Discovery of X-ray polarization angle rotation in the jet from blazar Mrk 421

Gesu, Laura Di; Marshall, Herman L.; Ehlert, Steven R.; Kim, Dawoon E.; Donnarumma, I.; Tavecchio, F.; Liodakis, Ioannis; Kiehlmann, S.; Agudo, I.; Jorstad, Svetlana G.; Muleri, Fabio; Marscher, A. P.; Puccetti, S.; Middei, R.; Perri, M.; Pacciani, L.; Negro, Michela; Romani, Roger W.; Marco, Alessandro Di; Blinov, D.; Bourbah, Ioakeim G.; Kontopodis, Evangelos; Mandarakas, N.; Romanopoulos, Stylianos; Skalidis, R.; Vervelaki, Anna; Casadio, C.; Escudero, Juan; Myserlis, I.; Gurwell, M. A.; Rao, Ramprasad; Keating, Garrett K.; Kouch, Pouya M.; Lindfors, E.; Aceituno, F. J.; Bernardos, M.; Bonnoli, G.; Casanova, V.; García‐Comas, M.; Beatriz, Agís-González,; Husillos, C.; Marchini, Alessandro; Sota, A.; Imazawa, Ryo; Sasada, Mahito; Fukazawa, Yasushi; Kawabata, Koji S.; Uemura, Makoto; Mizuno, T.; Nakaoka, Tatsuya; Akitaya, Hiroshi; Савченко, С. С.; Vasilyev, A. A.; Gómez, J. L.; Antonelli, L. A.; Barnouin, Thibault; Bonino, R.; Cavazzuti, E.; Costamante, L.; Chen, Chien-Ting; Cibrario, N.; Rosa, A. De; Pierro, F. Di; Errando, M.; Kaaret, Philip; Karas, V.; Krawczynski, H.; Lisalda, Lindsey; Madejski, G.; Malacaria, C.; Marin, Frédéric; Marinucci, Andrea; Massaro, F.; Matt, Giorgio; Mitsuishi, Ikuyuki; O’Dell, Stephen L.; Paggi, A.; Peirson, Abel L.; Petrucci, Pierre-Olivier; Ramsey, Brian D.; Tennant, Allyn F.; Wu, Kinwah; Bachetti, Matteo; Baldini, Luca; Baumgartner, W. H.; Bellazzini, R.; Bianchi, S.; Bongiorno, Stephen D.; Brez, A.; Bucciantini, N.; Capitanio, Fiamma; Castellano, Simone; Ciprini, S.; Costa, E.; Monte, E. Del; Lalla, N. Di; Doroshenko, V.; Dovčiak, Michal; Enoto, T.; Evangelista, Y.; Fabiani, Sergio; Ferrazzoli, Riccardo; Garcia, J. Rodriguez; Gunji, Shuichi; Hayashida, Kentaro; Heyl, Jeremy; Iwakiri, W.; Kislat, Fabian; Kitaguchi, Takao; Kolodziejczak, Jeffery J.; Monaca, Fabio La; Latronico, L.; Maldera, S.; Manfreda, Alberto; Ng, Chi-Yung; Omodei, N.; Oppedisano, C.; Papitto, A.; Pavlov, G. G.; Pesce-Rollins, M.; Pilia, M.; Possenti, A.; Poutanen, Juri; Rankin, John; Ratheesh, Ajay; Roberts, O. J.; Sgrò, C.; Slane, Patrick; Soffitta, P.; Spandre, G.; Swartz, Douglas A.; Tamagawa, Toru; Taverna, Roberto; Tawara, Yuzuru; Thomas, N.; Tombesi, Francesco; Trois, A.; S., Tsygankov, Sergey; Turolla, R.; Vink, Jacco; Weisskopf, Martin C.; Xie, Fei; Zane, S.

doi:10.1038/s41550-023-02032-7

Cited by 40 publications

(27 citation statements)

References 82 publications

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“…Rotations of the EVPA during the IXPE observation, especially for exposures longer than the typical variability timescales (∼1-2 days) in blazars, can lead to depolarization, as was demonstrated recently in the X-ray EVPA rotation detected by IXPE in Mrk 421 (Di Gesu et al 2023). We tested for rotations using the method described in Di Gesu et al (2023), employing an event-based likelihood method (Marshall 2021).…”

Section: Full-band Analysesmentioning

confidence: 98%

“…Results from an unbinned event-based likelihood analysis (Marshall 2021) that accounts for an unpolarized background (Marshall 2023) are shown in Fig. 2.…”

Section: Full-band Analysesmentioning

confidence: 99%

“…A value of ∆S as large as 15.05 is significant at the 99.95% confidence level but there were about 130 trial rates tested, giving a chance detection of a rotation of this significant of 6.8%. See Di Gesu et al (2023) for details of how the test was conducted.…”

Section: Notes On Individual Sourcesmentioning

confidence: 99%

“…How this component arises is somewhat uncertain; various suggestions involve compression of the disordered field at the shock (Hughes et al 1985), generation of a magnetic field component transverse to the shock normal (Tavecchio et al 2018), or a toroidal magnetic field component in the ambient jet (Lyutikov et al 2005). Complicating the physical picture of HSP blazar shocks are the observations that the EVPA can rotate in the X-ray band without rotation in the optical (Di Gesu et al 2023) or vice versa .…”

Section: Introductionmentioning

confidence: 99%

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Observations of 4U 1626–67 with the Imaging X-Ray Polarimetry Explorer

Marshall¹,

Ng²,

Rogantini³

et al. 2022

ApJ

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We present measurements of the polarization of X-rays in the 2–8 keV band from the pulsar in the ultracompact low-mass X-ray binary 4U 1626–67 using data from the Imaging X-Ray Polarimetry Explorer (IXPE). The 7.66 s pulsations were clearly detected throughout the IXPE observations as well as in the NICER soft X-ray observations, which we used as the basis for our timing analysis and to constrain the spectral shape over the 0.4–10 keV energy band. Chandra HETGS high-resolution X-ray spectra were also obtained near the times of the IXPE observations for firm spectral modeling. We found an upper limit on the pulse-averaged linear polarization of <4% (at 95% confidence). Similarly, there was no significant detection of polarized flux in pulse phase intervals when subdividing the bandpass by energy. However, spectropolarimetric modeling over the full bandpass in pulse phase intervals provided a marginal detection of polarization of the power-law spectral component at the 4.8% ± 2.3% level (90% confidence). We discuss the implications concerning the accretion geometry onto the pulsar, favoring two-component models of the pulsed emission.

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Section: Full-band Analysesmentioning

confidence: 98%

“…Results from an unbinned event-based likelihood analysis (Marshall 2021) that accounts for an unpolarized background (Marshall 2023) are shown in Fig. 2.…”

Section: Full-band Analysesmentioning

confidence: 99%

Section: Notes On Individual Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observations of 4U 1626–67 with the Imaging X-Ray Polarimetry Explorer

Marshall¹,

Ng²,

Rogantini³

et al. 2022

ApJ

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“…Accurately predicting the pitch-angle distribution of the emitting particles is of paramount importance for interpreting synchrotron radiation from high-energy sources such as pulsar wind nebulae (e.g., Hester 2008;Reynolds et al 2017;Lyutikov et al 2019), magnetospheres of supermassive black holes (e.g., Johnson et al 2015;Event Horizon Telescope Collaboration et al 2019, jets from active galactic nuclei (e.g., Tavecchio et al 2018;de Jaeger et al 2023;Di Gesu et al 2023), or γ-ray bursts (e.g., Burgess et al 2014Burgess et al , 2020Oganesyan et al 2017;Ravasio et al 2019). However, the role of isolated reconnection layers in generating pitch-angle anisotropy has remained unexplored.…”

Section: Introductionmentioning

confidence: 99%

Pitch-angle Anisotropy Imprinted by Relativistic Magnetic Reconnection

Comisso,

Jiang

2023

ApJ

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Radiation emitted by nonthermal particles accelerated during relativistic magnetic reconnection is critical for understanding the nonthermal emission in a variety of astrophysical systems, including blazar jets, black hole coronae, pulsars, and magnetars. By means of fully kinetic particle-in-cell simulations, we demonstrate that reconnection-driven particle acceleration imprints an energy-dependent pitch-angle anisotropy and gives rise to broken power laws in both the particle energy spectrum and the pitch-angle anisotropy. The particle distributions depend on the relative strength of the non-reconnecting (guide field) versus the reconnecting component of the magnetic field (B g /B 0) and the lepton magnetization (σ 0). Below the break Lorentz factor γ 0 (injection), the particle energy spectrum is ultra-hard (p < < 1), while above γ 0, the spectral index p > is highly sensitive to B g /B 0. Particles’ velocities align with the magnetic field, reaching minimum pitch angle α at a Lorentz factor γ min α controlled by B g /B 0 and σ 0. The energy-dependent pitch-angle anisotropy, evaluated through the mean of sin 2 α of particles at a given energy, exhibits power-law ranges with negative (m <) and positive (m >) slopes below and above γ min α , becoming steeper as B g /B 0 increases. The generation of anisotropic pitch-angle distributions has important astrophysical implications. We address their effects on regulating synchrotron luminosity, spectral energy distribution, polarization, particle cooling, the synchrotron burn-off limit, emission beaming, and temperature anisotropy.

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