Journal article
The GALAH survey: velocity fluctuations in the Milky Way using Red Clump giants
Monthly notices of the Royal Astronomical Society, Vol.482(3), pp.4215-4232
01/21/2019
DOI: 10.1093/mnras/sty2924
Abstract
If the Galaxy is axisymmetric and in dynamical equilibrium, we expect negligible fluctuations in the residual line-of-sight velocity field. Recent results using the APOGEE survey find significant fluctuations in velocity for stars in the mid-plane (vertical bar Z vertical bar <0.25 kpc) out to 5 kpc, suggesting that the dynamical influence of non-axisymmetric features, i.e. the Milky Way's bar, spiral arms, and merger events extends out to the Solar neighbourhood. Their measured power spectrum has a characteristic amplitude of 11 km s(-1) on a scale of 2.5 kpc. The existence of such large-scale streaming motions has important implications for determining the Sun's motion about the Galactic Centre. Using Red Clump stars from GALAH and APOGEE, we map the line-of-sight velocities around the Sun (d < 5 kpc), and vertical bar Z vertical bar <1.25 kpc from the mid-plane. By subtracting a smooth axisymmetric model for the velocity field, we study the residual fluctuations and compare our findings with mock survey generated by GALAXIA. We find negligible large-scale fluctuations away from the plane. In the mid-plane, we reproduce the earlier APOGEE power spectrum but with 20 percent smaller amplitude (9.3 km s(-1)) after taking into account a few systematics (e.g. volume completeness). Using a flexible axisymmetric model the power amplitude is further reduced to 6.3 km s(-1). Additionally, our simulations show that, in the plane, distances are underestimated for high-mass Red Clump stars which can lead to spurious power amplitude of about 5.2 km s(-1). Taking this into account, we estimate the amplitude of real fluctuations to be <4.6 km s(-1), about a factor of three less than the APOGEE result.
Details
- Title: Subtitle
- The GALAH survey: velocity fluctuations in the Milky Way using Red Clump giants
- Creators
- Shourya Khanna - The University of SydneySanjib Sharma - The University of SydneyJoss Bland-Hawthorn - The University of SydneyMichael Hayden - The University of SydneyDavid M. Nataf - Johns Hopkins UniversityYuan-Sen Ting - Institute for Advanced StudyJanez Kos - The University of SydneySarah Martell - UNSW SydneyTomaz Zwitter - University of LjubljanaGayandhi De Silva - The University of SydneyMartin Asplund - Australian National UniversitySven Buder - Max Planck Institute for AstronomyLy Duong - Australian National UniversityJane Lin - Australian National UniversityJeffrey D. Simpson - Australian Astronomical ObservatoryBorja Anguiano - University of VirginiaJonathan Horner - University of Southern QueenslandPrajwal R. Kafle - International Centre for Radio Astronomy ResearchGeraint F. Lewis - The University of SydneyThomas Nordlander - ARC Centre of Excellence for All-sky AstrophysicsRosemary F. G. Wyse - Johns Hopkins UniversityRobert A. Wittenmyer - UNSW SydneyDaniel B. Zucker - The University of Sydney
- Resource Type
- Journal article
- Publication Details
- Monthly notices of the Royal Astronomical Society, Vol.482(3), pp.4215-4232
- DOI
- 10.1093/mnras/sty2924
- ISSN
- 0035-8711
- eISSN
- 1365-2966
- Publisher
- Oxford Univ Press
- Number of pages
- 18
- Grant note
- University of Notre Dame New York University Universidad Nacional Autonoma de Mexico University of Utah Lawrence Berkeley National Laboratory; United States Department of Energy (DOE) A/2013B/13; A/2014A/25; A/2015A/19; A/2017A/18 / Australian Astronomical Observatory Observatario Nacional/MCTI Ohio State University Vanderbilt University Center for High-Performance Computing at the University of Utah
- Language
- English
- Date published
- 01/21/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701733502771
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