Monitoring the Galactic Centre with the Australia Telescope Compact Array

0458284 - ASÚ 2017 RIV GB eng J - Článek v odborném periodiku
Borkar, A. - Eckart, A. - Straubmeier, C. - Kunneriath, Devaky - Jalali, B. - Sabha, N. - Shahzamanian, B. - García-Marín, M. - Valencia-S, M. - Sjouwerman, L. - Britzen, S. - Karas, Vladimír - Dovčiak, Michal - Donea, A. - Zensus, A.
Monitoring the Galactic Centre with the Australia Telescope Compact Array.
Monthly Notices of the Royal Astronomical Society. Roč. 458, č. 3 (2016), s. 2336-2349. ISSN 0035-8711. E-ISSN 1365-2966
Grant CEP: GA ČR(CZ) GC13-00070J
Institucionální podpora: RVO:67985815
Klíčová slova: galactic Centre * black hole
Kód oboru RIV: BN - Astronomie a nebeská mechanika, astrofyzika
Impakt faktor: 4.961, rok: 2016

The supermassive black hole, Sagittarius A* (Sgr A*), at the centre of the Milky Way undergoes regular flaring activity, which is thought to arise from the innermost region of the accretion flow. Between 2010 and 2014, we performed monitoring observations of the Galactic Centre to study the flux-density variations at 3 mm using the Australia Telescope Compact Array (ATCA). We obtain light curves of Sgr A* by subtracting the contributions from the extended emission around it, and the elevation and time-dependent gains of the telescope. We perform structure function analysis and the Bayesian blocks representation to detect flare events. The observations detect six instances of significant variability in the flux density of Sgr A* in three observations. We use the adiabatically expanding plasmon model to explain the short time-scale variations. We derive the physical quantities of the modelled flare emission, such as the source expansion speed. No exceptional flux-density variation on short flare time-scales was observed during the approach and the flyby of the dusty S-cluster object (DSO/G2). This is consistent with its compactness and the absence of a large bow shock.
Trvalý link: http://hdl.handle.net/11104/0259822