The black hole metronome: X-ray Quasi-Periodic Eruptions from the core of a galaxy


Figure: Artistic view of an accretion disk around a BH with the silhouette of the XMM-Newton X-ray observatory superimposed. © Ignacio de la Calle (ESAC).


An international scientific team led by Centro de Astrobiología (CAB, cSIC-INTA) has discovered unprecedented X-ray variability from the core of a galaxy hardbouring an accreting black hole. This never-seen-before phenomenon, dubbed X-ray ‘Quasi-Periodic Eruptions’ (or QPEs), will likely help scientists to unveil some of the most puzzling aspects associated with accreting black holes.

X-ray mission from the core of GSN 069, a galaxy some 250 million light years away, was the fist detected in 2010 July during an ESA’s XMM Newton slew, that is the manoeuvre that the X-ray observatory makes to switch from one target to next.

Since 2010 the XMM-Newton and NASA’s Neil Gehrels Swift X-ray observatories have monitored the X-ray evolution of GSN 069 showing that the 2010 outburst is consistent with the disruption of a star (likely a giant star) that came too close to the black hole at the centre of the galaxy, an occurrence usually known as tidal disruption event.

As Giovanni Miniutti, researcher at Centro de Astrobiología and leading author of the present study, points out “although other explanations may be viable, we suspect that a star was disrupted at the centre of GSN 069, producing the 2010 X-ray outburst ad subsequent decay as the stellar debris accrete onto the central black hole”.

Although observing this tyoe of events is very important per se as they represent an exceptional opportunity to study black hole accretion in detail, this is only the beginning of the story.

What Giovanni and his team have discovered and published today in the journal Nature, is a new spectacular phenomenon that is taking place in GSN 069. During an XMM-Newton observation on 2018 Christmas Eve, massive repeating X-ray flares (never seen before in active galaxies) were observed in GSN 069. During these ‘quasi-periodic eruptions’ (QPEs as the authors nickname them) the X-ray output is up to 100 times brighter for about 1 hour and repeats every 9 hours.

These new, exceptional events, will likely improve our understanding of some of the most puzzling aspects associated with accreting black holes.

The Quasi-Periodic Eruptions of GSN 069 are such a new phenomenon that their physical origin needs to be firmly pinpointed still.

The GSN 069 team is an international collaboration led by Centro de Astrobiología and with the participation of institution from Spain, the USA, the UK, South Africa, France, Australia and Belgium. The team used astronomical data from the XMM-Newton, Chandra and Neil Gehrels Swift X-ray observatories, the Hubble Space Telescope (HST), the Karl G. Jansky Very Large Array (VLA), the Australia Telescope Compact Array (ATCA) and the South African MeerKAT radio telescopes.


Fuente: UCC-CAB

Fecha: 2019-09-11


Imágenes adicionales:

Time evolution of the X-ray image of GSN 069 and X-ray intensity. ©G. Miniutti and M. Giustini.

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