Biases in inferring dark matter profiles from dynamical and lensing measurements

Samantha Scibelli, Rosalba Perna, Charles Keeton

Research output: Contribution to journalArticle

Abstract

The degeneracy between disc and halo contributions in spiral galaxy rotation curves makes it difficult to obtain a full understanding of the distribution of baryons and dark matter in disc galaxies like our own Milky Way. Using mock data, we study how constraints on dark matter profiles obtained from kinematics, strong lensing, or a combination of the two are affected by assumptions about the halo model. We compare four different models: spherical isothermal and Navarro-Frenk-White (NFW) haloes, along with spherical and elliptical Burkert haloes. For both kinematics and lensing we find examples where different models fit the data well but give enclosed masses that are inconsistent with the true (i.e. input) values. This is especially notable when the input and fit models differ in having cored or cuspy profiles (such as fitting an NFW model when the underlying dark matter distribution follows a different profile). We find that mass biases are more pronounced with lensing than with kinematics, and using both methods can help reduce the bias and provide stronger constraints on the dark matter distributions.

Original languageEnglish (US)
Pages (from-to)5880-5890
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume485
Issue number4
DOIs
StatePublished - Mar 13 2019

Fingerprint

dark matter
halos
profiles
kinematics
disk galaxies
spiral galaxies
baryons
curves
distribution

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • cosmology: dark matter
  • galaxies: spiral
  • gravitiational lensing: strong

Cite this

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abstract = "The degeneracy between disc and halo contributions in spiral galaxy rotation curves makes it difficult to obtain a full understanding of the distribution of baryons and dark matter in disc galaxies like our own Milky Way. Using mock data, we study how constraints on dark matter profiles obtained from kinematics, strong lensing, or a combination of the two are affected by assumptions about the halo model. We compare four different models: spherical isothermal and Navarro-Frenk-White (NFW) haloes, along with spherical and elliptical Burkert haloes. For both kinematics and lensing we find examples where different models fit the data well but give enclosed masses that are inconsistent with the true (i.e. input) values. This is especially notable when the input and fit models differ in having cored or cuspy profiles (such as fitting an NFW model when the underlying dark matter distribution follows a different profile). We find that mass biases are more pronounced with lensing than with kinematics, and using both methods can help reduce the bias and provide stronger constraints on the dark matter distributions.",
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Biases in inferring dark matter profiles from dynamical and lensing measurements. / Scibelli, Samantha; Perna, Rosalba; Keeton, Charles.

In: Monthly Notices of the Royal Astronomical Society, Vol. 485, No. 4, 13.03.2019, p. 5880-5890.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Biases in inferring dark matter profiles from dynamical and lensing measurements

AU - Scibelli, Samantha

AU - Perna, Rosalba

AU - Keeton, Charles

PY - 2019/3/13

Y1 - 2019/3/13

N2 - The degeneracy between disc and halo contributions in spiral galaxy rotation curves makes it difficult to obtain a full understanding of the distribution of baryons and dark matter in disc galaxies like our own Milky Way. Using mock data, we study how constraints on dark matter profiles obtained from kinematics, strong lensing, or a combination of the two are affected by assumptions about the halo model. We compare four different models: spherical isothermal and Navarro-Frenk-White (NFW) haloes, along with spherical and elliptical Burkert haloes. For both kinematics and lensing we find examples where different models fit the data well but give enclosed masses that are inconsistent with the true (i.e. input) values. This is especially notable when the input and fit models differ in having cored or cuspy profiles (such as fitting an NFW model when the underlying dark matter distribution follows a different profile). We find that mass biases are more pronounced with lensing than with kinematics, and using both methods can help reduce the bias and provide stronger constraints on the dark matter distributions.

AB - The degeneracy between disc and halo contributions in spiral galaxy rotation curves makes it difficult to obtain a full understanding of the distribution of baryons and dark matter in disc galaxies like our own Milky Way. Using mock data, we study how constraints on dark matter profiles obtained from kinematics, strong lensing, or a combination of the two are affected by assumptions about the halo model. We compare four different models: spherical isothermal and Navarro-Frenk-White (NFW) haloes, along with spherical and elliptical Burkert haloes. For both kinematics and lensing we find examples where different models fit the data well but give enclosed masses that are inconsistent with the true (i.e. input) values. This is especially notable when the input and fit models differ in having cored or cuspy profiles (such as fitting an NFW model when the underlying dark matter distribution follows a different profile). We find that mass biases are more pronounced with lensing than with kinematics, and using both methods can help reduce the bias and provide stronger constraints on the dark matter distributions.

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