Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves
Spiral galaxies and their rotation curves have key characteristics of differentially spinning objects. Oblate spheroid shapes are a consequence of spin and reasonably describe galaxies, indicating that their matter is distributed in gravitationally interacting homeoidal shells. Here, previously publ...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-02-01
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| Series: | Galaxies |
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| Online Access: | https://www.mdpi.com/2075-4434/8/1/19 |
| _version_ | 1818851399530708992 |
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| author | Robert E. Criss Anne M. Hofmeister |
| author_facet | Robert E. Criss Anne M. Hofmeister |
| author_sort | Robert E. Criss |
| collection | DOAJ |
| description | Spiral galaxies and their rotation curves have key characteristics of differentially spinning objects. Oblate spheroid shapes are a consequence of spin and reasonably describe galaxies, indicating that their matter is distributed in gravitationally interacting homeoidal shells. Here, previously published equations describing differentially spinning oblate spheroids with radially varying density are applied to 51 galaxies, mostly spirals. A constant volumetric density (r, kg m<sup>−3</sup>) is assumed for each thin homeoid in these formulae, after Newton, which is consistent with RCs being reported simply as a function of equatorial radius <i>r</i>. We construct parameter-free inverse models that uniquely specify mass inside any given <i>r</i>, and thus directly constrain r vs. <i>r</i> solely from velocity <i>v </i>(<i>r</i>) and galactic aspect ratios (assumed as 1:10 for spirals when data are unavailable). Except for their innermost zones, r is proven to be closely proportional to <i>r<sup>n</sup></i>, where the statistical average of <i>n</i> for all 36 spirals studied is −1.80 ± 0.40. Our values for interior densities compare closely with independently measured baryon density in appropriate astronomical environments: for example, calculated r at galactic edges agrees with independently estimated r of intergalactic media (IGM). Our finding that central densities increase with galaxy size is consistent with behavior exhibited by diverse self-gravitating entities. Our calculated mass distributions are consistent with visible luminosity and require no non-baryonic component. |
| first_indexed | 2024-12-19T07:04:25Z |
| format | Article |
| id | doaj.art-17bbfd4693db4f24ac7f5b4ab0e7ad95 |
| institution | Directory Open Access Journal |
| issn | 2075-4434 |
| language | English |
| last_indexed | 2024-12-19T07:04:25Z |
| publishDate | 2020-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Galaxies |
| spelling | doaj.art-17bbfd4693db4f24ac7f5b4ab0e7ad952022-12-21T20:31:19ZengMDPI AGGalaxies2075-44342020-02-01811910.3390/galaxies8010019galaxies8010019Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation CurvesRobert E. Criss0Anne M. Hofmeister1Department of Earth and Planetary Science, Washington University, St Louis, Missouri 63130, USADepartment of Earth and Planetary Science, Washington University, St Louis, Missouri 63130, USASpiral galaxies and their rotation curves have key characteristics of differentially spinning objects. Oblate spheroid shapes are a consequence of spin and reasonably describe galaxies, indicating that their matter is distributed in gravitationally interacting homeoidal shells. Here, previously published equations describing differentially spinning oblate spheroids with radially varying density are applied to 51 galaxies, mostly spirals. A constant volumetric density (r, kg m<sup>−3</sup>) is assumed for each thin homeoid in these formulae, after Newton, which is consistent with RCs being reported simply as a function of equatorial radius <i>r</i>. We construct parameter-free inverse models that uniquely specify mass inside any given <i>r</i>, and thus directly constrain r vs. <i>r</i> solely from velocity <i>v </i>(<i>r</i>) and galactic aspect ratios (assumed as 1:10 for spirals when data are unavailable). Except for their innermost zones, r is proven to be closely proportional to <i>r<sup>n</sup></i>, where the statistical average of <i>n</i> for all 36 spirals studied is −1.80 ± 0.40. Our values for interior densities compare closely with independently measured baryon density in appropriate astronomical environments: for example, calculated r at galactic edges agrees with independently estimated r of intergalactic media (IGM). Our finding that central densities increase with galaxy size is consistent with behavior exhibited by diverse self-gravitating entities. Our calculated mass distributions are consistent with visible luminosity and require no non-baryonic component.https://www.mdpi.com/2075-4434/8/1/19inverse modelsrotation curvesgalactic densitygalactic massgalactic luminositynewtonian gravitationdark matter |
| spellingShingle | Robert E. Criss Anne M. Hofmeister Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves Galaxies inverse models rotation curves galactic density galactic mass galactic luminosity newtonian gravitation dark matter |
| title | Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves |
| title_full | Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves |
| title_fullStr | Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves |
| title_full_unstemmed | Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves |
| title_short | Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves |
| title_sort | density profiles of 51 galaxies from parameter free inverse models of their measured rotation curves |
| topic | inverse models rotation curves galactic density galactic mass galactic luminosity newtonian gravitation dark matter |
| url | https://www.mdpi.com/2075-4434/8/1/19 |
| work_keys_str_mv | AT robertecriss densityprofilesof51galaxiesfromparameterfreeinversemodelsoftheirmeasuredrotationcurves AT annemhofmeister densityprofilesof51galaxiesfromparameterfreeinversemodelsoftheirmeasuredrotationcurves |