The DREAMS Project: Disentangling the Impact of Halo-to-Halo Variance and Baryonic Feedback on Milky Way Dark Matter Density Profiles
Authors
Alex M. Garcia
Jonah C. Rose
Paul Torrey
Andrea Caputo
Mariangela Lisanti
Andrew B. Pace
Hongwan Liu
Abdelaziz Hussein
Haozhe Liu
Francisco Villaescusa-Navarro
John Barry
Ilem Leisher
Belén Costanza
Jonathan Kho
Ethan Lilie
Jiaxuan Li
Niusha Ahvazi
Aklant Bhowmick
Tri Nguyen
Stephanie O'Neil
Xiaowei Ou
Xuejian Shen
Arya Farahi
Nitya Kallivayalil
Lina Necib
Mark Vogelsberger
Abstract
Astrophysical searches for dark matter in the Milky Way require a reliable model for its density distribution, which in turn depends on the influence of baryonic feedback on the Galaxy. In this work, we utilize a new suite of Milky Way-mass halos from the DREAMS Project, simulated with Cold Dark Matter (CDM),to quantify the influence of baryon feedback and intrinsic halo-to-halo variance on dark matter density profiles. Our suite of 1024 halos varies over supernova and black hole feedback parameters from the IllustrisTNG model, as well as variations in two cosmological parameters. We find that Milky Way-mass dark matter density profiles in the IllustrisTNG model are largely insensitive to astrophysics and cosmology variations, with the dominant source of scatter instead arising from halo-to-halo variance. However, most of the (comparatively minor) feedback-driven variations come from the changes to supernova prescriptions. By comparing to dark matter-only simulations, we find that the strongest supernova wind energies are so effective at preventing galaxy formation that the halos are nearly entirely collisionless dark matter. Finally, regardless of physics variation, all the DREAMS halos are roughly consistent with a halo contracting adiabatically from the presence of baryons, unlike models that have bursty stellar feedback. This work represents a step toward assessing the robustness of Milky Way dark matter profiles, with direct implications for dark matter searches where systematic uncertainty in the density profile remains a major challenge.
