Patterns in the Multiwavelength Behavior of Candidate Neutrino Blazars

Franckowiak, A.; Garrappa, S.; Paliya, Vaidehi S.; Shappee, B. J.; Stein, R.; Strotjohann, N. L.; Kowalski, M.; Buson, S.; Kiehlmann, S.; Max-Moerbeck, W.; Angioni, R.

doi:10.3847/1538-4357/ab8307

Cited by 77 publications

(100 citation statements)

References 82 publications

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“…For example, δ γ = 11.40 for PKS B1424 − 418, that is. 4FGL J1427.9 − 4206, which was in coincidence with the arrival time of a PeV neutrino (Kadler et al 2016;Franckowiak et al 2020); δ γ = 3.67 for a distant BL Lac object MG3 J225517 + 2409, that is, 4FGL J2255.2 + 2411 with a redshift of 1.37 (Franckowiak et al 2020;Abdollahi et al 2020); δ γ = 6.48 for FSRQ S4 1716 + 68, that is, 4FGL J1716.1 + 6836, which the duration of the neutrino flare is short (Franckowiak et al 2020); δ γ = 6.71 for OJ 508, that is, 4FGL J1022.7 − 0112 with statistically significant potential for neutrino emission (Smith, Hooper, & Vieregg 2020); δ γ = 5.19 for HSP PMNJ0953 − 0840, that is, 4FGL J0953.0 − 0840 (Righi et al 2019). Therefore, from our comparison, it reaches to an interesting finding that the lower limit on γ-ray Doppler factor for these neutrino emitter candidates are relatively quite high, suggesting that these sources are also possibly strongly Doppler-boosted.…”

Section: More Implicationsmentioning

confidence: 74%

“…Another neutrino event IceCube-190730A was reported to be in spatial coincidence with the bright γ-ray FSRQ PKS 1502 + 106, that is, 4FGL J1504.4 + 1029, and the neutrino was reported with a signalness of 67% and an energy of 300 TeV (IceCube Collaboration et al 2018a;Franckowiak et al 2020). This source is also included in our present sample and δ γ = 13.41, which is much higher than the average value for our subsample of FSRQs.…”

Section: More Implicationsmentioning

confidence: 99%

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The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Pei

Jiang

Yang

et al. 2020

Publ. Astron. Soc. Aust.

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Blazars are a subclass of active galactic nuclei with extreme observation properties, which is caused by the beaming effect, expressed by a Doppler factor ( $\delta$ ), in a relativistic jet. Doppler factor is an important parameter in the blazars paradigm to indicate all of the observation properties, and many methods were proposed to estimate its value. In this paper, we present a method following Mattox et al. to calculate the lower limit on $\gamma$ -ray Doppler factor ( $\delta_{\gamma}$ ) for 809 selected Fermi/LAT-detected $\gamma$ -ray blazars by adopting the available $\gamma$ -ray and X-ray data. Our sample included 342 flat-spectrum radio quasars (FSRQs) and 467 BL Lac objects (BL Lacs), out of which 507 sources are compiled with available radio core-dominance parameter (R) from our previous study. Our calculation shows that the average values of the lower limit on $\delta_{\gamma}$ for FSRQs and BL Lacs are $\left\langle\delta_{\gamma}|_{\textrm{FSRQ}}\right\rangle = 6.87 \pm 4.07$ and $\left\langle\delta_{\gamma}|_{\textrm{BL\ Lac}}\right\rangle=4.31 \pm 2.97$ , respectively. We compare and discuss our results with those from the literature. We found that the derived lower limit on $\delta_{\gamma}$ for some sources is higher than that from the radio estimation, which could be possibly explained by the jet bending within those blazars. Our results also suggest that the $\gamma$ -ray and radio regions perhaps share the same relativistic effects. The $\gamma$ -ray Doppler factor has been found to be correlated with both the $\gamma$ -ray luminosity and core-dominance parameter, implying that the jet is possibly continuous in the $\gamma$ -ray bands, and R is perhaps an indicator for a beaming effect.

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Section: More Implicationsmentioning

confidence: 74%

Section: More Implicationsmentioning

confidence: 99%

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Pei

Jiang

Yang

et al. 2020

Publ. Astron. Soc. Aust.

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“…Abdo et al 2010). While the source did not show an excess in gamma rays during the arrival of IceCube-190730A, the radio flux shows a long-term outburst starting in 2014 and reaching the highest flux density ever reported from this source during the arrival of IC-190730A (Kiehlmann et al 2019;Franckowiak et al 2020), which may indicate a long-term activity of the central engine. IceCube-190730 has an estimated neutrino energy of 300 TeV and a 67% signalness 1 based on the procedure by Blaufuss et al (2020).…”

Section: Introductionmentioning

confidence: 80%

“…Other possible neutrino blazar associations at lower significance have been pointed out by e.g. Franckowiak et al (2020); Giommi et al (2020); Garrappa et al (2019); Krauß et al (2018); Kadler et al (2016). Of particular interest is the spatial coincidence of IceCube-190730A with PKS 1502+106, which is the 15th brightest gamma-ray source at > 100 MeV in terms of energy flux among 2863 sources in the fourth catalog of AGN detected by Fermi -LAT (4LAC, Ajello et al 2019).…”

Section: Introductionmentioning

confidence: 92%

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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“…Krauß et al (2018) studied the γ-ray fluxes of all sources coincident with IceCube neutrino events at E> 100 TeV, and found no direct correlation between the γ-ray flux and expected neutrino flux. Franckowiak et al (2020) also studied γ-ray detected A&A proofs: manuscript no. main (a) This source was added to OVRO monitoring only in December 2011 after its inclusion in the 2LAC catalog, which is why there is no activity index available for it around the neutrino event in October 2010.…”

Section: Number Of Associated Sourcesmentioning

confidence: 99%

Association of IceCube neutrinos with radio sources observed at Owens Valley and Metsähovi Radio Observatories

Hovatta

Lindfors

Kiehlmann

et al. 2021

A&A

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Context. Identifying the most likely sources for high-energy neutrino emission has been one of the main topics in high-energy astrophysics ever since the first observation of high-energy neutrinos by the IceCube Neutrino Observatory. Active galactic nuclei with relativistic jets, blazars, have been considered to be one of the main candidates due to their ability to accelerate particles to high energies.Aims. We study the connection between radio emission and IceCube neutrino events using data from the Owens Valley Radio Observatory and Metsähovi Radio Observatory blazar monitoring programs. Methods. We identify sources in our radio monitoring sample, which are positionally consistent with IceCube high-energy neutrino events. We estimate their mean flux density and variability amplitudes around the neutrino arrival time, and compare these with values from random samples to establish the significance of our results. Results. We find radio source associations within our samples with 16 high-energy neutrino events detected by IceCube. Nearly half of the associated sources are not detected in the γ-ray energies, but their radio variability properties and Doppler boosting factors are similar to the γ-ray detected objects in our sample so that they could still be potential neutrino emitters. We find that the number of strongly flaring objects in our samples is unlikely to occur due to a random coincidence (at 2σ level), and in the case of OVRO samples, the sample of associated sources is on average at an active state compared to random samples. Conclusions. Based on our results we conclude that although it is clear that not all neutrino events are associated with strong radio flaring blazars, when we see large amplitude radio flares in a blazar at the same time as a neutrino event, it is unlikely to happen by random coincidence.

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Patterns in the Multiwavelength Behavior of Candidate Neutrino Blazars

Cited by 77 publications

References 82 publications

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

The estimation of γ-ray Doppler factor forFermi/LAT-detected blazars

Multiwavelength and Neutrino Emission from Blazar PKS 1502 + 106

Association of IceCube neutrinos with radio sources observed at Owens Valley and Metsähovi Radio Observatories

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