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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 in the galaxy NGC 4845 by INTEGRAL in January 2011. This emission corresponds to the tidal disruption of a super-Jupiter close to the giant black hole at the center of the galaxy. The disrupted material heated up before falling in the black hole, emitting at high energies.
Nikolajuk & Walter 2013, A&A, in press   |   Press Release

ABSTRACT

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.
Tidal disuption of a super-Jupiter by a massive black hole
X-ray outburst observed at the core of the galaxy NGC 4845 and a simulation of a tidal disruption.


Credits: ISDC

Hard X-ray lightcurve of NGC 4845, compared with the expectations for a tidal disruption
The light-curve in the 17.3-80 keV energy band. Red squared points refer to INTEGRAL data, blue crosses show Swift and XMM-Newton observations. The solid line show a model of the form t−5/3, as expected for fallback of material after a tidal disruption event. The long-short dash and dotted lines indicate the predictions of simulations for the disruption of a sub-stellar object (γ = 5/3; β = 0.7) and, respectively of a star (γ = 4/3; β = 0.65) (Guillochon & Ramirez-Ruiz 2012).
Credits: ISDC/M. Nikolajuk
X-ray power spectrum obtained at flare maximum
The 19.1 ks XMM-Newton power spectrum (blue histogram) versus simulated power spectra (red histogram with error bars). The simulated light-curves have their power proportional to a single power law of the frequency. 1σ error bars are shown. An excess in the observed power near the log(frequency)=-3 suggests the presence of a QPO feature.
Credits: ISDC/M. Nikolajuk
Video: English, Français, Polski
by Roland Walter on 2013-04-02 >> INTEGRAL science results >> All science results