38 research outputs found
Search for Lorentz Invariance Violation with time-lag on gamma-ray Cherenkov Telescope data : From the data to the time lag constraints
No full textRecherche de violation de l'invariance de Lorentz avec le Large-Sized Telescope de CTAO
No full textInternational audienceThe fast variability of very-high energy (VHE) sources such as pulsars, gamma rays bursts (GRBs) or flares of active galactic nuclei (AGN) can be used to detect or constrain Lorentz invariance violation (LIV) by measuring lags in the arrival time of VHE photons. However, an important source of uncertainty arises from processes within the source that may induce intrinsic photon delays. Combining observations of different sources allows us to probe higher energy scales when LIV effects become relevant as well as to distinguish LIV-induced lags from intrinsic effects. We present the results of a standardized analysis performed on all AGN observations carried out by the first Large-Sized Telescope (LST-1) of CTAO. This analysis includes a general search of intra-night variability in archive observing nights that show significant excesses for the target candidates. The observing nights selected for LIV searches are then combined together to extract limits to the characteristic energies at which the LIV effect is expected to be significant. Finally, similar analysis have been performed on relevant data from other major imaging atmospheric Cherenkov telescopes, H.E.S.S., MAGIC and VERITAS, in order to combine all the data sets to extract combined limits that constrain one of the LIV effects
Recherche de violation de l'invariance de Lorentz avec le Large-Sized Telescope de CTAO
No full textInternational audienceThe fast variability of very-high energy (VHE) sources such as pulsars, gamma rays bursts (GRBs) or flares of active galactic nuclei (AGN) can be used to detect or constrain Lorentz invariance violation (LIV) by measuring lags in the arrival time of VHE photons. However, an important source of uncertainty arises from processes within the source that may induce intrinsic photon delays. Combining observations of different sources allows us to probe higher energy scales when LIV effects become relevant as well as to distinguish LIV-induced lags from intrinsic effects. We present the results of a standardized analysis performed on all AGN observations carried out by the first Large-Sized Telescope (LST-1) of CTAO. This analysis includes a general search of intra-night variability in archive observing nights that show significant excesses for the target candidates. The observing nights selected for LIV searches are then combined together to extract limits to the characteristic energies at which the LIV effect is expected to be significant. Finally, similar analysis have been performed on relevant data from other major imaging atmospheric Cherenkov telescopes, H.E.S.S., MAGIC and VERITAS, in order to combine all the data sets to extract combined limits that constrain one of the LIV effects
Recherche de brisure de l'invariance de Lorentz avec le Large-Sized Telescope de CTAO
No full textInternational audienceThe flares of active galactic nuclei (AGN) can be used to detect or constrain Lorentz invariance violation (LIV) by measuring time lags in the arrival times of high-energy photonss. An important source of uncertainty is our lack of knowledge of source intrinsic processes. However, combining observations of flares from different sources allows us to increase the precision of these measurements as well as to limit the noise of intrinsic source effects. Cherenkov Telescope Array Observatory (CTAO) is the next-generation TeV gamma-ray observatory. We will present the first results obtained searching for LIV from the observations performed with its first prototype, the Large-Sized Telescope (LST-1).Les éruptions des noyaux actifs de galaxie (AGN) peuvent être utilisées pour détecter ou contraindre la violation de l'invariance de Lorentz (LIV) en mesurant les décalages temporels dans les temps d'arrivée des photons de haute énergie. Une source importante d'incertitude est le manque de connaissance des processus intrinsèques à la source. Cependant, la combinaison d'observations d'éruptions provenant de différentes sources nous permet d'augmenter la précision de ces mesures et de limiter le bruit des effets intrinsèques des sources. Le Cherenkov Telescope Array Observatory (CTAO) est la la prochaine génération d'observatoire de rayons gamma au TeV . Nous présentons les premiers résultats obtenus sur la recherche de LIV à partir des observations réalisées avec son premier prototype, le Large-Sized Telescope (LST-1). </div
Recherche de brisure de l'invariance de Lorentz avec le Large-Sized Telescope de CTAO
No full textInternational audienceThe flares of active galactic nuclei (AGN) can be used to detect or constrain Lorentz invariance violation (LIV) by measuring time lags in the arrival times of high-energy photonss. An important source of uncertainty is our lack of knowledge of source intrinsic processes. However, combining observations of flares from different sources allows us to increase the precision of these measurements as well as to limit the noise of intrinsic source effects. Cherenkov Telescope Array Observatory (CTAO) is the next-generation TeV gamma-ray observatory. We will present the first results obtained searching for LIV from the observations performed with its first prototype, the Large-Sized Telescope (LST-1).Les éruptions des noyaux actifs de galaxie (AGN) peuvent être utilisées pour détecter ou contraindre la violation de l'invariance de Lorentz (LIV) en mesurant les décalages temporels dans les temps d'arrivée des photons de haute énergie. Une source importante d'incertitude est le manque de connaissance des processus intrinsèques à la source. Cependant, la combinaison d'observations d'éruptions provenant de différentes sources nous permet d'augmenter la précision de ces mesures et de limiter le bruit des effets intrinsèques des sources. Le Cherenkov Telescope Array Observatory (CTAO) est la la prochaine génération d'observatoire de rayons gamma au TeV . Nous présentons les premiers résultats obtenus sur la recherche de LIV à partir des observations réalisées avec son premier prototype, le Large-Sized Telescope (LST-1). </div
Deep Learning and IACT: Bridging the gap between Monte-Carlo simulations and LST-1 data using domain adaptation
No full textInternational audienceThe Cherenkov Telescope Array Observatory (CTAO) is the next generation of observatories employing the imaging air Cherenkov technique for the study of very high energy gamma rays. The deployment of deep learning methods for the reconstruction of physical attributes of incident particles has evinced promising outcomes when conducted on simulations. However, the transition of this approach to observational data is accompanied by challenges, as deep learning-based models are susceptible to domain shifts. In this paper, we integrate domain adaptation in the physics-based context of the CTAO and shed light on the gain in performance that these techniques bring using LST-1 real acquisitions
Deep Learning and IACT: Bridging the gap between Monte-Carlo simulations and LST-1 data using domain adaptation
No full textInternational audienceThe Cherenkov Telescope Array Observatory (CTAO) is the next generation of observatories employing the imaging air Cherenkov technique for the study of very high energy gamma rays. The deployment of deep learning methods for the reconstruction of physical attributes of incident particles has evinced promising outcomes when conducted on simulations. However, the transition of this approach to observational data is accompanied by challenges, as deep learning-based models are susceptible to domain shifts. In this paper, we integrate domain adaptation in the physics-based context of the CTAO and shed light on the gain in performance that these techniques bring using LST-1 real acquisitions
Première contrainte sur la violation de l'invariance de Lorentz avec une coopération de télescopes à imagerie Cherenkov
No full textInternational audienceLorentz invariance violation (LIV) may arise from modifications to the dispersion relation of massless particles in effective models attempting to merge quantum field theories and general relativity. One way to detect or constrain LIV effects is by measuring time delays in the arrival of high-energy photons from astrophysical sources. Suitable targets are variable, distant and highly energetic objects such as pulsars, gamma-ray bursts (GRBs), and active galactic nuclei (AGN) flares. However, a major challenge arises from intrinsic time lags due to source-specific emission processes. To improve the precision of these measurements and distinguish potential LIV-induced delays from intrinsic effects, as well as improve the current exploration of LIV up to a higher energy scale, a collaborative effort has been established among major Imaging Atmospheric Cherenkov Telescopes (IACTs): H.E.S.S., MAGIC, VERITAS, and the first Large-Sized Telescope (LST-1) of CTAO. The so-called Gamma-ray LIV Working Group aims to combine observational data from multiple sources, enhancing the sensitivity and robustness of LIV searches. We present the first set of limits on the LIV energy scale derived from a combination of real data from IACTs experiments
JRJC 2023 - Journées de Rencontres Jeunes Chercheurs. Book of Proceedings
No full textJournées de Rencontres Jeunes Chercheurs (JRJC2023). 22-28 octobre 2023, Saint Jean de Monts (France).International audienc
JRJC 2023 - Journées de Rencontres Jeunes Chercheurs. Book of Proceedings
No full textJournées de Rencontres Jeunes Chercheurs (JRJC2023). 22-28 octobre 2023, Saint Jean de Monts (France).International audienc
