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SUMMARY:Stability of asymptotically de Sitter and anti-de Sitter black hol
es in 4D regularized Einstein-Gauss-Bonnet theory
DTSTART;VALUE=DATE-TIME:20201022T091000Z
DTEND;VALUE=DATE-TIME:20201022T093500Z
DTSTAMP;VALUE=DATE-TIME:20231205T023802Z
UID:indico-contribution-15-46@indico.slu.cz
DESCRIPTION:Speakers: Marco Cuyubamba (University of Oldenburg)\nThe regul
arized four-dimensional Einstein-Gauss-Bonnet model has been recently prop
osed in [D. Glavan and C. Lin\, Phys. Rev. Lett. \\textbf{124}\, 081301 (2
020)] whose formulation is different of the Einstein theory\, allowing us
to bypass the Lovelock theorem. The action is formulated in higher dimensi
ons (D>4) by adding the Gauss-Bonnet correction to the conventional Einste
in-Hilbert action with a cosmological constant. The four-dimensional space
time is constructed through dimensional regularization by taking the limit
Dâ†’4. We find explicitly the parametric regions of stability of black ho
les for the asymptotically flat and (anti-)de Sitter spacetimes by analyzi
ng the time-domain profiles for gravitational perturbations in both vector
and scalar channels. In addition to the known eikonal instability\, we fi
nd the instability due to the positive cosmological constant. On the contr
ary\, asymptotically anti-de Sitter black holes have no other instability
than the eikonal one.\n\nhttps://indico.slu.cz/event/4/contributions/46/
LOCATION:
URL:https://indico.slu.cz/event/4/contributions/46/
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SUMMARY:ISCO as a tool to alternate the Kerr metric with the charged strin
gy black hole metric.
DTSTART;VALUE=DATE-TIME:20201022T084500Z
DTEND;VALUE=DATE-TIME:20201022T091000Z
DTSTAMP;VALUE=DATE-TIME:20231205T023802Z
UID:indico-contribution-15-23@indico.slu.cz
DESCRIPTION:Speakers: Bakhtiyor Narzilloev (Fudan university\, Shanghai\,
China\; Ulugh Beg Astronomical Institute\, Tashkent\, Uzbekistan)\nWe show
that in some ranges of the charge parameters charged stringy black hole m
etric can provide the same ISCO as in the case of the well known Kerr metr
ic for the test particles. Based on the idea that charge parameters of the
stringy black hole metric can provide the same ISCO for the test particle
s it would be difficult to distinguish these two metrics if one relies on
the observations that have a strong dependence on the ISCO radius. So\, ba
sed on this idea we show that in the case of electrically charged stringy
black hole the charge parameter can completely mimic the rotation paramete
r of the Kerr metric\; black hole with magnetic charge can mimic the spin
up to $a=0.85$ for magnetic dipoles endowed with a magnetic dipole moment
\; and up to $a=0.8$ for magnetic monopoles.\n\nhttps://indico.slu.cz/even
t/4/contributions/23/
LOCATION:
URL:https://indico.slu.cz/event/4/contributions/23/
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