Gaussian processes, median statistics, Milky Way rotation curves
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ORIGINAL ARTICLE
Gaussian processes, median statistics, Milky Way rotation curves Hai Yu1,2,3 · Aman Singal1,4
· Jacob Peyton1,5 · Sara Crandall1,6 · Bharat Ratra1
Received: 15 October 2019 / Accepted: 18 August 2020 / Published online: 31 August 2020 © Springer Nature B.V. 2020
Abstract We use the Iocco et al. (2015) compilation of 2,780 circular velocity measurements as a baseline sample to analyze the Milky Way rotation curve. We focus on techniques that adequately capture the small-scale structure (structure on the order of ∼0.5 kpc) present in the Milky Way rotation curve and that can be used to show the azimuthal anisotropy of the Milky Way rotation curve. We fit the data with simple, few parameter, rotation curve functions which are unable to adequately capture the significant smallscale spatial structure in these data and so provide poor fits. We introduce and use the Gaussian Processes (GP) method to derive Milky Way rotation curves from the dataset which
describe the small-scale structure more effectively than simple fits. The GP method rotation curves present significant small-scale spatial structure superimposed on a broad rise to galactocentric radius R ≈ 7 kpc and a decline at larger R. We find that our rotation curve is consistent with previous data, and study correlations in the residual circular velocities which are consistent with the measurements of McClureGriffiths and Dickey (2016). Keywords Galaxy: fundamental parameters · Galaxy: kinematics and dynamics · Methods: statistical · Methods: data analysis
B A. Singal
[email protected] H. Yu [email protected] J. Peyton [email protected] S. Crandall [email protected] B. Ratra [email protected]
1
Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, KS 66506, USA
2
School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China
3
Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
4
Department of Physics, Stony Brook University, Stony Brook, NY 11794, USA
5
Department of Physics, New Mexico State University, Las Cruces, NM, 88003-8001, USA
6
Department of Astronomy & Astrophysics, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
1 Introduction The Milky Way rotation curve, i.e., the circular velocity v(R) of tracers in the disk as a function of the distance R from the galactic center, is an important kinematic characteristic of the Milky Way and is used to constrain the mass distribution of the Milky Way (for example, see Kwee et al. 1954; Kerr 1961; Burton 1966; Shane and Bieger-Smith 1966; Sofue 2013, 2017; Russeil et al. 2017; Sysoliatina et al. 2018; Fernández-Hernández et al. 2018; Mróz et al. 2018; Eilers et al. 2018). Dark matter (for reviews see Ratra and Vogeley 2008; Bertone and Tait 2018; Drees 2018, and references therein) has a significant influence on the Milky Way rotation curve. There is convincing evidence for dark matter from cosmic microwave background anisotropy measurements (Planck Collabo
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