Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions?
According to the current concordance cosmological model, dark matter (DM) particles are collisionless and produce self-gravitating structures with a central cusp, which, generally, is not observed. The observed density tends to a central plateau or core, explained within the cosmological model throu...
| 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/ace534 |
| _version_ | 1797689566557110272 |
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| author | Jorge Sánchez Almeida Angel R. Plastino Ignacio Trujillo |
| author_facet | Jorge Sánchez Almeida Angel R. Plastino Ignacio Trujillo |
| author_sort | Jorge Sánchez Almeida |
| collection | DOAJ |
| description | According to the current concordance cosmological model, dark matter (DM) particles are collisionless and produce self-gravitating structures with a central cusp, which, generally, is not observed. The observed density tends to a central plateau or core, explained within the cosmological model through the gravitational feedback of baryons on DM. This mechanism becomes inefficient when decreasing the galaxy’s stellar mass so that in the low-mass regime ( M _⋆ ≪ 10 ^6 M _⊙ ) the energy provided by the baryons is insufficient to modify cusps into cores. Thus, if cores exist in these galaxies they have to reflect departures from the collisionless nature of DM. Measuring the DM mass distribution in these faint galaxies is extremely challenging; however, their stellar mass distribution can be characterized through deep photometry. Here we provide a way of using only the stellar mass distribution to constrain the underlying DM distribution. The so-called Eddington inversion method allows us to discard pairs of stellar distributions and DM potentials requiring (unphysical) negative distribution functions in the phase space. In particular, cored stellar density profiles are incompatible with the Navarro–Frenk–White (NFW) potential expected from collisionless DM if the velocity distribution is isotropic and the system spherically symmetric. Through a case-by-case analysis, we are able to relax these assumptions to consider anisotropic velocity distributions and systems that do not have exact cores. In general, stellar distributions with radially biased orbits are difficult to reconcile with NFW-like potentials, and cores in the baryon distribution tend to require cores in the DM distribution. |
| first_indexed | 2024-03-12T01:48:21Z |
| format | Article |
| id | doaj.art-6bb400e60fe2492cbe9614a4b6c330a7 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T01:48:21Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-6bb400e60fe2492cbe9614a4b6c330a72023-09-08T18:55:34ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01954215310.3847/1538-4357/ace534Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions?Jorge Sánchez Almeida0https://orcid.org/0000-0003-1123-6003Angel R. Plastino1https://orcid.org/0000-0001-5848-0770Ignacio Trujillo2https://orcid.org/0000-0001-8647-2874Instituto de Astrofísica de Canarias , La Laguna, Tenerife, E-38200, Spain ; jos@iac.es; Departamento de Astrofísica, Universidad de La Laguna , SpainCeBio y Departamento de Ciencias Básicas, Universidad Nacional del Noroeste de la Provincia de Buenos Aires , UNNOBA, CONICET, Roque Saenz Peña 456, Junin, ArgentinaInstituto de Astrofísica de Canarias , La Laguna, Tenerife, E-38200, Spain ; jos@iac.es; Departamento de Astrofísica, Universidad de La Laguna , SpainAccording to the current concordance cosmological model, dark matter (DM) particles are collisionless and produce self-gravitating structures with a central cusp, which, generally, is not observed. The observed density tends to a central plateau or core, explained within the cosmological model through the gravitational feedback of baryons on DM. This mechanism becomes inefficient when decreasing the galaxy’s stellar mass so that in the low-mass regime ( M _⋆ ≪ 10 ^6 M _⊙ ) the energy provided by the baryons is insufficient to modify cusps into cores. Thus, if cores exist in these galaxies they have to reflect departures from the collisionless nature of DM. Measuring the DM mass distribution in these faint galaxies is extremely challenging; however, their stellar mass distribution can be characterized through deep photometry. Here we provide a way of using only the stellar mass distribution to constrain the underlying DM distribution. The so-called Eddington inversion method allows us to discard pairs of stellar distributions and DM potentials requiring (unphysical) negative distribution functions in the phase space. In particular, cored stellar density profiles are incompatible with the Navarro–Frenk–White (NFW) potential expected from collisionless DM if the velocity distribution is isotropic and the system spherically symmetric. Through a case-by-case analysis, we are able to relax these assumptions to consider anisotropic velocity distributions and systems that do not have exact cores. In general, stellar distributions with radially biased orbits are difficult to reconcile with NFW-like potentials, and cores in the baryon distribution tend to require cores in the DM distribution.https://doi.org/10.3847/1538-4357/ace534Cold dark matterDwarf galaxiesGalaxy mass distributionNavarro-Frenk-White profileGalaxy dark matter halosLow surface brightness galaxies |
| spellingShingle | Jorge Sánchez Almeida Angel R. Plastino Ignacio Trujillo Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions? The Astrophysical Journal Cold dark matter Dwarf galaxies Galaxy mass distribution Navarro-Frenk-White profile Galaxy dark matter halos Low surface brightness galaxies |
| title | Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions? |
| title_full | Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions? |
| title_fullStr | Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions? |
| title_full_unstemmed | Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions? |
| title_short | Can Cuspy Dark-matter-dominated Halos Hold Cored Stellar Mass Distributions? |
| title_sort | can cuspy dark matter dominated halos hold cored stellar mass distributions |
| topic | Cold dark matter Dwarf galaxies Galaxy mass distribution Navarro-Frenk-White profile Galaxy dark matter halos Low surface brightness galaxies |
| url | https://doi.org/10.3847/1538-4357/ace534 |
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