Abstract Details

Name: Tek Prasad Adhikari
Affiliation: Inter-University Center for Astronomy and Astrophysics, IUCAA, Pune
Conference ID: ASI2021_275
Title : Multiphase medium in the centre of Centaurus A
Authors and Co-Authors : Adhikari, T. P.^(1), Borkar, A.^(2), Różańska, A.^(3), Markowitz, A. G.^(3), Boorman, P.^(2), Czerny, B. ^(4), Migliori, G.^(5), De Marco, B. ^(3), Karas, V.^(2) 1 Inter-University Center for Astronomy and Astrophysics (IUCAA), Pune, India 2 Astronomical Institute, Czech Academy of Sciences, Boční II 1401, CZ-14100 Prague, Czech Republic 3 Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, PL-00-716 Warsaw, Poland 4 Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02-668 Warsaw, Poland 5 Dipartamento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, I-40127 Bologna, Italy
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : We investigate the multiphase medium in the vicinity of the active galactic nucleus Centaurus A (Cen A) by using combined high-resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) and Chandra X-ray Observatory. Our study indicates that the hot X-ray emitting plasma coexists with the warm and cold media in Cen A. We utilize the images from the two instruments covering the nuclear region (diameter of 10 arcsec, i.e. ∼180 pc) to study the conditions for plasma thermal equilibrium and possible coexistence of cool clouds embedded within the hot gas. We show that the multiphase medium originates naturally by the thermal instability induced due to the interaction of the radiation field from the center with the ambient gas and dust. We demonstrate that cold gas clouds can coexist in the mutual contact with hot plasma, but even colder dusty molecular clouds have to be distanced by several hundred pc from the central hot region. We propose a 3D model of the appearance of the hot plasma and the CO line-emitting regions consistent with the Chandra image, and we derive the emissivity in specific molecular lines observed by ALMA from this model. To reproduce the observed images and the CO line luminosity the dusty shell has to be ∼420 pc thick and located at ∼1000 pc from the centre.