Exploring the Origin of Multiwavelength Activities of High-redshift Flat-spectrum Radio Quasar PKS 1502+106 during 2014–2018

Ding, Nan; Gu, Qiusheng; Geng, Xiongfei; Xiong, Dingrong; Xue, Rui; Wang, Xiang-Yu; Guo, Xiaotong

doi:10.3847/1538-4357/ab2f7e

Cited by 18 publications

(19 citation statements)

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“…Since then, PKS 1502+106 has been extensively studied across the electromagnetic spectrum (cf. Pian et al 2011;Karamanavis et al 2016;Paliya et al 2017;Ding et al 2019;Shao et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength and Neutrino Emission from Blazar PKS 1502 + 106

Rodrigues

Garrappa

Gao

et al. 2021

ApJ

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In July of 2019, the IceCube experiment detected a high-energy neutrino from the direction of the powerful blazar PKS 1502+106. We perform multi-wavelength and multi-messenger modeling of this source, using a fully self-consistent one-zone model that includes the contribution of external radiation fields typical of flat-spectrum radio quasars (FSRQs). We identify three different activity states of the blazar: the quiescent state, and two distinct flaring states with hard and soft gamma-ray spectra. We find two hadronic models that can both describe the multi-wavelength emission during all three states: a leptohadronic model with a contribution from photo-hadronic processes to X-rays and high-energy gamma rays, and a proton synchrotron model, where the emission from keV to 10 GeV comes from proton synchrotron radiation. Both models predict a substantial neutrino flux that is correlated with the gamma-ray and soft X-ray fluxes. Our results are compatible with the detection of a neutrino during the quiescent state, based on event rate statistics. Upon an extensive parameter scan, we conclude that the soft X-ray spectra observed during bright gamma-ray flares strongly suggest a hadronic contribution, which can be interpreted as additional evidence for cosmic ray acceleration in the source independently of neutrino observations. We find that more arguments can be made in favor of the leptohadronic model vis-a-vis the proton synchrotron scenario, such as a lower energetic demand during the quiescent state, and the fact that the same model has also been shown to describe the observation of neutrinos from blazar TXS 0506+056. The leptohadronic model would be disfavored for flaring states of PKS 1502+106 if no IceCube events were found from the direction of the source before 2010, which would require an archival search.

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“…Since then, PKS 1502+106 has been extensively studied across the electromagnetic spectrum (cf. Pian et al 2011;Karamanavis et al 2016;Paliya et al 2017;Ding et al 2019;Shao et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength and Neutrino Emission from Blazar PKS 1502 + 106

Rodrigues

Garrappa

Gao

et al. 2021

ApJ

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“…γ-ray outbursts, accompanied by variability of the γ-ray spectral index, have been reported in many previous studies (Rani et al 2013bKim, D. et al 2018;Ding et al 2019). The usual combination is an increase of γ-ray flux density and hardening of photon indices.…”

Section: γ-Ray Spectramentioning

confidence: 69%

“…When a moving blob with high kinetic energy starts interacting with the standing RCS localized in the region where the magnetic field becomes unstable, there could be (1) an enhancement of non-thermal emission, (2) a strong instability of the magnetic field configuration (e.g., tearing instability; Del Zanna et al 2016), and (3) a positional displacement by the underlying flow with increasing kinetic power of the jet (Hervet et al 2016). This scenario also predicts some fast γ-ray emission induced by magnetic reconnection, though the observed photon indices around MJD 57405 in Figure 2 appear too soft (Ding et al 2019). A more conventional interpretation for the S 2 motions would be an opacity effect (e.g., Lobanov 1998); variations in opacity can occur when flaring components pass through these regions (e.g., Plavin et al 2019), resulting in an apparent spatial drift.…”

Section: Positional Variations Of the Stationary Componentsmentioning

confidence: 92%

Investigating the connection between γ-ray activity and the relativistic jet in 3C 273 during 2015−2019

Kim

Trippe

Kravchenko

2020

A&A

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Context. Due to its powerful radiation over the entire electromagnetic spectrum and its radio jet activity, the blazar 3C 273 offers the opportunity to study the physics of γ-ray emission from active galactic nuclei. Since a historically strong outburst in 2009, 3C 273 showed relatively weak emission in the γ-ray band over multiple years. However, recent Fermi-Large Area Telescope observations indicate elevated activity during 2015-2019. Aims. We aim at constraining the origin of the γ-ray outbursts towards 3C 273 and investigate their connection to the parsec-scale jet. Methods. We generate Fermi-LAT γ-ray light curves with multiple binning intervals and study the spectral properties of the γ-ray emission. Using a 3 mm ALMA light curve, we study the correlation between radio and γ-ray emission. Relevant activity in the parsec-scale jet of 3C 273 is investigated with 7 mm VLBA observations obtained close in time to notable γ-ray outbursts. Results. We find two prominent γ-ray outbursts in 2016 (MJD 57382) and 2017 (MJD 57883) accompanied by mm-wavelength flaring activity. The γ-ray photon index time series show a weak hump-like feature around the γ-ray outbursts. The monthly γ-ray flux-index plot indicates a transition from softer-when-brighter to harder-when-brighter at 1.03 × 10 −7 ph cm −2 s −1 . A significant correlation between the γ-ray and mm-wavelength emission is found, with the radio lagging the γ-rays by about 105-112 days. The 43 GHz jet images reveal the known stationary features (i.e., the core, S 1, and S 2) in a region upstream of the jet. We find indication for a propagating disturbance and a polarized knot between the stationary components around the times of both γ-ray outbursts. Conclusions. Our results support a parsec-scale origin for the observed γ-ray elevated activity, suggesting association with standing shocks in the jet.

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“…For comparison, the time averaged data from CTA 102 observations are shown in light gray, which highlights the changes observed in different energy bands. A deviation from the power-law model has been observed in the spectra of several blazars (e.g., Abdo et al 2009Abdo et al , 2010bHarris et al 2012;Kohler & Nalewajko 2015;Rani et al 2013b;Paliya 2015;Paliya et al 2015;Ding et al 2019). The internal or external attenuation cannot be responsible for the observed steepening as demonstrated in Section 3.…”

Section: Origin Of Multiwavelength Emissionmentioning

confidence: 96%

Investigation of the γ-ray spectrum of CTA 102 during the exceptional flaring state in 2016–2017

Sahakyan

2020

A&A

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The flat spectrum radio quasar CTA 102 entered an extended period of activity from 2016 to 2017 during which several strong γ-ray flares were observed. Using Fermi large area telescope data a detailed investigation of γ-ray spectra of CTA 102 during the flaring period is performed. In several periods the γ-ray spectrum is not consistent with a simple power-law, having a hard photon index with an index of ∼ (1.8 − 2.0) that shows a spectral cutoff around an observed photon energy of ∼ (9 − 16) GeV. The internal γ-ray absorption via photon-photon pair production on the broad-line-region-reflected photons cannot account for the observed cutoff/break even if the emitting region is very close to the central source. This cut-off/break is likely due to a similar intrinsic break in the energy distribution of emitting particles. The origin of the spectral break is investigated through the multiwavelength modeling of the spectral energy distribution, considering a different location for the emitting region. The observed X-ray and γ-ray data is modeled as inverse Compton scattering of synchrotron and/or external photons on the electron population that produce the radio-to-optical emission which allowed to constrain the power-law index and cut-off energy in the electron energy distribution. The obtained results are discussed in the context of a diffusive acceleration of electrons in the CTA 102 jet.

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Exploring the Origin of Multiwavelength Activities of High-redshift Flat-spectrum Radio Quasar PKS 1502+106 during 2014–2018

Cited by 18 publications

References 100 publications

Multiwavelength and Neutrino Emission from Blazar PKS 1502 + 106

Multiwavelength and Neutrino Emission from Blazar PKS 1502 + 106

Investigating the connection between γ-ray activity and the relativistic jet in 3C 273 during 2015−2019

Investigation of the γ-ray spectrum of CTA 102 during the exceptional flaring state in 2016–2017

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