Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic Observations
We forecast parameter uncertainties on the mass profile of a typical Milky Way dwarf spheroidal galaxy (dSph) using the spherical Jeans equation and Fisher matrix formalism. For a Draco-like system we show that radial velocity measurements for 1000 individual stars can constrain the mass contained w...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/aca8a5 |
| _version_ | 1797701277594943488 |
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| author | Juan Guerra Marla Geha Louis E. Strigari |
| author_facet | Juan Guerra Marla Geha Louis E. Strigari |
| author_sort | Juan Guerra |
| collection | DOAJ |
| description | We forecast parameter uncertainties on the mass profile of a typical Milky Way dwarf spheroidal galaxy (dSph) using the spherical Jeans equation and Fisher matrix formalism. For a Draco-like system we show that radial velocity measurements for 1000 individual stars can constrain the mass contained within the effective radius of a dSph to within 5%. This is consistent with constraints extracted from current observational data. We compare two systems, a cusp and core, and demonstrate that a minimum sample of 100,000 (10,000) stars with both radial and proper motions measurements is required to disentangle their inner slopes at the 2 σ (1 σ ) level. If using the log-slope measured at the half-light radius as a proxy for differentiating between a core or cusp slope, only 1000 line-of-sight and proper motions measurements are required; however, we show this choice of radius does not always unambiguously differentiate between core and cusped profiles. Once observational errors are below half the value of the intrinsic dispersion, improving the observational precision yields little change in the density profile uncertainties. The choice of priors in our profile shape analysis plays a crucial role when the number of stars in a system is less than 100 but does not affect the resulting uncertainties for larger kinematic samples. Our predicted 2D confidence regions agree well with those from a full likelihood analysis run on a mock kinematic data set taken from the Gaia Challenge, validating our Fisher predictions. Our methodology is flexible, allowing us to predict density profile uncertainties for a wide range of current and future kinematic data sets. |
| first_indexed | 2024-03-12T04:34:07Z |
| format | Article |
| id | doaj.art-b4d7e70203a94d49aa3364782aa723ec |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:34:07Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-b4d7e70203a94d49aa3364782aa723ec2023-09-03T09:58:13ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01943212110.3847/1538-4357/aca8a5Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic ObservationsJuan Guerra0https://orcid.org/0000-0002-7600-5110Marla Geha1https://orcid.org/0000-0002-7007-9725Louis E. Strigari2https://orcid.org/0000-0001-5672-6079Department of Astronomy, Yale University , New Haven, CT 06520, USA ; juan.guerra@yale.eduDepartment of Astronomy, Yale University , New Haven, CT 06520, USA ; juan.guerra@yale.eduMitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A&M University , College Station, TX 77845, USAWe forecast parameter uncertainties on the mass profile of a typical Milky Way dwarf spheroidal galaxy (dSph) using the spherical Jeans equation and Fisher matrix formalism. For a Draco-like system we show that radial velocity measurements for 1000 individual stars can constrain the mass contained within the effective radius of a dSph to within 5%. This is consistent with constraints extracted from current observational data. We compare two systems, a cusp and core, and demonstrate that a minimum sample of 100,000 (10,000) stars with both radial and proper motions measurements is required to disentangle their inner slopes at the 2 σ (1 σ ) level. If using the log-slope measured at the half-light radius as a proxy for differentiating between a core or cusp slope, only 1000 line-of-sight and proper motions measurements are required; however, we show this choice of radius does not always unambiguously differentiate between core and cusped profiles. Once observational errors are below half the value of the intrinsic dispersion, improving the observational precision yields little change in the density profile uncertainties. The choice of priors in our profile shape analysis plays a crucial role when the number of stars in a system is less than 100 but does not affect the resulting uncertainties for larger kinematic samples. Our predicted 2D confidence regions agree well with those from a full likelihood analysis run on a mock kinematic data set taken from the Gaia Challenge, validating our Fisher predictions. Our methodology is flexible, allowing us to predict density profile uncertainties for a wide range of current and future kinematic data sets.https://doi.org/10.3847/1538-4357/aca8a5Dwarf galaxiesFisher’s InformationDark matterStellar kinematicsCosmology |
| spellingShingle | Juan Guerra Marla Geha Louis E. Strigari Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic Observations The Astrophysical Journal Dwarf galaxies Fisher’s Information Dark matter Stellar kinematics Cosmology |
| title | Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic Observations |
| title_full | Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic Observations |
| title_fullStr | Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic Observations |
| title_full_unstemmed | Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic Observations |
| title_short | Forecasts on the Dark Matter Density Profiles of Dwarf Spheroidal Galaxies with Current and Future Kinematic Observations |
| title_sort | forecasts on the dark matter density profiles of dwarf spheroidal galaxies with current and future kinematic observations |
| topic | Dwarf galaxies Fisher’s Information Dark matter Stellar kinematics Cosmology |
| url | https://doi.org/10.3847/1538-4357/aca8a5 |
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