Department of Physics, University of Surrey, Guildford GU2 7XH, UK
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK; Center for Computational Astrophysics, Flatiron Institute, 162 5th Avenue, New York, NY 10010, USA
Department of Physics and Astornomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK; Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA
Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510, USA; Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
IPAC, Mail Code 314-6, Caltech, 1200 E. California Blvd., Pasadena, CA 91125, USA
Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904, USA
Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
Department of Astronomy, The University of Texas at Austin, 2515 Speedway Boulevard, Austin, TX 78712, USA
Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
Departamento de Astronomía, Instituto de Física, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay
Department of Physics, University of Surrey, Guildford GU2 7XH, UK; Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA
In a companion paper by Koposov et al., RR Lyrae from Gaia Data Release 2 are used to demonstrate that stars in the Orphan stream have velocity vectors significantly misaligned with the stream track, suggesting that it has received a large gravitational perturbation from a satellite of the Milky Way. We argue that such a mismatch cannot arise due to any realistic static Milky Way potential and then explore the perturbative effects of the Large Magellanic Cloud (LMC). We find that the LMC can produce precisely, the observed motion-track mismatch and we therefore use the Orphan stream to measure the mass of the Cloud. We simultaneously fit the Milky Way and LMC potentials and infer that a total LMC mass of |$$1.38^{+0.27}_{-0.24} \times 10^{11}\, \rm {M_\odot}$$| is required to bend the Orphan stream, showing for the first time that the LMC has a large and measurable effect on structures orbiting the Milky Way. This has far-reaching consequences for any technique which assumes that tracers are orbiting a static Milky Way. Furthermore, we measure the Milky Way mass within 50 kpc to be |$$3.80^{+0.14}_{-0.11}\times 10^{11} \, \mathrm{M}_\odot$$|. Finally, we use these results to predict that, due to the reflex motion of the Milky Way in response to the LMC, the outskirts of the Milky Way’s stellar halo should exhibit a bulk, upwards motion.
Erkal, D., et al. "The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream." Monthly Notices of the Royal Astronomical Society, vol. 487, no. 2, May. 2019. https://doi.org/10.1093/mnras/stz1371
Erkal, D., Belokurov, V., Laporte, C. F. P., Koposov, S. E., Li, T. S., Grillmair, C. J., Kallivayalil, N., Price-Whelan, A. M., Evans, N. W., Hawkins, K., Hendel, D., Mateu, C., Navarro, J. F., del Pino, A., Slater, C. T., & Sohn, S. T. (2019). The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream. Monthly Notices of the Royal Astronomical Society, 487(2). https://doi.org/10.1093/mnras/stz1371
Erkal, D., Belokurov, V., Laporte, C. F. P., et al., "The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream," Monthly Notices of the Royal Astronomical Society 487, no. 2 (2019), https://doi.org/10.1093/mnras/stz1371
@article{osti_1556967,
author = {Erkal, D. and Belokurov, V. and Laporte, C. F. P. and Koposov, S. E. and Li, T. S. and Grillmair, C. J. and Kallivayalil, N. and Price-Whelan, A. M. and Evans, N. W. and Hawkins, K. and others},
title = {The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream},
annote = {In a companion paper by Koposov et al., RR Lyrae from Gaia Data Release 2 are used to demonstrate that stars in the Orphan stream have velocity vectors significantly misaligned with the stream track, suggesting that it has received a large gravitational perturbation from a satellite of the Milky Way. We argue that such a mismatch cannot arise due to any realistic static Milky Way potential and then explore the perturbative effects of the Large Magellanic Cloud (LMC). We find that the LMC can produce precisely, the observed motion-track mismatch and we therefore use the Orphan stream to measure the mass of the Cloud. We simultaneously fit the Milky Way and LMC potentials and infer that a total LMC mass of |$1.38^{+0.27}_{-0.24} \times 10^{11}\, \rm {M_\odot}$| is required to bend the Orphan stream, showing for the first time that the LMC has a large and measurable effect on structures orbiting the Milky Way. This has far-reaching consequences for any technique which assumes that tracers are orbiting a static Milky Way. Furthermore, we measure the Milky Way mass within 50 kpc to be |$3.80^{+0.14}_{-0.11}\times 10^{11} \, \mathrm{M}_\odot$|. Finally, we use these results to predict that, due to the reflex motion of the Milky Way in response to the LMC, the outskirts of the Milky Way’s stellar halo should exhibit a bulk, upwards motion.},
doi = {10.1093/mnras/stz1371},
url = {https://www.osti.gov/biblio/1556967},
journal = {Monthly Notices of the Royal Astronomical Society},
issn = {ISSN 0035-8711},
number = {2},
volume = {487},
place = {United States},
publisher = {Royal Astronomical Society},
year = {2019},
month = {05}}
Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 2 Vol. 487; ISSN 0035-8711