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Article: X-Ray Polarization of BL Lacertae in Outburst

TitleX-Ray Polarization of BL Lacertae in Outburst
Authors
Issue Date1-May-2023
PublisherAmerican Astronomical Society
Citation
Astrophysical Journal Letters, 2023, v. 948, n. 2, p. 1-12 How to Cite?
Abstract

We report the first >99% confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/γ-ray outburst, a 287 ks observation (2022 November 27–30) was taken using the Imaging X-ray Polarimetry Explorer (IXPE), together with contemporaneous multiwavelength observations from the Neil Gehrels Swift observatory and XMM-Newton in soft X-rays (0.3–10 keV), NuSTAR in hard X-rays (3–70 keV), and optical polarization from the Calar Alto and Perkins Telescope observatories. Our contemporaneous X-ray data suggest that the IXPE energy band is at the crossover between the low- and high-frequency blazar emission humps. The source displays significant variability during the observation, and we measure polarization in three separate time bins. Contemporaneous X-ray spectra allow us to determine the relative contribution from each emission hump. We find >99% confidence X-ray polarization ${{\rm{\Pi }}}_{2\mbox{--}4\mathrm{keV}}={21.7}_{-7.9}^{+5.6} \% $ and electric vector polarization angle ψ2–4keV = −28fdg7 ± 8fdg7 in the time bin with highest estimated synchrotron flux contribution. We discuss possible implications of our observations, including previous IXPE BL Lacertae pointings, tentatively concluding that synchrotron self-Compton emission dominates over hadronic emission processes during the observed epochs.


Persistent Identifierhttp://hdl.handle.net/10722/331300
ISSN
2021 Impact Factor: 8.811
2020 SCImago Journal Rankings: 3.639
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorPeirsaon, AL-
dc.contributor.authorNetgro, M-
dc.contributor.authorLTiodakis, I-
dc.contributor.authorMidFdei, R-
dc.contributor.authorKim, DE-
dc.contributor.authorMarscher, AP-
dc.contributor.authorMarshall, HL-
dc.contributor.authorPacciani, L-
dc.contributor.authorRomani, RW-
dc.contributor.authorWu, KW-
dc.contributor.authorDi Marco, A-
dc.contributor.authorDi Lalla, N-
dc.contributor.authorOmodei, N-
dc.contributor.authorJorstad, SG-
dc.contributor.authorAgudo, I-
dc.contributor.authorKouch, PM-
dc.contributor.authorLindfors, E-
dc.contributor.authorAceituno, FJ-
dc.contributor.authorBernardos, MI-
dc.contributor.authorBonnoli, G-
dc.contributor.authorCasanova, V-
dc.contributor.authorGarcia-Comas, M-
dc.contributor.authorAgis-Gonzalez, B-
dc.contributor.authorHusillos, C-
dc.contributor.authorMarchini, A-
dc.contributor.authorSota, A-
dc.contributor.authorCasadio, C-
dc.contributor.authorEscudero, J-
dc.contributor.authorMyserlis, I-
dc.contributor.authorSievers, A-
dc.contributor.authorGurwell, M-
dc.contributor.authorRao, RMS-
dc.contributor.authorNg, CY-
dc.contributor.authoret al-
dc.date.accessioned2023-09-21T06:54:30Z-
dc.date.available2023-09-21T06:54:30Z-
dc.date.issued2023-05-01-
dc.identifier.citationAstrophysical Journal Letters, 2023, v. 948, n. 2, p. 1-12-
dc.identifier.issn2041-8205-
dc.identifier.urihttp://hdl.handle.net/10722/331300-
dc.description.abstract<p>We report the first >99% confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/<em>γ</em>-ray outburst, a 287 ks observation (2022 November 27–30) was taken using the Imaging X-ray Polarimetry Explorer (IXPE), together with contemporaneous multiwavelength observations from the Neil Gehrels Swift observatory and XMM-Newton in soft X-rays (0.3–10 keV), NuSTAR in hard X-rays (3–70 keV), and optical polarization from the Calar Alto and Perkins Telescope observatories. Our contemporaneous X-ray data suggest that the IXPE energy band is at the crossover between the low- and high-frequency blazar emission humps. The source displays significant variability during the observation, and we measure polarization in three separate time bins. Contemporaneous X-ray spectra allow us to determine the relative contribution from each emission hump. We find >99% confidence X-ray polarization <img alt="${{\rm{\Pi }}}_{2\mbox{--}4\mathrm{keV}}={21.7}_{-7.9}^{+5.6} \% $" src="https://cfn-live-content-bucket-iop-org.s3.amazonaws.com/journals/2041-8205/948/2/L25/revision2/apjlacd242ieqn1.gif?AWSAccessKeyId=AKIAYDKQL6LTV7YY2HIK&Expires=1692843820&Signature=eFDzWFawEVUm9sHTSS%2F%2FxRrCCMM%3D"> and electric vector polarization angle <em>ψ</em><sub>2–4keV</sub> = −28<img src="https://cdn.images.iop.org/Entities/fdg.gif" alt="fdg">7 ± 8<img src="https://cdn.images.iop.org/Entities/fdg.gif" alt="fdg">7 in the time bin with highest estimated synchrotron flux contribution. We discuss possible implications of our observations, including previous IXPE BL Lacertae pointings, tentatively concluding that synchrotron self-Compton emission dominates over hadronic emission processes during the observed epochs.<br></p>-
dc.languageeng-
dc.publisherAmerican Astronomical Society-
dc.relation.ispartofAstrophysical Journal Letters-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.titleX-Ray Polarization of BL Lacertae in Outburst-
dc.typeArticle-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.3847/2041-8213/acd242-
dc.identifier.scopuseid_2-s2.0-85159697882-
dc.identifier.volume948-
dc.identifier.issue2-
dc.identifier.spage1-
dc.identifier.epage12-
dc.identifier.eissn2041-8213-
dc.identifier.isiWOS:000992537100001-
dc.identifier.issnl2041-8205-

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