تقرير
Minimum-entropy constraints on galactic potentials
| العنوان: | Minimum-entropy constraints on galactic potentials |
|---|---|
| المؤلفون: | Silva, Leandro Beraldo e, Valluri, Monica, Vasiliev, Eugene, Hattori, Kohei, Pedra, Walter de Siqueira, Daniel, Kathryne J. |
| سنة النشر: | 2024 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies |
| الوصف: | A tracer sample in a gravitational potential, starting from a generic initial condition, phase-mixes towards a stationary state. This evolution is accompanied by an entropy increase, and the final state is characterized by a distribution function (DF) that depends only on integrals of motion (Jeans theorem). In terms of angle-action variables, the final state is uniform in angles (high entropy) and maximally clustered in actions (low entropy). We present a method exploring this fact to constrain a gravitational potential using a sample that is stationary in it. We estimate the entropy in the action space of trial potentials and recover the true potential by minimizing this entropy. This method avoids assuming a known DF, and may be applicable to other sets of integrals. We provide expressions for the entropy of DFs depending on energy, $f(E)$, energy and angular momentum, $f(E,L)$, or three actions, $f(\vec{J})$, and investigate the bias and fluctuations in their estimates. We show that the method correctly recovers the potential parameters for spherical and axisymmetric potentials. We also present a methodology to characterize the posterior probability distribution of the parameters with an Approximate Bayesian Computation, and indicate a pathway for application to observational data. Using $N=10^4$ tracers with $20\%$-uncertainties in the 6D coordinates, we recover the flattening parameter $q$ of an axisymmetric potential with $\sigma_q/q\sim 10\%$. Comment: 17 pages + appendix + references, 13 figs. Comments are very welcome! |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2407.07947 |
| رقم الأكسشن: | edsarx.2407.07947 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |