Jay Baptista, Robyn Sanderson, Dan Huber, Andrew Wetzel, Omid Sameie, Michael Boylan-Kolchin, Jeremy Bailin, Philip F. Hopkins, Claude-André Faucher-Giguere, Sukanya Chakrabarti, Drona Vargya, Nondh Panithanpaisal, Arpit Arora, Emily Cunningham
{"title":"火-2银河系质量星系中暗物质晕的方向","authors":"Jay Baptista, Robyn Sanderson, Dan Huber, Andrew Wetzel, Omid Sameie, Michael Boylan-Kolchin, Jeremy Bailin, Philip F. Hopkins, Claude-André Faucher-Giguere, Sukanya Chakrabarti, Drona Vargya, Nondh Panithanpaisal, Arpit Arora, Emily Cunningham","doi":"10.3847/1538-4357/acea79","DOIUrl":null,"url":null,"abstract":"Abstract The shape and orientation of dark matter (DM) halos are sensitive to the microphysics of the DM particles, yet in many mass models, the symmetry axes of the Milky Way’s DM halo are often assumed to be aligned with the symmetry axes of the stellar disk. This is well motivated for the inner DM halo, but not for the outer halo. We use zoomed-in cosmological baryonic simulations from the Latte suite of FIRE-2 Milky Way–mass galaxies to explore the evolution of the DM halo’s orientation with radius and time, with or without a major merger with a Large Magellanic Cloud analog, and when varying the DM model. In three of the four cold DM halos we examine, the orientation of the halo minor axis diverges from the stellar disk vector by more than 20° beyond about 30 galactocentric kpc, reaching a maximum of 30°–90°, depending on the individual halo’s formation history. In identical simulations using a model of self-interacting DM with σ = 1 cm 2 g −1 , the halo remains aligned with the stellar disk out to ∼200–400 kpc. Interactions with massive satellites ( M ≳ 4 × 10 10 M ⊙ at pericenter; M ≳ 3.3 × 10 10 M ⊙ at infall) affect the orientation of the halo significantly, aligning the halo’s major axis with the satellite galaxy from the disk to the virial radius. The relative orientation of the halo and disk beyond 30 kpc is a potential diagnostic of self-interacting DM, if the effects of massive satellites can be accounted for.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"37 5","pages":"0"},"PeriodicalIF":4.8000,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Orientations of Dark Matter Halos in FIRE-2 Milky Way–mass Galaxies\",\"authors\":\"Jay Baptista, Robyn Sanderson, Dan Huber, Andrew Wetzel, Omid Sameie, Michael Boylan-Kolchin, Jeremy Bailin, Philip F. Hopkins, Claude-André Faucher-Giguere, Sukanya Chakrabarti, Drona Vargya, Nondh Panithanpaisal, Arpit Arora, Emily Cunningham\",\"doi\":\"10.3847/1538-4357/acea79\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Abstract The shape and orientation of dark matter (DM) halos are sensitive to the microphysics of the DM particles, yet in many mass models, the symmetry axes of the Milky Way’s DM halo are often assumed to be aligned with the symmetry axes of the stellar disk. This is well motivated for the inner DM halo, but not for the outer halo. We use zoomed-in cosmological baryonic simulations from the Latte suite of FIRE-2 Milky Way–mass galaxies to explore the evolution of the DM halo’s orientation with radius and time, with or without a major merger with a Large Magellanic Cloud analog, and when varying the DM model. In three of the four cold DM halos we examine, the orientation of the halo minor axis diverges from the stellar disk vector by more than 20° beyond about 30 galactocentric kpc, reaching a maximum of 30°–90°, depending on the individual halo’s formation history. In identical simulations using a model of self-interacting DM with σ = 1 cm 2 g −1 , the halo remains aligned with the stellar disk out to ∼200–400 kpc. Interactions with massive satellites ( M ≳ 4 × 10 10 M ⊙ at pericenter; M ≳ 3.3 × 10 10 M ⊙ at infall) affect the orientation of the halo significantly, aligning the halo’s major axis with the satellite galaxy from the disk to the virial radius. 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Orientations of Dark Matter Halos in FIRE-2 Milky Way–mass Galaxies
Abstract The shape and orientation of dark matter (DM) halos are sensitive to the microphysics of the DM particles, yet in many mass models, the symmetry axes of the Milky Way’s DM halo are often assumed to be aligned with the symmetry axes of the stellar disk. This is well motivated for the inner DM halo, but not for the outer halo. We use zoomed-in cosmological baryonic simulations from the Latte suite of FIRE-2 Milky Way–mass galaxies to explore the evolution of the DM halo’s orientation with radius and time, with or without a major merger with a Large Magellanic Cloud analog, and when varying the DM model. In three of the four cold DM halos we examine, the orientation of the halo minor axis diverges from the stellar disk vector by more than 20° beyond about 30 galactocentric kpc, reaching a maximum of 30°–90°, depending on the individual halo’s formation history. In identical simulations using a model of self-interacting DM with σ = 1 cm 2 g −1 , the halo remains aligned with the stellar disk out to ∼200–400 kpc. Interactions with massive satellites ( M ≳ 4 × 10 10 M ⊙ at pericenter; M ≳ 3.3 × 10 10 M ⊙ at infall) affect the orientation of the halo significantly, aligning the halo’s major axis with the satellite galaxy from the disk to the virial radius. The relative orientation of the halo and disk beyond 30 kpc is a potential diagnostic of self-interacting DM, if the effects of massive satellites can be accounted for.
期刊介绍:
The Astrophysical Journal is the foremost research journal in the world devoted to recent developments, discoveries, and theories in astronomy and astrophysics.