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arXiv · 2304.00889

Flux-resolved Spectropolarimetric Evolution of the X-Ray Pulsar Hercules X-1 Using IXPE

Akash Garg·Divya Rawat·Yash Bhargava·Mariano Méndez·Sudip Bhattacharyya
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Abstract

We conduct a spectro-polarimetric study of the accreting X-ray pulsar Hercules X-1 using observations with the Imaging X-ray Polarimetry Explorer (IXPE). IXPE monitored the source in three different Epochs, sampling two Main-on and one Short-on state of the well-known super-orbital period of the source. We find that the 2-7 keV polarization fraction increases significantly from ~ $7-9$ % in the Main-on state to ~ $15-19$ % in the Short-on state, while the polarization angle remains more or less constant or changes slightly, ~ $47-59$ degrees, in all three Epochs. The polarization degree and polarization angle are consistent with being energy-independent for all three Epochs. We propose that in the Short-on state, when the neutron star is partially blocked by the disk warp, the increase in the polarization fraction can be explained as a result of the preferential obstruction of one of the magnetic poles of the neutron star.

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Akash Garg, Divya Rawat, Yash Bhargava, Mariano Méndez, Sudip Bhattacharyya. 2023-04-03. Flux-resolved Spectropolarimetric Evolution of the X-Ray Pulsar Hercules X-1 Using IXPE. https://doi.org/10.3847/2041-8213%2Facccfa

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