Data Centre for Astrophysics
Astronomy Department of the University of Geneva

Tidal disruption of a super-Jupiter by a massive black hole


A strong hard X-ray flare was discovered (IGR J12580+0134) by INTEGRAL in 2011, associated to NGC 4845, a Seyfert 2 galaxy never detected at high-energy previously. In order to understand what happened we observed this event in the X-ray band at several occasions. Follow-up observations with XMM-Newton, Swift and MAXI are presented together with the INTEGRAL data. Long and short term variability are analysed and its wide band spectral shape is presented. The spectrum of the source can be well described with an absorbed (NH ∼ 7×1022 cm−2) power-law (Γ ≃ 2.2), characteristic of an accreting source, plus a soft X-ray excess, likely of diffuse nature. The hard X-ray flux increased to maximum in a few weeks and decreased during a year, with the evolution expected for a tidal disruption event. The fast variations observed near the flare maximum allowed to estimate the mass of the central black-hole in NGC 4845 to ∼ 300000 M. The observed flare corresponds to the disruption of about 10% of an object with a mass of 14-30 Jupiter. The hard X-ray emission should come from a corona forming around the accretion flow close to the black-hole. This is the first tidal event where such a corona is observed.
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