Speaker
Dr
Melania Del Santo
(National Institute for Astrophysics - INAF)
Description
In 2011 a new hard X-ray source, IGR J17361-4441, was discovered by INTEGRAL close the centre of the globular cluster NGC 6388.
Based on its peak luminosity, it was classified as very faint X-ray transient.
A Swift/XRT monitoring campaign showed an evident t^(-5/3) trend in the light curve,
and a thermal emission of ~0.08 keV that did not evolve significantly with time.
We investigated whether this source could be a tidal disruption event,
and for certain assumptions, we found an accretion efficiency consistent with a massive white dwarf and a disrupted minor body mass ~2E+27 M/M_Ch g in the terrestrial-icy planet regime.
Although the density of white dwarfs and the number of free-floating planets are uncertain, we estimated the rate of planetary tidal disruptions in NGC 6388 to be
in the range 3E-6 up to 3E-4 yr^(-1). Averaged over the 150 globular clusters in the Milky Way, the upper limit value corresponds to 0.05 yr^(-1), consistent with the life-time of INTEGRAL and Swift.
Author
Dr
Melania Del Santo
(National Institute for Astrophysics - INAF)
Co-authors
Dr
Achille Nucita
(Università del Salento)
Dr
Alberto Segreto
(INAF)
Prof.
Francesco De Paolis
(Università del Salento)
Dr
Giovanni De Cesare
(INAF)
Prof.
Giuseppe Lodato
(Università degli Studi di Milano)
Prof.
Jay Farihi
(University College London)
Dr
Luigi Manni
(Università del salento)
