The Implications of Local Fluctuations in the Galactic Midplane for Dynamical Analysis in the Gaia Era

被引:15
作者
Beane, Angus [1 ,2 ]
Sanderson, Robyn E. [1 ,2 ]
Ness, Melissa K. [1 ,3 ]
Johnston, Kathryn V. [1 ,3 ]
Filho, Douglas Grion [3 ]
Mac Low, Mordecai-Mark [1 ,4 ]
Angles-Alcazar, Daniel [1 ]
Hogg, David W. [1 ,5 ,6 ,7 ]
Laporte, Chervin F. P. [8 ]
机构
[1] Flatiron Inst, Ctr Computat Astrophys, 162 5th Ave, New York, NY 10010 USA
[2] Univ Penn, Dept Phys & Astron, 209 South 33rd St, Philadelphia, PA 19104 USA
[3] Columbia Univ, Dept Astron, 550 West 120th St, New York, NY 10027 USA
[4] Amer Museum Nat Hist, Dept Astrophys, Cent Pk West & 79th St, New York, NY 10024 USA
[5] NYU, Dept Phys, Ctr Cosmol & Particle Phys, 726 Broadway, New York, NY 10003 USA
[6] NYU, Ctr Data Sci, 60 5th Ave, New York, NY 10011 USA
[7] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany
[8] Univ Victoria, Dept Phys & Astron, 3800 Finnerty Rd, Victoria, BC V8P 4HN, Canada
基金
美国国家科学基金会;
关键词
STELLAR HALO; SOLAR NEIGHBORHOOD; TIDAL STREAMS; MILKY; GALAXY; SAGITTARIUS; MASS; DISC; STARS; SIMULATIONS;
D O I
10.3847/1538-4357/ab3d3c
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Orbital properties of stars, computed from their six-dimensional phase-space measurements and an assumed Galactic potential, are used to understand the structure and evolution of the Galaxy. Stellar actions, computed from orbits, have the attractive quality of being invariant under certain assumptions and are therefore used as quantitative labels of a star's orbit. We report a subtle but important systematic error that is induced in the actions as a consequence of local midplane variations expected for the Milky Way. This error is difficult to model because it is non-Gaussian and bimodal, with neither mode peaking on the null value. An offset in the vertical position of the Galactic midplane of similar to 15 pc for a thin disk-like orbit or similar to 120 pc for a thick disk-like orbit induces a 25% systematic error in the vertical action J(z). In Feedback in Realistic Environments simulations of Milky Way-mass galaxies, these variations are on the order of similar to 100 pc at the solar circle. From observations of the mean vertical velocity variation of similar to 5-10 km s(-1) with radius, we estimate that the Milky Way midplane variations are similar to 60-170 pc, consistent with three-dimensional dust maps. Action calculations and orbit integrations, which assume the global and local midplanes are identical, are likely to include this induced error, depending on the volume considered. Variation in the local standard of rest or distance to the Galactic center causes similar issues. The variation of the midplane must be taken into account when performing dynamical analysis across the large regions of the disk accessible to Gaia and future missions.
引用
收藏
页数:17
相关论文
共 107 条
[1]  
Abdalla H, 2018, ASTRON ASTROPHYS, V610, DOI [10.1051/0004-6361/201833052, 10.1051/0004-6361/201732426]
[2]  
Abuter R., 2019, ARXIV190405721
[3]   A Galactic Plane Defined by the Milky Way H II Region Distribution [J].
Anderson, L. D. ;
Wenger, Trey V. ;
Armentrout, W. P. ;
Balser, Dana S. ;
Bania, T. M. .
ASTROPHYSICAL JOURNAL, 2019, 871 (02)
[4]   The cosmic baryon cycle and galaxy mass assembly in the FIRE simulations [J].
Angles-Alcazar, Daniel ;
Faucher-Giguere, Claude-Andre ;
Keres, Dusan ;
Hopkins, Philip F. ;
Quataert, Eliot ;
Murray, Norman .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2017, 470 (04) :4698-4719
[5]  
[Anonymous], APJ
[6]  
[Anonymous], 2008, Galactic Dynamics: Second Edition
[7]   A dynamically young and perturbed Milky Way disk [J].
Antoja, T. ;
Helmi, A. ;
Romero-Gomez, M. ;
Katz, D. ;
Babusiaux, C. ;
Drimmel, R. ;
Evans, D. W. ;
Figueras, F. ;
Poggio, E. ;
Reyle, C. ;
Robin, A. C. ;
Seabroke, G. ;
Soubiran, C. .
NATURE, 2018, 561 (7723) :360-+
[8]   New stellar encounters discovered in the second Gaia data release [J].
Bailer-Jones, C. A. L. ;
Rybizki, J. ;
Andrae, R. ;
Fouesneau, M. .
ASTRONOMY & ASTROPHYSICS, 2018, 616
[9]  
BEANE A, 2018, APJ, V867, DOI DOI 10.3847/1538-4357/AAE07F
[10]   Co-formation of the disc and the stellar halo [J].
Belokurov, V. ;
Erkal, D. ;
Evans, N. W. ;
Koposov, S. E. ;
Deason, A. J. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2018, 478 (01) :611-619