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Beyond the bulge–halo conspiracy? Density profiles of early-type galaxies from extended-source strong lensing

Etherington, Amy; Nightingale, James W; Massey, Richard; Robertson, Andrew; Cao, XiaoYue; Amvrosiadis, Aristeidis; Cole, Shaun; Frenk, Carlos S; He, Qiuhan; Lagattuta, David J; Lange, Samuel; Li, Ran

Beyond the bulge–halo conspiracy? Density profiles of early-type galaxies from extended-source strong lensing Thumbnail


Authors

XiaoYue Cao

Aristeidis Amvrosiadis

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Dr Qiuhan He qiuhan.he@durham.ac.uk
Post Doctoral Research Associate

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Sam Lange samuel.c.lange@durham.ac.uk
PGR Student Doctor of Philosophy

Ran Li



Abstract

Observations suggest that the dark matter and stars in early-type galaxies ‘conspire’ to produce a surprisingly simple distribution of total mass, ρ(r) ∝ ρ−γ, with γ ≈ 2. We measure the distribution of mass in 48 early-type galaxies that gravitationally lens a resolved background source. By fitting the source light in every pixel of images from the Hubble Space Telescope, we find a mean ⟨γ⟩=2.075+0.023−0.024 with an intrinsic scatter between galaxies of σγ=0.172+0.022−0.032 for the overall sample. This is consistent with and has similar precision to traditional techniques that employ spectroscopic observations to supplement lensing with mass estimates from stellar dynamics. Comparing measurements of γ for individual lenses using both techniques, we find a statistically insignificant correlation of −0.150+0.223−0.217 between the two, indicating a lack of statistical power or deviations from a power-law density in certain lenses. At fixed surface mass density, we measure a redshift dependence, ∂⟨γ⟩/z=0.345+0.322−0.296⁠, that is consistent with traditional techniques for the same sample of Sloan Lens ACS and GALaxy-Lyα EmitteR sYstems (GALLERY) lenses. Interestingly, the consistency breaks down when we measure the dependence of γ on the surface mass density of a lens galaxy. We argue that this is tentative evidence for an inflection point in the total mass-density profile at a few times the galaxy effective radius – breaking the conspiracy.

Citation

Etherington, A., Nightingale, J. W., Massey, R., Robertson, A., Cao, X., Amvrosiadis, A., …Li, R. (2023). Beyond the bulge–halo conspiracy? Density profiles of early-type galaxies from extended-source strong lensing. Monthly Notices of the Royal Astronomical Society, 521(4), 6005-6018. https://doi.org/10.1093/mnras/stad582

Journal Article Type Article
Acceptance Date Feb 16, 2023
Online Publication Date Mar 7, 2023
Publication Date 2023-06
Deposit Date Aug 16, 2023
Publicly Available Date Aug 16, 2023
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 521
Issue 4
Pages 6005-6018
DOI https://doi.org/10.1093/mnras/stad582
Keywords Space and Planetary Science; Astronomy and Astrophysics
Public URL https://durham-repository.worktribe.com/output/1719403

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Copyright Statement
© 2023 The Author(s).
Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited




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