Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Faculty Publications Article Faculty Publications -Articles Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Creator An entity primarily responsible for making the resource Bharathan, Athira M.; Stalin, C.S.; Sahayanathan, Sunder; Mathew, Blesson Title A name given to the resource Clues on the X-ray emission mechanism of blazars PKS 2155?304 and 3C 454.3 through polarization studies Date A point or period of time associated with an event in the lifecycle of the resource 01-01-2026 Source A related resource from which the described resource is derived Journal of High Energy Astrophysics;Volume;50;Issue;;Article No.;100472; Identifier An unambiguous reference to the resource within a given context <a href="https://doi.org/10.1016/j.jheap.2025.100472" target="_blank" rel="noreferrer noopener">https://doi.org/10.1016/j.jheap.2025.100472</a> <br /><br /><a href="https://www.scopus.com/pages/publications/105017445317?origin=resultslist" target="_blank" rel="noreferrer noopener">https://www.scopus.com/pages/publications/105017445317?origin=resultslist</a> Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Bharathan A.M., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bangalore, 560029, India; Stalin C.S., Indian Institute of Astrophysics, Block II, Koramangala, Karnataka, Bangalore, 560029, India; Sahayanathan S., Astrophysical Sciences Division, Bhabha Atomic Research Centre, Maharashtra, Mumbai, 400085, India, Homi Bhabha National Institute, Maharashtra, Mumbai, 400094, India; Mathew B., Department of Physics and Electronics, CHRIST (Deemed to be University), Karnataka, Bangalore, 560029, India Description An account of the resource X-ray polarization measurable with the imaging X-ray Polarimetry Explorer (IXPE) could constrain the long debated leptonic versus hadronic origin for the high energy component in the broad band spectral energy distribution (SED) of blazars. We report here the results from IXPE and SED modeling of PKS 2155?304 and 3C 454.3, a high and low synchrotron peaked blazar. For PKS 2155?304, from model-independent analysis, we found polarization angle ?X = (130 2.5) deg and polarization degree ?X = (20.9 1.8)% in the 2?8 keV band in agreement with spectro-polarimetric analysis. We found ?X to vary with time and indications of it to vary between energies, suggesting that the emission regions are stratified. For 3C 454.3, we did not detect X-ray polarization in the June 2023 observation, analyzed here for the first time. The detection of X-ray polarization in PKS 2155?304 and its non-detection in 3C 454.3 is in accordance with the X-ray emission from synchrotron and inverse Compton process, respectively, operating in these sources. Further, our division of the dataset into finer time bins allows a more granular view of polarization variability. Additionally, we modeled the broadband SEDs of both the sources using data acquired quasi-simultaneously with IXPE, in the optical, UV and X-rays from Swift, AstroSat and ?-rays from Fermi. In PKS 2155?304, the observed X-ray is found to lie in the high energy tail of the synchrotron component of the SED, while in 3C 454.3 the observed X-ray lies in the rising part of the inverse Compton component of the SED. Our SED modeling along with X-ray polarization observations favor a leptonic scenario for the observed X-ray emission in PKS 2155?304. The SED modeling for these specific IXPE epochs has not been presented before, allowing us to place additional constraints on the physical conditions in the jet. These results strengthen the case for a structured jet model where X-ray emission originates from a compact acceleration zone near the shock front, while lower-energy optical emission is produced in a broader, more turbulent region. 2025 Elsevier B.V. Subject The topic of the resource BL Lacertae objects: individual: PKS 2155-304; Galaxies: active; Quasars: individual 3C 454.3; Techniques: polarization; X-rays: galaxies Publisher An entity responsible for making the resource available Elsevier B.V. Relation A related resource ISSN: 22144048; Language A language of the resource English Type The nature or genre of the resource Article Rights Information about rights held in and over the resource Restricted Access; Hardcopy may be available in the library Format The file format, physical medium, or dimensions of the resource online