Year: 2026
Type: preprint
Abstract: Stellar streams are excellent probes of the gravitational potential in which they evolve. In the Milky Way (MW), globular cluster (GC) streams are routinely used to infer properties about time-dependent perturbations of the underlying potential. This implies that streams with Galactocentric radii small enough to be perturbed by the MW bar should offer constraints on it, such as its pattern speed, which currently has a wide range of values reported in the literature and is important when studying stellar kinematics. The GC M92 has a small pericentre and should be affected by the bar. It has a diffuse stellar stream, but confirming stream members has previously been hindered by a lack of spectroscopic data. In this paper, we use Dark Energy Spectroscopic Instrument (DESI) observations together with photometric and astrometric data to obtain spectroscopic members of the M92 stream for the first time. We identify a clear spatial distribution and gradients in distance moduli, proper motions, and radial velocities that confirm the stream's existence. We compare the observed stream to mock streams generated in different barred potentials and estimate the MW bar's pattern speed $Ω= 29.1^{+0.7}_{-0.4}$ km s$^{-1}$ kpc$^{-1}$ and $\dot Ω= 0.7^{+3.5}_{-2.3}$ km s$^{-1}$ kpc$^{-1}$ Gyr$^{-1}$. This is the first time a stellar stream is used to probabilistically infer these bar properties, and it opens up an exciting realm of inner Galactic potential characterisation using stellar streams.
Source: arXiv (Cornell University)
Authors: Byström, Amanda, Koposov, Sergey E., Li, Ting. S., Rockosi, Constance M., Dey, Arjun, Thomas, Guillaume F., Carlberg, Raymond G., Gnedin, Oleg Y., Kizhuprakkat, Namitha, Lambert, Mika, Mohammed, Nasser, Medina, Gustavo E., Najita, Joan, Riley, Alexander H., Sandford, Nathan R., Silva, Leandro Beraldo e, Aguilar, Jessica N., Ahlen, Steven, Bianchi, Davide, Brooks, David, Claybaugh, Todd, Cooper, Andrew P., Cuceu, Andrei, de la Macorra, Axel, Doel, Peter, Forero-Romero, Jaime E., Gontcho, Satya Gontcho A, Gutierrez, Gaston, Joyce, Richard, Juneau, Stephanie, Kremin, Anthony, Landriau, Martin, Guillou, Laurent Le, Meisner, Aaron, Miquel, Ramon, Percival, Will J., Prada, Francisco, Pérez-Ràfols, Ignasi, Rossi, Graziano, Sanchez, Eusebio, Schlegel, David, Silber, Joseph H., Tarlé, Gregory, Weaver, Benjamin A., Zou, Hu
Institutions: Royal Observatory, University of Edinburgh, University of Cambridge, University of California, Santa Cruz, NSF NOIRLab, Universidad de La Laguna, Instituto de Astrofísica de Canarias, University of Toronto, University of Michigan, National Tsing Hua University, Institute of Astronomy, Lund University, Valongo Observatory, Lawrence Berkeley National Laboratory, Boston University, University of Milan, Brera Astronomical Observatory, University College London, Universidad Nacional Autónoma de México, Universidad de Los Andes, Fermi National Accelerator Laboratory, Institució Catalana de Recerca i Estudis Avançats, Institute for High Energy Physics, Barcelona Institute of Science and Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, Ministerio de Ciencia, Innovación y Universidades, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Office of Science, Science and Technology Facilities Council, Agencia Estatal de Investigación, Division of Astronomical Sciences
Awards: G1044631029, G1105844351, G1175115578, G1286236842, G1813527838, G1863003419, G2262748287, G294895050, G300979063, G3083819904, G3452655474, G3480869486, G408465701, G419881185, G425668148, G42916606, G4501827968, G4526231891, G491712853, G498139845, G5080475149, G5635532810, G5910366635, G593054264, G6652958823, G6731524417, G6876926712, Probing dark matter distribution in the Milky Way with the DESI survey, G7084143925, Management and Operations of the National Optical Astronomy Observatory, G7395345766, G7805626310, G7863371703, G8345352404, G8497050386, G8667377315, G969889393
OpenAlex ID: W7160873266
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