Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data
Here are analyzed 3D velocity distribution functions (VDFs) of protons in the suprathermal energy-per-charge ( E / Q ) domain of 6.2 to 223.1 keV/e, as observed by the WIND Suprathermal Ion Composition Spectrometer (WIND/STICS) between 1995 and 2019, upon passage of interplanetary (IP) shocks. “Supr...
Saved in:
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2024-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad7134 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850184919904419840 |
|---|---|
| author | Johann Rubens Mejia-Ott Brent M. Randol |
| author_facet | Johann Rubens Mejia-Ott Brent M. Randol |
| author_sort | Johann Rubens Mejia-Ott |
| collection | DOAJ |
| description | Here are analyzed 3D velocity distribution functions (VDFs) of protons in the suprathermal energy-per-charge ( E / Q ) domain of 6.2 to 223.1 keV/e, as observed by the WIND Suprathermal Ion Composition Spectrometer (WIND/STICS) between 1995 and 2019, upon passage of interplanetary (IP) shocks. “Suprathermal” designates energies above the bulk, “thermal” solar wind, including inner-source pickup ions, cometary ions, solar energetic particles, and suprathermal tail particles. Within the WIND/STICS measurements, here treated as a standalone data set, only 3D VDFs within 9 hr prior to and following the shock passage are selected, as identified by the Center for Astrophysics (CfA) Harvard Interplanetary Shock Database. These are subsequently averaged, first over the STICS field of view, then over 3 hr intervals in the 9 hr about the shock. The averages, with errors assuming Poisson statistics, are then fitted using the Levenburg–Marquardt nonlinear least squares technique to two simple, observationally suggested functions arising from diffusive shock acceleration (DSA) formalism: a power law in E / Q with spectral index (model I), and a power-law with exponential rollover having a cutoff in E / Q (model II). The first result is a comparison of upstream spectral indices, e-folding energies, and normalization constants with corresponding downstream values. The second is a comparison of fitted spectral indices against those given by measured CfA shock compression ratios and a comparison of fitted e-folding energies with those given by measured ratios and shock normal angles, per DSA-derived predictions. There is additionally a comparison between fitted parameters given by the two functional forms. Little agreement is found with values given by DSA. |
| format | Article |
| id | doaj-art-48b006d032f84a519db29807c4a91eb4 |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-48b006d032f84a519db29807c4a91eb42025-08-20T02:16:55ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01974225510.3847/1538-4357/ad7134Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS DataJohann Rubens Mejia-Ott0Brent M. Randol1https://orcid.org/0000-0002-9307-4804Department of Physics, The Catholic University of America , Washington, DC, USANASA Goddard Space Flight Center , Greenbelt, MD, USAHere are analyzed 3D velocity distribution functions (VDFs) of protons in the suprathermal energy-per-charge ( E / Q ) domain of 6.2 to 223.1 keV/e, as observed by the WIND Suprathermal Ion Composition Spectrometer (WIND/STICS) between 1995 and 2019, upon passage of interplanetary (IP) shocks. “Suprathermal” designates energies above the bulk, “thermal” solar wind, including inner-source pickup ions, cometary ions, solar energetic particles, and suprathermal tail particles. Within the WIND/STICS measurements, here treated as a standalone data set, only 3D VDFs within 9 hr prior to and following the shock passage are selected, as identified by the Center for Astrophysics (CfA) Harvard Interplanetary Shock Database. These are subsequently averaged, first over the STICS field of view, then over 3 hr intervals in the 9 hr about the shock. The averages, with errors assuming Poisson statistics, are then fitted using the Levenburg–Marquardt nonlinear least squares technique to two simple, observationally suggested functions arising from diffusive shock acceleration (DSA) formalism: a power law in E / Q with spectral index (model I), and a power-law with exponential rollover having a cutoff in E / Q (model II). The first result is a comparison of upstream spectral indices, e-folding energies, and normalization constants with corresponding downstream values. The second is a comparison of fitted spectral indices against those given by measured CfA shock compression ratios and a comparison of fitted e-folding energies with those given by measured ratios and shock normal angles, per DSA-derived predictions. There is additionally a comparison between fitted parameters given by the two functional forms. Little agreement is found with values given by DSA.https://doi.org/10.3847/1538-4357/ad7134Interplanetary physics |
| spellingShingle | Johann Rubens Mejia-Ott Brent M. Randol Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data The Astrophysical Journal Interplanetary physics |
| title | Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data |
| title_full | Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data |
| title_fullStr | Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data |
| title_full_unstemmed | Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data |
| title_short | Spectral Properties of Suprathermal Protons Associated with Interplanetary Shocks from WIND/STICS Data |
| title_sort | spectral properties of suprathermal protons associated with interplanetary shocks from wind stics data |
| topic | Interplanetary physics |
| url | https://doi.org/10.3847/1538-4357/ad7134 |
| work_keys_str_mv | AT johannrubensmejiaott spectralpropertiesofsuprathermalprotonsassociatedwithinterplanetaryshocksfromwindsticsdata AT brentmrandol spectralpropertiesofsuprathermalprotonsassociatedwithinterplanetaryshocksfromwindsticsdata |