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 35 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%

See 2 more Smart Citations

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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Magnetic field properties inside the jet of Mrk 421

Kim,

Di Gesu,

Liodakis

et al. 2024

A&A

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Aims. We aim to probe the magnetic field geometry and particle acceleration mechanism in the relativistic jets of supermassive black holes. Methods. We conducted a polarimetry campaign from radio to X-ray wavelengths of the high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging X-ray Polarimetry Explorer (IXPE) measurements from 2022 December 6–8. During the IXPE observation, we also monitored Mrk 421 using Swift-XRT and obtained a single observation with XMM-Newton to improve the X-ray spectral analysis. The time-averaged X-ray polarization was determined consistently using the event-by-event Stokes parameter analysis, spectropolarimetric fit, and maximum likelihood methods. We examined the polarization variability over both time and energy, the former via analysis of IXPE data obtained over a time span of 7 months. Results. We detected X-ray polarization of Mrk 421 with a degree of ΠX = 14 ± 1% and an electric-vector position angle ψX = 107 ± 3° in the 2–8 keV band. From the time variability analysis, we find a significant episodic variation in ψX. During the 7 months from the first IXPE pointing of Mrk 421 in 2022 May, ψX varied in the range 0° to 180°, while ΠX remained relatively constant within ∼10–15%. Furthermore, a swing in ψX in 2022 June was accompanied by simultaneous spectral variations. The results of the multiwavelength polarimetry show that ΠX was generally ∼2–3 times greater than Π at longer wavelengths, while ψ fluctuated. Additionally, based on radio, infrared, and optical polarimetry, we find that the rotation of ψ occurred in the opposite direction with respect to the rotation of ψX and over longer timescales at similar epochs. Conclusions. The polarization behavior observed across multiple wavelengths is consistent with previous IXPE findings for HSP blazars. This result favors the energy-stratified shock model developed to explain variable emission in relativistic jets. We considered two versions of the model, one with linear and the other with radial stratification geometry, to explain the rotation of ψX. The accompanying spectral variation during the ψX rotation can be explained by a fluctuation in the physical conditions, for example in the energy distribution of relativistic electrons. The opposite rotation direction of ψ between the X-ray and longer wavelength polarization accentuates the conclusion that the X-ray emitting region is spatially separated from that at longer wavelengths. Moreover, we identify a highly polarized knot of radio emission moving down the parsec-scale jet during the episode of ψX rotation, although it is unclear whether there is any connection between the two events.

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

Cited by 35 publications

References 82 publications

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

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

Pitch-angle Anisotropy Imprinted by Relativistic Magnetic Reconnection

Magnetic field properties inside the jet of Mrk 421

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