A Two-week IXPE Monitoring Campaign on Mrk 421

Abstract X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blazar Mrk 421. Our observations were accompanied by an even denser radio and optical polarization campaign. We find significant short-timescale variability in both X-ray polarization degree and angle, including an ∼90° angle rotation about the jet axis. We attribute this to random variations of the magnetic field, consistent with the presence of turbulence but also unlikely to be explained by turbulence alone. At the same time, the degree of lower-energy polarization is significantly lower and shows no more than mild variability. Our campaign provides further evidence for a scenario in which energy-stratified shock-acceleration of relativistic electrons, combined with a turbulent magnetic field, is responsible for optical to X-ray synchrotron emission in blazar jets.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-06-20
DOI
https://doi.org/10.3847/1538-4357/adce6b
Citations
1
Primary Topic
Astrophysics and Cosmic Phenomena
Type
article
Field-Weighted Citation Impact
1.87

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A Two-week IXPE Monitoring Campaign on Mrk 421

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A Two-week IXPE Monitoring Campaign on Mrk 421

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article en
1 citations

Abstract

Abstract X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blazar Mrk 421. Our observations were accompanied by an even denser radio and optical polarization campaign. We find significant short-timescale variability in both X-ray polarization degree and angle, including an ∼90° angle rotation about the jet axis. We attribute this to random variations of the magnetic field, consistent with the presence of turbulence but also unlikely to be explained by turbulence alone. At the same time, the degree of lower-energy polarization is significantly lower and shows no more than mild variability. Our campaign provides further evidence for a scenario in which energy-stratified shock-acceleration of relativistic electrons, combined with a turbulent magnetic field, is responsible for optical to X-ray synchrotron emission in blazar jets.

The Astrophysical JournalVol. 986(2)
National Aeronautics and Space Administration, Academy of Finland, National Research Foundation of Korea, Agenzia Spaziale Italiana, Ministerio de Ciencia e Innovación, Istituto Nazionale di Astrofisica, Istituto Nazionale di Fisica Nucleare, Marshall Space Flight Center
Openalex Percentile: Top 13%
Astrophysics and Cosmic Phenomena
1.87
DOIOpen Access PDFOpenAlex
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