Stefan Funk
Friedrich-Alexander-Universität Erlangen-Nürnberg
H-index: 156
Europe-Germany
About Stefan Funk
Stefan Funk, With an exceptional h-index of 156 and a recent h-index of 78 (since 2020), a distinguished researcher at Friedrich-Alexander-Universität Erlangen-Nürnberg,
His recent articles reflect a diverse array of research interests and contributions to the field:
Evidence for γ-ray emission from the remnant of Kepler’s supernova based on deep HESS observations (Corrigendum)
Speed of sound in methane under conditions of planetary interiors
Curvature in the very-high energy gamma-ray spectrum of M87
Ultra-fast generation of air shower images for Imaging Air Cherenkov Telescopes using Generative Adversarial Networks
Unveiling extended gamma-ray emission around HESS J1813-178
First intensity interferometry measurements with the HESS telescopes
Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433
Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and HESS analysis
Stefan Funk Information
University | Friedrich-Alexander-Universität Erlangen-Nürnberg |
|---|---|
Position | Stanford University SLAC |
Citations(all) | 89326 |
Citations(since 2020) | 30848 |
Cited By | 72056 |
hIndex(all) | 156 |
hIndex(since 2020) | 78 |
i10Index(all) | 393 |
i10Index(since 2020) | 339 |
University Profile Page | Friedrich-Alexander-Universität Erlangen-Nürnberg |
Top articles of Stefan Funk
Evidence for γ-ray emission from the remnant of Kepler’s supernova based on deep HESS observations (Corrigendum)
Authors
F Aharonian,F Ait Benkhali,EO Angüner,H Ashkar,M Backes,V Barbosa Martins,R Batzofin,Yvonne Becherini,D Berge,K Bernloehr,M Boettcher,C Boisson,J Bolmont,M de Bony de Lavergne,M Breuhaus,R Brose,F Brun,T Bulik,Tomas Bylund,F Cangemi,S Caroff,S Casanova,M Cerruti,T Chand,A Chen,O Chibueze,G Cotter,P Cristofari,J Damascene Mbarubucyeye,J Devin,A Djannati-Atai,A Dmytriiev,K Egberts,S Einecke,J-P Ernenwein,K Feijen,A Fiasson,G Fichet de Clairfontaine,G Fontaine,S Funk,S Gabici,YA Gallant,S Ghafourizadeh,G Giavitto,L Giunti,D Glawion,JF Glicenstein,M-H Grondin,M Hoerbe,W Hofmann,TL Holch,M Holler,D Horns,Zhiqiu Huang,Marek Jamrozy,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,U Katz,B Khélifi,W Kluźniak,Nu Komin,K Kosack,D Kostunin,A Lemière,M Lemoine-Goumard,J-P Lenain,F Leuschner,T Lohse,A Luashvili,I Lypova,J Mackey,D Malyshev,V Marandon,P Marchegiani,A Marcowith,G Martí-Devesa,R Marx,G Maurin,PJ Meintjes,M Meyer,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,J Muller,K Nakashima,M de Naurois,A Nayerhoda,J Niemiec,A Priyana Noel,P O’Brien,S Ohm,L Olivera-Nieto,E de Ona Wilhelmi,Michał Ostrowski,S Panny,M Panter,RD Parsons,G Peron,V Poireau,DA Prokhorov,G Pühlhofer,Michael Punch,A Quirrenbach,P Reichherzer,A Reimer,O Reimer,M Renaud,B Reville,F Rieger,G Rowell,B Rudak,H Rueda Ricarte,V Sahakian,S Sailer,H Salzmann,DA Sanchez,A Santangelo,M Sasaki,J Schäfer,F Schüssler,HM Schutte,U Schwanke,JNS Shapopi,R Simoni,H Sol,A Specovius,S Spencer,S Steinmassl,C Steppa,I Sushch,T Takahashi,T Tanaka,AM Taylor,R Terrier,M Tsirou,Y Uchiyama,T Unbehaun,C van Eldik,J Veh,J Vink,HJ Voelk,SJ Wagner,F Werner,R White,A Wierzcholska,Yu Wun Wong
Journal
Astronomy & Astrophysics
Published Date
2022/6/1
Observations with imaging atmospheric Cherenkov telescopes (IACTs) have enhanced our knowledge of nearby supernova (SN) remnants with ages younger than 500 yr by establishing Cassiopeia A and the remnant of Tycho’s SN as very-high-energy (VHE) γ-ray sources. The remnant of Kepler’s SN, which is the product of the most recent naked-eye SN in our Galaxy, is comparable in age to the other two, but is significantly more distant. If the γ-ray luminosities of the remnants of Tycho’s and Kepler’s SNe are similar, then the latter is expected to be one of the faintest γ-ray sources within reach of the current generation IACT arrays. Here we report evidence at a statistical level of 4.6σ for a VHE signal from the remnant of Kepler’s SN based on deep observations by the High Energy Stereoscopic System (H.E.S.S.) with an exposure of 152 h. The measured integral flux above an energy of 226 GeV is ∼0.3% of the …
Speed of sound in methane under conditions of planetary interiors
Authors
Thomas G White,Hannah Poole,Emma E McBride,Matthew Oliver,Adrien Descamps,Luke B Fletcher,W Alex Angermeier,Cameron H Allen,Karen Appel,Florian P Condamine,Chandra B Curry,Francesco Dallari,Stefan Funk,Eric Galtier,Eliseo J Gamboa,Maxence Gauthier,Peter Graham,Sebastian Goede,Daniel Haden,Jongjin B Kim,Hae Ja Lee,Benjamin K Ofori-Okai,Scott Richardson,Alex Rigby,Christopher Schoenwaelder,Peihao Sun,Bastian L Witte,Thomas Tschentscher,Ulf Zastrau,Bob Nagler,JB Hastings,Giulio Monaco,Dirk O Gericke,Siegfried H Glenzer,Gianluca Gregori
Journal
Physical Review Research
Published Date
2024/5/2
We present direct observations of acoustic waves in warm dense matter. We analyze wave-number-and energy-resolved x-ray spectra taken from warm dense methane created by laser heating a cryogenic liquid jet. X-ray diffraction and inelastic free-electron scattering yield sample conditions of 0.3±0.1 eV and 0.8±0.1 g/cm− 3, corresponding to a pressure of∼ 13 GPa. Inelastic x-ray scattering was used to observe the collective oscillations of the ions. With a highly improved energy resolution of∼ 50 meV, we could clearly distinguish the Brillouin peaks from the quasielastic Rayleigh feature. Data at different wave numbers were utilized to derive a sound speed of 5.9±0.5 km/s, marking a high-temperature data point for methane and demonstrating consistency with Birch's law in this parameter regime.
Curvature in the very-high energy gamma-ray spectrum of M87
Authors
HESS Collaboration,F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,V Barbosa Martins,R Batzofin,Y Becherini,D Berge,K Bernlöhr,M Böttcher,C Boisson,J Bolmont,M de Lavergne,F Bradascio,R Brose,F Brun,B Bruno,T Bulik C Burger-Scheidlin,T Bylund,S Casanova,R Cecil,J Celic,M Cerruti,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,T Collins,G Cotter,J Mbarubucyeye,A Djannati-Ataï,J Djuvsland,A Dmytriiev,K Egberts,S Einecke,S Fegan,G Fontaine,S Funk,S Gabici,JF Glicenstein,J Glombitza,G Grolleron,L Haerer,W Hofmann,TL Holch,M Holler,D Horns,M Jamrozy,F Jankowsky,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,R Khatoon,B Khélifi,W Kluźniak,Nu Komin,K Kosack,D Kostunin,A Kundu,RG Lang,S Le Stum,F Leitl,A Lemière,M Lemoine-Goumard,J-P Lenain,I Lypova,A Luashvili,J Mackey,D Malyshev,G Martí-Devesa,R Marx,A Mehta,M Meyer,A Mitchell,R Moderski,MO Moghadam,L Mohrmann,A Montanari,E Moulin,T Murach,M de Naurois,J Niemiec,S Ohm,L Olivera-Nieto,E Wilhelmi,S Panny,M Panter,RD Parsons,U Pensec,S Pita,G Pühlhofer,M Punch,A Quirrenbach,M Regeard,A Reimer,O Reimer,H Ren,B Reville,F Rieger,B Rudak,E Ruiz-Velasco,V Sahakian,H Salzmann,A Santangelo,M Sasaki,F Schüssler,HM Schutte,JNS Shapopi,H Sol,S Spencer,Ł Stawarz,R Steenkamp,S Steinmassl,C Steppa,K Streil,T Takahashi,T Tanaka,AM Taylor,R Terrier,M Tsirou,C van Eldik,C Venter,J Vink,T Wach,SJ Wagner,A Wierzcholska,M Zacharias,AA Zdziarski,A Zech,P Zilberman,N Zywucka
Journal
arXiv preprint arXiv:2402.13330
Published Date
2024/2/20
The radio galaxy M87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is yet to be understood. In this study, we investigate the VHE gamma-ray spectrum of M87 during states of high gamma-ray activity, utilizing 20.2 hours the 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 0.3TeV at the 4 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 mainly sensitive in the wavelength range 12.4m - 40m.
Ultra-fast generation of air shower images for Imaging Air Cherenkov Telescopes using Generative Adversarial Networks
Authors
Christian Elflein,Stefan Funk,Jonas Glombitza
Journal
Journal of Instrumentation
Published Date
2024/4/9
For the analysis of data taken by Imaging Air Cherenkov Telescopes (IACTs), a large number of air shower simulations are needed to derive the instrument response. The simulations are very complex, involving computational and memory-intensive calculations, and are usually performed repeatedly for different observation intervals to take into account the varying optical sensitivity of the instrument. The use of generative models based on deep neural networks offers the prospect for memory-efficient storing of huge simulation libraries and cost-effective generation of a large number of simulations in an extremely short time. In this work, we use Wasserstein Generative Adversarial Networks to generate photon showers for an IACT equipped with the FlashCam design, which has more than 1,500 pixels. Using simulations of the HESS experiment, we demonstrate the successful generation of high-quality IACT images …
Unveiling extended gamma-ray emission around HESS J1813-178
Authors
F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,A Baktash,V Barbosa Martins,J Barnard,R Batzofin,Y Becherini,D Berge,K Bernlöhr,B Bi,M Böttcher,C Boisson,J Bolmont,M de Lavergne,J Borowska,M Bouyahiaoui,M Breuhaus,R Brose,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,S Caroff,S Casanova,R Cecil,J Celic,M Cerruti,P Chambery,T Chand,A Chen,J Chibueze,O Chibueze,G Cotter,J Mbarubucyeye,A Djannati-Ataï,A Dmytriiev,V Doroshenko,S Einecke,J-P Ernenwein,K Feijen,M Filipovic,G Fontaine,M Füßling,S Funk,S Gabici,YA Gallant,S Ghafourizadeh,G Giavitt,D Glawion,JF Glicenstein,P Goswami,G Grolleron,M-H Grondin,JA Hinton,W Hofmann,TL Holch,M Holler,M Jamrozy,F Jankowsky,V Joshi,I Jung-Richardt,K Katarzyński,R Khatoon,B Khélifi,S Klepser,W Kluźniak,Nu Komin,K Kosack,D Kostunin,A Kundu,RG Lang,S Le Stum,F Leitl,A Lemière,M Lemoine-Goumard,J-P Lenain,F Leuschner,J Mackey,D Malyshev,V Marandon,P Marinos,G Martí-Devesa,R Marx,A Mehta,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,T Murach,M de Naurois,J Niemiec,A Priyana Noel,P O'Brien,S Ohm,L Olivera-Nieto,E Wilhelmi,M Ostrowski,S Panny,M Panter,RD Parsons,DA Prokhorov,G Pühlhofer,M Punch,A Quirrenbach,M Regeard,P Reichherzer,A Reimer,O Reimer,H Ren,M Renaud,B Reville,F Rieger,G Roellinghoff,B Rudak,V Sahakian,H Salzmann,M Sasaki,F Schüssler,HM Schutte,JNS Shapopi,A Specovius,S Spencer,R Steenkamp,S Steinmassl,C Steppa,I Sushch,H Suzuki,T Takahashi,T Tanaka,R Terrier,M Tluczykont,N Tsuji,T Unbehaun,C van Eldik,M Vecchi,J Veh,C Venter,J Vink,T Wach,SJ Wagner,A Wierzcholska,M Zacharias,D Zargaryan,AA Zdziarski,S Zouari,N Żywucka
Journal
arXiv preprint arXiv:2403.16802
Published Date
2024/3/25
HESS J1813178 is a very-high-energy -ray source spatially coincident with the young and energetic pulsar PSR J18131749 and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813178 region, taking advantage of improved analysis methods and an extended data set. Using data taken by the High Energy Stereoscopic System (H.E.S.S.) experiment and the Fermi-LAT, we aim to describe the -ray emission in the region with a consistent model, to provide insights into its origin. We performed a likelihood-based analysis on 32 hours of H.E.S.S. data and 12 years of Fermi-LAT data and fit a spectro-morphological model to the combined datasets. These results allowed us to develop a physical model for the origin of the observed -ray emission in the region. In addition to the compact very-high-energy -ray emission centered on the pulsar, we find a significant yet previously undetected component along the Galactic plane. With Fermi-LAT data, we confirm extended high-energy emission consistent with the position and elongation of the extended emission observed with H.E.S.S. These results establish a consistent description of the emission in the region from GeV energies to several tens of TeV. This study suggests that HESS J1813178 is associated with a -ray PWN powered by PSR J18131749. A possible origin of the extended emission component is inverse Compton emission from electrons and positrons that have escaped the confines …
First intensity interferometry measurements with the HESS telescopes
Authors
Andreas Zmija,Naomi Vogel,Frederik Wohlleben,Gisela Anton,Adrian Zink,Stefan Funk
Journal
Monthly Notices of the Royal Astronomical Society
Published Date
2024/2
Intensity interferometry for astrophysical observations has gained increasing interest in the last decade. The method of correlating photon fluxes at different telescopes for high resolution astronomy without access to the phase of the incoming light is insensitive to atmospheric turbulence and does not require high-precision optical path control. The necessary large collection areas can be provided by Imaging Atmospheric Cherenkov Telescopes. Implementation of intensity interferometers to existing telescope systems such as VERITAS and MAGIC has proven to be successful for high-resolution imaging of stars. In 2022 April we equipped two telescopes of the H.E.S.S. array in Namibia with an intensity interferometry setup to measure southern sky stars and star systems during the bright moon period. We mounted an external optical system to the lid of the telescope cameras, which splits the incoming light and …
Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433
Authors
HESS Collaboration*†,F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,V Barbosa Martins,R Batzofin,Y Becherini,D Berge,K Bernlöhr,B Bi,M Böttcher,C Boisson,J Bolmont,M de Bony de Lavergne,J Borowska,M Bouyahiaoui,M Breuhaus,R Brose,AM Brown,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,S Caroff,S Casanova,R Cecil,J Celic,M Cerruti,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,G Cotter,S Dai,J Damascene Mbarubucyeye,A Djannati-Ataï,A Dmytriiev,V Doroshenko,K Egberts,S Einecke,J-P Ernenwein,M Filipovic,G Fontaine,M Füßling,S Funk,S Gabici,S Ghafourizadeh,G Giavitto,D Glawion,J-F Glicenstein,G Grolleron,L Haerer,JA Hinton,W Hofmann,TL Holch,M Holler,D Horns,M Jamrozy,F Jankowsky,A Jardin-Blicq,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,R Khatoon,B Khélifi,S Klepser,W Kluźniak,Nu Komin,K Kosack,D Kostunin,A Kundu,RG Lang,S Le Stum,F Leitl,A Lemière,J-P Lenain,F Leuschner,T Lohse,A Luashvili,I Lypova,J Mackey,D Malyshev,D Malyshev,V Marandon,P Marchegiani,A Marcowith,G Martí-Devesa,R Marx,A Mehta,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,T Murach,K Nakashima,M de Naurois,J Niemiec,A Priyana Noel,S Ohm,L Olivera-Nieto,E de Ona Wilhelmi,M Ostrowski,S Panny,M Panter,RD Parsons,G Peron,DA Prokhorov,G Pühlhofer,M Punch,A Quirrenbach,P Reichherzer,A Reimer,O Reimer,H Ren,M Renaud,B Reville,F Rieger,G Rowell,B Rudak,H Rueda Ricarte,E Ruiz-Velasco,V Sahakian,H Salzmann,A Santangelo,M Sasaki,J Schäfer,F Schüssler,U Schwanke,JNS Shapopi,H Sol,A Specovius,S Spencer,L Stawarz,R Steenkamp,S Steinmassl,C Steppa,K Streil,I Sushch,H Suzuki,T Takahashi,T Tanaka,AM Taylor,R Terrier,M Tsirou,N Tsuji
Journal
Science
Published Date
2024/1/26
SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.
Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and HESS analysis
Authors
F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,A Baktash,V Barbosa Martins,R Batzofin,Y Becherini,D Berge,K Bernlöhr,B Bi,M Böttcher,C Boisson,J Bolmont,M de Lavergne,J Borowska,F Bradascio,M Breuhaus,R Brose,A Brown,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,T Bylund,S Caroff,S Casanova,R Cecil,J Celic,M Cerruti,P Chambery,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,G Cotter,P Cristofari,J Devin,A Djannati-Ataï,J Djuvsland,A Dmytriiev,S Einecke,J-P Ernenwein,S Fegan,K Feijen,M Filipović,G Fontaine,M Füßling,S Funk,S Gabici,YA Gallant,G Giavitto,D Glawion,JF Glicenstein,J Glombitza,P Goswami,G Grolleron,M-H Grondin,L Haerer,JA Hinton,W Hofmann,TL Holch,M Holler,D Horns,M Jamrozy,F Jankowsky,V Joshi,E Kasai,K Katarzyński,R Khatoon,B Khélifi,W Kluźniak,Nu Komin,K Kosack,D Kostunin,A Kundu,RG Lang,S Le Stum,F Leitl,A Lemière,M Lemoine-Goumard,J-P Lenain,F Leuschner,A Luashvili,J Mackey,D Malyshev,V Marandon,P Marinos,G Martí-Devesa,R Marx,A Mehta,M Meyer,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,T Murach,M de Naurois,J Niemiec,P O'Brien,S Ohm,L Olivera-Nieto,E Wilhelmi,M Ostrowski,S Panny,M Panter,RD Parsons,G Peron,DA Prokhorov,G Pühlhofer,M Punch,A Quirrenbach,M Regeard,P Reichherzer,A Reimer,O Reimer,H Ren,M Renaud,B Reville,F Rieger,G Roellinghoff,B Rudak,V Sahakian,H Salzmann,M Sasaki,F Schüssler,HM Schutte,JNS Shapopi,A Specovius,S Spencer,Ł Stawarz,R Steenkamp,S Steinmassl,C Steppa,K Streil,I Sushch,H Suzuki,T Takahashi,T Tanaka,R Terrier,M Tluczykont,N Tsuji,T Unbehaun,C van Eldik,M Vecchi,J Veh,C Venter
Journal
arXiv preprint arXiv:2403.12608
Published Date
2024/3/19
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 rays from the Crab Nebula have provided important constraints for modelling its broadband emission. We present the first fully self-consistent analysis of the Crab Nebula's -ray emission between 1 GeV and 100 TeV, that is over five orders of magnitude in energy. Using the open-source software package Gammapy, we combine 11.4 yr of data from the Fermi Large Area Telescope and 80 h of High Energy Stereoscopic System (H.E.S.S.) data at the event level and provide a measurement of the spatial extension of the nebula and its energy spectrum. We find evidence for a shrinking of the nebula with increasing -ray energy. Furthermore, we fit several phenomenological models to the measured data, finding that none of them can fully describe the spatial extension and the spectral energy distribution at the same time. Especially the extension measured at TeV energies appears too large when compared to the X-ray emission. Our measurements probe the structure of the magnetic field between the pulsar wind termination shock and the dust torus, and we conclude that the magnetic field strength decreases with increasing distance from the pulsar. We complement our study with a careful assessment of systematic uncertainties.
TeV flaring activity of the AGN PKS 0625-354 in November 2018
Authors
HESS Collaboration,F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,A Baktash,V Barbosa Martins,J Barnard,R Batzofin,Y Becherini,D Berge,K Bernlöhr,B Bi,M Böttcher,C Boisson,J Bolmont,M de Lavergne,J Borowska,F Bradascio,M Breuhaus,R Brose,A Brown,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,T Bylund,S Caroff,S Casanova,R Cecil,J Celic,M Cerruti,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,G Cotter,J Mbarubucyeye,ID Davids,J Djuvsland,A Dmytriiev,V Doroshenko,K Egberts,S Einecke,J-P Ernenwein,G Fontaine,M Füßling,S Funk,S Gabici,S Ghafourizadeh,G Giavitto,D Glawion,JF Glicenstein,J Glombitza,P Goswami,G Grolleron,L Haerer,JA Hinton,TL Holch,M Holler,D Horns,M Jamrozy,F Jankowsky,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,R Khatoon,B Kh'elifi,Nu Komin,K Kosack,D Kostunin,RG Lang,S Le Stum,F Leitl,A Lemière,J-P Lenain,F Leuschner,A Luashvili,J Mackey,R Marx,A Mehta,M Meyer,A Mitchell,R Moderski,A Montanari,E Moulin,M de Naurois,J Niemiec,P O'Brien,S Ohm,L Olivera-Nieto,E Wilhelmi,M Ostrowski,S Panny,RD Parsons,S Pita,DA Prokhorov,G Pühlhofer,M Punch,A Quirrenbach,P Reichherzer,A Reimer,O Reimer,H Ren,F Rieger,B Rudak,V Sahakian,H Salzmann,DA Sanchez,M Sasaki,F Schüssler,HM Schutte,JNS Shapopi,H Sol,A Specovius,S Spencer,R Steenkamp,S Steinmassl,K Streil,I Sushch,H Suzuki,T Takahashi,T Tanaka,C van Eldik,M Vecchi,J Veh,C Venter,SJ Wagner,A Wierzcholska,M Zacharias,D Zargaryan,AA Zdziarski,A Zech,S Zouari,N Żywucka
Journal
arXiv preprint arXiv:2401.07071
Published Date
2024/1/13
Most -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 object PKS 0625-354, its -ray flux and spectral variability and its broad-band spectral emission with observations from H.E.S.S., Fermi-LAT, Swift-XRT, and UVOT taken in November 2018. The H.E.S.S. light curve above 200 GeV shows an outburst in the first night of observations followed by a declining flux with a halving time scale of 5.9h. The -opacity constrains the upper limit of the angle between the jet and the line of sight to . The broad-band spectral energy distribution shows two humps and can be well fitted with a single-zone synchrotron self Compton emission model. We conclude that PKS 0625-354, as an object showing clear features of both blazars and radio galaxies, can be classified as an intermediate active galactic nuclei. Multi-wavelength studies of such intermediate objects exhibiting features of both blazars and radio galaxies are sparse but crucial for the understanding of the broad-band emission of -ray detected active galactic nuclei in general.
Evidence for gamma-ray emission from the remnant of Kepler's supernova based on deep H.E.S.S. observations (vol 662, artn A65, 2022)
Authors
HESS Collaboration,F Aharonian,F Ait Benkhali,EO Anguner,H Ashkar,M Backes,V Barbosa Martins,R Batzofin,Y Becherini,D Berge,K Bernloehr,M Boettcher,C Boisson,J Bolmont,M de Lavergne,M Breuhaus,R Brose,F Brun,T Bulik,T Bylund,F Cangemi,S Caroff,S Casanova,M Cerruti,T Chand,A Chen,O Chibueze,G Cotter,P Cristofari,J Mbarubucyeye,J Devin,A Djannati-Atai,A Dmytriiev,K Egberts,S Einecke,J-P Ernenwein,K Feijen,A Fiasson,G Fichet de Clairfontaine,G Fontaine,S Funk,S Gabici,YA Gallant,S Ghafourizadeh,G Giavitto,L Giunti,D Glawion,JF Glicenstein,M-H Grondin,M Hoerbe,W Hofmann,TL Holch,M Holler,D Horns,Zhiqiu Huang,M Jamrozy,V Joshi,I Jung-Richardt,E Kasai,K Katarzynski,U Katz,B Khelifi,W Kluzniak,Nu Komin,K Kosack,D Kostunin,A Lemiere,M Lemoine-Goumard,J-P Lenain,F Leuschner,T Lohse,A Luashvili,I Lypova,J Mackey,D Malyshev,V Marandon,P Marchegiani,A Marcowith,G Marti-Devesa,R Marx,G Maurin,PJ Meintjes,M Meyer,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,J Muller,K Nakashima,M de Naurois,A Nayerhoda,J Niemiec,A Priyana Noel,P O'Brien,S Ohm,L Olivera-Nieto,E Wilhelmi,M Ostrowski,S Panny,M Panter,RD Parsons,G Peron,V Poireau,DA Prokhorov,G Puehlhofer,M Punch,A Quirrenbach,P Reichherzer,A Reimer,O Reimer,M Renaud,B Reville,F Rieger,G Rowell,B Rudak,H Rueda Ricarte,V Sahakian,S Sailer,H Salzmann,DA Sanchez,A Santangelo,M Sasaki,J Schafer,F Schussler,HM Schutte,U Schwanke,JNS Shapopi,R Simoni,H Sol,A Specovius,S Spencer,L Stawarz,S Steinmassl,C Steppa,I Sushch,T Takahashi,T Tanaka,AM Taylor,R Terrier,M Tsirou,Y Uchiyama,T Unbehaun,C van Eldik,J Veh,J Vink,HJ Voelk,SJ Wagner,F Werner,R White
Journal
arXiv preprint arXiv:2201.05839
Published Date
2022/1/15
Observations with imaging atmospheric Cherenkov telescopes (IACTs) have enhanced our knowledge of nearby supernova (SN) remnants with ages younger than 500 years by establishing Cassiopeia A and the remnant of Tycho's SN as very-high-energy (VHE) gamma-ray sources. The remnant of Kepler's SN, which is the product of the most recent naked-eye supernova in our Galaxy, is comparable in age to the other two, but is significantly more distant. If the gamma-ray luminosities of the remnants of Tycho's and Kepler's SNe are similar, then the latter is expected to be one of the faintest gamma-ray sources within reach of the current generation IACT arrays. Here we report evidence at a statistical level of 4.6 sigma for a VHE signal from the remnant of Kepler's SN based on deep observations by the High Energy Stereoscopic System (H.E.S.S.) with an exposure of 152 hours. The measured integral flux above an energy of 226 GeV is ~0.3% of the flux of the Crab Nebula. The spectral energy distribution (SED) reveals a gamma-ray emitting component connecting the VHE emission observed with H.E.S.S. to the emission observed at GeV energies with Fermi-LAT. The overall SED is similar to that of the remnant of Tycho's SN, possibly indicating the same non-thermal emission processes acting in both these young remnants of thermonuclear SNe.
Fermi-GBM discovery of GRB 221009A: An extraordinarily bright GRB from onset to afterglow
Authors
S Lesage,P Veres,MS Briggs,A Goldstein,D Kocevski,E Burns,CA Wilson-Hodge,PN Bhat,D Huppenkothen,CL Fryer,R Hamburg,J Racusin,E Bissaldi,WH Cleveland,S Dalessi,C Fletcher,MM Giles,BA Hristov,CM Hui,B Mailyan,C Malacaria,S Poolakkil,OJ Roberts,A von Kienlin,J Wood,M Ajello,M Arimoto,L Baldini,J Ballet,MG Baring,D Bastieri,J Becerra Gonzalez,R Bellazzini,RD Blandford,R Bonino,P Bruel,S Buson,RA Cameron,R Caputo,PA Caraveo,E Cavazzuti,G Chiaro,N Cibrario,S Ciprini,P Cristarella Orestano,M Crnogorcevic,A Cuoco,S Cutini,F D’Ammando,S De Gaetano,N Di Lalla,L Di Venere,A Dominguez,SJ Fegan,EC Ferrara,H Fleischhack,Y Fukazawa,S Funk,P Fusco,G Galanti,V Gammaldi,F Gargano,C Gasbarra,D Gasparrini,S Germani,F Giacchino,N Giglietto,R Gill,M Giroletti,J Granot,D Green,IA Grenier,S Guiriec,M Gustafsson,E Hays,JW Hewitt,D Horan,X Hou,M Kuss,L Latronico,A Laviron,M Lemoine-Goumard,J Li,I Liodakis,F Longo,F Loparco,L Lorusso,MN Lovellette,P Lubrano,S Maldera,A Manfreda,G Marti-Devesa,MN Mazziotta,JE McEnery,I Mereu,M Meyer,PF Michelson,T Mizuno,ME Monzani,A Morselli,IV Moskalenko,M Negro,E Nuss,N Omodei,E Orlando,JF Ormes,D Paneque,G Panzarini,M Persic,M Pesce-Rollins,R Pillera,F Piron,H Poon,TA Porter,G Principe,S Rainò,R Rando,B Rani,M Razzano,S Razzaque,A Reimer,O Reimer,F Ryde,M Sánchez-Conde,PM Saz Parkinson,L Scotton,D Serini,C Sgrò,V Sharma,EJ Siskind,G Spandre,P Spinelli,H Tajima,DF Torres,J Valverde,T Venters,Z Wadiasingh,K Wood,G Zaharijas
Journal
The Astrophysical Journal Letters
Published Date
2023/8/3
We report the discovery of GRB 221009A, the highest flux gamma-ray burst (GRB) ever observed by the Fermi Gamma-ray Burst Monitor (Fermi-GBM). This GRB has continuous prompt emission lasting more than 600 s, which smoothly transitions to afterglow emission visible in the Fermi-GBM energy range (8 keV–40 MeV), and total energetics higher than any other burst in the Fermi-GBM sample. By using a variety of new and existing analysis techniques we probe the spectral and temporal evolution of GRB 221009A. We find no emission prior to the Fermi-GBM trigger time (t 0; 2022 October 9 at 13: 16: 59.99 UTC), indicating that this is the time of prompt emission onset. The triggering pulse exhibits distinct spectral and temporal properties suggestive of the thermal, photospheric emission of shock breakout, with significant emission up to∼ 15 MeV. We characterize the onset of external shock at t 0+ 600 s and find …
Constraints on the intergalactic magnetic field using Fermi-LAT and HESS blazar observations
Authors
F Aharonian,J Aschersleben,M Backes,V Barbosa Martins,R Batzofin,Yvonne Becherini,D Berge,B Bi,M Bouyahiaoui,M Breuhaus,R Brose,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,Tomas Bylund,S Caroff,S Casanova,J Celic,M Cerruti,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,G Cotter,M De Bony,K Egberts,J-P Ernenwein,G Fichet De Clairfontaine,Miroslav Filipovic,G Fontaine,M Füssling,S Funk,S Gabici,S Ghafourizadeh,G Giavitto,D Glawion,JF Glicenstein,P Goswami,M-H Grondin,L Haerer,TL Holch,M Holler,D Horns,Marek Jamrozy,F Jankowsky,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,R Khatoon,B Khélifi,W Kluźniak,Nu Komin,K Kosack,D Kostunin,RG Lang,S Le Stum,F Leitl,A Lemière,J-P Lenain,F Leuschner,T Lohse,A Luashvili,I Lypova,J Mackey,D Malyshev,V Marandon,P Marchegiani,A Marcowith,G Martí-Devesa,R Marx,M Meyer,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,J Muller,T Murach,K Nakashima,J Niemiec,S Ohm,L Olivera-Nieto,E de Ona Wilhelmi,S Panny,M Panter,RD Parsons,G Peron,DA Prokhorov,H Prokoph,G Pühlhofer,M Punch,A Quirrenbach,P Reichherzer,A Reimer,O Reimer,B Reville,F Rieger,G Rowell,B Rudak,E Ruiz-Velasco,V Sahakian,DA Sanchez,M Sasaki,F Schüssler,HM Schutte,U Schwanke,JNS Shapopi,H Sol,S Spencer,S Steinmassl,H Suzuki,T Takahashi,T Tanaka,AM Taylor,R Terrier,C Thorpe-Morgan,M Tsirou,N Tsuji,Y Uchiyama,C Van Eldik,J Veh,C Venter,SJ Wagner,R White,Alicja Wierzcholska,Yu Wun Wong,M Zacharias,D Zargaryan,AA Zdziarski,S Zouari,N Żywucka,HESS Collaboration,Fermi-LAT Collaboration
Journal
The Astrophysical Journal Letters
Published Date
2023/6/21
Magnetic fields in galaxies and galaxy clusters are believed to be the result of the amplification of intergalactic seed fields during the formation of large-scale structures in the universe. However, the origin, strength, and morphology of this intergalactic magnetic field (IGMF) remain unknown. Lower limits on (or indirect detection of) the IGMF can be obtained from observations of high-energy gamma rays from distant blazars. Gamma rays interact with the extragalactic background light to produce electron− positron pairs, which can subsequently initiate electromagnetic cascades. The gamma-ray signature of the cascade depends on the IGMF since it deflects the pairs. Here we report on a new search for this cascade emission using a combined data set from the Fermi Large Area Telescope and the High Energy Stereoscopic System. Using state-of-the-art Monte Carlo predictions for the cascade signal, our results place …
HESS follow-up observations of GRB221009A
Authors
HESS Collaboration,F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,A Baktash,V Barbosa Martins,R Batzofin,Y Becherini,D Berge,K Bernlöhr,B Bi,M Böttcher,C Boisson,J Bolmont,M de Lavergne,J Borowska,M Bouyahiaoui,F Bradascio,M Breuhaus,R Brose,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,S Caroff,S Casanova,J Celic,M Cerruti,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,G Cotter,S Dai,J Mbarubucyeye,J Devin,A Djannati-Ataï,A Dmytriiev,V Doroshenko,K Egberts,S Einecke,J-P Ernenwein,S Fegan,G Fichet de Clairfontaine,M Filipovic,G Fontaine,M Füßling,S Funk,S Gabici,S Ghafourizadeh,G Giavitto,D Glawion,JF Glicenstein,P Goswami,G Grolleron,M-H Hinton,TL Holch,M Holler,D Horns,Zhiqiu Huang,M Jamrozy,F Jankowsky,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,R Khatoon,B Khélifi,W Kluźniak,Nu Komin,R Konno,K Kosack,D Kostunin,RG Lang,S Le Stum,F Leitl,A Lemière,M Lemoine-Goumard,JP Lenain,F Leuschner,T Lohse,I Lypova,J Mackey,D Malyshev,V Marandon,P Marchegiani,A Marcowith,G Martí-Devesa,R Marx,M Meyer,A Mitchell,L Mohrmann,A Montanari,E Moulin,T Murach,K Nakashima,M de Naurois,J Niemiec,A Priyana Noel,P O'Brien,S Ohm,L Olivera-Nieto,E Wilhelmi,M Ostrowski,S Panny,M Panter,RD Parsons,G Peron,DA Prokhorov,H Prokoph,G Pühlhofer,M Punch,A Quirrenbach,P Reichherzer,A Reimer,O Reimer,H Ren,M Renaud,B Reville,F Rieger,G Rowell,B Rudak,E Ruiz-Velasco,V Sahakian,H Salzmann,A Santangelo,M Sasaki,J Schäfer,F Schüssler,HM Schutte,U Schwanke,JNS Shapopi,A Specovius,S Spencer,Ł Stawarz,R Steenkamp,S Steinmassl,C Steppa,I Sushch,H Suzuki,T Takahashi,T Tanaka,R Terrier,N Tsuji,Y Uchiyama,M Vecchi,C Venter
Journal
arXiv preprint arXiv:2303.10558
Published Date
2023/3/19
GRB221009A is the brightest gamma-ray burst ever detected. To probe the very-high-energy (VHE, \!100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hours after the triggering event, when the brightness of the moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from the third, fourth, and ninth nights after the initial GRB detection, after applying atmospheric corrections. The combined observations yield an integral energy flux upper limit of above GeV. The constraints derived from the H.E.S.S. observations complement the available multiwavelength data. The radio to X-ray data are consistent with synchrotron emission from a single electron population, with the peak in the SED occurring above the X-ray band. Compared to the VHE-bright GRB190829A, the upper limits for GRB221009A imply a smaller gamma-ray to X-ray flux ratio in the afterglow. Even in the absence of a detection, the H.E.S.S. upper limits thus contribute to the multiwavelength picture of GRB221009A, effectively ruling out an IC dominated scenario.
Chasing Gravitational Waves with the Chereknov Telescope Array
Authors
Jarred Gershon Green,Monica Seglar-Arroyo,Cta Consortium,Kazuki Abe,Shotaro Abe,Atreya Acharyya,Remi Adam,Arnau Aguasca-Cabot,Ivan Agudo,Jorge Alfaro,Nuria Alvarez-Crespo,Rafael Alves Batista,Jean-Philippe Amans,Elena Amato,Filippo Ambrosino,Ekrem Oguzhan Angüner,Lucio Angelo Antonelli,Carla Aramo,Cornelia Arcaro,Luisa Arrabito,Katsuaki Asano,Jann Aschersleben,Halim Ashkar,Luiz Augusto Stuani,Dominik Baack,Michael Backes,Csaba Balazs,Matteo Balbo,Andres Baquero Larriva,Victor Barbosa Martins,Ulisses Barres de Almeida,Juan Abel Barrio,Denis Bastieri,Pedro Ivo Batista,Ivana Batković,Rowan William Batzofin,Joshua Ryo Baxter,Geoffrey Beck,Julia Becker Tjus,Lukas Beiske,Daniele Belardinelli,Wystan Benbow,Elisa Bernardini,Juan Bernete Medrano,Konrad Bernlöhr,Alessio Berti,Vasyl Beshley,Pooja Bhattacharjee,Saptashwa Bhattacharyya,Baiyang Bi,Noah Biederbeck,Adrian Biland,Elisabetta Bissaldi,Oscar Blanch,Jiri Blazek,Catherine Boisson,Julien Bolmont,Giacomo Bonnoli,Pol Bordas,Željka Bošnjak,Federica Bradascio,Catherine Braiding,Ettore Bronzini,Robert Brose,Anthony M Brown,Francois Brun,Giulia Brunelli,Andrea Bulgarelli,Irene Burelli,Leonid Burmistrov,Michael Burton,Tomas Bylund,Paolo Gherardo Calisse,Anna Campoy-Ordaz,Brandon Khan Cantlay,Milvia Capalbi,Anderson Caproni,Roberto Capuzzo-Dolcetta,Colin Carlile,Sami Caroff,Alessandro Carosi,Roberto Carosi,Marie-Sophie Carrasco,Enrico Cascone,Franca Cassol,Noelia Castrejon,Fernando Catalani,Davide Cerasole,Matteo Cerruti,Sylvain Chaty,Andrew W Chen,Maria Chernyakova,Andrea Chiavassa,Jiří Chudoba,Carlos Henrique Coimbra Araujo,Vito Conforti,Francesco Conte,Jose Luis Contreras,Christophe Cossou,Alessandro Costa,Heide Costantini,Pierre Cristofari,Omar Cuevas,Zachary Curtis-Ginsberg,Giacomo D'Amico,Filippo D'Ammando,Mauro Dadina,Mykhailo Dalchenko,Ludovic David,Isak Delberth Davids,Francesco Dazzi,Alessandro De Angelis,Mathieu de Bony de Lavergne,Vincenzo De Caprio,Giovanni De Cesare,Elisabete M Pino,Barbara De Lotto,Mario de Lucia,Raniere de Menezes,Mathieu de Naurois,Emma de Oña Wilhelmi,Nicola De Simone,Vitor de Souza,Luis Del Peral,Maria Victoria del Valle,Eric Delagnes,Andres Gabriel Delgado Giler,Carlos Delgado,Michael Dell'aiera,Roberto Della Ceca,Massimo Della Valle,Davide Depaoli,Antonios Dettlaff,Tristano Di Girolamo,Ambra Di Piano,Federico Di Pierro,Riccardo Di Tria,Leonardo Di Venere,Christian Díaz-Bahamondes,Claudio Dib,Sebastian Diebold,Razvan Dima,Adithiya Dinesh,Arache Djannati-Ataï,Julia Isabel Djuvsland,Alberto Dominguez,Rune Michael Dominik,Alice Donini,Daniela Dorner,Julien Dörner
Journal
arXiv preprint arXiv:2310.07413
Published Date
2023/10/11
The detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a gravitational wave signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. New observing modes and follow-up strategies are being developed for CTA to rapidly cover localization areas of gravitational wave events that are typically larger than the CTA field of view. This work will evaluate and provide estimations on the expected number of of gravitational wave events that will be observable with CTA, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA.
The Speed of Sound in Methane under Conditions of the Thermal Boundary Layer of Uranus
Authors
Thomas G White,Hannah Poole,Emma E McBride,Matthew Oliver,Adrien Descamps,Luke B Fletcher,W Alex Angermeier,Cameron H Allen,Karen Appel,Florian P Condamine,Chandra B Curry,Francesco Dallari,Stefan Funk,Eric Galtier,Eliseo J Gamboa,Maxence Gauthier,Peter Graham,Sebastian Goede,Daniel Haden,Jongjin B Kim,Hae Ja Lee,Benjamin K Ofori-Okai,Scott Richardson,Alex Rigby,Christopher Schoenwaelder,Peihao Sun,Bastian L Witte,Thomas Tschentscher,Ulf Zastrau,Bob Nagler,Jerome Hastings,Giulio Monaco,Dirk O Gericke,Siegfried H Glenzer,Gianluca Gregori
Journal
arXiv preprint arXiv:2311.07774
Published Date
2023/11/13
We present the first direct observations of acoustic waves in warm dense matter. We analyze wavenumber- and energy-resolved X-ray spectra taken from warm dense methane created by laser-heating a cryogenic liquid jet. X-ray diffraction and inelastic free electron scattering yield sample conditions of 0.30.1 eV and 0.80.1 g/cm, corresponding to a pressure of 13 GPa and matching the conditions predicted in the thermal boundary layer between the inner and outer envelope of Uranus. Inelastic X-ray scattering was used to observe the collective oscillations of the ions. With a highly improved energy resolution of 50 meV, we could clearly distinguish the Brillouin peaks from the quasi-elastic Rayleigh feature. Data at different wavenumbers were used to obtain a sound speed of 5.90.5 km/s, which enabled us to validate the use of Birch's law in this new parameter regime.
The Vanishing of the Primary Emission Region in PKS 1510–089
Authors
F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,V Barbosa Martins,J Barnard,R Batzofin,Yvonne Becherini,D Berge,K Bernlöhr,B Bi,M de Bony de Lavergne,M Böttcher,C Boisson,J Bolmont,J Borowska,M Bouyahiaoui,F Bradascio,M Breuhaus,R Brose,AM Brown,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,S Caroff,S Casanova,R Cecil,J Celic,M Cerruti,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,G Cotter,J Damascene Mbarubucyeye,ID Davids,A Djannati-Atai,A Dmytriiev,V Doroshenko,K Egberts,S Einecke,J-P Ernenwein,S Fegan,G Fontaine,M Fuessling,S Funk,S Gabici,S Ghafourizadeh,G Giavitto,D Glawion,JF Glicenstein,P Goswami,G Grolleron,L Haerer,W Hofmann,TL Holch,M Holler,D Horns,Marek Jamrozy,F Jankowsky,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,R Khatoon,B Khelifi,W Kluźniak,Nu Komin,K Kosack,D Kostunin,RG Lang,S Le Stum,F Leitl,A Lemière,J-P Lenain,F Leuschner,A Luashvili,J Mackey,V Marandon,P Marchegiani,G Martí-Devesa,R Marx,A Mehta,M Meyer,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,M de Naurois,J Niemiec,A Priyana Noel,P O’Brien,S Ohm,L Olivera-Nieto,E de Ona Wilhelmi,Michał Ostrowski,S Panny,M Panter,G Peron,DA Prokhorov,G Pühlhofer,M Punch,A Quirrenbach,P Reichherzer,A Reimer,O Reimer,H Ren,F Rieger,G Rowell,B Rudak,H Rueda Ricarte,E Ruiz-Velasco,V Sahakian,H Salzmann,DA Sanchez,A Santangelo,M Sasaki,F Schüssler,HM Schutte,U Schwanke,JNS Shapopi,H Sol,A Specovius,S Spencer,R Steenkamp,S Steinmassl,C Steppa,I Sushch,H Suzuki,T Takahashi,T Tanaka,R Terrier,N Tsuji,C van Eldik,B van Soelen,M Vecchi,J Veh,J Vink,T Wach,SJ Wagner,A Wierzcholska,M Zacharias,D Zargaryan,AA Zdziarski,A Zech,S Zouari
Journal
The Astrophysical Journal Letters
Published Date
2023/8/1
In 2021 July, PKS 1510− 089 exhibited a significant flux drop in the high-energy γ-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. Similarly, the optical polarization in the source vanished, resulting in the optical spectrum being fully explained through the steady flux of the accretion disk and the broad-line region. Unlike the aforementioned bands, the very-high-energy γ-ray and X-ray fluxes did not exhibit a significant flux drop from year to year. This suggests that the steady-state very-high-energy γ-ray and X-ray fluxes originate from a different emission region than the vanished parts of the high-energy γ-ray and optical jet fluxes. The latter component has disappeared through either a swing of the jet away from the line of sight or a significant drop in the photon production efficiency of the jet close to the black hole. Either change could become visible in high …
Detection of extended γ-ray emission around the Geminga pulsar with HESS
Authors
F Aharonian,F Ait Benkhali,J Aschersleben,H Ashkar,M Backes,V Barbosa Martins,R Batzofin,Yvonne Becherini,D Berge,K Bernlöhr,B Bi,M Böttcher,C Boisson,J Bolmont,J Borowska,M Bouyahiaoui,F Bradascio,R Brose,F Brun,B Bruno,T Bulik,C Burger-Scheidlin,F Cangemi,S Caroff,S Casanova,J Celic,M Cerruti,P Chambery,T Chand,S Chandra,A Chen,J Chibueze,O Chibueze,G Cotter,J Damascene Mbarubucyeye,J Devin,A Djannati-Ataï,A Dmytriiev,K Egberts,S Einecke,J-P Ernenwein,K Feijen,G Fichet De Clairfontaine,Miroslav Filipovic,G Fontaine,M Füßling,S Funk,S Gabici,YA Gallant,S Ghafourizadeh,G Giavitto,L Giunti,D Glawion,JF Glicenstein,P Goswami,G Grolleron,M-H Grondin,L Haerer,M Haupt,G Hermann,JA Hinton,W Hofmann,TL Holch,M Holler,D Horns,Zhiqiu Huang,Marek Jamrozy,F Jankowsky,V Joshi,I Jung-Richardt,E Kasai,K Katarzyński,B Khélifi,W Kluźniak,Nu Komin,K Kosack,D Kostunin,RG Lang,S Le Stum,F Leitl,A Lemière,M Lemoine-Goumard,J-P Lenain,F Leuschner,T Lohse,A Luashvili,I Lypova,J Mackey,D Malyshev,V Marandon,P Marchegiani,A Marcowith,P Marinos,G Martí-Devesa,R Marx,G Maurin,PJ Meintjes,M Meyer,A Mitchell,R Moderski,L Mohrmann,A Montanari,E Moulin,J Muller,K Nakashima,M de Naurois,J Niemiec,A Priyana Noel,P O’Brien,S Ohm,L Olivera-Nieto,E de Ona Wilhelmi,Michał Ostrowski,S Panny,M Panter,RD Parsons,G Peron,DA Prokhorov,G Pühlhofer,A Quirrenbach,A Reimer,O Reimer,M Renaud,B Reville,F Rieger,G Rowell,B Rudak,H Rueda Ricarte,E Ruiz-Velasco,V Sahakian,H Salzmann,A Santangelo,M Sasaki,F Schüssler,HM Schutte,U Schwanke,JNS Shapopi,A Sinha,H Sol,A Specovius,S Spencer,S Steinmassl,I Sushch,H Suzuki,T Takahashi,T Tanaka,T Tavernier,AM Taylor,R Terrier,C Thorpe-Morgan
Journal
Astronomy & Astrophysics
Published Date
2023/5/1
Geminga is an enigmatic radio-quiet γ-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy γ-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are both water Cherenkov detector-based experiments. However, evidence for the Geminga pulsar wind nebula in gamma rays has long evaded detection by imaging atmospheric Cherenkov telescopes (IACTs) despite targeted observations. The detection of γ-ray emission on angular scales ≳2º poses a considerable challenge for the background estimation in IACT data analysis. With recent developments in understanding the complementary background estimation techniques of water Cherenkov and atmospheric Cherenkov instruments, the H.E.S.S. IACT array can now confirm the detection of highly extended γ-ray emission around the Geminga pulsar with a radius of at least 3º in the energy …
VizieR Online Data Catalog: Fermi cat. of High-lat. Extended Sources (FHES)(Ackermann+, 2018)
Authors
M Ackermann,M Ajello,L Baldini,J Ballet,G Barbiellini,D Bastieri,R Bellazzini,E Bissaldi,RD Blandford,ED Bloom,R Bonino,E Bottacini,TJ Brandt,J Bregeon,P Bruel,R Buehler,RA Cameron,R Caputo,PA Caraveo,D Castro,E Cavazzuti,E Charles,CC Cheung,G Chiaro,S Ciprini,J Cohen-Tanugi,D Costantin,S Cutini,F D'Ammando,F de Palma,A Desai,N di Lalla,M di Mauro,L di Venere,C Favuzzi,J Finke,A Franckowiak,Y Fukazawa,S Funk,P Fusco,F Gargano,D Gasparrini,N Giglietto,F Giordano,M Giroletti,D Green,IA Grenier,L Guillemot,S Guiriec,E Hays,JW Hewitt,D Horan,G Johannesson,S Kensei,M Kuss,S Larsson,L Latronico,M Lemoine-Goumard,J Li,F Longo,F Loparco,MN Lovellette,P Lubrano,JD Magill,S Maldera,A Manfreda,MN Mazziotta,JE McEnery,M Meyer,T Mizuno,ME Monzani,A Morselli,IV Moskalenko,M Negro,E Nuss,N Omodei,M Orienti,E Orlando,M Palatiello,VS Paliya,D Paneque,JS Perkins,M Persic,M Pesce-Rollins,F Piron,TA Porter,G Principe,S Raino,R Rando,B Rani,S Razzaque,A Reimer,O Reimer,T Reposeur,C Sgro,EJ Siskind,G Spandre,P Spinelli,DJ Suson,H Tajima,JB Thayer,L Tibaldo,DF Torres,G Tosti,J Valverde,TM Venters,M Vogel,K Wood,M Wood,G Zaharijas,J Biteau,Fermi-Lat Collaboration
Journal
VizieR Online Data Catalog
Published Date
2023/10
We report here on the Fermi High-Latitude Extended Sources Catalog (FHES), a comprehensive search for spatially extended γ-ray sources above 5 Galactic latitude using 7.5 yrs of Pass 8 data above 1GeV.
Validating Monte Carlo simulations for an analysis chain in HESS
Authors
Fabian Leuschner,Johannes Schäfer,Simon Steinmassl,Tim Lukas Holch,Konrad Bernlöhr,Stefan Funk,Jim Hinton,Stefan Ohm,Gerd Pühlhofer
Journal
arXiv preprint arXiv:2303.00412
Published Date
2023/3/1
Imaging Air Cherenkov Telescopes (IACTs) detect very high energetic (VHE) gamma rays. They observe the Cherenkov light emitted in electromagnetic shower cascades that gamma rays induce in the atmosphere. A precise reconstruction of the primary photon energy and the source flux depends heavily on accurate Monte Carlo (MC) simulations of the shower propagation and the detector response, and therefore also on adequate assumptions about the atmosphere at the site and time of a measurement. Here, we present the results of an extensive validation of the MC simulations for an analysis chain of the H.E.S.S. experiment with special focus on the recently installed FlashCam camera on the large 28 m telescope. One goal of this work was to create a flexible and easy-to-use framework to facilitate the detailed validation of MC simulations also for past and future phases of the H.E.S.S. experiment. Guided by the underlying physics, the detector simulation and the atmospheric transmission profiles were gradually improved until low level parameters such as cosmic ray (CR) trigger rates matched within a few percent between simulations and observational data. This led to instrument response functions (IRFs) with which the analysis of current H.E.S.S. data can ultimately be carried out within percent accuracy, substantially improving earlier simulations.
Application of graph networks to background rejection in Imaging Air Cherenkov Telescopes
Authors
Jonas Glombitza,Vikas Joshi,Benedetta Bruno,Stefan Funk
Journal
Journal of Cosmology and Astroparticle Physics
Published Date
2023/11/6
Imaging Air Cherenkov Telescopes (IACTs) are essential to ground-based observations of gamma rays in the GeV to TeV regime. One particular challenge of ground-based gamma-ray astronomy is an effective rejection of the hadronic background. We propose a new deep-learning-based algorithm for classifying images measured using single or multiple Imaging Air Cherenkov Telescopes. We interpret the detected images as a collection of triggered sensors that can be represented by graphs and analyzed by graph convolutional networks. For images cleaned of the light from the night sky, this allows for an efficient algorithm design that bypasses the challenge of sparse images in deep learning approaches based on computer vision techniques such as convolutional neural networks. We investigate different graph network architectures and find a promising performance with improvements to previous machine …
Stefan Funk FAQs
What is Stefan Funk's h-index at Friedrich-Alexander-Universität Erlangen-Nürnberg?
The h-index of Stefan Funk has been 78 since 2020 and 156 in total.
What are Stefan Funk's top articles?
The articles with the titles of
Evidence for γ-ray emission from the remnant of Kepler’s supernova based on deep HESS observations (Corrigendum)
Speed of sound in methane under conditions of planetary interiors
Curvature in the very-high energy gamma-ray spectrum of M87
Ultra-fast generation of air shower images for Imaging Air Cherenkov Telescopes using Generative Adversarial Networks
Unveiling extended gamma-ray emission around HESS J1813-178
First intensity interferometry measurements with the HESS telescopes
Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433
Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and HESS analysis
...
are the top articles of Stefan Funk at Friedrich-Alexander-Universität Erlangen-Nürnberg.
What is Stefan Funk's total number of citations?
Stefan Funk has 89,326 citations in total.
Useful Links