X-Ray Polarization of BL Lacertae in Outburst

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

doi:10.3847/2041-8213/acd242

Cited by 21 publications

(24 citation statements)

References 54 publications

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“…Instead, we are able to constrain Π X in the 2-8 keV band to be < 13% for 3C 273 and 3C 279 and < 28% for 3C 454.3 and S5 0716+714. The non-detection of X-ray polarization in these sources is consistent with previous IXPE results on BL Lac in both LSP and ISP states Peirson et al 2023) as well as other radio galaxies (Ehlert et al 2022). For 3C 273 and 3C 454.3, the undetected X-ray polarization could point towards inverse-Compton scattering, either external Compton or SSC, however the unpolarized optical/IR emission during the IXPE observations is preventing us from coming to definitive conclusions.…”

Section: Discussionsupporting

confidence: 88%

“…On the other hand, 3C 279 shows fairly stable Π and EVPA in the optical/IR that remains persistently high (> 10%) and the upper limit to the Π X that is comparable (< 12.7%). IXPE observations of BL Lac showed a similar picture, i.e., undetected X-ray polarization (< 16%) with Π O that is comparable or exceeds the X-ray limits Peirson et al 2023). However, in the case of BL Lac the highly variable EVPA we observe in the optical could lead to depolarization of the otherwise highly polarized proton synchrotron emission making it consistent with the Π X limits.…”

Section: Discussionsupporting

confidence: 72%

“…During the first two observations, there was only a 99% confidence upper limit of Π X < 13%, while the contemporaneous Π O exceeded the X-ray limits ). In the third observation, 22% polarization was detected in the 2-4 keV band during a time dominated by synchrotron-emitting electrons from the low-energy hump of the SED (Peirson et al 2023). There are still only upper limits to the X-ray polarization from the high-energy component.…”

Section: Introductionmentioning

confidence: 93%

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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: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 93%

See 1 more Smart Citation

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

Marshall¹,

Ng²,

Rogantini³

et al. 2022

ApJ

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“…The second hump is located in the GeV-TeV range, with the mechanism behind the emission still debated. Both hadronic and leptonic frameworks have been proposed (e.g., Maraschi et al 1992;Boettcher 2012;Cerruti et al 2015), although recent X-ray spectropolarimetric observations seem to favor a leptonic scenario in which synchrotron self-Compton emission plays a key role in shaping the SED of some blazars (see, e.g., Middei et al 2023;Peirson et al 2023). Depending on the frequency at which the synchrotron component peaks (ν peak ), blazars are classified as high synchrotron peak (HSP), intermediate synchrotron peak (ISP), or low synchrotron peak 66 Deceased.…”

Section: Introductionmentioning

confidence: 99%

IXPE and Multiwavelength Observations of Blazar PG 1553+113 Reveal an Orphan Optical Polarization Swing

Middei

Perri

Puccetti

et al. 2023

ApJL

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The lower-energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consensus regarding jet emission processes, the particle acceleration mechanism is still debated. Here, we present the first X-ray polarization observations of PG 1553+113, a high-synchrotron-peak blazar observed by the Imaging X-ray Polarimetry Explorer (IXPE). We detect an X-ray polarization degree of (10 ± 2)% along an electric-vector position angle of ψ X = 86° ± 8°. At the same time, the radio and optical polarization degrees are lower by a factor of ∼3. During our IXPE pointing, we observed the first orphan optical polarization swing of the IXPE era, as the optical angle of PG 1553+113 underwent a smooth monotonic rotation by about 125°, with a rate of ∼17° day–1. We do not find evidence of a similar rotation in either radio or X-rays, which suggests that the X-ray and optically emitting regions are separate or, at most, partially cospatial. Our spectropolarimetric results provide further evidence that the steady-state X-ray emission in blazars originates in a shock-accelerated and energy-stratified electron population.

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“…The origin of the second emission hump is Compton scattering of photons by higher-energy particles, but questions about the origin of the particles responsible for the scattering and the source of the seed photons remain unanswered. Recent results from the Imaging X-ray Polarimetry Explorer (IXPE) collaboration for blazars and AGNs with synchrotron peaks well below the IXPE bandpass (e.g., Ehlert et al 2022;Middei et al 2023;Peirson et al 2023) suggest relativistic electrons are the dominant scattering particles, but the results are not yet sensitive enough to distinguish between different seed photon populations.…”

Section: Introductionmentioning

confidence: 99%

X-Ray Polarization of the BL Lacertae Type Blazar 1ES 0229+200

Ehlert,

Liodakis,

Middei

et al. 2023

ApJ

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We present polarization measurements in the 2–8 keV band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated by about two weeks, we find the degree of polarization to be ΠX = 17.9% ± 2.8% at an electric-vector position angle ψ X = 25.°0 ± 4.°6 using a spectro-polarimetric fit from joint IXPE and XMM-Newton observations. There is no evidence for the polarization degree or angle varying significantly with energy or time on both short timescales (hours) or longer timescales (days). The contemporaneous polarization degree at optical wavelengths was >7× lower, making 1ES 0229+200 the most strongly chromatic blazar yet observed. This high X-ray polarization compared to the optical provides further support that X-ray emission in high-peaked blazars originates in shock-accelerated, energy-stratified electron populations, but is in tension with many recent modeling efforts attempting to reproduce the spectral energy distribution of 1ES 0229+200, which attribute the extremely high energy synchrotron and Compton peaks to Fermi acceleration in the vicinity of strongly turbulent magnetic fields.

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X-Ray Polarization of BL Lacertae in Outburst

Cited by 21 publications

References 54 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

IXPE and Multiwavelength Observations of Blazar PG 1553+113 Reveal an Orphan Optical Polarization Swing

X-Ray Polarization of the BL Lacertae Type Blazar 1ES 0229+200

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