J/A+A/700/L12 High energy multimessenger blazar PKS 1424+240 (Kovalev+ 2025)
Looking into the jet cone of the neutrino-associated very high energy blazar
PKS 1424+240.
Kovalev Y.Y., Pushkarev A.B., Gomez J.L., Homan D.C., Lister M.L.,
Livingston J.D., Pashchenko I.N., Plavin A.V., Savolainen T., Troitsky S.V.
<Astron. Astrophys. 700, L12 (2025)>
=2025A&A...700L..12K 2025A&A...700L..12K (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, radio ; Radio continuum ; VLBI
Keywords: neutrinos - galaxies: active -
BL Lacertae objects: individual: PKS 1424+240 - galaxies: jets -
radio continuum: galaxies
Abstract:
The acceleration process of massive particles as well as the
production of very high-energy (VHE) photons and neutrinos remains a
fundamental challenge in astrophysics. We investigate the parsec-scale
jet structure and magnetic field of the blazar PKS 1424+240, which was
selected on the basis of strong VHE gamma-ray emission and is
identified with one of the highest peaks in the IceCube 9-year
neutrino sky. We analyzed 15GHz VLBA observations of this BL Lac
object by stacking 42 polarization-sensitive images collected in
2009-2025 to enhance the signal and reveal the persistent parsec-scale
structure. Our observations uncover a rare scenario. The object is
viewed inside the jet cone, very close to the axis of its relativistic
jet, with a viewing angle of <0.6deg. This effectively maximizes
Doppler boosting to values ∼30 and enhances the electromagnetic and
neutrino emission in the direction of the observer. Based on
polarimetric observations, we unambiguously detect a net toroidal
component in the magnetic field of the jet. This indicates a
current-carrying jet that flows almost directly toward our line of
sight. Blazars with very small jet viewing angles offer a solution to
the Doppler factor crisis, i.e., to the longstanding mismatch between
Doppler factors inferred from the low apparent jet speed in very
long-baseline interferometry and those derived from VHE observations.
We show that relativistic beaming plays the critical role in the
gamma-ray and neutrino emission of blazars. This has direct
implications for models of their multimessenger emission.
Description:
Files 1424+240.u.stacked.icn.fits, 1424+240.u.stacked.qcn.fits,
1424+240.u.stacked.ucn.fits are FITS files presenting stacked images
for the blazar PKS 1424+240 in Stokes I, Q, and U, respectively. The
images are produced from 42 single-epoch polarization 15GHz VLBA
observations within the MOJAVE program, covering 2009-2025. They are
reconstructed with the same circular beam of the FWHM size of 0.8mas.
The images are aligned before stacking on their modeled core position.
Objects:
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RA (2000) DE Designation(s)
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14 27 00.39 +23 48 00.0 PKS 1424+240 = SDSS J142700.39+234800.0
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 147 4 List of fits images
fits/* . 4 Individual fits images
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See also:
J/ApJS/234/12 : MOJAVE XV. VLBA obs. of AGN jets 1996-2016 (Lister+, 2018)
J/MNRAS/520/6053 : MOJAVE XX. Linear polarization in AGN (Pushkarev+, 2023)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 39 A10 --- Obs.date Observation date
41- 48 F8.5 GHz Freq Observed frequency
50- 53 I4 Kibyte size Size of FITS file
55- 65 A11 --- FileName Name of FITS file, in subdirectory fits
67-147 A81 --- Title Title of the FITS file
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Acknowledgements:
Yuri Kovalev, yykovalev(at)gmail.com
References:
Lister et al. MOJAVE XV 2018ApJS..234...12L 2018ApJS..234...12L, Cat. J/ApJS/234/12
Pushkarev et al. MOJAVE XX 2023MNRAS.520.6053P 2023MNRAS.520.6053P, Cat. J/MNRAS/520/6053
Plavin et al. Blazar beaming arXiv:2503.08667
(End) Yuri Kovalev [MPIfR, Germany], Patricia Vannier [CDS] 21-Jul-2025