1997/08/22 by Aaron J. Romanowsky, C. S. Kochanek, Christopher S. Kochanek · 4 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/305151
18 pages, with 9 inline Postscript figures, LaTeX, aaspp4.sty, submitted to ApJ; postscript paper w/figs (200 kb) also avaliable at http://cfa-www.harvard.edu/~romanow/int.email.v2.ps.gz
arxiv created 1997/08/22 · openalex publication_date 1998/02/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We investigate X-ray isophote twists created by triaxiality differences between the luminous stellar distributions and the dark halos in elliptical galaxies. For a typically oblate luminous galaxy embedded in a more prolate halo formed by dissipationless collapse, the triaxiality difference of Δ T ≃ 0.7 leads to typical isophote twists of ⟨Δψ X ⟩ ≃ 16° ± 19° at 3 effective stellar radii. In a model that includes baryonic dissipation, the effect is smaller, with Δ T ≃ 0.3 and ⟨Δψ X ⟩ ≃ 5° ± 8°. Thus, accurate measurements of X-ray isophote twists may be able to set constraints on the interactions between baryons and dissipationless dark matter during galaxy formation. The 30° X-ray isophote twist in the E4 galaxy NGC 720 cannot be reproduced by our model, suggesting an intrinsic misalignment between the halo and the stars rather than a projection effect.