Signatures of a Tidally Induced Spiral Arm at the Anticenter of the Milky Way and a Kinematically Extended Anticenter Stream Using DESI DR2

Journal Article · Wed Jan 21 00:00:00 EST 2026 · No journal information

OSTI ID:3017923

Lambert, Mika ^[1]; Rockosi, Constance M. ^[1]; Koposov, Sergey E. ^[2]; Li, Ting S. ^[3]; Valluri, Monica ^[4]; Silva, L. e. ^[5]; Li, Songting ^[6]; Amarante, João A.S.; Byström, Amanda ^[2]; Medina, Gustavo E. ^[3]; Sandford, Nathan R. ^[3]; Najita, Joan ^[7]; Kizhuprakkat, Namitha ^[8]; Aguilar, Jessica N. ^[9]; Ahlen, Steven ^[10]; Bianchi, Davide ^[11]; Brooks, David ^[12]; Claybaugh, Todd ^[9]; Dawson, Kyle ^[13]; de la Macorra, Axel ^[14] ; Doel, Peter ^[12]; Forero-Romero, Jaime E. ^[15]; Gaztañaga, Enrique ^[16]; Gontcho A. Gontcho, Satya ^[17]; Gutierrez, Gaston ^[18]; Joyce, Dick ^[7]; Kremin, Anthony ^[9]; Lamman, Claire ^[19]; Landriau, Martin ^[9]; Le Guillou, Laurent ^[20]; Manera, Marc ^[21]; Meisner, Aaron ^[7]; Miquel, Ramon ^[22]; Moustakas, John ^[23]; Myers, Adam ^[24]; Nadathur, Seshadri ^[25]; Percival, Will ^[26]; Prada, Francisco ^[27]; Pérez-Ràfols, Ignasi ^[28]; Rossi, Graziano ^[29]; Sanchez, Eusebio ^[30]; Schlegel, David ^[9]; Schubnell, Michael ^[31]; Silber, Joseph H. ^[9]; Sprayberry, David ^[7]; Tarlé, Gregory ^[32]; Weaver, Benjamin A. ^[7]; Zhou, Rongpu ^[9]; Zou, Hu ^[33]

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1. UC, Santa Cruz
2. Edinburgh U., Inst. Astron.
3. Toronto U., Astron. Dept.
4. U. Michigan, Dept. Astron.; Michigan U.; KEK, Tsukuba; Hiroshima Shudo U.
5. Rio de Janeiro Observ.
6. Shanghai Jiao Tong U.; Shanghai Jiaotong U.
7. Natl. Solar Observ., Tucson
8. Taiwan, Natl. Tsing Hua U.
9. LBL, Berkeley
10. Boston U.
11. Milan U.; Brera Observ.
12. University Coll. London
13. Utah U.
14. UNAM, Mexico
15. Andes U., Bogota
16. Barcelona, IEEC; Portsmouth U., ICG; ICE, Bellaterra
17. LBL, Berkeley; Virginia U.
18. Fermilab
19. Ohio State U.
20. LPNHE, Paris
21. Barcelona, IFAE; Barcelona, Autonoma U.
22. ICREA, Barcelona; Barcelona, IFAE
23. Siena Coll., Loudonville
24. Wyoming U.
25. Portsmouth U., ICG
26. Waterloo U.; Perimeter Inst. Theor. Phys.
27. Granada U., Theor. Phys. Astrophys.
28. Barcelona, Polytechnic U.
29. Sejong U.
30. Madrid, CIEMAT
31. Michigan U., MCTP; Syracuse U.; Michigan U.; KEK, Tsukuba; Hiroshima Shudo U.
32. Michigan U.; KEK, Tsukuba; Hiroshima Shudo U.
33. Beijing Observ.

Using the Dark Energy Spectroscopic Instrument Milky Way Survey (DESI MWS), we examine the 6D space of the anticenter region of the stellar disk (150$$^\circ$$$$<$ Galactic longitude $<$ 220$$^\circ$$) using 61,883 main sequence turn-off stars. We focus on two well-known stellar overdensities in the anticenter, the Monoceros Ring (MRi) and Anticenter Stream (ACS). We find that the MRi overdensity has kinematics consistent with a tidally induced spiral arm, a type of dynamic spiral arm created by an interaction with a satellite galaxy, most likely the Sagittarius Dwarf Spheroidal galaxy (Sgr). We use the kinematics of the MRi to calculate the two most recent passage times of Sgr are 0.25 $$\pm$$ 0.09 Gyrs and 1.10 $$\pm$$ 0.23 Gyrs 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 are not confined to 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.

• Research Organization: Michigan U.; Wyoming U.; University Coll. London; Andes U., Bogota; Madrid, CIEMAT; Natl. Solar Observ., Tucson; Shanghai Jiaotong U.; Taiwan, Natl. Tsing Hua U.; UNAM, Mexico; Michigan U., MCTP; UC, Santa Cruz; Shanghai Jiao Tong U.; Portsmouth U., ICG; Granada U., Theor. Phys. Astrophys.; Ohio State U.; Beijing Observ.; KEK, Tsukuba; Waterloo U.; Sejong U.; Barcelona, Autonoma U.; Hiroshima Shudo U.; Barcelona, IFAE; LPNHE, Paris; Barcelona, IEEC; Rio de Janeiro Observ.; Toronto U., Astron. Dept.; Syracuse U.; ICE, Bellaterra; Barcelona, Polytechnic U.; Brera Observ.; ICREA, Barcelona; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Perimeter Inst. Theor. Phys.; Edinburgh U., Inst. Astron.; U. Michigan, Dept. Astron.; Utah U.; Virginia U.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Milan U.; Boston U.; Siena Coll., Loudonville
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: 89243024CSC000002
• OSTI ID: 3017923
• Report Number(s): FERMILAB-PUB-26-0072-PPD; oai:inspirehep.net:3112292; arXiv:2601.14562
• Journal Information: No journal information, Journal Name: No journal information
• Country of Publication: United States
• Language: English