Gamma-ray observations of MAXI J1820+070 during the 2018 outburst
Authors: Abe H , Abe S , Acciari V A , Aniello T , Ansoldi S , Antonelli L A , Arbet Engels A , Arcaro C , Artero M , Asano K , Baack D , Babić A , Baquero A , Barres de Almeida U , Barrio J A , Batković I , Baxter J , Becerra González J , Bednarek W , Bernardini E , Bernardos M , Berti A , Besenrieder J , Bhattacharyya W , Bigongiari C , Biland A , Blanch O , Bonnoli G , Bošnjak Ž , Burelli I , Busetto G , Carosi R , Carretero-Castrillo M , Ceribella G , Chai Y , Chilingarian A , Cikota S , Colombo E , Contreras J L , Cortina J , Covino S , D’Amico G , D’Elia V , Da Vela P , Dazzi F , De Angelis A , De Lotto B , Del Popolo A , Delfino M , Delgado J , Delgado Mendez C , Depaoli D , Di Pierro F , Di Venere L , Dominis Prester D , Donini A , Dorner D , Doro M , Elsaesser D , Emery G , Fallah Ramazani V , Fariña L , Fattorini A , Font L , Fruck C , Fukami S , Fukazawa Y , García López R J , Garczarczyk M , Gasparyan S , Gaug M , Giesbrecht Paiva J G , Giglietto N , Giordano F , Gliwny P , Godinović N , Grau R , Green D , Green J G , Hadasch D , Hahn A , Hassan T , Heckmann L , Herrera J , Hoang J , Hrupec D , Hütten M , Imazawa R , Inada T , Iotov R , Ishio K , Jiménez Martínez I , Jormanainen J , Kerszberg D , Kobayashi Y , Kubo H , Kushida J , Lamastra A , Lelas D , Leone F , Lindfors E , Linhoff L , Lombardi S , Longo F , López-Coto R , López-Moya M , López-Oramas A , Loporchio S , Lorini A , Lyard E , Fraga B Machado de Oliveira , Majumdar P , Makariev M , Maneva G , Mang N , Manganaro M , Mangano S , Mannheim K , Mariotti M , Martínez M , Mas Aguilar A , Mazin D , Menchiari S , Mender S , Mićanović S , Miceli D , Miener T , Miranda J M , Mirzoyan R , Molina E , Mondal H A , Moralejo A , Morcuende D , Moreno V , Nakamori T , Nanci C , Nava L , Neustroev V , Nievas Rosillo M , Nigro C , Nilsson K , Nishijima K , Njoh Ekoume T , Noda K , Nozaki S , Ohtani Y , Oka T , Okumura A , Otero-Santos J , Paiano S , Palatiello M , Paneque D , Paoletti R , Paredes J M , Pavletić L , Persic M , Pihet M , Pirola G , Podobnik F , Prada Moroni P G , Prandini E , Principe G , Priyadarshi C , Puljak I , Rhode W , Ribó M , Rico J , Righi C , Rugliancich A , Sahakyan N , Saito T , Sakurai S , Satalecka K , Saturni F G , Schleicher B , Schmidt K , Schmuckermaier F , Schubert J L , Schweizer T , Sitarek J , Sliusar V , Sobczynska D , Spolon A , Stamerra A , Strišković J , Strom D , Strzys M , Suda Y , Surić T , Tajima H , Takahashi M , Takeishi R , Tavecchio F , Temnikov P , Terauchi K , Terzić T , Teshima M , Tosti L , Truzzi S , Tutone A , Ubach S , van Scherpenberg J , Vazquez Acosta M , Ventura S , Verguilov V , Viale I , Vigorito C F , Vitale V , Vovk I , Walter R , Will M , Wunderlich C , Yamamoto T , Zarić D ,   The MAGIC Collaboration, Abdalla H , Aharonian F , Ait Benkhali F , Angüner E O , Ashkar H , Backes M , Baghmanyan V , Barbosa Martins V , Batzofin R , Becherini Y , Berge D , Bernlöhr K , Böttcher M , Boisson C , Bolmont J , de Bony de Lavergne M , Bradascio F , Breuhaus M , Brose R , Brun F , Bulik T , Bylund T , Cangemi F , Caroff S , Casanova S , Cerruti M , Chand T , Chandra S , Chen A , Chibueze O U , Cotter G , Cristofari P , Damascene Mbarubucyeye J , Devin J , Djannati-Ataï A , Dmytriiev A , Egberts K , Ernenwein J-P , Fiasson A , Fichet de Clairfontaine G , Fontaine G , Füßling M , Funk S , Gabici S , Ghafourizadeh S , Giavitto G , Glawion D , Glicenstein J F , Goswami P , Grolleron G , Hinton J A , Hörbe M , Hoischen C , Holch T L , Holler M , Horns D , Huang Zhiqiu , Jamrozy M , Jankowsky F , Joshi V , Jung-Richardt I , Kasai E , Katarzyński K , Katz U , Khélifi B , Kluźniak W , Komin Nu , Kosack K , Kostunin D , Lang R G , Le Stum S , Lemière A , Lemoine-Goumard M , Lenain J-P , Leuschner F , Lohse T , Luashvili A , Lypova I , Mackey J , Majumdar J , Malyshev D , Malyshev D , Marandon V , Marchegiani P , Martí-Devesa G , Marx R , Maurin G , Meyer M , Mitchell A , Moderski R , Mohrmann L , Montanari A , Moulin E , Muller J , Murach T , Nakashima K , de Naurois M , Nayerhoda A , Niemiec J , Priyana Noel A , O’Brien P , Ohm S , Olivera-Nieto L , de Ona Wilhelmi E , Ostrowski M , Panny S , Panter M , Parsons R D , Poireau V , Prokhorov D A , Prokoph H , Pühlhofer G , Punch M , Quirrenbach A , Reichherzer P , Reimer A , Reimer O , Renaud M , Rieger F , Rowell G , Rudak B , Rueda Ricarte H , Ruiz-Velasco E , Sahakian V , Salzmann H , Santangelo A , Sasaki M , Schäfer J , Schüssler F , Schutte H M , Schwanke U , Shapopi J N S , Sol H , Specovius A , Spencer S , Stawarz Ł , Steenkamp R , Steinmassl S , Steppa C , Sushch I , Suzuki H , Takahashi T , Tanaka T , Thorpe-Morgan C , Tluczykont M , Tomankova L , Tsuji N , Uchiyama Y , van Eldik C , van Soelen B , Vecchi M , Veh J , Venter C , Vink J , Wagner S J , White R , Wierzcholska A , Wong Yu Wun , Yusafzai A , Zacharias M , Zanin R , Zargaryan D , Zdziarski A A , Zech A , Zhu S J , Zouari S , Żywucka N ,   The H.E.S.S. Collaboration, Acharyya A , Adams C B , Batista P , Benbow W , Capasso M , Christiansen J L , Chromey A J , Errando M , Falcone A , Feng Q , Finley J P , Foote J M , Fortson L , Furniss A , Gent A , Hanlon W F , Hervet O , Holder J , Hona B , Humensky T B , Jin W , Kaaret P , Kertzman M , Kherlakian M , Kleiner T K , Kumar S , Lang M J , Lundy M , Maier G , McGrath C E , Millis J , Moriarty P , Mukherjee R , O’Brien S , Ong R A , Park N , Patel S R , Pfrang K , Pohl M , Pueschel E , Quinn J , Ragan K , Reynolds P T , Ribeiro D , Roache E , Ryan J L , Sadeh I , Saha L , Santander M , Sembroski G H , Shang R , Splettstoesser M , Tak D , Tucci J V , Weinstein A , Williams D A , Williamson T J ,   The VERITAS Collaboration, Bosch-Ramon V , Celma C , Linares M , Russell D M , Sala G 
Published: September 2022

ABSTRACT
MAXI J1820+070 is a low-mass X-ray binary with a black hole (BH) as a compact object. This binary underwent an exceptionally bright X-ray outburst from 2018 March to October, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 h of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy (HE) gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to ∼500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential HE and very-HE gamma-ray emitting region should be located at a distance from the BH ranging between 1011 and 1013 cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA.