The broad-band spectral energy distribution of candidate neutrino blazars
subject: (galaxies:)BL Lacertae objects: individual: TXS 0506+056; galaxies: active; galaxies: jets; gamma-rays: general
description: Blazars, the jet-dominated class of active galactic nuclei comprising flat-spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs), are now increasingly identified as potential sources of high-energy neutrinos. Such neutrino blazars are ideal targets to investigate the high-energy emission processes and to understand their role as neutrino sources. We report results on four candidate neutrino blazars, PKS 0446+112, TXS 0506+056, PKS 1424(Formula presented) 418, and PKS 1502+106. We carried out (Formula presented) -ray spectral and timing analysis on three time periods that comprise a quiescent epoch, an epoch that corresponds to neutrino detection, and a flaring epoch. We also carried out modelling of the broad-band spectral energy distribution (SED) on those three epochs. We found that the (Formula presented) -ray spectra of the BL Lac TXS 0506+056 can be adequately described by a power law, while the spectra of the other three FSRQs require a log-parabola model. On shorter time-scales, we observed flux variability with doubling/halving time-scales of 4.70, 9.24, 30.76, and 15.42 h for PKS 0446+112, TXS 0506+056, PKS 1424(Formula presented) 418, and PKS 1502+106, respectively. The SEDs of most of the epochs for the sources are well explained by a leptonic scenario. However, the quiescent epoch of PKS 1502+106 and the neutrino-emission epoch of PKS 0446+112 required an additional hadronic component to reproduce the observed SEDs. Our analysis reveals a complex interplay of leptonic and hadronic processes. While certain neutrino-associated epochs align with a leptonic model, others necessitate a hadronic component to explain the emission features. The Author(s) 2026. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in…
creator: Bharathan, Athira M; Stalin, C.S.; Btcher, Markus; Sahayanathan, S.; Mathew, Blesson; Bhattacharyya, Subir
source: Monthly Notices of the Royal Astronomical Society;Volume;548;Issue;2;Article No.;stag674;
publisher: Oxford University Press
date: 01-01-2026
rights: All Open Access; Gold Open Access
relation: ISSN: 358711; CODEN: MNRAA
format: online
language: English
type: Article
coverage: Bharathan A.M., Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India, Centre for Space Research, North-West University, Potchefstroom, 2531, South Africa; Stalin C.S., Indian Institute of Astrophysics, Block II, Koramangala, Bangalore, 560 034, India; Btcher M., Centre for Space Research, North-West University, Potchefstroom, 2531, South Africa; Sahayanathan S., Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India, Homi Bhabha National Institute, Mumbai, 400094, India; Mathew B., Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, 560029, India; Bhattacharyya S., Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India, Homi Bhabha National Institute, Mumbai, 400094, India