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SUMMARY:Sharmila Gunasekaran (Memorial University of Newfoundland)
DTSTART:20200729T160000Z
DTEND:20200729T163000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/1
DESCRIPTION:Title: Slow decay of waves in gravitational solitons\nby Sh
armila Gunasekaran (Memorial University of Newfoundland) as part of Atlant
ic General Relativity 2020 Online Postdoc/Student Seminar Series\n\n\nAbst
ract\nGravitational solitons are globally stationary horizonless asymptoti
cally flat spacetimes. In this talk\, I will describe the methodology used
to prove that massless scalar waves in a particular family of soliton spa
cetimes decay very slowly. The proof involves the construction of quasimod
es which are approximate solutions to the wave equation. This slow decay c
an be attributed to the stable trapping of null geodesics and is suggestiv
e of instability at the nonlinear level. This is joint work with Hari Kund
uri.\n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Santacruz (University of New Brunswick)
DTSTART:20200729T163000Z
DTEND:20200729T170000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/2
DESCRIPTION:Title: Quantizing gravity is not that hard if you know how: An
undergraduate guide to black holes\nby Robert Santacruz (University of
New Brunswick) as part of Atlantic General Relativity 2020 Online Postdoc
/Student Seminar Series\n\n\nAbstract\nIt is expected that singularities a
ppearing in GR are to be resolved in a theory of Quantum Gravity. In the c
ontext of Loop Quantum Gravity\, the Big Bang singularity is replaced by a
bounce and so one would assume that this can be translated into Black Hol
es. In this talk I will explain you how to find an effective model for Sch
warzschild black hole by using Loop Quantum Cosmology techniques and\, the
best part is\, you only need Hamiltonian Mechanics!!\n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/2/
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BEGIN:VEVENT
SUMMARY:Sharmin Akhter (Memorial University of Newfoundland)
DTSTART:20200826T163000Z
DTEND:20200826T170000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/3
DESCRIPTION:Title: Rigidity of Marginally Outer Trapped Surfaces in RNdS Sp
acetime\nby Sharmin Akhter (Memorial University of Newfoundland) as pa
rt of Atlantic General Relativity 2020 Online Postdoc/Student Seminar Seri
es\n\n\nAbstract\nWe investigate the rigidity of MOTS in four dimensional
Reissner-Nordstrom-de Sitter spacetime. This is connected to the study of
the first order derivative of stability operator (and hence the second der
ivative of outgoing null expansion). Since the stability operator has a ze
ro eigenvalue in our case\, we use the Lyapunov-Schmidt reduction to estab
lish rigidity. This is joint work with Dr. Ivan Booth and Dr. Graham Cox.\
n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/3/
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SUMMARY:Kam To Billy Chan (Memorial University of Newfoundland)
DTSTART:20200930T160000Z
DTEND:20200930T163000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/4
DESCRIPTION:Title: The Reissner-Nordstrom Near Horizon Geometry is a Tangen
t Spacetime\nby Kam To Billy Chan (Memorial University of Newfoundland
) as part of Atlantic General Relativity 2020 Online Postdoc/Student Semin
ar Series\n\n\nAbstract\nThe near horizon geometry (NHG) of an extremal Re
issner-Nordstrom black hole is obtained in conventional global AdS coordin
ates and in the coordinates of the parent spacetime. Geometrical objects\,
specifically Killing vectors and spacetime points\, are mapped from the b
oundary and horizon of the NHG into the parent spacetime coordinates. The
outcome is that the NHG is a tangent spacetime to the extremal Reissner-No
rdstrom black hole’s degenerate horizon and that the degenerate horizon
does not bifurcate. A generalization is made for N-dimensional Reissner-No
rdstrom black holes. This work is an extension of Sean Stotyn’s A Tale o
f Two Horizons.\n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Turkuler Durgut (Memorial University of Newfoundland)
DTSTART:20201028T160000Z
DTEND:20201028T163000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/5
DESCRIPTION:Title: Asymptotically Anti-de Sitter Gravitational Solitons
\nby Turkuler Durgut (Memorial University of Newfoundland) as part of Atla
ntic General Relativity 2020 Online Postdoc/Student Seminar Series\n\n\nAb
stract\nIn this talk\, I will consider the stability of asymptotically ant
i-de Sitter gravitational solitons. These are globally stationary\, asympt
otically (globally) AdS spacetimes with positive energy but without horizo
ns. I will introduce my ongoing project investigating solutions of the lin
ear wave equation in this class of backgrounds. I will provide analytical
expressions for the behavior of the scalar field near the soliton bubble a
nd at spatial infinity. The special BPS (supersymmetric) case will then be
examined as an example of a solution where stable trapping occurs. This p
roject is joint work with Dr. Hari K. Kunduri and Dr. Robie A. Hennigar.\n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/5/
END:VEVENT
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SUMMARY:Jinzhao Wang (Institute of Theoretical Physics\, ETH Zurich)
DTSTART:20201125T160000Z
DTEND:20201125T163000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/6
DESCRIPTION:Title: Outer entropy equals Bartnik-Bray inner mass\, and the g
ravitational ant conjecture\nby Jinzhao Wang (Institute of Theoretical
Physics\, ETH Zurich) as part of Atlantic General Relativity 2020 Online
Postdoc/Student Seminar Series\n\n\nAbstract\nEntropy and energy are found
to be closely tied on our quest for quantum gravity. We point out an inte
resting connection between the recently proposed outer entropy\, a coarse-
grained entropy defined for a compact spacetime domain motivated by the ho
lographic duality\, and the Bartnik-Bray quasilocal mass long known in the
mathematics community. In both scenarios\, one seeks an optimal spacetime
fill-in of a given closed\, connected\, spacelike\, codimension-two bound
ary. We show that for an outer-minimizing mean-convex surface\, the Bartni
k-Bray inner mass matches exactly with the irreducible mass corresponding
to the outer entropy. The equivalence implies that the area laws derived f
rom the outer entropy are mathematically equivalent as the monotonicity pr
operty of the quasilocal mass. It also gives rise to new bounds between en
tropy and the gravitational energy\, which naturally gives the gravitation
al counterpart to Wall's ant conjecture. We also observe that the equality
can be achieved in a conformal flow of metrics\, which is structurally si
milar to the Ceyhan-Faulkner proof of the ant conjecture. We compute the s
mall sphere limit of the outer entropy and it is proportional to the bulk
stress tensor as one would expect for a quasilocal mass.\n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/6/
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BEGIN:VEVENT
SUMMARY:Saikat Mondal (Memorial University of Newfoundland)
DTSTART:20201125T163000Z
DTEND:20201125T170000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/7
DESCRIPTION:Title: Marginally outer trapped (open) surfaces in Schwarzschil
d geometry and extreme mass ratio merger\nby Saikat Mondal (Memorial U
niversity of Newfoundland) as part of Atlantic General Relativity 2020 Onl
ine Postdoc/Student Seminar Series\n\n\nAbstract\nBlack holes are one of t
he common objects in astrophysics. Some are formed from a dying star\, cal
led a stellar black hole. There are also supermassive black holes consisti
ng of mass millions or even billions times that of the sun. Such black hol
es are thought to lie at the center of almost every galaxy. In this talk w
e will explore the evolution of horizons of black hole mergers in a specia
l limit called the " extreme mass ratio" limit. For example\, a supermassi
ve black hole merges with a stellar black hole to become a single black ho
le. In this limit\, the merging horizons can be studied with the help of s
imple numerics. We will discuss mainly about marginally outer trapped surf
aces (MOTS). Interestingly\, the MOTSs we find in our numerical analysis h
ave an arbitrary number of self-intersections.\n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/7/
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SUMMARY:Sarah Mime MacDonald Muth (Memorial University of Newfoundland)
DTSTART:20210224T160000Z
DTEND:20210224T170000Z
DTSTAMP:20260404T111005Z
UID:general-relativity/8
DESCRIPTION:Title: Marginally Outer Trapped (Open) Surfaces in 4+1 Dimensio
nal Schwarzschild\nby Sarah Mime MacDonald Muth (Memorial University o
f Newfoundland) as part of Atlantic General Relativity 2020 Online Postdoc
/Student Seminar Series\n\n\nAbstract\nIn the case of binary black hole me
rgers\, the surface of most obvious interest\, the Event Horizon\, is ofte
n computationally difficult to locate. Instead\, it is useful to turn to
quasi-local characterizations of black hole boundaries\, such as Marginall
y Outer Trapped Surfaces (MOTS)\, which are defined for a single time slic
e of the spacetime\, and the outer-most of which is the apparent horizon.
In this talk\, I will describe ongoing work focused on understanding MOTS
in the interior of a five-dimensional Schwarzschild black hole. Similar t
o the four-dimensional case previously studied\, we find examples of self-
intersecting MOTS with an arbitrary number of self-intersections. This pro
vides further support that self-intersecting behavior is rather generic.
I will also briefly discuss the next stage of our research\, which involve
s further examples of these self-intersecting MOTS\, this time in the full
Kruskal extension of Schwarzschild.\n
LOCATION:https://stable.researchseminars.org/talk/general-relativity/8/
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