TeV flaring activity of the AGN PKS 0625-354 in November 2018

F Aharonian , F Ait Benkhali , J Aschersleben , H Ashkar (1) , M Backes , A Baktash , V. Barbosa Martins , J Barnard , R Batzofin , Y Becherini (2) , D Berge , K Bernlöhr , B Bi , M Böttcher , C Boisson (3) , J Bolmont (4) , M de Bony de Lavergne (5) , J Borowska , F Bradascio (5) , M Breuhaus , R Brose , A Brown , F Brun (5) , B Bruno , T Bulik , C Burger-Scheidlin , T Bylund (5) , S Caroff (6) , S Casanova , R Cecil , J Celic , M Cerruti (2) , T Chand , S Chandra , A Chen , J Chibueze , O Chibueze , G Cotter , J. Damascene Mbarubucyeye , I.D Davids , J Djuvsland , A Dmytriiev , V Doroshenko , K Egberts , S Einecke , J.-P Ernenwein (7) , G Fontaine (1) , M Füßling , S Funk , S Gabici (2) , S Ghafourizadeh , G Giavitto , D Glawion , J.F Glicenstein (5) , J Glombitza , P Goswami (2) , G Grolleron (4) , L Haerer , J.A Hinton , T.L Holch , M Holler , D Horns , M Jamrozy , F Jankowsky , V Joshi , I Jung-Richardt , E Kasai , K Katarzynski , R Khatoon , B Khélifi (2) , W Klúzniak , Nu Komin , K Kosack (5) , D Kostunin , R.G Lang , S Le Stum (7) , F Leitl , A Lemière (2) , J.-P Lenain (4) , F Leuschner , A Luashvili (3) , J Mackey , R Marx , A Mehta , M Meyer , A Mitchell , R Moderski , A Montanari , E Moulin (5) , M de Naurois (1) , J Niemiec , P O'Brien , S Ohm , L Olivera-Nieto , E de Ona Wilhelmi , M Ostrowski , S Panny , R.D Parsons , S Pita (2) , D.A Prokhorov , G Pühlhofer , M Punch (2) , A Quirrenbach , P Reichherzer (5) , A Reimer , O Reimer , H Ren , F Rieger , B Rudak , V Sahakian , H Salzmann , D.A Sanchez (6) , M Sasaki , F Schüssler (5) , H.M Schutte , J.N.S Shapopi , H Sol (3) , A Specovius , S Spencer , Ł Stawarz , R Steenkamp , S Steinmassl , K Streil , I Sushch , H Suzuki , T Takahashi , T Tanaka , C van Eldik , M Vecchi , J Veh , C Venter , S.J Wagner , A Wierzcholska , M Zacharias , D Zargaryan , A.A Zdziarski , A Zech (3) , S Zouari (2) , N Zywucka

1 LLR - Laboratoire Leprince-Ringuet
2 APC (UMR_7164) - AstroParticule et Cosmologie
3 LUTH (UMR_8102) - Laboratoire Univers et Théories
4 LPNHE (UMR_7585) - Laboratoire de Physique Nucléaire et de Hautes Énergies
5 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
6 LAPP - Laboratoire d'Annecy de Physique des Particules
7 CPPM - Centre de Physique des Particules de Marseille

Most $\gamma$-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 $\gamma$-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 $\gamma\gamma$-opacity constrains the upper limit of the angle between the jet and the line of sight to $\sim10^\circ$. 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 $\gamma$-ray detected active galactic nuclei in general.

Keywords: galaxy; radio wave; jet; relativistic; emission; model; AGN; blazar; spectral; flux; HESS; GeV; variability; spectral energy distribution; GLAST; synchrotron; TeV

Domains: Astrophysics [astro-ph]

F Aharonian, F Ait Benkhali, J Aschersleben, H Ashkar, M Backes, et al.. TeV flaring activity of the AGN PKS 0625-354 in November 2018. Astron.Astrophys., 2024, 683, pp.A70. ⟨10.1051/0004-6361/202348063⟩. ⟨hal-04426010⟩