Combining magneto-hydrostatic constraints with Stokes profile inversions. IV. Imposing $\nabla\cdot{\bf B}=0$ condition
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arXiv
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| Format: | Preprint |
| Publié: |
2024
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| _version_ | 1866910396359639040 |
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| author | Borrero, Juan M. Yabar, Adur Pastor Cobo, Basilio Ruiz |
| author_facet | Borrero, Juan M. Yabar, Adur Pastor Cobo, Basilio Ruiz |
| contents | Inferences of the magnetic field in the solar atmosphere by means of spectropolarimetric inversions (i.e., Stokes inversion codes) yield magnetic fields that are non-solenoidal($\nabla\cdot{\bf B} \ne 0$). Because of this, results obtained by such methods are sometimes put into question. We aim to develop and implement a new technique that can retrieve magnetic fields that are simultaneously consistent with observed polarization signals and with the null divergence condition. The method used in this work strictly imposes $\nabla\cdot{\bf B}=0$ by determining the vertical component of the magnetic field ($B_{\rm z}$) from the horizontal ones ($B_{\rm x},B_{\rm y}$). We implement this solenoidal inversion into the FIRTEZ Stokes inversion code and apply it to spectropolarimetric observations of a sunspot observed with the Hinode/SP instrument. We show that the solenoidal inversion retrieves a vertical component of the magnetic field that is consistent with the vertical component of the magnetic field inferred from the non-solenoidal one. We demonstrate that the solenoidal inversion is capable of a better overall fitting to the observed Stokes vector than the non-solenoidal inversion. In fact, the solenoidal magnetic field fits Stokes $V$ worse, but this is compensated by a better fit to Stokes $I$. We find a direct correlation between the worsening in the fit to the circular polarization profiles by the solenoidal inversion and the deviations in the inferred $B_{\rm z}$ with respect to the non-solenoidal inversion. These results support the idea that common Stokes inversion techniques fail to reproduce $\nabla\cdot{\bf B}=0$ mainly as a consequence of the uncertainties in the determination of the individual components of the magnetic field. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_02045 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Combining magneto-hydrostatic constraints with Stokes profile inversions. IV. Imposing $\nabla\cdot{\bf B}=0$ condition Borrero, Juan M. Yabar, Adur Pastor Cobo, Basilio Ruiz Solar and Stellar Astrophysics Inferences of the magnetic field in the solar atmosphere by means of spectropolarimetric inversions (i.e., Stokes inversion codes) yield magnetic fields that are non-solenoidal($\nabla\cdot{\bf B} \ne 0$). Because of this, results obtained by such methods are sometimes put into question. We aim to develop and implement a new technique that can retrieve magnetic fields that are simultaneously consistent with observed polarization signals and with the null divergence condition. The method used in this work strictly imposes $\nabla\cdot{\bf B}=0$ by determining the vertical component of the magnetic field ($B_{\rm z}$) from the horizontal ones ($B_{\rm x},B_{\rm y}$). We implement this solenoidal inversion into the FIRTEZ Stokes inversion code and apply it to spectropolarimetric observations of a sunspot observed with the Hinode/SP instrument. We show that the solenoidal inversion retrieves a vertical component of the magnetic field that is consistent with the vertical component of the magnetic field inferred from the non-solenoidal one. We demonstrate that the solenoidal inversion is capable of a better overall fitting to the observed Stokes vector than the non-solenoidal inversion. In fact, the solenoidal magnetic field fits Stokes $V$ worse, but this is compensated by a better fit to Stokes $I$. We find a direct correlation between the worsening in the fit to the circular polarization profiles by the solenoidal inversion and the deviations in the inferred $B_{\rm z}$ with respect to the non-solenoidal inversion. These results support the idea that common Stokes inversion techniques fail to reproduce $\nabla\cdot{\bf B}=0$ mainly as a consequence of the uncertainties in the determination of the individual components of the magnetic field. |
| title | Combining magneto-hydrostatic constraints with Stokes profile inversions. IV. Imposing $\nabla\cdot{\bf B}=0$ condition |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2404.02045 |