X-ray Polarization Observations of BL Lacertae

Abstract

Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus the Synchrotron emission to be responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae performed with the Imaging X-ray Polarimetry Explorer ({IXPE}), from which an upper limit to the polarization degree ${\Pi }_X<$12.6\% was found in the 2-8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac.

17 pages, 5 figures, accepted for publication in ApJL

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Cited by in corpus (17)

• X-ray Polarization of BL Lacertae in Outburst
• Detection of X-ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-ray Polarimetry Explorer
• High optical to X-ray polarization ratio reveals Compton scattering in BL Lacertae's jet
• The variability of blazars throughout the electromagnetic spectrum
• Revisiting the proton synchrotron radiation in blazar jets: Possible contributions from X-ray to $\gamma$-ray bands
• IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare
• Multifrequency polarimetry of High-Synchrotron Peaked blazars probes the shape of their jets
• Determining the origin of the X-ray emission in blazars through multiwavelength polarization
• Axion-like Particle Effects on Photon Polarization in High-Energy Astrophysics
• X-ray Polarization of the High-Synchrotron-Peak BL Lacertae Object 1ES 1959+650 during Intermediate and High X-ray Flux States
• Optical Spectropolarimetric Variability Properties in Blazars PKS 0637-75 and PKS 1510-089
• Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations
• Spectral Energy Distribution Modeling of BL Lacertae During a Large Submillimeter Outburst and Low X-Ray Polarization State
• Detection of Compton scattering in the jet of 3C 84
• Detectability of Polarized Gamma-ray Emission from Blazar Flares with COSI
• On the statistical characterization of the synchrotron multi-zone polarization of blazars
• Intraday variations of polarization vector in blazars: a key to the optical jet structure?