The Making of Catalogues of Very-High-Energy γ-ray Sources

Naurois, M. de

doi:10.3390/universe7110421

Cited by 6 publications

(5 citation statements)

References 51 publications

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“…Note that the situation depicted in Figure 30 (left) is not the same as the one shown here. Figure from [3]. mirror support structure.…”

Section: Julien Bolmontmentioning

confidence: 99%

“…The meaning of "ON", "OFF", and "ON-OFF" will be explained later in §5.2. from [3]. Figure 32 shows an example of MSW and MSL distributions for observations of the Crab Nebula.…”

Section: Pos(qg-mmschools)003mentioning

confidence: 99%

“…Once the model has been built, it is essential to verify its accuracy by comparing it with full In both plots, the model is very accurate up to an impact distance of ∼300 m. Above that limits, the discrepancies can be interpreted as coming from trigger effects. Figure from [3].…”

Section: Julien Bolmontmentioning

confidence: 99%

“…As can be seen, a small fraction of real hadrons are included (dark red area), hence the name "gamma-like". Figure from [3].…”

Section: Pos(qg-mmschools)003mentioning

confidence: 99%

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Gamma-ray data collection, calibration and analysis for Lorentz invariance violation studies

Bolmont,

Campoy-Ordaz,

Strišković

2023

Proceedings of Winter School of Theoretical Physics, Second and Third Training School of COST Action CA18108 "Quantum Gravity P

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presents the lecture notes of a course given during the second training school of COST Action CA18108 "Quantum gravity phenomenology in the multi-messenger approach", which occurred in Belgrade in September 2022. It aims to provide a comprehensive introduction on various aspects of data acquisition and analysis in the context of high-energy gamma-ray astrophysics. A special effort was made so that these lecture notes can be understood by PhD students with no background on instrumentation or gamma-ray astrophysics. So that the lecture is kept short enough, the choice was made to focus on the imaging atmospheric Cherenkov technique. These lecture notes will walk the reader through the whole analysis process: how raw images are collected and how the raw data are produced, how these raw data are calibrated, how primary particle parameters are reconstructed and how the physical properties of the observed source are extracted. Finally, we will go through the different important points to consider regarding hardware, reconstruction and analysis when Lorentz Invariance Violation (LIV) studies have to be carried out.

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“…Note that the situation depicted in Figure 30 (left) is not the same as the one shown here. Figure from [3]. mirror support structure.…”

Section: Julien Bolmontmentioning

confidence: 99%

“…The meaning of "ON", "OFF", and "ON-OFF" will be explained later in §5.2. from [3]. Figure 32 shows an example of MSW and MSL distributions for observations of the Crab Nebula.…”

Section: Pos(qg-mmschools)003mentioning

confidence: 99%

Section: Julien Bolmontmentioning

confidence: 99%

“…As can be seen, a small fraction of real hadrons are included (dark red area), hence the name "gamma-like". Figure from [3].…”

Section: Pos(qg-mmschools)003mentioning

confidence: 99%

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Gamma-ray data collection, calibration and analysis for Lorentz invariance violation studies

Bolmont,

Campoy-Ordaz,

Strišković

2023

Proceedings of Winter School of Theoretical Physics, Second and Third Training School of COST Action CA18108 "Quantum Gravity P

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“…[2], MAGIC [3] and VERITAS [4]. Currently, the TeVCat catalog [5] contains more than 70 extragalactic objects with measured gamma-ray spectra at those energies, most of them being blazars of the BL Lac type [6,7]. With the next generation of IACTs, the Cherenkov Telescope Array (CTA) [8], many new VHE sources are expected to be discovered [9] due to CTA's improved sensitivity, extended energy coverage, and survey capabilities.…”

Section: Introductionmentioning

confidence: 99%

Simultaneously unveiling the EBL and intrinsic spectral parameters of gamma-ray sources with Hamiltonian Monte Carlo

Genaro,

Stuani Pereira,

de Matos Pimentel

et al. 2024

J. Cosmol. Astropart. Phys.

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The Extragalactic Background Light (EBL) is the main radiation field responsible for attenuating extragalactic gamma-ray emission at very high energies, but its precise spectral intensity is not fully determined. Therefore, disentangling propagation effects from the intrinsic spectral properties of gamma-ray sources (such as active galactic nuclei, AGN) is the primary challenge to interpret observations of these objects. We present a Bayesian and Markov Chain Monte Carlo approach to simultaneously infer parameters characterizing the EBL and the intrinsic spectra in a combined fit of a set of sources, which has the advantage of easily incorporating the uncertainties of both sets of parameters into one another through marginalization of the posterior distribution. Taking a sample of synthetic blazars observed by the ideal CTA configuration, we study the effects on the EBL constraints of combining multiple observations and varying their exposure. We also apply the methodology to a set of 65 gamma-ray spectra of 36 different AGNs measured by current Imaging Atmospheric Cherenkov Telescopes, using Hamiltonian Monte Carlo as a solution to the difficult task of sampling in spaces with a high number of parameters. We find robust constraints in the mid-IR region while simultaneously obtaining intrinsic spectral parameters for all of these objects. In particular, we identify Markarian 501 (Mkn 501) flare data (HEGRA/1997) as essential for constraining the EBL above 30 μm.

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Multiwavelength study of the galactic PeVatron candidate LHAASO J2108+5157

Project¹,

Jurysek²,

Balbo³

et al. 2023

A&A

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Context. Several new ultrahigh-energy (UHE) γ-ray sources have recently been discovered by the Large High Altitude Air Shower Observatory (LHAASO) collaboration. These represent a step forward in the search for the so-called Galactic PeVatrons, the enigmatic sources of the Galactic cosmic rays up to PeV energies. However, it has been shown that multi-TeV γ-ray emission does not necessarily prove the existence of a hadronic accelerator in the source; indeed this emission could also be explained as inverse Compton scattering from electrons in a radiation-dominated environment. A clear distinction between the two major emission mechanisms would only be made possible by taking into account multi-wavelength data and detailed morphology of the source. Aims. We aim to understand the nature of the unidentified source LHAASO J2108+5157, which is one of the few known UHE sources with no very high-energy (VHE) counterpart. Methods. We observed LHAASO J2108+5157 in the X-ray band with XMM-Newton in 2021 for a total of 3.8 hours and at TeV energies with the Large-Sized Telescope prototype (LST-1), yielding 49 hours of good-quality data. In addition, we analyzed 12 years of Fermi-LAT data, to better constrain emission of its high-energy (HE) counterpart 4FGL J2108.0+5155. We used naima and jetset software packages to examine the leptonic and hadronic scenario of the multi-wavelength emission of the source. Results. We found an excess (3.7σ) in the LST-1 data at energies E > 3 TeV. Further analysis of the whole LST-1 energy range, assuming a point-like source, resulted in a hint (2.2σ) of hard emission, which can be described with a single power law with a photon index of Γ = 1.6 ± 0.2 the range of 0.3 − 100 TeV. We did not find any significant extended emission that could be related to a supernova remnant (SNR) or pulsar wind nebula (PWN) in the XMM-Newton data, which puts strong constraints on possible synchrotron emission of relativistic electrons. We revealed a new potential hard source in Fermi-LAT data with a significance of 4σ and a photon index of Γ = 1.9 ± 0.2, which is not spatially correlated with LHAASO J2108+5157, but including it in the source model we were able to improve spectral representation of the HE counterpart 4FGL J2108.0+5155. Conclusions. The LST-1 and LHAASO observations can be explained as inverse Compton-dominated leptonic emission of relativistic electrons with a cutoff energy of 100−30+70 TeV. The low magnetic field in the source imposed by the X-ray upper limits on synchrotron emission is compatible with a hypothesis of a PWN or a TeV halo. Furthermore, the spectral properties of the HE counterpart are consistent with a Geminga-like pulsar, which would be able to power the VHE-UHE emission. Nevertheless, the lack of a pulsar in the neighborhood of the UHE source is a challenge to the PWN/TeV-halo scenario. The UHE γ rays can also be explained as π0 decay-dominated hadronic emission due to interaction of relativistic protons with one of the two known molecular clouds in the direction of the source. Indeed, the hard spectrum in the LST-1 band is compatible with protons escaping a shock around a middle-aged SNR because of their high low-energy cut-off, but the origin of the HE γ-ray emission remains an open question.

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The Making of Catalogues of Very-High-Energy γ-ray Sources

Cited by 6 publications

References 51 publications

Gamma-ray data collection, calibration and analysis for Lorentz invariance violation studies

Gamma-ray data collection, calibration and analysis for Lorentz invariance violation studies

Simultaneously unveiling the EBL and intrinsic spectral parameters of gamma-ray sources with Hamiltonian Monte Carlo

Multiwavelength study of the galactic PeVatron candidate LHAASO J2108+5157

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