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IXPE Observations of the Blazar Mrk 501 in 2022: A Multiwavelength View

T0 review · 4 major / 3 minor · reviewed 2026-08-06 · deepseek-v4-flash

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Pith's one-line read In its third 2022 observation, IXPE measured Mrk 501's X-ray polarization at 6 percent, and the paper argues the polarization stayed stable across all three epochs and aligns with the jet.

desk verdict Solid but incremental third-epoch IXPE result for Mrk 501; the modeling is illustrative rather than predictive. read the letter →

arxiv 2507.07232 v1 pith:JNFOETXY submitted 2025-07-09 astro-ph.HE astro-ph.GA

L. Lisalda , E. Gau , H. Krawczynski , F. Tavecchio , I. Liodakis , A. Gokus , N. Rodriguez Cavero , M. Nowak
show 152 more authors
M. Negro R. Middei M. Perri S. Puccetti S. G. Jorstad I. Agudo A. P. Marscher B. Agís-González A. V. Berdyugin M. I. Bernardos D. Blinov G. Bonnoli G. A. Borman I. G. Bourbah C. Casadio V. Casanova A. J. Castro-Tirado E. Fernández-García M. García-Comas T. S. Grishina P. Hakala T. Hovatta Y. D. Hu C. Husillos J. Escudero J. Jormanainen F. José Aceituno M. Kagitani S. Kiehlmann E. Kontopodis E. N. Kopatskaya P. M. Kouch V. Kravtsov A. Lähteenmäki E. G. Larionova E. Lindfors N. Mandarakas A. Marchini J. R. Masiero D. Mawet W. Max-Moerbeck D. A. Morozova I. Myserlis K. Nilsson G. V. Panopoulou T. J. Pearson A. C. S. Readhead R. Reeves S. Romanopoulos T. Sakanoi Q. Salomé S. S. Savchenko R. Skalidis A. Sota I. Syrjärinne S. Tinyanont M. Tornikoski Yu. V. Troitskaya I. S. Troitskiy A. A. Vasilyev A. Vervelaki A. V. Zhovtan L. A. Antonelli M. Bachetti L. Baldini W. H. Baumgartner R. Bellazzini S. Bianchi S. D. Bongiorno R. Bonino A. Brez N. Bucciantini F. Capitanio S. Castellano E. Cavazzuti C. Chen S. Ciprini E. Costa A. De Rosa E. Del Monte L. Di Gesu N. Di Lalla A. Di Marco I. Donnarumma V. Doroshenko M. Dovčiak S. R. Ehlert T. Enoto Y. Evangelista S. Fabiani R. Ferrazzoli J. A. Garcia S. Gunji M. Gurwell K. Hayashida J. Heyl W. Iwakiri P. Kaaret V. Karas G. Keating F. Kislat T. Kitaguchi J. J. Kolodziejczak F. La Monaca L. Latronico S. Maldera A. Manfreda F. Marin A. Marinucci H. L. Marshall F. Massaro G. Matt I. Mitsuishi T. Mizuno F. Muleri C. Ng S. L. O'Dell N. Omodei C. Oppedisano A. Papitto G. G. Pavlov A. L. Peirson M. Pesce-Rollins P. Petrucci M. Pilia A. Possenti J. Poutanen B. D. Ramsey J. Rankin R. Rao A. Ratheesh O. J. Roberts R. W. Romani C. Sgrò P. Slane P. Soffitta G. Spandre D. A. Swartz T. Tamagawa R. Taverna Y. Tawara A. F. Tennant N. E. Thomas F. Tombesi A. Trois S. S. Tsygankov R. Turolla J. Vink M. C. Weisskopf K. Wu F. Xie S. Zane
This is my paper · ORCID
classification astro-ph.HEastro-ph.GA
keywords blazarMrk501X-raypolarimetryIXPEsynchrotronself-Comptonshockaccelerationmagneticfieldanisotropymultiwavelengthpolarization
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

Using IXPE, the paper reports the third X-ray polarization measurement of the blazar Mrk 501 made in 2022 and argues that the source's X-ray polarization remained essentially constant across all three epochs. The new July 2022 observation gives a linear polarization degree of $\Pi_X = 6 \pm 2$ per cent at an angle $\Psi_X = 143^\circ \pm 11^\circ$ in the 2–8 keV band, and combining all three epochs raises the detection significance to $7.5\sigma$ with the polarization angle aligned with the radio jet. The paper also shows that the polarization degree rising from radio through optical to X-rays can be reproduced by two different models: a one-zone synchrotron self-Compton model with a mildly anisotropic magnetic field, and an energy-stratified shock model. A reader should care because these results tie X-ray polarization to the magnetic field geometry and particle acceleration in relativistic jets, and they show that only small deviations from an isotropic field are needed to explain the data.

What carries the argument

The argument is carried by X-ray polarimetry from IXPE combined with two emission models. The first model is a one-zone synchrotron self-Compton code in which the magnetic field direction within each small sub-volume follows the axisymmetric probability distribution $p_B(\mu, n) = (n+1)(1-|\mu|)^n/2$, where $\mu$ is the cosine of the angle between the local field and the jet axis; $n=0$ is isotropic and large $n$ pins the field perpendicular to the jet, so the fit values quantify how anisotropic the field must be. The second model is a shock-in-jet calculation in which a mildly relativistic shock generates an intense magnetic field parallel to the shock front and perpendicular to the jet axis, with strength decaying downstream as $B_\perp(d) = B_{\perp,0}[1 + d/\lambda]^{-m}$; because high-energy X-ray electrons cool over short distances they radiate close to the shock in the strong ordered field, while lower-energy optical electrons sample a larger, more disordered volume. The chromatic polarization is the observable that discriminates the two geometries, and the energy-stratified shock model predicts a polarization-angle swing from $\approx 90^\circ$ below $10^{12}$ Hz to $\approx 0^\circ$ above it.

What would settle it

Take simultaneous optical and X-ray polarization measurements of Mrk 501 during a bright flare: if the X-ray polarization degree dropped to the optical level, or the X-ray angle rotated by more than about 20 degrees while the optical and radio angles stayed fixed, the fixed shock geometry and the single-zone anisotropic-field picture presented here would both fail.

Watch

Extended reading notes

Core claim

The paper's central claim is that the third IXPE pointing at Mrk 501, taken 2022 July 9–12, detected X-ray polarization at $\Pi_X = 6 \pm 2$ per cent with $\Psi_X = 143^\circ \pm 11^\circ$, statistically consistent with the two March 2022 observations ($\Pi_X = 10 \pm 2$ per cent and $11 \pm 2$ per cent). Over the four-month campaign the X-ray polarization angle remained consistent with the jet axis ($\psi_{\rm jet} = 120^\circ \pm 12^\circ$), and the multiwavelength pattern — lowest polarization in the radio, higher in the optical, highest in X-rays — persisted. The authors show that both a one-zone synchrotron self-Compton model with an axisymmetric magnetic field direction distribution and an energy-stratified shock model with a shock-generated perpendicular field that decays downstream can fit the spectral energy distribution and the energy-dependent polarization. They conclude that the steady, jet-aligned X-ray polarization supports particle acceleration at shocks and that small magnetic field anisotropies, characterized by parameters $n = 0.041$ in the optical and $n = 0.205$ in the X-ray band, are sufficient to explain the measurements.

Load-bearing premise

The model fits rest on the assumption that the magnetic field direction distribution has exactly the axisymmetric form $p_B(\mu, n) \propto (1 - |\mu|)^n$ and that the same emitting region can be assigned two different anisotropy values, $n = 0.041$ for optical and $n = 0.205$ for X-ray, without a physical mechanism tying field orientation to electron energy.

Editorial extensions

If this is right

  • X-ray polarization of Mrk 501 in its quiescent state is stable in both degree and angle over at least four months, so the magnetic field configuration in the X-ray-emitting region did not change dramatically between March and July 2022.
  • If shocks in blazar jets are generally oriented perpendicular to the jet axis, the persistent jet-aligned X-ray polarization supports the shock acceleration scenario over reconnection models that predict faster polarization swings.
  • Only small levels of magnetic field anisotropy, with $n$ well below unity, are required to produce the observed optical-to-X-ray polarization rise, meaning the field need not be highly ordered.
  • The two models predict different wavelength-dependent polarization behavior, so future simultaneous multi-band polarimetry can distinguish the one-zone anisotropic-field picture from the energy-stratified shock picture.
  • The absence of polarization-angle swings of the kind seen in Mrk 421 implies that whatever mechanism drives those swings is not active in Mrk 501 during these observations.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Beyond the paper: if the chromatic polarization pattern is generic, IXPE observations of other high-synchrotron-peaked blazars should reveal a similar monotonic rise in polarization degree from optical to X-ray, and a null result in one object would indicate that the Mrk 501 pattern is not universal.
  • Beyond the paper: the need for two different $n$ values in the same one-zone model suggests the magnetic field anisotropy is scale-dependent; energy-resolved IXPE polarization in finer bins could map $n$ as a function of electron energy and test whether the transition aligns with the electron cooling break.
  • Beyond the paper: the degeneracy the paper notes between anisotropy and viewing angle means that combining IXPE data with very-long-baseline interferometric images of the jet orientation could break the degeneracy and actually locate the field geometry.
  • Beyond the paper: a direct comparison prediction is that during a flare, the energy-stratified shock model would produce a harder X-ray spectrum with higher polarization degree, while the one-zone model would keep polarization nearly constant unless the anisotropy parameter itself changes.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 3 minor

Summary. The paper presents the third IXPE observation of the blazar Mrk 501, taken in July 2022, reports the X-ray polarization measurement and its multiwavelength context, and confronts the data with two emission models: a one-zone SSC model with a parameterized anisotropic magnetic field distribution and an energy-stratified shock-in-jet model. The authors find that the X-ray polarization degree and angle in the third observation are consistent with the two earlier 2022 IXPE campaigns, and that the radio-to-X-ray polarization chromaticity (increasing degree with frequency) is reproduced by both models, leading them to argue for small magnetic field anisotropy in the SSC framework and support for the shock scenario.

Significance. If the X-ray polarization stability across four months is confirmed, it constitutes a useful constraint on magnetic field geometry in a high-synchrotron-peaked blazar, complementing the variability seen in Mrk 421. The multiwavelength polarization data are of good quality and the reduction uses standard tools, with carefully quoted errors and a combined three-epoch significance of 7.5 sigma. However, the modeling claims are not yet on an equal footing: the SSC 'explanation' of the chromatic polarization uses two separate anisotropy parameters for two data points, so the cited conclusion about small anisotropy is a parameterization rather than a test, and the shock model is presented qualitatively without fit statistics. The observational core is solid, but the interpretive conclusions need revision.

major comments (4)
  1. [Section 3.2, Table 1] The abstract and Section 3.2 state that IXPE 'detected' a polarization degree of 6±2 per cent in the third observation, but the model-free PCUBE analysis in Table 1 reports a significance of only 1.88 sigma for that epoch. 'Detected' overstates the individual-epoch result; the combined three-epoch detection at 7.5 sigma is what supports the stability claim. The wording should be revised to 'measured' or 'reported,' with the significance explicitly stated.
  2. [Section 5.1, Eqs. (3)-(5), Fig. 6] The SSC model with p_B(mu,n) in Eq. (3) has no gamma dependence in the integrals of Eqs. (4)-(5); the polarization degree is determined by the single parameter n. Reproducing the optical and X-ray polarization degrees with two different values (n=0.041 and n=0.205) means fitting the two data points with two free parameters, not testing a prediction. The chromatic polarization is not explained by the model; it is imposed through the parameterization. The abstract's claim that 'small levels of magnetic field anisotropy can explain the observed polarization' is therefore not established by this model. The authors should either implement a physical energy dependence (for example, energy-stratified sub-regions with different n) or explicitly reframe the result as a demonstration that the p_B(mu,n) family can accommodate the data.
  3. [Section 5.2, Fig. 8] The shock-in-jet model is only qualitatively described, with a detailed treatment deferred to Tavecchio et al. (in preparation). The curves in Fig. 8 are presented without any statistical comparison to the observed SED or polarization data: no residuals, fit statistics, or parameter uncertainties are given. This is insufficient to 'support' the shock scenario over other models. At minimum, a chi-square or likelihood comparison should be provided, or the conclusion should be softened to state that the model is consistent with the data.
  4. [Section 5.1, paragraph on degeneracy] The authors note that the inferred n is degenerate with the jet-frame viewing angle and fix theta_j=90 deg to minimize the required anisotropy. Consequently, the quoted values n=0.041 and n=0.205 are lower bounds; larger anisotropies or different viewing angles would also fit the data. The statement that 'small' anisotropy is sufficient is therefore conditional on this geometric choice. This conditionality should be stated in the conclusions, and the uncertainty on n arising from the unknown geometry should be propagated or at least discussed.
minor comments (3)
  1. [Section 2.2, Table 1] The text says the XMM-Newton observations were taken on 22 and 24 March 2022, but Table 1 lists them as 2022-03-22 and 2022-03-24; the text and table are consistent, but the earlier sentence in Section 2.2 says '22and24March2022' without spaces due to a typographic issue; please fix the formatting.
  2. [Section 3.3 / Figure 5] In the caption of Figure 5, the phrase 'host-galaxy-corrected optical polarization degree' is used, but the correction is described only vaguely in Section 2.4 as in previous papers; a brief explanation of the host-galaxy contamination level would help the reader judge the systematic uncertainty.
  3. [Section 4.1, Eq. (3)] The normalization of the distribution p_B(mu,n) is stated as integral from -1 to 1 equals 1, which is correct for the given expression. However, the text later refers to the isotropic distribution as p_B=1/2, which would be consistent only if mu is dimensionless; the relationship between the normalization and the variable mu could be clarified.

Circularity Check

1 steps flagged · score 6.0 of 10

The SSC model's agreement on optical/X-ray polarization degrees is constructed by fitting n=0.041 and n=0.205 to the two measured values, so the 'small anisotropy' conclusion is a parameterization rather than an independent prediction.

  1. fitted input called prediction [Section 4.1, Section 5.1, Eqs. (4)-(5), Fig. 7 caption]
    "We can reproduce the polarization degrees observed in the optical and X-ray bands with anisotropy parameters of n=0.041 and n=0.205, respectively. ... The values of n inferred in our models thus represent the minimum amount of magnetic field anisotropy required to describe the observed polarization degrees. ... For the polarization degree we show the modeling results for magnetic field anisotropies described by n=0.041 (dashed green line, to match optical polarization results) and n=0.205 (solid cyan line, for X-ray polarization results)."

    In Eqs. (4)-(5), p_B(μ,n) multiplies the electron distribution independently of γ, so a fixed one-zone SSC model with a single n yields one synchrotron polarization degree across the optically thin bands. The paper chooses n=0.041 to match the optical Π and n=0.205 to match the X-ray Π: two data points are used to fix two parameters, so the model's 'reproduction' of those points is the inverse of the fit, not a prediction of the chromatic trend. The abstract's claim that small levels of magnetic field anisotropy can explain the observed polarization is thus a statement that the two-parameter family p_B(μ,n) contains curves that hit the two measured values, with no physical mechanism in the SSC model coupling n to electron energy.

full rationale

The genuinely new observational result—the third IXPE measurement of Π_X=6±2% at Ψ_X=143°±11°—is a model-free detection and is consistent with the prior epochs; that part is not circular. The shock-in-jet model also has independent content, since its frequency-dependent polarization rise follows from cooling-length segregation rather than from per-band tuning of the field geometry, although a detailed description is deferred to an in-preparation paper. However, the paper's other central modeling conclusion, that small levels of magnetic field anisotropy explain the multiwavelength polarization, rests on the SSC model where n=0.041 and n=0.205 are explicitly selected to match the observed optical and X-ray polarization degrees. Because p_B(μ,n) is independent of electron Lorentz factor in Eqs. (4)-(5), a single n cannot produce the optical-to-X-ray rise; the two curves in Fig. 7 are two separate fits to two data points. The SSC 'explanation' of the chromaticity therefore reduces for those two points to the values of the fitted parameters, giving partial circularity. The polarization-angle alignment is an independent success of the assumed axisymmetry, so the overall circularity is partial rather than total.

Assumptions & free parameters 22 free parameters · 7 assumptions · 0 invented entities

The polarization and SED conclusions rest on a large set of fitted model parameters (12 in the SSC model, 10 in the shock model) and on several modeling assumptions, including the axisymmetric p_B(mu,n) prescription and the shock field decay ansatz. The numbers are not derived from first principles and are not cross-checked against independent observables. No new particles or fields are introduced.

free parameters (22)
  • SSC gamma_min = 10 MeV
    Lower electron energy cutoff, fitted to reproduce the radio-to-optical SED turnover; Section 5.1.
  • SSC gamma_b = 2.5 GeV
    Break energy that sets the synchrotron peak frequency; fitted to the SED; Section 5.1.
  • SSC gamma_max = 398 GeV
    Maximum electron energy, fitted to the high-energy cutoff of the SED; Section 5.1.
  • SSC p1 = 1.44
    Electron spectral index below the break, fitted to the X-ray spectral shape; Section 5.1.
  • SSC p2 = 2.44
    Electron spectral index above the break, fitted to the SED; Section 5.1.
  • SSC B = 0.033 G
    Magnetic field strength, fitted to the SED normalization and peak; Section 5.1.
  • SSC R = 7.4e15 cm
    Emission region radius, fitted to the variability timescale and SED; Section 5.1.
  • SSC beta = 0.9995
    Jet speed parameter, chosen with Gamma to produce the Doppler factor; Section 5.1.
  • SSC Gamma = 33
    Bulk Lorentz factor, fixed along with theta_obs to give a jet-frame viewing angle of 90 degrees; Section 5.1.
  • SSC theta_obs = 1.6 deg
    Observing angle, fixed with Gamma to set the Doppler factor and jet-frame angle; Section 5.1.
  • SSC n_opt = 0.041
    Magnetic field anisotropy parameter chosen to match the optical polarization degree; Section 5.1 and Fig. 6.
  • SSC n_X = 0.205
    Magnetic field anisotropy parameter chosen to match the X-ray polarization degree; Section 5.1 and Fig. 6.
  • Shock gamma_min = 100
    Minimum injected electron Lorentz factor in the shock model; Section 5.2.
  • Shock gamma_max = 8e5
    Maximum injected electron Lorentz factor in the shock model; Section 5.2.
  • Shock electron index n = 2.2
    Injection power-law index of electrons at the shock; Section 5.2.
  • Shock B_perp0 = 0.27 G
    Initial transverse magnetic field strength at the shock; fitted to the SED and polarization; Section 5.2.
  • Shock B_parallel = 0.034 G
    Parallel (poloidal) magnetic field component; fitted to the lower-frequency emission; Section 5.2.
  • Shock radius R = 4.3e15 cm
    Jet radius, fitted to the SED normalization; Section 5.2.
  • Shock lambda = 5e13 cm
    Effective decay length of the self-generated transverse field; Section 5.2.
  • Shock decay index m = 0.5
    Decay exponent of the transverse field with distance downstream; Section 5.2.
  • Shock Gamma = 22
    Bulk Lorentz factor in the shock model, set with theta_obs to give Doppler factor 35; Section 5.2.
  • Shock theta_obs = 1.3 deg
    Observing angle in the shock model, set with Gamma to give Doppler factor 35; Section 5.2.
assumptions (7)
  • standard math Standard synchrotron and SSC formulas (Rybicki & Lightman 1986; Blumenthal & Gould 1970) describe the emitted Stokes I, Q and the SED.
    Used in Section 4.1, Eqs. (4)-(5), and for the SSC kernel; no derivation repeated.
  • domain assumption The X-ray and multiwavelength emission of Mrk 501 is produced by leptonic synchrotron and inverse-Compton processes; hadronic contributions are ignored.
    Baseline for both models; not tested by the data.
  • ad hoc to paper Magnetic field directions in the SSC emission volume follow the axisymmetric distribution p_B(mu,n) = (n+1)/2 (1-|mu|)^n.
    Introduced in Section 4.1 as Eq. (3); the fitted n values determine the polarization result.
  • ad hoc to paper In the shock model, the self-generated transverse magnetic field decays as B_perp(d)=B_perp0 [1+d/lambda]^{-m}, and the upstream field is parallel to the jet.
    Assumed in Section 4.2; no direct observational validation is presented.
  • domain assumption The Fermi-LAT 4FGL time-averaged spectrum represents the gamma-ray SED during the July 2022 observation.
    Stated in Section 2.5; the source was near its average but the spectrum is not strictly simultaneous.
  • domain assumption The CIB extinction model of Franceschini et al. (2008) correctly corrects the gamma-ray fluxes.
    Used in Section 4.1 to compute the observed high-energy SED.
  • ad hoc to paper The observer viewing angle and bulk Lorentz factor are fixed so that the jet-frame viewing angle is 90 degrees, maximizing the predicted polarization.
    Section 5.1 states theta_obs=1.6 deg and Gamma=33 give theta_j=90 deg; Section 5.2 makes the same choice. This choice inflates the polarization the models can produce.

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Pith. "Pith review of IXPE Observations of the Blazar Mrk 501 in 2022: A Multiwavelength View." pith.science (2026). https://pith.science/paper/JNFOETXY

@misc{pith2026250707232,
  author       = {Pith},
  title        = {Pith review of: IXPE Observations of the Blazar Mrk 501 in 2022: A Multiwavelength View},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/JNFOETXY}},
  note         = {Machine review of arXiv:2507.07232}
}
abstract

The blazar Markarian 501 (Mrk 501) was observed on three occasions over a 4-month period between 2022 March and 2022 July with the Imaging X-ray Polarimetry Explorer (IXPE). In this paper, we report for the first time on the third IXPE observation, performed between 2022 July 9 and 12, during which IXPE detected a linear polarization degree of $\Pi_X=6\pm2$ per cent at a polarization angle, measured east of north, of $\Psi_X=143^\circ\pm11^\circ$ within the 2-8 keV X-ray band. The X-ray polarization angle and degree during this observation are consistent with those obtained during the first two observations. The chromaticity of the polarization across radio, optical, and X-ray bands is likewise consistent with the result from the simultaneous campaigns during the first two observations. Furthermore, we present two types of models to explain the observed spectral energy distributions (SEDs) and energy-resolved polarization: a synchrotron self-Compton model with an anisotropic magnetic field probability distribution in the emitting volume, as well as an energy-stratified shock model. Our results support both the shock scenario as well as support that small levels of magnetic field anisotropy can explain the observed polarization.

Figures

Figures reproduced from arXiv: 2507.07232 by the authors.

Figure 1
Figure 1. Fluxes (upper panel) and spectral parameters 𝛼 (middle panel) and 𝛽 (lower panel) retrieved via modelling the Swift-XRT Mrk 501 observations from January to August 2022 with a log-parabola model. The grey vertical bands show the times of the three IXPE observations campaigns. Detailed results from fitting the XMM-Newton, NuSTAR, and Swift-XRT data are found in Tables 2 - 4 in the Appendix [PITH_FULL_IMAGE:figures/f… view at source ↗
Figure 2
Figure 2. Light curves and 4–8 keV/2–4 keV hardness ratios for each of the three IXPE campaigns. The first observation has 7647 seconds per bin for both the light curve and hardness ratios; the second, 7060 seconds per bin; the third, 7069 seconds per bin. A more coarse-grained time-binning of the counts in the second observation will reveal a similar rise in flux to that shown in the SWIFT-XRT light curve of [PITH_FULL_IMAG… view at source ↗
Figure 3
Figure 3. Detected Stokes Q and U for the three IXPE observations of Mrk 501, as well as for all three observations taken together. The circles around the result display, from innermost to outermost, the 1, 2, and 3𝜎 uncertainty regions. Note that a polarization angle of 135◦ is equivalent to −45◦ [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figures from the paper (5 more)
Figure 4
Figure 4. Figure 4: SWIFT-XRT and IXPE data for Stokes I, fitted with an absorbed power-law model (left) and an absorbed log-parabola model (right). The data have been re-binned to have a minimum signal-to-noise ratio of 5 in each bin. The lower flux blue-green-purple data points, with er…
Figure 5
Figure 5. Figure 5: Contemporaneous radio, optical, and X-ray polarization observa￾tions around the time of the third IXPE observation. The top panel shows the R-band magnitudes, the middle panel the measured polarization degrees, and the bottom panel the measured polarization angles. The…
Figure 6
Figure 6. Figure 6: We use a simple phenomenological prescription to study the impact of anisotropies in the magnetic field distribution. We assume that the overall distribution of magnetic field directions in all minuscule sub-volumes of the sphere can be described by a probability distr…
Figure 7
Figure 7. Figure 7: shows the multiwavelength SED and polarization energy spectra, together with the results from the SSC model with an anisotropic magnetic field distribution. The top panel shows the spec￾tral energy distribution, while the two bottom panels show the po￾larization degree…
Figure 8
Figure 8. Figure 8: Comparison of the observed (data points) and modeled (lines) SED (top), polarization degree (middle), and EVPA (bottom) of Mrk 501 for the shock-in-jet model. The solid blue line shows our fiducial model, and the dashed cyan line shows the results for a different viewi…

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Works this paper leans on

50 extracted references · 7 canonical work pages

  1. [1]

    Abdollahi S., et al., 2020, @doi [ ] 10.3847/1538-4365/ab6bcb , https://ui.adsabs.harvard.edu/abs/2020ApJS..247...33A 247, 33

    doi:10.3847/1538-4365/ab6bcb 2020

  2. [2]

    N., Casadio C., G \'o mez J

    Agudo I., Thum C., Ramakrishnan V., Molina S. N., Casadio C., G \'o mez J. L., 2018a, @doi [ ] 10.1093/mnras/stx2437 , https://ui.adsabs.harvard.edu/abs/2018MNRAS.473.1850A 473, 1850

    doi:10.1093/mnras/stx2437

  3. [3]

    Agudo I., et al., 2018b, @doi [ ] 10.1093/mnras/stx2435 , https://ui.adsabs.harvard.edu/abs/2018MNRAS.474.1427A 474, 1427

    doi:10.1093/mnras/stx2435

  4. [4]

    The time averaged TeV energy spectrum of Mkn 501 of the extraordinary 1997 outburst as measured with the stereoscopic Cherenkov telescope system of HEGRA

    Aharonian F. A., et al., 1999, @doi [ ] 10.48550/arXiv.astro-ph/9903386 , https://ui.adsabs.harvard.edu/abs/1999A&A...349...11A 349, 11

    work page Pith review arXiv doi:10.48550/arxiv.astro-ph/9903386 1999

  5. [5]

    Baldini L., et al., 2022, @doi [SoftwareX] 10.1016/j.softx.2022.101194 , https://ui.adsabs.harvard.edu/abs/2022SoftX..1901194B 19, 101194

    arXiv 2022

  6. [6]

    R., Gould R

    Blumenthal G. R., Gould R. J., 1970, @doi [Reviews of Modern Physics] 10.1103/RevModPhys.42.237 , https://ui.adsabs.harvard.edu/abs/1970RvMP...42..237B 42, 237

    doi:10.1103/revmodphys.42.237 1970

  7. [7]

    Boettcher M., 2010, Models for the Spectral Energy Distributions and Variability of Blazars ( @eprint arXiv 1006.5048 )

    arXiv 2010

  8. [8]

    J., et al., 2012, in Astronomical Society of India Conference Series

    Castro-Tirado A. J., et al., 2012, in Astronomical Society of India Conference Series. pp 313--320

    work page 2012

Show all 50 references
  1. [9]

    J., et al., 2024, @doi [ ] 10.3847/1538-4357/ad63a1 , https://ui.adsabs.harvard.edu/abs/2024ApJ...974...50C 974, 50

    Chen C.-T. J., et al., 2024, @doi [ ] 10.3847/1538-4357/ad63a1 , https://ui.adsabs.harvard.edu/abs/2024ApJ...974...50C 974, 50

    2024 doi

  2. [10]

    Chiaberge M., Ghisellini G., 1999, @doi [ ] 10.1046/j.1365-8711.1999.02538.x , https://ui.adsabs.harvard.edu/abs/1999MNRAS.306..551C 306, 551

    1999

  3. [11]

    Di Gesu L., Tavecchio F., Donnarumma I., Marscher A., Pesce-Rollins M., Landoni M., 2022a, @doi [ ] 10.1051/0004-6361/202243168 , https://ui.adsabs.harvard.edu/abs/2022A&A...662A..83D 662, A83

    doi

  4. [12]

    Di Gesu L., et al., 2022b, @doi [ ] 10.3847/2041-8213/ac913a , https://ui.adsabs.harvard.edu/abs/2022ApJ...938L...7D 938, L7

    doi

  5. [13]

    arXiv:2305.13497

    Di Gesu L., et al., 2023, @doi [arXiv e-prints] 10.48550/arXiv.2305.13497 , https://ui.adsabs.harvard.edu/abs/2023arXiv230513497D p. arXiv:2305.13497

    2023 doi arXiv

  6. [14]

    Franceschini A., Rodighiero G., Vaccari M., 2008, @doi [ ] 10.1051/0004-6361:200809691 , https://ui.adsabs.harvard.edu/abs/2008A&A...487..837F 487, 837

    2008 doi

  7. [15]

    D., eds, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series Vol

    Freeman P., Doe S., Siemiginowska A., 2001, in Starck J.-L., Murtagh F. D., eds, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series Vol. 4477, Astronomical Data Analysis. pp 76--87 ( @eprint arXiv astro-ph/0108426 ), @doi 10.1117/12.447161

    2001 arXiv

  8. [16]

    Gehrels N., et al., 2004, @doi [ ] 10.1086/422091 , https://ui.adsabs.harvard.edu/abs/2004ApJ...611.1005G 611, 1005

    2004 doi

  9. [17]

    HI4PI Collaboration et al., 2016, @doi [ ] 10.1051/0004-6361/201629178 , https://ui.adsabs.harvard.edu/abs/2016A&A...594A.116H 594, A116

    2016 doi

  10. [18]

    A., et al., 2013, @doi [ ] 10.1088/0004-637X/770/2/103 , https://ui.adsabs.harvard.edu/abs/2013ApJ...770..103H 770, 103

    Harrison F. A., et al., 2013, @doi [ ] 10.1088/0004-637X/770/2/103 , https://ui.adsabs.harvard.edu/abs/2013ApJ...770..103H 770, 103

    2013 doi

  11. [19]

    Ho P. T. P., Moran J. M., Lo K. Y., 2004, @doi [ ] 10.1086/423245 , https://ui.adsabs.harvard.edu/abs/2004ApJ...616L...1H 616, L1

    2004 doi

  12. [20]

    Hovatta T., et al., 2016, @doi [ ] 10.1051/0004-6361/201628974 , https://ui.adsabs.harvard.edu/abs/2016A&A...596A..78H 596, A78

    2016 doi

  13. [21]

    Hu Y.-D., et al., 2023, Frontiers in Astronomy and Space Sciences, 10, 952887

    2023

  14. [22]

    Jansen F., et al., 2001, @doi [ ] 10.1051/0004-6361:20000036 , https://ui.adsabs.harvard.edu/abs/2001A&A...365L...1J 365, L1

    2001 doi

  15. [23]

    W., O'Dell S

    Jones T. W., O'Dell S. L., Stein W. A., 1974, @doi [ ] 10.1086/152724 , https://ui.adsabs.harvard.edu/abs/1974ApJ...188..353J 188, 353

    1974 doi

  16. [24]

    S., Maccarone T., Aharonian F

    Krawczynski H., Coppi P. S., Maccarone T., Aharonian F. A., 2000, @doi [ ] 10.48550/arXiv.astro-ph/9911224 , https://ui.adsabs.harvard.edu/abs/2000A&A...353...97K 353, 97

    2000 doi arXiv

  17. [25]

    Krawczynski H., et al., 2004, @doi [ ] 10.1086/380393 , https://ui.adsabs.harvard.edu/abs/2004ApJ...601..151K 601, 151

    2004 doi

  18. [26]

    Laing R., 2002, @doi [Monthly Notices of the Royal Astronomical Society] 10.1046/j.1365-8711.2002.05000.x , 329, 417

    2002

  19. [27]

    Liodakis I., et al., 2022, @doi [ ] 10.1038/s41586-022-05338-0 , https://ui.adsabs.harvard.edu/abs/2022Natur.611..677L 611, 677

    2022 doi

  20. [28]

    S., 2010, High energy astrophysics

    Longair M. S., 2010, High energy astrophysics. Cambridge university press

    2010

  21. [29]

    I., Gabuzda D

    Lyutikov M., Pariev V. I., Gabuzda D. C., 2005, @doi [ ] 10.1111/j.1365-2966.2005.08954.x , https://ui.adsabs.harvard.edu/abs/2005MNRAS.360..869L 360, 869

    2005

  22. [30]

    P., Rao R., 2008, in Duncan W

    Marrone D. P., Rao R., 2008, in Duncan W. D., Holland W. S., Withington S., Zmuidzinas J., eds, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series Vol. 7020, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy IV. p. 70202B ( @epri...

    2008 arXiv

  23. [31]

    P., Gear W

    Marscher A. P., Gear W. K., 1985, @doi [ApJ] 10.1086/163592 , 298, 114

    1985 doi

  24. [32]

    Middei R., et al., 2023, @doi [ ] 10.3847/2041-8213/aca281 , https://ui.adsabs.harvard.edu/abs/2023ApJ...942L..10M 942, L10

    2023 doi

  25. [33]

    O., Lindfors E., Berdyugin A., Ciprini S., Pforr J., 2007, @doi [ ] 10.1051/0004-6361:20077624 , https://ui.adsabs.harvard.edu/abs/2007A&A...475..199N 475, 199

    Nilsson K., Pasanen M., Takalo L. O., Lindfors E., Berdyugin A., Ciprini S., Pforr J., 2007, @doi [ ] 10.1051/0004-6361:20077624 , https://ui.adsabs.harvard.edu/abs/2007A&A...475..199N 475, 199

    2007 doi

  26. [34]

    Pian E., et al., 1998, @doi [ ] 10.1086/311083 , https://ui.adsabs.harvard.edu/abs/1998ApJ...492L..17P 492, L17

    1998 doi

  27. [35]

    A., et al., 2016, @doi [Journal of Astronomical Instrumentation] 10.1142/S2251171716410063 , https://ui.adsabs.harvard.edu/abs/2016JAI.....541006P 5, 1641006

    Primiani R. A., et al., 2016, @doi [Journal of Astronomical Instrumentation] 10.1142/S2251171716410063 , https://ui.adsabs.harvard.edu/abs/2016JAI.....541006P 5, 1641006

    2016 doi

  28. [36]

    L., et al., 2011, @doi [ ] 10.1088/0067-0049/194/2/29 , https://ui.adsabs.harvard.edu/abs/2011ApJS..194...29R 194, 29

    Richards J. L., et al., 2011, @doi [ ] 10.1088/0067-0049/194/2/29 , https://ui.adsabs.harvard.edu/abs/2011ApJS..194...29R 194, 29

    2011 doi

  29. [37]

    B., Lightman A

    Rybicki G. B., Lightman A. P., 1986, Radiative Processes in Astrophysics

    1986

  30. [38]

    J., Teuben P

    Sault R. J., Teuben P. J., Wright M. C. H., 1995, in Shaw R. A., Payne H. E., Hayes J. J. E., eds, Astronomical Society of the Pacific Conference Series Vol. 77, Astronomical Data Analysis Software and Systems IV. p. 433 ( @eprint arXiv astro-ph/0612759 )

    1995 arXiv

  31. [39]

    Sol H., Zech A., 2022, @doi [Galaxies] 10.3390/galaxies10060105 , https://ui.adsabs.harvard.edu/abs/2022Galax..10..105S 10, 105

    2022 doi

  32. [40]

    Tavecchio F., Landoni M., Sironi L., Coppi P., 2018, @doi [ ] 10.1093/mnras/sty1491 , https://ui.adsabs.harvard.edu/abs/2018MNRAS.480.2872T 480, 2872

    2018 doi

  33. [41]

    Ter\"asranta H., et al., 1998, @doi [ ] 10.1051/aas:1998297 , https://ui.adsabs.harvard.edu/abs/1998A&AS..132..305T 132, 305

    1998 doi

  34. [42]

    Thum C., Wiesemeyer H., Paubert G., Navarro S., Morris D., 2008, @doi [ ] 10.1086/590190 , https://ui.adsabs.harvard.edu/abs/2008PASP..120..777T 120, 777

    2008 doi

  35. [43]

    N., Casadio C., G \'o mez J

    Thum C., Agudo I., Molina S. N., Casadio C., G \'o mez J. L., Morris D., Ramakrishnan V., Sievers A., 2018, @doi [ ] 10.1093/mnras/stx2436 , https://ui.adsabs.harvard.edu/abs/2018MNRAS.473.2506T 473, 2506

    2018 doi

  36. [44]

    A., Ferland G

    Verner D. A., Ferland G. J., Korista K. T., Yakovlev D. G., 1996, @doi [ ] 10.1086/177435 , https://ui.adsabs.harvard.edu/abs/1996ApJ...465..487V 465, 487

    1996 doi

  37. [45]

    R., et al., 2022, @doi [ ] 10.3847/1538-4365/ac589c , https://ui.adsabs.harvard.edu/abs/2022ApJS..260...12W 260, 12

    Weaver Z. R., et al., 2022, @doi [ ] 10.3847/1538-4365/ac589c , https://ui.adsabs.harvard.edu/abs/2022ApJS..260...12W 260, 12

    2022 doi

  38. [46]

    C., et al., 2022, @doi [Journal of Astronomical Telescopes, Instruments, and Systems] 10.1117/1.JATIS.8.2.026002 , https://ui.adsabs.harvard.edu/abs/2022JATIS...8b6002W 8, 026002

    Weisskopf M. C., et al., 2022, @doi [Journal of Astronomical Telescopes, Instruments, and Systems] 10.1117/1.JATIS.8.2.026002 , https://ui.adsabs.harvard.edu/abs/2022JATIS...8b6002W 8, 026002

    2022 doi

  39. [47]

    Wilms J., Allen A., McCray R., 2000, @doi [ ] 10.1086/317016 , https://ui.adsabs.harvard.edu/abs/2000ApJ...542..914W 542, 914

    2000 doi

  40. [48]

    L., 2022, @doi [PTEP] 10.1093/ptep/ptac097 , 2022, 083C01

    Workman R. L., 2022, @doi [PTEP] 10.1093/ptep/ptac097 , 2022, 083C01

    2022 doi

  41. [49]

    Zhang H., Li X., Giannios D., Guo F., 2021, @doi [The Astrophysical Journal] 10.3847/1538-4357/abf2be , 912, 129

    2021 doi

  42. [50]

    write newline

    " write newline "" before.all 'output.state := FUNCTION fin.entry write newline FUNCTION new.block output.state before.all = 'skip after.block 'output.state := if FUNCTION new.sentence output.state after.block = 'skip output.state before.all = 'skip after.sentence 'output.stat...

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.