Mika Lambert, Constance M. Rockosi, Sergey E. Koposov, T J Li, Monica Valluri, Leandro Beraldo e Silva, S X Li, João A. S. Amarante, Amanda Byström, Gustavo E. Medina, Nathan R. Sandford, Joan Najita, Namitha Kizhuprakkat, J. Aguilar, S. P. Ahlen, Davide Bianchi, David Brooks, Todd Claybaugh, Kyle Dawson, Axel de la Macorra, P. Doel, J. E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, G. Gutiérrez, Richard Joyce, Anthony Kremin, C. Lamman, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, R. Miquel, John Moustakas, Adam Myers, S. Nadathur, Will J. Percival, Francisco Prada, Ignasi Pérez-Ràfols, Graziano Rossi, Eusebio Sanchez, David J. Schlegel, Michael Schubnell, Joseph H. Silber, David Sprayberry, G Tarle, B. A. Weaver, Rongpu Zhou, Hu Zou
Abstract Using the Dark Energy Spectroscopic Instrument (DESI) Milky Way Survey, we examine the six-dimensional space of the anticenter region of the Milky Way stellar disk (150° < Galactic longitude < 220°) using 61,883 main-sequence turnoff stars. We focus on two well-known stellar overdensities in the anticenter: the Monoceros Ring (MRi) and Anticenter Stream (ACS). We find that the MRi overdensity has kinematic signatures consistent with a tidally induced spiral arm, a type of dynamic spiral arm created by an interaction with a satellite galaxy, most likely the Sagittarius dwarf spheroidal galaxy (Sgr). We use the kinematics of the MRi to calculate the two most recent passage times of Sgr, finding 0.25 ± 0.09 Gyr and 1.10 ± 0.23 Gyr from the present day. We validate that the ACS is kinematically decoupled from the MRi because they are moving in opposite radial and vertical directions. We find that the kinematics associated with the ACS extends beyond our defined overdensity. The features we see in the ACS region are likely part of a broader distribution of stars with the same kinematic signature as detected in other places, like the vertical wave in the outer disk and phase spiral.