Gamma-ray Activity Research Articles

Fermi-LAT follow-up observations in seven years of real-time high-energy neutrino alerts

The realtime program for high-energy neutrino track events detected by the IceCube South Pole Neutrino Observatory releases alerts to the astronomical community with the goal of identifying electromagnetic counterparts to astrophysical neutrinos. Gamma-ray observations from theFermi-Large Area Telescope (LAT) enabled the identification of the flaring gamma-ray blazar TXS 0506+056 as a likely counterpart to the neutrino event IC-170922A. By continuously monitoring the gamma-ray sky,Fermi-LAT plays a key role in the identification of candidate counterparts to realtime neutrino alerts. In this paper, we present theFermi-LAT strategy for following up high-energy neutrino alerts applied to seven years of IceCube data. Right after receiving an alert, a search is performed in order to identify gamma-ray activity from known and newly detected sources that are positionally consistent with the neutrino localization. In this work, we study the population of blazars found in coincidence with high-energy neutrinos and compare them to the full population of gamma-ray blazars detected byFermi-LAT. We also evaluate the relationship between the neutrino and gamma-ray luminosities, finding different trends between the two blazar classes BL Lacs and flat-spectrum radio quasars.

Curvature in the very-high energy gamma-ray spectrum of M 87

The radio galaxy M 87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares, which were reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is not yet fully understood. In this study, we investigate the VHE gamma-ray spectrum of M 87 during states of high gamma-ray activity, utilizing 20.2 h of H.E.S.S. observations. Our findings indicate a preference for a curved spectrum, characterized by a log-parabola model with extra-galactic background light (EBL) model above 0.3 TeV at the 4σ level, compared to a power-law spectrum with EBL. We investigate the degeneracy between the absorption feature and the EBL normalization and derive upper limits on EBL models that are mainly sensitive in the wavelength range of 12.4 μm–40 μm.

Up around the bend: A multiwavelength view of the quasar 3C 345

Context. The flat-spectrum radio quasar 3C 345 has been showing γ-ray activity since the mid-2000s, along with activity across the electromagnetic spectrum. A γ-ray burst in 2009 was successfully linked to relativistic outflow in 43 GHz very long baseline interferometry (VLBI) observations and has since also been analyzed using single-dish measurements. A multiwavelength follow-up VLBI observation of the 2009 flare in conjunction with 43 GHz catalog data from the VLBA-BU-BLAZAR and BEAM-ME programs are analyzed in this study in the context of the long-term evolution of the source. Aims. We aim to probe the innermost few milliarcseconds of the ultracompact 3C 345 jet. To do so, we analyzed the long-term kinematics of the inner jet and discuss the magnetic field morphology at different scales, as well as the origin of the γ-ray emission. Methods. New observations at 23, 43, and 86 GHz were carried out at ten epochs between 2017 and 2019. We calibrated the 30 datasets using the rPicard pipeline, imaged them in Difmap, and carried out polarization calibration using the GPCAL pipeline. We complemented our VLBI data by 43 GHz observations carried out in the framework of the BEAM-ME and VLBA-BU-BLAZAR monitoring programs. Results. We find multiple distinct component paths in the inner jet, which together have a helical geometry. The helix appears to be anchored at a stationary feature some 0.16 mas from the 43 GHz VLBI core and has an evolution timescale of about 8 yr. The characteristic bends in the jet morphology are caused by variations in the component ejection angle. We confirm the result of previous studies: the γ-ray emission is caused by relativistic outflow and violent interactions within the jet.

Evaluation of Gamma-Ray Dose Distribution in the Toroidal Direction of LHD Vacuum Vessel from Radionuclides Generated in Deuterium Plasma Experiments

The evaluation of activities from radionuclides inside a vacuum vessel is required for the safe maintenance and estimation of the activation level of fusion devices. The Large Helical Device (LHD), Toki, Japan, has been performing deuterium plasma experiments since 2017, and radionuclides have accumulated in components such as vacuum vessels. In this work, the gamma-ray spectrum and activity of each detected radionuclide in an LHD vacuum vessel were evaluated using portable high-purity germanium (P-HPGe) and numerical calculations of photon transport for comparison with the removed armor tiles to evaluate the occupational exposure in the maintenance of LHD experiments. Measurements using the P-HPGe detector were performed at 20 positions along the toroidal direction of the LHD, at each O port, and between each pair of adjacent O ports. Using the estimated efficiency of the photoelectronic effects inside the P-HPGe detector calculated by Monte Carlo N-particle code version 6.1, the activities of the radionuclides in the armor tiles attached to the vacuum vessel were evaluated. The estimated activity concentrations were compared with the measured activities of the armor tiles removed from the vacuum vessel. Gamma rays from 58Co, 54Mn, and 60Co were detected, and the measured activities of 58Co and 54Mn generated by fast neutrons in the armor tile were almost consistent with those obtained from the removed armor tiles. The radioactivity of 60Co in the armor tile was underestimated compared with the activity obtained from the removed armor tiles. The measurement of activation by fast neutrons is feasible, whereas activation by thermal neutrons requires more accurate calculations and surveys to be measured using this method.

Searching for temporary gamma-ray dark blazars associated with IceCube neutrinos

Context. Tensions between the diffuse gamma-ray sky observed by the Fermi Large Area Telescope (Fermi-LAT) and the diffuse, high-energy neutrino sky detected by the IceCube South Pole Neutrino Observatory raise questions about our knowledge of high-energy neutrino sources in the gamma-ray regime. While blazars are among the most energetic persistent particle accelerators in the Universe, studies suggest that they could account for up to 10–30% of the neutrino flux measured by IceCube. Aims. Our recent results highlight that the associated IceCube neutrinos arrived in a local gamma-ray minimum (dip) of three strong neutrino point-source candidates. Here, we increase the sample of neutrino-source candidates in order to study their gamma-ray light curves. Methods. We generated the one-year Fermi-LAT light curve for eight neutrino-source candidate blazars (RBS 0958, GB6 J1040+0617, PKS 1313-333, TXS 0506+056, PKS 1454-354, NVSS J042025-374443, PKS 0426-380, and PKS 1502+106), centered on the detection time of the associated IceCube neutrinos. We applied the Bayesian block algorithm to the light curves to characterize their variability. Results. Our results indicate that GB6 J1040+0617 was in a phase of high gamma-ray activity, while none of the other seven neutrino-source candidates were statistically bright during the detection of the corresponding neutrinos; indeed, most of the time neutrinos arrived in a faint gamma-ray phase of the light curves. This suggests either that the eight source candidate blazars (associated with seven neutrino events) in our reduced sample are not the sources of the corresponding IceCube neutrinos, or that an in-source effect (e.g., the suppression of gamma rays due to high gamma-gamma opacity) complicates the multimessenger scenario of neutrino emission for these blazars.

Measurement of dosimetrical cross sections with 14.05 MeV neutrons from compact neutron generator

This paper deals with the measurement of the differential dosimetry cross sections using a small compact D-T neutron generator with 14.05 ± 0.08 MeV neutron emission (1 × 108 n/s into 4π). In spite of low neutron flux, it is possible to get measurable gamma-ray activities by irradiating a larger amount of target material placed in close geometry. The experimentally determined cross sections are in good agreement with the cross sections in the IRDFF-II dosimetry library. The comparison with other nuclear data libraries was performed as well. It is worth noting that the mean standard deviation in IRDFF-II library is about 4 %, while in the case of other data libraries they are from 5.5 % to 7.5 %. This result can be understood as a validation of IRDFF-II using 14.05 MeV neutrons and also a confirmation of the applicability of small compact generators in the measurement of activation cross sections.

Multiwavelength Analysis of the IceCube Neutrino Source Candidate Blazar PKS 1424+240

The true nature of sources of cosmic neutrinos recorded by the Antarctic IceCube Neutrino Detector is still an enigma of high-energy astrophysics. Time-integrated neutrino source searches with the 10 years of IceCube data unfolded neutrino hot-spots of the sky; among them, one is associated with the blazar PKS 1424+240, which is the third most significant neutrino source candidate in the Northern sky. In this paper, we analyze VLBI radio data of PKS 1424+240 taken with the Very Large Baseline Array at 15 GHz as part of the MOJAVE Survey. We generate the adaptively binned gamma-ray light curve of the source, employing Fermi-LAT data between 100 MeV and 300 GeV. We find that the VLBI jet components maintain quasi-stationary core separations at 15 GHz. We find a quiescence and a perturbed phase of the VLBI core of PKS 1424+240, based on that its Doppler factor increased tenfold after 2016 compared to the quiescence phase. We do not find elevated gamma-ray activity after 2016, while archive Swift-XRT measurements show a highly increased 0.3–10 keV X-ray flux in the beginning of 2017. Substantial increase of the activity of the radio core might help us to identify episodes of particle acceleration in lepto-hadronic blazar jets that eventually lead to the emission of high-energy neutrinos.

Measurement of excitation functions for nat Cu(α, x) reactions with detailed covariance analysis

The excitation functions of 66Ga, 67Ga, 65Zn and 64Cu radioisotopes produced via alpha-induced reaction on nat Cu were measured using a stacked foil activation method. The gamma-ray activity produced by the above mentioned radionuclides was measured using the HPGe detector. The covariance analysis was performed to quantify the measured cross-section uncertainties as well as the correlation between different alpha energy cross-sections. A covariance matrix and cross-sections for the nat Cu(α, x)66Ga, nat Cu(α, x)67Ga, nat Cu(α, x)65Zn and nat Cu(α, x)64Cu nuclear reactions in the projectile energy range of 15–37 MeV are reported in the present work. The measured reaction cross-sections are compared with the existing experimental data and theoretically simulated results from the TALYS code.

Reconstruction of gamma-ray source activity in a multiple samples set-up

When numerous radioactive samples irradiated simultaneously have to be measured using a single photon detector, the resulting energy spectrum comprises not only the yield from the source closest to the detector but also from all other sources. This case is particularly important when the sources are placed in a set-up exchanging them in an automated manner. In order to obtain relevant data for each source, correction procedures were developed and tested via Monte-Carlo simulations and with radioactive sources, in a set-up with up to 16 samples placed on a rotating wheel. In a test experiment, the cross-section of 12C(p, X)11C (X=d or pn) was determined using a stack of 15 carbon targets irradiated with a proton beam of initial 58 MeV kinetic energy. The 11C activity of simultaneously irradiated targets was measured (through 511 keV photons) and reconstructed using the developed correction procedures. The results of cross-section measurements are in agreement with the previous experiments, supporting the correctness of the reconstruction procedure.

MOMO – V. Effelsberg, Swift, and Fermi study of the blazar and supermassive binary black hole candidate OJ 287 in a period of high activity

ABSTRACT We report results from our ongoing project MOMO (Multiwavelength Observations and Modelling of OJ 287). In this latest publication of a sequence, we combine our Swift UVOT–XRT and Effelsberg radio data (2.6–44 GHz) between 2019 and 2022.04 with public SMA data and gamma-ray data from the Fermi satellite. The observational epoch covers OJ 287 in a high state of activity from radio to X-rays. The epoch also covers two major events predicted by the binary supermassive black hole (SMBH) model of OJ 287. Spectral and timing analyses clearly establish: a new UV–optical minimum state in 2021 December at an epoch where the secondary SMBH is predicted to cross the disc surrounding the primary SMBH; an overall low level of gamma-ray activity in comparison to pre-2017 epochs; the presence of a remarkable, long-lasting UV–optical flare event of intermediate amplitude in 2020–2021; a high level of activity in the radio band with multiple flares; and particularly a bright, ongoing radio flare peaking in 2021 November that may be associated with a gamma-ray flare, the strongest in 6 yr. Several explanations for the UV–optical minimum state are explored, including the possibility that a secondary SMBH launches a temporary jet, but the observations are best explained by variability associated with the main jet.

Post-Neutron Mass Yield Distribution in the Thermal Neutron Induced–Fission of 239Pu

Mass chain yield distribution has been done in the thermal neutron–induced fission of 239Pu by measuring the cumulative yields of various fission products within the mass range of 78 to 159 and the independent yields of a few products. An off-line gamma-ray spectrometric technique was used to measure the gamma-ray activities of the fission products. From the measured values of the cumulative yields, the post-neutron mass chain yield distribution was obtained after applying the charge distribution correction. Data from the present and earlier work of our laboratory in the 239Pu(nth,f) reaction were compared with similar data of 238,241Pu(nth,f) and 240Pu(n,f) reactions, and it was found that the fine structures of the mass yield distributions are similar. The mass yield distribution in the 239Pu(nth,f) reaction was also compared with those of 229Th(nth,f) and 252Cf(SF) reactions to examine the effect of charge and mass difference of the fissioning systems on the mass yield distribution. It was found that the asymmetric standard I mode of fission is favorable in the 238,239,241Pu(nth,f) and 240Pu(n,f) reactions whereas the standard II mode is favorable in the 229Th(nth,f) and 252Cf(SF) reactions.

Waiting times between gamma-ray flares of flat spectrum radio quasars, and constraints on emission processes

Context.The physical scenario responsible for gamma-ray flaring activity and its location for flat spectrum radio quasars is still debated.Aims.The study of the statistical distribution of waiting times between flares, defined as the time intervals between consecutive activity peaks, can give information on the distribution of flaring times and constrain the physical mechanism responsible for gamma-ray emission.Methods.We adopt here a scan statistic-driven clustering method (iSRS) to recognize flaring states within theFermi-LAT archival data, and identify the time of activity peaks.Results.We obtained that waiting times between flares can be described with a Poissonian process, consisting of a set of overlapping bursts of flares, with an average burst duration of ∼0.6 year and average rate of ∼1.3 y−1. For short waiting times (below 1 d host-frame) we found a statistically relevant second population, the fast component, consisting of a few tens of cases, most of them revealed for CTA 102. Interestingly, the period of conspicuous detection of the fast component of waiting times for CTA 102 coincides with the reported crossing time of the superluminal K1 feature with the C1 stationary feature in radio.Conclusions.To reconcile the recollimation shock scenario with the bursting activity, we have to assume that plasma streams with a typical length of ∼2 pc (in the stream reference frame) reach the recollimation shock. Otherwise, the distribution of waiting times can be interpreted as originating from relativistic plasma moving along the jet for a deprojected length of ∼30−50 pc (assuming a bulk Γ = 10) that sporadically produces gamma-ray flares. In the magnetic reconnection scenario, reconnection events or plasma injection to the reconnection sites should be intermittent. Individual plasmoids can be resolved in a few favourable cases only, and could be responsible for the fast component.

Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

Aims. We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with a special focus on the multi-band flux correlations. Methods. The dataset has been collected through an extensive multi-wavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina, and Metsähovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. Results. The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance for a few days without a simultaneous increase in the X-ray flux (i.e., orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. The peak frequency of the synchrotron bump varies by two orders of magnitude throughout the campaign. Our multi-band correlation study also hints at an anti-correlation between UV-optical and X-ray at a significance higher than 3σ. A VHE flare observed on MJD 57788 (2017 February 4) shows gamma-ray variability on multi-hour timescales, with a factor ten increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors, from γ′min=2×104 to γ′max=6×105.

Half-a-century of gamma-ray astrophysics at the Max-Planck Institute for Extraterrestrial Physics

Gamma-ray astronomy has been one of the prime scientific research fields of the Max-Planck Institute for Extraterrestrial Physics (MPE) from its beginning. Over the years, the entire gamma-ray energy range accessible from space was explored. The purpose of this review article is to summarise the achievements of the gamma-ray group at MPE during the last 50+ years. This covers a substantial part of the general history of space-based gamma-ray astronomy, for which both, general review articles (e.g. Pinkau in Exp Astron 5: 157, 2009; Schönfelder in AN 323: 524, 2002; Trimble in AIP Conf Proc 304: 40, 1994) and a detailed tabular list of events and missions (Leonard and Gehrels in https://heasarc.gsfc.nasa.gov/docs/history, version 1.0.8, 2009), have been compiled. Here, we describe the gamma-ray activities at MPE from the beginning till the present, reviewing the tight interplay between new technological developments towards new instruments and scientific progress in understanding gamma-ray sources in the sky. This covers (i) the early development of instruments and their tests on half a dozen balloon flights, (ii) the involvement in the most important space missions at the time, i.e. ESA’s COS-B satellite, NASA’s Compton Gamma-ray Observatory and Fermi Space Telescope, as well as ESA’s INTEGRAL observatory, (iii) the participation in several other missions such as TD-1, Solar Maximum Mission, or Ulysses, and (iv) the complementary ground-based optical instruments OPTIMA and GROND to enhance selected science topics (pulsars, gamma-ray bursts). With the gradual running-out of institutional support since 2010, gamma-ray astrophysics as a main research field has now come to an end at MPE.

Possibilities of the use of CeBr3 scintillation detectors for the measurement of the content of radionuclides in samples for environmental monitoring

The investigation of radioactivity in samples is an application of gamma-ray spectrometry dealing with low and very low level gamma-ray activities of different isotopes. Gamma-ray spectrometry performed in the framework of radiological environmental monitoring may be done after selective sampling processes or after a chemical purification of a sample. Both cases imply that only some specific radionuclides should contribute to the obtained spectrum. Gamma-ray spectrometry performed with medium energy resolution detectors may allow the possible distinction of their photopeaks. Therefore, a cerium bromide (CeBr3) detector can be particularly attractive for routine tasks in radiological environmental monitoring as it has a high efficiency, medium energy resolution and it can work at room temperature. This study describes the conditions under which a CeBr3 detector can serve for some routine analysis in radiological analysis of samples collected in the environment or collected by air-samplers in environmental radiological monitoring programmes.

The time-dependent distribution of optical polarization angle changes in blazars

ABSTRACT At optical wavelengths, blazar Electric Vector Position Angle (EVPA) rotations linked with gamma-ray activity have been the subject of intense interest and systematic investigation for over a decade. One difficulty in the interpretation of EVPA rotations is the inherent 180° ambiguity in the measurements. It is therefore essential, when studying EVPA rotations, to ensure that the typical time-interval between successive observations – i.e. the cadence – is short enough to ensure that the correct modulo 180° value is selected. This optimal cadence depends on the maximum intrinsic EVPA rotation speed in blazars, which is currently not known. In this paper, we address the following questions for the RoboPol sample: What range of rotation speeds for rotations greater than 90° can we expect? What observation cadence is required to detect such rotations? Have rapid rotations been missed in EVPA rotation studies thus far? What fraction of data is affected by the ambiguity? And how likely are detected rotations affected by the ambiguity? We answer these questions with three seasons of optical polarimetric observations of a statistical sample of blazars sampled weekly with the RoboPol instrument and an additional season with daily observations. We model the distribution of EVPA changes on time-scales from 1–30 d and estimate the fraction of changes exceeding 90°. We show that at least daily observations are necessary to measure ${\gt}96{{\ \rm per\ cent}}$ of optical EVPA variability in the RoboPol sample of blazars correctly and that intraday observations are needed to measure the fastest rotations that have been seen thus far.

Determination of chemical elements in magnesium-based materials by neutron activation analysis

Over the last decades there was an increasing interest in using magnesium alloys for medical applications due to their biodegradability in the human body, providing a temporary mechanical support and corroding completely after the tissue healing. Although magnesium is a non-toxic element, it is of great importance to evaluate the element concentration, as well as the impurities present in both, pure magnesium and magnesium alloys, as the AZ31. The purpose of this study was to analyze the element composition of these materials using the method of neutron activation analysis (NAA). Standard Reference Materials (SRMs) acquired from National Institute of Standards and Technology (NIST) were analyzed for analytical quality control. Short and long term irradiations were carried out at the IEA-R1 nuclear research reactor and gamma-ray activities induced to the samples and element standard were measured using HPGe detector coupled to a Digital Spectrum Analyzer. The radioisotopes were identified by gamma ray energies and half-life. Concentrations of the elements As, Cr, Cd, Co, Fe, In, La, Mg, Mn, Mo, Na, Sb, V, W and Zn were determined in pure magnesium sample and the Al, As, La, Mg, Mn, Na, Sb and Zn in the AZ31 alloy, calculated by comparative method. The SRMs were analyzed by applying the same experimental conditions used for magnesium-based materials and their results presented good accuracy and precision. Thus, from the measurements obtained in this study it can be concluded that NAA is a suitable method for element determinations in magnesium-based materials providing reliable results.

New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash.

Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials.

Natural radioactivity of soil in the Baghdad governorate

The radioactive field is important for the human health due to the biologic impact that the radiation might cause (e.g., cancer induction), so it must be studied to see the changes in the doses of human exposure. In this study, 114 soil samples were collected from different locations in residential areas within the Baghdad governorate. The specific gamma-ray activity of the naturally occurring radionuclides 238U, 232Th and 40K for soil samples was measured spectroscopically using a NaI(Tl) detector. The results of the Karkh side show that the average value of specific activity of terrestrial gamma radiation (238U, 232Th and 40K) was (16.5 ± 0.9) Bq/kg, (9.7 ± 0.4) Bq/kg and (368 ± 11) Bq/kg, respectively. The results of the Rasafa side show that the average value of the specific activity of 238U, 232Th and 40K in samples of the present study were (17.4 ± 1.0) Bq/kg, (9.1 ± 0.3) Bq/k and (381 ± 22) Bq/kg, respectively. The results show that across the area, the natural radioactivity lies within the acceptable level as indicated by UNSCEAR 2008. It is subjected to the natural spatial averaging of the estimations, with the except for the sample (R3) which needs future study. GIS tools were used to map the specific activity for all samples in this study, which were divided into two groups: Karkh side and Rasafa side for simplified results.

A Two-zone Blazar Radiation Model for “Orphan” Neutrino Flares

Abstract In this work, we investigate the 2014–2015 neutrino flare associated with the blazar TXS 0506+056 and a recently discovered muon neutrino event IceCube-200107A in spatial coincidence with the blazar 4FGL J0955.1+3551, under the framework of a two-zone radiation model of blazars where an inner/outer blob close to/far from the supermassive black hole is invoked. An interesting feature that the two sources have in common is that no evidence of GeV gamma-ray activity is found during the neutrino detection period, probably implying a large opacity for GeV gamma rays in the neutrino production region. In our model, continuous particle acceleration/injection takes place in the inner blob at the jet base, where the hot X-ray corona of the supermassive black hole provides target photon fields for efficient neutrino production and strong GeV gamma-ray absorption. We show that this model can self-consistently interpret the neutrino emission from both blazars in a large parameter space. In the meantime, the dissipation processes in outer blob are responsible for the simultaneous multiwavelength emission of both sources. In agreement with previous studies of TXS 0506+056, an intense MeV emission from the induced electromagnetic cascade in the inner blob is robustly expected to accompany the neutrino flare in our model and could be used to test the model using the next-generation MeV gamma-ray detector in the future.