Constraints on self-interacting dark matter models from the structure of Milky-Way-mass galaxies and the dynamics of the solar neighborhood / Davis Varghese.

Format:

Book

Thesis/Dissertation

Author/Creator:

Varghese, Davis, author.

Contributor:

Sanderson, Robyn E., degree supervisor.

University of Pennsylvania. Department of Physics and Astronomy, degree granting institution.

Language:

English

Subjects (All):

Astrophysics.

Astronomy.

Statistical physics.

Physics and Astronomy--Penn dissertations.

Penn dissertations--Physics and Astronomy.

Local Subjects:

Astrophysics.

Astronomy.

Statistical physics.

Physics and Astronomy--Penn dissertations.

Penn dissertations--Physics and Astronomy.

Genre:

Academic theses.

Physical Description:

1 online resource (108 pages)

Contained In:

Dissertations Abstracts International 82-07B.

Place of Publication:

[Philadelphia, Pennsylvania] : University of Pennsylvania ; Ann Arbor : ProQuest Dissertations & Theses, 2020.

Language Note:

English

System Details:

Mode of access: World Wide Web.

text file

Summary:

Self-interacting dark matter (SIDM) models offer one way to reconcile inconsistencies between observations and predictions from collisionless cold dark matter (CDM) models on dwarf-galaxy scales. In order to incorporate the effects of both baryonic and SIDM interactions, I study a suite of cosmological-hydrodynamical simulations of Milky Way (MW)-mass galaxies from the Feedback in Realistic Environments (FIRE-2) project, where the SIDM self-interaction cross-section σ/m is varied. The shape of the main dark matter (DM) halo predicted by SIDM simulations is compared to CDM simulations with the same initial conditions. In the presence of baryonic feedback effects, I find that SIDM models do not produce the large differences in the inner structure of MW-mass galaxies predicted by DM-only models. In the local collision region (LCR), where the rate of SIDM interactions is one or more per age of the Universe, the baryonic component of the galaxy erases many differences expected between the shapes of CDM and SIDM halos. However, I do find that the radius where the shape of the total mass distribution departs from the stellar mass distribution is dependent on σ/m, and could potentially be used to set limits on the SIDM cross-section in MW-mass galaxies by combining constraints from dynamical tracers with stellar population mapping. Furthermore, using analytical potential models of the MW and numerical calculations, I demonstrate that "Nemesis" stars (predicted to have a close encounter within 1 pc of the Sun within ±15 Myr) are sensitive tracers of the galactic potential through their perihelion distance. I show that the measurement precision of the Gaia satellite's phase-space positions for solar neighborhood (SN) stars is sufficient to use perihelion distances to model the potential near the solar circle. Finally, I explore the co-evolution of the DM and baryonic components to infer the processes leading to the present-day shape. Subsequently, I assess whether adopting simulation-based potential models of the CDM and SIDM MW-mass galaxies might lead to differences in the structure of stellar orbits within a region similar to the SN.

Notes:

Source: Dissertations Abstracts International, Volume: 82-07, Section: B.

Advisors: Sanderson, Robyn E.; Committee members: Gary Bernstein; Mariangela Bernardi; Mark Devlin; Joshua Klein.

Department: Physics and Astronomy.

Ph.D. University of Pennsylvania 2020.

Local Notes:

School code: 0175

ISBN:

9798557060509

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Restricted for use by site license.

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