A Bayesian approach to modelling multimessenger emission from blazars using lepto-hadronic kinetic equations

ABSTRACT Blazar TXS 0506+056 is the main candidate for a coincident neutrino and gamma-ray flare event. In this paper, we present a detailed kinetic lepto-hadronic emission model capable of producing a photon and neutrino spectrum given a set of parameters. Our model includes a range of large-scale geometries and both dynamical and steady-state injection models for electrons and protons. We link this model with a Markov chain Monte Carlo sampler to obtain a powerful statistical tool that allows us to both fit the Spectral Energy Distribution and study the probability density functions and correlations of the parameters. Assuming a fiducial neutrino flux, we demonstrate how multimessenger observations can be modelled jointly in a Bayesian framework. We find the best parameters for each of the variants of the model tested and report on their cross-correlations. Additionally, we confirm that reproducing the neutrino flux of TXS 0506+056 requires an extreme proton to electron ratio either in the local acceleration process or from external injection.

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Detection of a flaring blazar coincident with an IceCube high-energy neutrino

EPJ Web of Conferences ◽

10.1051/epjconf/201920702001 ◽

2019 ◽

Vol 207 ◽

pp. 02001

Author(s):

Anna Franckowiak

Keyword(s):

Gamma Ray ◽

Spectral Energy Distribution ◽

Neutrino Flux ◽

High Energy ◽

Spectral Energy ◽

Large Area ◽

High Energy Neutrino ◽

Energy Neutrino ◽

Radio Wavelength ◽

First Time

In September 22, 2017, IceCube released a public alert announcing the detection of a 290 TeV neutrino track event with an angular uncertainty of one square degree (90% containment). A multi-messenger follow-up campaign was initiated resulting in the detection of a GeV gamma-ray flare by the Fermi Large Area Telescope positionally consistent with the location of the known Bl Lac object, TXS 0506+056 , located only 0.1 degrees from the best-fit neutrino position. The probability of finding a GeV gamma-ray flare in coincidence with a high-energy neutrino event assuming a correlation of the neutrino flux with the gamma-ray energy flux in the energy band between 1 and 100 GeV was calculated to be 3σ (after trials correction). Following the detection of the flaring blazar the imaging air Cherenkov telescope MAGIC detected the source for the first time in the > 100 GeV gamma-ray band. The activity of the source was confirmed in X-ray, optical and radio wavelength. Several groups have developed lepto-hadronic models which succeed to explain the multi-messenger spectral energy distribution.

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Detection of persistent VHE gamma-ray emission from PKS 1510–089 by the MAGIC telescopes during low states between 2012 and 2017

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833618 ◽

2018 ◽

Vol 619 ◽

pp. A159 ◽

Cited By ~ 9

Author(s):

◽

V. A. Acciari ◽

S. Ansoldi ◽

L. A. Antonelli ◽

A. Arbet Engels ◽

...

Keyword(s):

Gamma Ray ◽

Spectral Energy Distribution ◽

High Energy ◽

Outer Radius ◽

Spectral Energy ◽

Emission Region ◽

Emission Model ◽

Broadband Emission ◽

Very High Energy ◽

Gamma Ray Emission

Context. PKS 1510–089 is a flat spectrum radio quasar strongly variable in the optical and GeV range. To date, very high-energy (VHE, > 100 GeV) emission has been observed from this source either during long high states of optical and GeV activity or during short flares. Aims. We search for low-state VHE gamma-ray emission from PKS 1510–089. We characterize and model the source in a broadband context, which would provide a baseline over which high states and flares could be better understood. Methods. PKS 1510–089 has been monitored by the MAGIC telescopes since 2012. We use daily binned Fermi-LAT flux measurements of PKS 1510–089 to characterize the GeV emission and select the observation periods of MAGIC during low state of activity. For the selected times we compute the average radio, IR, optical, UV, X-ray, and gamma-ray emission to construct a low-state spectral energy distribution of the source. The broadband emission is modeled within an external Compton scenario with a stationary emission region through which plasma and magnetic fields are flowing. We also perform the emission-model-independent calculations of the maximum absorption in the broad line region (BLR) using two different models. Results. The MAGIC telescopes collected 75 hr of data during times when the Fermi-LAT flux measured above 1 GeV was below 3 × 10−8 cm−2 s−1, which is the threshold adopted for the definition of a low gamma-ray activity state. The data show a strongly significant (9.5σ) VHE gamma-ray emission at the level of (4.27 ± 0.61stat) × 10−12 cm−2 s−1 above 150 GeV, a factor of 80 lower than the highest flare observed so far from this object. Despite the lower flux, the spectral shape is consistent with earlier detections in the VHE band. The broadband emission is compatible with the external Compton scenario assuming a large emission region located beyond the BLR. For the first time the gamma-ray data allow us to place a limit on the location of the emission region during a low gamma-ray state of a FSRQ. For the used model of the BLR, the 95% confidence level on the location of the emission region allows us to place it at a distance > 74% of the outer radius of the BLR.

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Particle acceleration in Blazars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311007095 ◽

2010 ◽

Vol 6 (S274) ◽

pp. 263-266

Author(s):

Matthias Weidinger ◽

Felix Spanier

Keyword(s):

Particle Acceleration ◽

Gamma Ray ◽

Spectral Energy Distribution ◽

Theoretical Models ◽

Maximum Energy ◽

Radiative Energy ◽

Spectral Energy ◽

Type I ◽

Emission Model ◽

Energy Gains

AbstractUnderstanding the variable emission of blazars observed with gamma-ray telescopes and Fermi has become a major challenge for theoretical models of particle acceleration. Here, we introduce a novel time-dependent emission model in which the maximum energy of particles is determined from a balance between Fermi type I and II acceleration energy gains and radiative energy losses, allowing for an explanation of both the characteristic spectral energy distribution of blazars and their intrinsic sub-hour variability. Additionally, we can determine the physical condition of the emitting plasma concerning its turbulence and typical shock speeds.

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Testing emission models on the extreme blazar 2WHSP J073326.7+515354 detected at very high energies with the MAGIC telescopes

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2725 ◽

2019 ◽

Vol 490 (2) ◽

pp. 2284-2299 ◽

Cited By ~ 5

Author(s):

◽

V A Acciari ◽

S Ansoldi ◽

L A Antonelli ◽

...

Keyword(s):

Gamma Ray ◽

Spectral Energy Distribution ◽

Broad Band ◽

Physical Nature ◽

High Energy ◽

Spectral Energy ◽

Emission Model ◽

Theoretical Frameworks ◽

Spectral Parameters ◽

Bl Lac Objects

ABSTRACT Extreme high-energy-peaked BL Lac objects (EHBLs) are an emerging class of blazars. Their typical two-hump-structured spectral energy distribution (SED) peaks at higher energies with respect to conventional blazars. Multiwavelength (MWL) observations constrain their synchrotron peak in the medium to hard X-ray band. Their gamma-ray SED peaks above the GeV band, and in some objects it extends up to several TeV. Up to now, only a few EHBLs have been detected in the TeV gamma-ray range. In this paper, we report the detection of the EHBL 2WHSP J073326.7+515354, observed and detected during 2018 in TeV gamma rays with the MAGIC telescopes. The broad-band SED is studied within an MWL context, including an analysis of the Fermi-LAT data over 10 yr of observation and with simultaneous Swift-XRT, Swift-UVOT, and KVA data. Our analysis results in a set of spectral parameters that confirms the classification of the source as an EHBL. In order to investigate the physical nature of this extreme emission, different theoretical frameworks were tested to model the broad-band SED. The hard TeV spectrum of 2WHSP J073326.7+515354 sets the SED far from the energy equipartition regime in the standard one-zone leptonic scenario of blazar emission. Conversely, more complex models of the jet, represented by either a two-zone spine-layer model or a hadronic emission model, better represent the broad-band SED.

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The Crab nebula variability at short time-scales with the Cherenkov telescope array

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3599 ◽

2020 ◽

Vol 501 (1) ◽

pp. 337-346

Author(s):

E Mestre ◽

E de Oña Wilhelmi ◽

D Khangulyan ◽

R Zanin ◽

F Acero ◽

...

Keyword(s):

Gamma Ray ◽

Crab Nebula ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Telescope Array ◽

Cherenkov Telescopes ◽

Cherenkov Telescope ◽

Emission Models ◽

Short Time ◽

The Crab Nebula

ABSTRACT Since 2009, several rapid and bright flares have been observed at high energies (>100 MeV) from the direction of the Crab nebula. Several hypotheses have been put forward to explain this phenomenon, but the origin is still unclear. The detection of counterparts at higher energies with the next generation of Cherenkov telescopes will be determinant to constrain the underlying emission mechanisms. We aim at studying the capability of the Cherenkov Telescope Array (CTA) to explore the physics behind the flares, by performing simulations of the Crab nebula spectral energy distribution, both in flaring and steady state, for different parameters related to the physical conditions in the nebula. In particular, we explore the data recorded by Fermi during two particular flares that occurred in 2011 and 2013. The expected GeV and TeV gamma-ray emission is derived using different radiation models. The resulting emission is convoluted with the CTA response and tested for detection, obtaining an exclusion region for the space of parameters that rule the different flare emission models. Our simulations show different scenarios that may be favourable for achieving the detection of the flares in Crab with CTA, in different regimes of energy. In particular, we find that observations with low sub-100 GeV energy threshold telescopes could provide the most model-constraining results.

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Modeling Gamma-Ray SEDs and Angular Extensions of Extreme TeV Blazars from Intergalactic Proton-Initiated Cascades in Contemporary Astrophysical EGMF Models

Universe ◽

10.3390/universe7070220 ◽

2021 ◽

Vol 7 (7) ◽

pp. 220

Author(s):

Emil Khalikov

Keyword(s):

Gamma Rays ◽

Large Scale ◽

Gamma Ray ◽

High Energy ◽

Cascade Model ◽

Point Sources ◽

Spectral Energy ◽

Observation Data ◽

Cherenkov Telescopes ◽

The Universe

The intrinsic spectra of some distant blazars known as “extreme TeV blazars” have shown a hint at an anomalous hardening in the TeV energy region. Several extragalactic propagation models have been proposed to explain this possible excess transparency of the Universe to gamma-rays starting from a model which assumes the existence of so-called axion-like particles (ALPs) and the new process of gamma-ALP oscillations. Alternative models suppose that some of the observable gamma-rays are produced in the intergalactic cascades. This work focuses on investigating the spectral and angular features of one of the cascade models, the Intergalactic Hadronic Cascade Model (IHCM) in the contemporary astrophysical models of Extragalactic Magnetic Field (EGMF). For IHCM, EGMF largely determines the deflection of primary cosmic rays and electrons of intergalactic cascades and, thus, is of vital importance. Contemporary Hackstein models are considered in this paper and compared to the model of Dolag. The models assumed are based on simulations of the local part of large-scale structure of the Universe and differ in the assumptions for the seed field. This work provides spectral energy distributions (SEDs) and angular extensions of two extreme TeV blazars, 1ES 0229+200 and 1ES 0414+009. It is demonstrated that observable SEDs inside a typical point spread function of imaging atmospheric Cherenkov telescopes (IACTs) for IHCM would exhibit a characteristic high-energy attenuation compared to the ones obtained in hadronic models that do not consider EGMF, which makes it possible to distinguish among these models. At the same time, the spectra for IHCM models would have longer high energy tails than some available spectra for the ALP models and the universal spectra for the Electromagnetic Cascade Model (ECM). The analysis of the IHCM observable angular extensions shows that the sources would likely be identified by most IACTs not as point sources but rather as extended ones. These spectra could later be compared with future observation data of such instruments as Cherenkov Telescope Array (CTA) and LHAASO.

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Limits on quantum gravity effects from Swift short gamma-ray bursts

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731332 ◽

2017 ◽

Vol 607 ◽

pp. A121 ◽

Cited By ~ 5

Author(s):

M. G. Bernardini ◽

G. Ghirlanda ◽

S. Campana ◽

P. D’Avanzo ◽

J.-L. Atteia ◽

...

Keyword(s):

Quantum Gravity ◽

Gamma Ray ◽

Lorentz Invariance ◽

Spectral Energy Distribution ◽

Gamma Ray Bursts ◽

Low Energy ◽

Energy Separation ◽

Spectral Energy ◽

Spectral Evolution ◽

Short Grbs

The delay in arrival times between high and low energy photons from cosmic sources can be used to test the violation of the Lorentz invariance (LIV), predicted by some quantum gravity theories, and to constrain its characteristic energy scale EQG that is of the order of the Planck energy. Gamma-ray bursts (GRBs) and blazars are ideal for this purpose thanks to their broad spectral energy distribution and cosmological distances: at first order approximation, the constraints on EQG are proportional to the photon energy separation and the distance of the source. However, the LIV tiny contribution to the total time delay can be dominated by intrinsic delays related to the physics of the sources: long GRBs typically show a delay between high and low energy photons related to their spectral evolution (spectral lag). Short GRBs have null intrinsic spectral lags and are therefore an ideal tool to measure any LIV effect. We considered a sample of 15 short GRBs with known redshift observed by Swift and we estimate a limit on EQG ≳ 1.5 × 1016 GeV. Our estimate represents an improvement with respect to the limit obtained with a larger (double) sample of long GRBs and is more robust than the estimates on single events because it accounts for the intrinsic delay in a statistical sense.

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SNR G39.2−0.3, an hadronic cosmic rays accelerator

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2045 ◽

2020 ◽

Vol 497 (3) ◽

pp. 3581-3590

Author(s):

Emma de Oña Wilhelmi ◽

Iurii Sushch ◽

Robert Brose ◽

Enrique Mestre ◽

Yang Su ◽

...

Keyword(s):

Magnetic Field ◽

Cosmic Rays ◽

Supernova Remnants ◽

Gamma Ray ◽

Spectral Energy Distribution ◽

Galactic Cosmic Rays ◽

Spectral Energy ◽

Core Collapse ◽

Heavy Nuclei ◽

The Rich

ABSTRACT Recent results obtained with gamma-ray satellites have established supernova remnants as accelerators of GeV hadronic cosmic rays. In such processes, CRs accelerated in SNR shocks interact with particles from gas clouds in their surrounding. In particular, the rich medium in which core-collapse SNRs explode provides a large target density to boost hadronic gamma-rays. SNR G39.2–0.3 is one of the brightest SNR in infrared wavelengths, and its broad multiwavelength coverage allows a detailed modelling of its radiation from radio to high energies. We reanalysed the Fermi-LAT data on this region and compare it with new radio observations from the MWISP survey. The modelling of the spectral energy distribution from radio to GeV energies favours a hadronic origin of the gamma-ray emission and constrains the SNR magnetic field to be at least ∼100 µG. Despite the large magnetic field, the present acceleration of protons seems to be limited to ∼10 GeV, which points to a drastic slow down of the shock velocity due to the dense wall traced by the CO observations, surrounding the remnant. Further investigation of the gamma-ray spectral shape points to a dynamically old remnant subjected to severe escape of CRs and a decrease of acceleration efficiency. The low-energy peak of the gamma-ray spectrum also suggests that that the composition of accelerated particles might be enriched by heavy nuclei which is certainly expected for a core-collapse SNR. Alternatively, the contribution of the compressed pre-existing Galactic cosmic rays is discussed, which is, however, found to not likely be the dominant process for gamma-ray production.

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Metallicity, temperature, and gravity scales of M subdwarfs,

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935299 ◽

2019 ◽

Vol 628 ◽

pp. A61 ◽

Cited By ~ 2

Author(s):

N. Lodieu ◽

F. Allard ◽

C. Rodrigo ◽

Y. Pavlenko ◽

A. Burgasser ◽

...

Keyword(s):

Large Scale ◽

Near Infrared ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

M Dwarfs ◽

Low Mass Stars ◽

Very Large Telescope ◽

Wide Range ◽

Solar Metallicity ◽

Effective Temperatures

Aims. The aim of the project is to define metallicity/gravity/temperature scales for different spectral types of metal-poor M dwarfs. Methods. We obtained intermediate-resolution ultraviolet (R ∼ 3300), optical (R ∼ 5400), and near-infrared (R ∼ 3900) spectra of 43 M subdwarfs (sdM), extreme subdwarfs (esdM), and ultra-subdwarfs (usdM) with the X-shooter spectrograph on the European Southern Observatory Very Large Telescope. We compared our atlas of spectra to the latest BT-Settl synthetic spectral energy distribution over a wide range of metallicities, gravities, and effective temperatures to infer the physical properties for the whole M dwarf sequence (M0–M9.5) at sub-solar metallicities and constrain the latest atmospheric models. Results. The BT-Settl models accurately reproduce the observed spectra across the 450–2500 nm wavelength range except for a few regions. We find that the best fits are obtained for gravities of log (g) = 5.0–5.5 for the three metal classes. We infer metallicities of [Fe/H] = −0.5, −1.5, and −2.0 ± 0.5 dex and effective temperatures of 3700–2600 K, 3800–2900 K, and 3700–2900 K for subdwarfs, extreme subdwarfs, and ultra-subdwarfs, respectively. Metal-poor M dwarfs tend to be warmer by about 200 ± 100 K and exhibit higher gravity than their solar-metallicity counterparts. We derive abundances of several elements (Fe, Na, K, Ca, Ti) for our sample but cannot describe their atmospheres with a single metallicity parameter. Our metallicity scale expands the current scales available for mildly metal-poor planet-host low-mass stars. Our compendium of moderate-resolution spectra covering the 0.45–2.5 micron range represents an important resource for large-scale surveys and space missions to come.

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GRB spectral parameter modeling

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311007034 ◽

2010 ◽

Vol 6 (S274) ◽

pp. 243-245

Author(s):

Gregory D. Fleishman ◽

Fedor A. Urtiev

Keyword(s):

Synchrotron Radiation ◽

Electric Fields ◽

Large Scale ◽

Gamma Ray ◽

Small Scale ◽

Random Waves ◽

Spectral Parameters ◽

Random Magnetic Field ◽

Cross Correlations ◽

Accelerated Particles

AbstractFireball model of the gamma-ray bursts (GRBs) predicts generation of numerous internal shocks, which efficiently accelerate charged particles and generate relatively small-scale stochastic magnetic and electric fields. The accelerated particles diffuse in space due to interaction with the random waves and so emit so called Diffusive Synchrotron Radiation (DSR) in contrast to standard synchrotron radiation they would produce in a large-scale regular magnetic fields. In this contribution we present key results of detailed modeling of the GRB spectral parameters, which demonstrate that the non-perturbative DSR emission mechanism in a strong random magnetic field is consistent with observed distributions of the Band parameters and also with cross-correlations between them.

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