [NAS5-26555]
- [AYA2010-17631]
- Science and Technology Facilities Council [ST/J001538/1, ST/H00243X/1] Funding Source: researchfish
- STFC [ST/J001538/1] Funding Source: UKRI
We introduce the Minimum Entropy Method, a simple statistical technique for constraining the Milky Way gravitational potential and simultaneously testing different gravity theories directly from 6D phase-space surveys and without adopting dynamical models. We demonstrate that orbital energy distributions that are separable (i.e., independent of position) have an associated entropy that increases under wrong assumptions about the gravitational potential and/or gravity theory. Of known objects, cold tidal streams from low-mass progenitors follow orbital distributions that most nearly satisfy the condition of separability. Although the orbits of tidally stripped stars are perturbed by the progenitor's self-gravity, systematic variations of the energy distribution can be quantified in terms of the cross-entropy of individual tails, giving further sensitivity to theoretical biases in the host potential. The feasibility of using the Minimum Entropy Method to test a wide range of gravity theories is illustrated by evolving restricted N-body models in a Newtonian potential and examining the changes in entropy introduced by Dirac, MONDian, and f(R) gravity modifications.
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