M. Böttcher
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View article: Searching for Internal Absorption Signatures in High-Redshift Blazars
Searching for Internal Absorption Signatures in High-Redshift Blazars Open
The gamma-ray emission from Flat Spectrum Radio Quasars (FSRQs), a sub-class of blazars, is believed to be generated through interactions of high-energy leptons and/or hadrons in the jet with the ambient photon fields, including those from…
View article: A Comprehensive Hadronic Code Comparison for Active Galactic Nuclei
A Comprehensive Hadronic Code Comparison for Active Galactic Nuclei Open
We perform the first dedicated comparison of five hadronic codes (AM$^3$, ATHE$ν$A, B13, LeHa-Paris, and LeHaMoC) that have been extensively used in modeling of the spectral energy distribution (SED) of jetted active galactic nuclei. The p…
View article: A Gamma-Ray Flare from TXS 1508+572: Characterizing the Jet of a z = 4.31 Blazar in the Early Universe
A Gamma-Ray Flare from TXS 1508+572: Characterizing the Jet of a z = 4.31 Blazar in the Early Universe Open
Blazars can be detected from very large distances due to their high luminosity. However, the detection of γ -ray emission of blazars beyond z = 3 has only been confirmed for a small number of sources. Such observations probe the growth of …
View article: The Relation between Simulated Multiwavelength Blazar Variability and Stochastic Fluctuations
The Relation between Simulated Multiwavelength Blazar Variability and Stochastic Fluctuations Open
Blazars exhibit multiwavelength variability, a phenomenon whose underlying mechanisms remain elusive. This study investigates the origin of such variability through leptonic blazar emission simulations, focusing on stochastic fluctuations …
View article: The relation between Simulated Multiwavelength Blazar Variability and Stochastic Fluctuations
The relation between Simulated Multiwavelength Blazar Variability and Stochastic Fluctuations Open
Blazars exhibit multiwavelength variability, a phenomenon whose underlying mechanisms remain elusive. This study investigates the origin of such variability through leptonic blazar emission simulations, focusing on stochastic fluctuations …
View article: The high energy X-ray probe (HEX-P): the most powerful jets through the lens of a superb X-ray eye
The high energy X-ray probe (HEX-P): the most powerful jets through the lens of a superb X-ray eye Open
A fraction of the active supermassive black holes at the centers of galaxies in our Universe are capable of launching extreme kiloparsec-long relativistic jets. These jets are known multiband (radio to -ray) and multimessenger (neutrino) …
View article: Measurement of the electric potential and the magnetic field in the shifted analysing plane of the KATRIN experiment
Measurement of the electric potential and the magnetic field in the shifted analysing plane of the KATRIN experiment Open
The projected sensitivity of the effective electron neutrino-mass measurement with the KATRIN experiment is below 0.3 eV (90 % CL) after five years of data acquisition. The sensitivity is affected by the increased rate of the background el…
View article: Dark matter line searches with the Cherenkov Telescope Array
Dark matter line searches with the Cherenkov Telescope Array Open
Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an upd…
View article: Very-high-energy γ-Ray Emission from Young Massive Star Clusters in the Large Magellanic Cloud
Very-high-energy γ-Ray Emission from Young Massive Star Clusters in the Large Magellanic Cloud Open
The Tarantula Nebula in the Large Magellanic Cloud is known for its high star formation activity. At its center lies the young massive star cluster R136, providing a significant amount of the energy that makes the nebula shine so brightly …
View article: The optical spectropolarimetric behaviour of a selection of high-energy blazars
The optical spectropolarimetric behaviour of a selection of high-energy blazars Open
At optical/ultraviolet energies, blazars display an underlying thermal (unpolarized) contribution from the accretion disc, torus, and line-emitting regions, diluting the polarized emission from the jet-component. Optical polarimetry can be…
View article: Influence of cosmic voids on the propagation of TeV gamma-rays and the puzzle of GRB 221009A
Influence of cosmic voids on the propagation of TeV gamma-rays and the puzzle of GRB 221009A Open
The recent detection of gamma-ray burst GRB 221009A has attracted attention due to its record brightness and first-ever detection of $\gtrsim 10$ TeV gamma-rays from a GRB. Despite being the second-nearest GRB ever detected, at a redshift …
View article: Influence of Cosmic Voids on the propagation of TeV Gamma Rays and the Puzzle of GRB 221009A
Influence of Cosmic Voids on the propagation of TeV Gamma Rays and the Puzzle of GRB 221009A Open
The recent detection of gamma-ray burst GRB~221009A has attracted attention due to its record brightness and first-ever detection of $\gtrsim 10$ TeV $γ$ rays from a GRB. Despite being the second-nearest GRB ever detected, at a redshift of…
View article: A gamma-ray flare from TXS 1508+572: characterizing the jet of a $z=4.31$ blazar in the early Universe
A gamma-ray flare from TXS 1508+572: characterizing the jet of a $z=4.31$ blazar in the early Universe Open
Blazars can be detected from very large distances due to their high luminosity. However, the detection of $γ$-ray emission of blazars beyond $z=3$ has only been confirmed for a small number of sources. Such observations probe the growth of…
View article: Optical Spectropolarimetric Variability Properties in Blazars PKS 0637–75 and PKS 1510–089
Optical Spectropolarimetric Variability Properties in Blazars PKS 0637–75 and PKS 1510–089 Open
Spectropolarimetry is a powerful tool to investigate the central regions of active galactic nuclei (AGNs) as polarization signatures are key to probing magnetic field structure, evolution, and the physics of particle acceleration in jets. …
View article: Revisiting High-energy Polarization from Leptonic and Hadronic Blazar Scenarios
Revisiting High-energy Polarization from Leptonic and Hadronic Blazar Scenarios Open
X-ray and MeV polarization can be powerful diagnostics for leptonic and hadronic blazar models. Previous predictions are mostly based on a one-zone framework. However, recent IXPE observations of Mrk 421 and 501 strongly favor a multizone …
View article: Probe AGNs variability with the Cerenkov Telescope Array
Probe AGNs variability with the Cerenkov Telescope Array Open
Relativistic jets launched by Active Galactic Nuclei are among the most powerful particle accelerators in the Universe. The emission over the entire electromagnetic spectrum of these relativistic jets can be extremely variable with scales …
View article: H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883
H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883 Open
PSR B1259–63/LS 2883 is a gamma-ray binary system that hosts a pulsar in an eccentric orbit, with a 3.4 yr period, around an O9.5Ve star (LS 2883). At orbital phases close to periastron passages, the system radiates bright and variable non…
View article: Anisotropy and polarization effects in blazar emission
Anisotropy and polarization effects in blazar emission Open
Blazars, characterized by radio-loud active galactic nuclei with relativistic jets directed at us, exhibit features such as polarization in various wavebands and double-peak spectral energy distribution (SED). These features are influenced…
View article: Revisiting High-Energy Polarization from Leptonic and Hadronic Blazar Scenarios
Revisiting High-Energy Polarization from Leptonic and Hadronic Blazar Scenarios Open
X-ray and MeV polarization can be powerful diagnostics for leptonic and hadronic blazar models. Previous predictions are mostly based on a one-zone framework. However, recent IXPE observations of Mrk~421 and 501 strongly favor a multi-zone…
View article: Effects of non-continuous inverse Compton cooling in blazars
Effects of non-continuous inverse Compton cooling in blazars Open
Context. Blazar flares provide a window onto the extreme physical processes occurring in relativistic outflows. Most numerical codes used for modelling blazar emission during flares use a simplified continuous-loss description of particle …
View article: TeV flaring activity of the AGN PKS 0625–354 in November 2018
TeV flaring activity of the AGN PKS 0625–354 in November 2018 Open
Most γ -ray detected active galactic nuclei are blazars with one of their relativistic jets pointing towards the Earth. Only a few objects belong to the class of radio galaxies or misaligned blazars. Here, we investigate the nature of the …
View article: Revisiting the TeV flare of PKS 2155-304 in 2006
Revisiting the TeV flare of PKS 2155-304 in 2006 Open
Blazars, a subclass of active galactic nuclei (AGN), are known to be bright γ-ray sources, frequently exhibiting active (flaring) periods. Blazar PKS 2155-304 is a high synchrotron-peaked BL Lac object located at redshift z = 0.116. On 200…
View article: Curvature in the very-high energy gamma-ray spectrum of M 87
Curvature in the very-high energy gamma-ray spectrum of M 87 Open
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 u…
View article: Inverse Compton Emission and Cooling of Relativistic Particles Accelerated at Shear Boundary Layers in Relativistic Jets
Inverse Compton Emission and Cooling of Relativistic Particles Accelerated at Shear Boundary Layers in Relativistic Jets Open
Both observational evidence and theoretical considerations from magnetohydrodynamic simulations of jets suggest that the relativistic jets of active galactic nuclei (AGN) are radially stratified, with a fast inner spine surrounded by a slo…
View article: Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and H.E.S.S. analysis
Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and H.E.S.S. analysis Open
The Crab Nebula is a unique laboratory for studying the acceleration of electrons and positrons through their non-thermal radiation. Observations of very-high-energy $\gamma$ rays from the Crab Nebula have provided important constraints fo…
View article: Unveiling extended gamma-ray emission around HESS J1813-178
Unveiling extended gamma-ray emission around HESS J1813-178 Open
Context. HESS J1813−178 is a very-high-energy γ-ray source spatially coincident with the young and energetic pulsar PSR J1813−1749and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy e…
View article: Investigating the Lorentz invariance violation effect using different cosmological backgrounds
Investigating the Lorentz invariance violation effect using different cosmological backgrounds Open
Familiar concepts in physics, such as Lorentz symmetry, are expected to be broken at energies approaching the Planck energy scale as predicted by several quantum-gravity theories. However, such very large energies are unreachable by curren…
View article: Revisiting the TeV flare of PKS 2155-304 in 2006
Revisiting the TeV flare of PKS 2155-304 in 2006 Open
Blazars, a subclass of active galactic nuclei (AGN), are known to be bright $γ$-ray sources, frequently exhibiting active (flaring) periods. The blazar PKS~2155-304 is a high synchrotron-peaked BL Lac object located at redshift $z=0.116$. …
View article: Investigating the Lorentz Invariance Violation effect using different cosmological backgrounds
Investigating the Lorentz Invariance Violation effect using different cosmological backgrounds Open
Familiar concepts in physics, such as Lorentz symmetry, are expected to be broken at energies approaching the Planck energy scale as predicted by several quantum-gravity theories. However, such very large energies are unreachable by curren…