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BEGIN:VEVENT
SUMMARY:Tests of general relativity through the direct detection of gravit
ational waves
DTSTART;VALUE=DATE-TIME:20200925T091500Z
DTEND;VALUE=DATE-TIME:20200925T094500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025996@indico.cern.ch
DESCRIPTION:Speakers: Chris Van Den Broeck (Utrecht University)\nThe detec
tion by LIGO and Virgo of gravitational waves from compact binary coalesce
nces has given us access to the genuinely strong-field\, dynamical regime
of gravity\, enabling tests of general relativity in the fully nonlinear d
omain. Moreover\, the nature of gravitational waves can be tested by looki
ng at the way they propagate over large distances. As the sensitivity of t
he detectors improves\, it will soon also be possible to probe the nature
of compact objects themselves. In the case of presumed black holes\, are t
hey really the Kerr black holes of general relativity\, or even more exoti
c objects? Thus\, key questions about gravity - possibly including quantum
gravity - can finally be addressed through direct observation.\n\nhttps:/
/indico.cern.ch/event/948828/contributions/4025996/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025996/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Computable Loop Quantum Gravity
DTSTART;VALUE=DATE-TIME:20200926T161500Z
DTEND;VALUE=DATE-TIME:20200926T163000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4030391@indico.cern.ch
DESCRIPTION:Speakers: Gioele Botta (University of Warsaw)\nThe full theory
of LQG presents enormous challenge to create physical computable models.
In this talk we will present the new modern version of Quantume Reduced Lo
op Gravity (QRLG). We will show that this framework provide an arena to st
udy the full LQG in a certain limit\, where the quantum computations are p
ossible. We will analyze all the major step necessary to build this framew
ork\, how is connected with the full theory\, its matematical consistency
and the physical intuition behind It.\n\nhttps://indico.cern.ch/event/9488
28/contributions/4030391/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4030391/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational Entropy and the Second Law of Thermodynamics
DTSTART;VALUE=DATE-TIME:20200926T113000Z
DTEND;VALUE=DATE-TIME:20200926T122500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4028719@indico.cern.ch
DESCRIPTION:Speakers: Paul Davies (Arizona State University)\nThe identifi
cation of black hole event horizon area with entropy by Bekenstein and Haw
king suggested a generalized second law of thermodynamics. This was later
extended to cosmological horizons. However\, there remain some deep unsolv
ed problems about the validity of the generalized law in the cosmological
case\, and unanswered questions about whether a more comprehensive notion
of gravitational entropy is required. These issues have important philosop
hical implications for the nature of physical law.\n\nhttps://indico.cern.
ch/event/948828/contributions/4028719/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4028719/
END:VEVENT
BEGIN:VEVENT
SUMMARY:GRBs pancromatic events observed even to the GEV ad TeV emission a
nd their implications as cosmological standard candles
DTSTART;VALUE=DATE-TIME:20200924T134500Z
DTEND;VALUE=DATE-TIME:20200924T141500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025229@indico.cern.ch
DESCRIPTION:Speakers: Maria Dainotti (Jagiellonian University)\nGRBs are p
anchromatic events\, very attractive sources of study from very high energ
y (GeV and TeV) to very low frequency until radio. This gives the unique o
pportunity to study their emission mechanism in multiwavelength. Relevant
cases are the GRB 190114C observed by the Major Atmospheric Gamma Imaging
Cherenkov telescopes detected above 0.2 TeV\, recording the most energetic
photons ever observed. I will discuss the implications of such discovery.
There are many intriguing cases of GRBs observed at high energy by the Fe
rmi satellites. One of the most important issue in GRB investigation is th
eir wide range of energies and features which make difficult an exact clas
sification.\n\nI will discuss on how GRBs at high energy will obey correla
tions among prompt and afterglow parameters and what it is the implication
for the use of GRBs as cosmological probes.\n\nhttps://indico.cern.ch/eve
nt/948828/contributions/4025229/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025229/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Multi-messenger astronomy including gravitational-wave
DTSTART;VALUE=DATE-TIME:20200925T080000Z
DTEND;VALUE=DATE-TIME:20200925T084500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025994@indico.cern.ch
DESCRIPTION:Speakers: Marica Branchesi (Gran Sasso Science Institute)\nA n
ew exploration of the Universe has recently started through gravitational-
wave observations. On August 17\, 2017\, the first observation of gravitat
ional waves from the inspiral and merger of a binary neutron-star system b
y the Advanced LIGO and Virgo network\, followed 1.7 s later by a weak sho
rt gamma-ray burst detected by the Fermi and INTEGRAL satellites initiated
the most extensive world-wide observing campaign which led to the detecti
on of multi-wavelength electromagnetic counterparts. Multi-messenger disco
veries are revealing the enigmas of the most energetic transients in the s
ky\, probing neutron-stars physics\, relativistic astrophysics\, nuclear p
hysics\, nucleosynthesis\, and cosmology. The talk will give an overview o
f the astrophysical implications of the gravitational-wave and multi-messe
nger observations\, the prospects and challenges of the current and future
gravitational-wave detectors.\n\nhttps://indico.cern.ch/event/948828/cont
ributions/4025994/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025994/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Effective-one-body waveform from coalescing binaries: recent devel
opments
DTSTART;VALUE=DATE-TIME:20200925T084500Z
DTEND;VALUE=DATE-TIME:20200925T091500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025995@indico.cern.ch
DESCRIPTION:Speakers: Alessandro Nagar (INFN\, Sezione di Torino & IHES)\n
I will report on recent developments of TEOBResumS\, an effective-one-body
based waveform model for coalescing relativistic binaries. In particular\
, I will discuss: (i) spin-aligned quasi-circular binaries\; (ii) spin-ali
gned eccentric binaries\; (iii) hyperbolic encounters and dynamical captur
e.\n\nhttps://indico.cern.ch/event/948828/contributions/4025995/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025995/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hairy black holes and the dark sector influence
DTSTART;VALUE=DATE-TIME:20200926T164500Z
DTEND;VALUE=DATE-TIME:20200926T170000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025953@indico.cern.ch
DESCRIPTION:Speakers: Bartłomiej Kiczek (Maria Curie-Skłodowska Universi
ty)\nIn this short talk I will briefly discuss the hairy black hole soluti
ons obtained within Einstein-Maxwell-Scalar theory with so called box boun
dary conditions and the influence of dark sector fields on the modelled sy
stem. The phase diagram of the theory will be presented with the explanati
on of the influence of the hidden sector on the thermodynamics of particul
ar phases (hairy black holes\, boson stars\, RN-like black holes). Finally
I will show that dark matter in the presented model can significantly dec
rease the chance of the emergence of a hairy solution.\n\nhttps://indico.c
ern.ch/event/948828/contributions/4025953/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025953/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The kinetic gas universe - Lifting the Einstein Vlasov system to t
he tangent bundle
DTSTART;VALUE=DATE-TIME:20200926T163000Z
DTEND;VALUE=DATE-TIME:20200926T164500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025952@indico.cern.ch
DESCRIPTION:Speakers: Christian Pfeifer (University of Tartu)\nIn this tal
k I will present a new model for the description of a gravitating kinetic
gas\, by coupling the 1-particle distribution function (1PDF) of the gas d
irectly to the gravitational field\, lifted to the tangent bundle of space
time. This procedure takes the influence of the velocity distribution of t
he kinetic gas particles on their gravitational field fully into account\,
instead of only on average\, as it is the case for the Einstein-Vlasov sy
stem.\n\nBy using Finsler spacetime geometry I construct an action for the
kinetic gas on the tangent bundle\, which is added as matter action to a
canonical Finslerian generalisation of the Einstein-Hilbert action. The in
variance of the kinetic gas action under coordinate changes gives rise to
a new notion of energy-momentum conservation of a kinetic gas in terms of
an energy-momentum distribution tensor. The variation of the total action
with respect to the spacetime geometry defining Finsler Lagrangian yields
a gravitational field equation on the tangent bundle\, which determines th
e geometry of spacetime directly from the full non-averaged 1PDF. This equ
ation can be regarded as generalisation of the Einstein-Vlasov system\, wh
ich takes all features of the kinetic gas into account.\n\nThe talk will b
e based on the essay [The Kinetic Gas Universe][1] and the article [Relati
vistic kinetic gases as direct sources of gravity][2].\n\n [1]: https://a
rxiv.org/abs/2005.13561\n [2]: https://arxiv.org/abs/1910.14044\n\nhttps:
//indico.cern.ch/event/948828/contributions/4025952/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025952/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum fluctuations of the compact phase space cosmology
DTSTART;VALUE=DATE-TIME:20200926T160000Z
DTEND;VALUE=DATE-TIME:20200926T161500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025950@indico.cern.ch
DESCRIPTION:Speakers: Sean Crowe (Georgia Southern University)\nIn the rec
ent article Phys. Rev. D 100\, no. 4\, 043533 (2019) a compact phase space
generalization of the flat de Sitter cosmology has been proposed. The mai
n advantages of the compactification is that physical quantities are bound
ed\, and the quantum theory is characterized by finite dimensional Hilbert
space. The purpose of this presentation is to discuss the extraction of s
emiclassical effects from this model by way of canonical effective methods
. First\, a brief review of canonical effective methods is given. Afterwar
ds\, we discuss the character of the semiclassical solutions of the compac
t phase space cosmological model. Finally\, a relation between the behavio
r of the quantum fluctuations of the cosmological sector and the holograph
ic Bousso bound is discussed\n\nhttps://indico.cern.ch/event/948828/contri
butions/4025950/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025950/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Asymptotic generalized extended uncertainty principle
DTSTART;VALUE=DATE-TIME:20200926T154500Z
DTEND;VALUE=DATE-TIME:20200926T160000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025948@indico.cern.ch
DESCRIPTION:Speakers: Fabian Wagner (University of Szczecin)\nWe present a
formalism which allows for the perturbative derivation of the Extended Un
certainty Principle for arbitrary spatial curvature models. The leading cu
rvature induced correction is proportional to the Ricci scalar evaluated a
t the expectation value of the position operator. By Born reciprocity this
method can be equivalently applied in curved momentum space allowing for
a general uncertainty principle or curved momentum space quantum mechanics
.\n\nhttps://indico.cern.ch/event/948828/contributions/4025948/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025948/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Prospects of Probing Dark Energy with eLISA: Standard versus Null
Diagnostics
DTSTART;VALUE=DATE-TIME:20200924T164500Z
DTEND;VALUE=DATE-TIME:20200924T170000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025901@indico.cern.ch
DESCRIPTION:Speakers: Pratyusava Baral ()\nGravitational waves from superm
assive black hole binary mergers along with an electromagnetic counterpart
has the potential to shed `light' on the nature of dark energy in the int
ermediate redshift regime. An accurate measurement of dark energy paramete
rs at intermediate redshift is extremely essential to improve our understa
nding of dark energy\, and to possibly resolve couple of tensions involvin
g cosmological parameters. We present a Fisher matrix forecast analysis in
the context of eLISA to predict the errors for three different cases: the
non-interacting dark energy with constant and evolving equation of state
(EoS)\, and interacting dark sectors with a generalized parametrization. I
n all three cases\, we perform the analysis for two separate formalisms\,
namely\, the standard EoS formalism and the model-independent null diagnos
tics using \\textit{Om} parametrization for a wide range of fiducial value
s in both phantom and non-phantom regions\, in order to make a comparative
analysis between the prospects of these two diagnostics in eLISA. Our ana
lysis reveals that it is wiser and more effective to probe null diagnostic
s instead of the standard EoS parameters for any possible signature of dar
k energy at intermediate redshift measurements like eLISA.\n\nhttps://indi
co.cern.ch/event/948828/contributions/4025901/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025901/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shadow of Naked Singularity
DTSTART;VALUE=DATE-TIME:20200924T154500Z
DTEND;VALUE=DATE-TIME:20200924T160000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025900@indico.cern.ch
DESCRIPTION:Speakers: Dipanjan Dey (International Center for Cosmology\, C
HARUSAT\, India)\nRecent observation of the shadow of the Messier 87 (M87)
galactic center by the Event Horizon Telescope (EHT) group has triggered
a great interest to investigate the causal structure of spacetime around t
he galactic center. From the recent investigations on gravitational lensin
g\, it is now established that the shadow is not the signature of a black
hole alone\, it can also be cast by timelike or nulllike naked singulariti
es in the presence of a photon sphere. In my talk\, I will show a naked si
ngularity\, even without the photon sphere\, can cast a shadow. I will sho
w some noble features of the shadow cast by timelike and nulllike naked si
ngularities in the absence of the photon sphere. Those noble features of t
he shadows of nulllike and timelike naked singularities may help us to dis
tinguish between black holes and naked singularities observationally.\n\nh
ttps://indico.cern.ch/event/948828/contributions/4025900/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025900/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the canonical energy of weak gravitational fields with a positi
ve cosmological constant
DTSTART;VALUE=DATE-TIME:20200924T163000Z
DTEND;VALUE=DATE-TIME:20200924T164500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025899@indico.cern.ch
DESCRIPTION:Speakers: Tomasz Smołka (University of Warsaw)\nThe Hamiltoni
an energy\, and its flux\, of weak gravitational waves on a de Sitter back
ground will be discussed. A new renormalized energy will be proposed. Used
asymptotic conditions on the linearized metric have been modeled on the a
symptotic behavior of the full solutions of the Einstein equations with po
sitive cosmological constant. Considered space of solutions is greater tha
n the solutions which fulfill so called Bondi asymptotic conditions. This
is joint work with P. T. Chruściel and J. Hoque.\n\nhttps://indico.cern.c
h/event/948828/contributions/4025899/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025899/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Self-gravitating tori around black holes: Bifurcation\, ergoregion
s\, and geometrical properties
DTSTART;VALUE=DATE-TIME:20200924T161500Z
DTEND;VALUE=DATE-TIME:20200924T163000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025898@indico.cern.ch
DESCRIPTION:Speakers: Wojciech Dyba (Jagiellonian University)\nThis talk i
s based on the paper “Self-gravitating perfect-fluid tori around black h
oles: Bifurcations\, ergoregions\, and geometrical properties” by W. Dyb
a\, W. Kulczycki\, P. Mach\, Phys. Rev. D (2020). \nWe investigate numeric
al solutions of Einstein field equations corresponding to a stationary\, a
xial symmetric spacetime containing a self-gravitating perfect-fluid torus
rotating around a black hole. We assume that the gas is polytropic and mo
ves according to the Keplerian rotation law. We have found a new type of b
ifurcation in the parameter space of solutions—for a given maximal densi
ty within the torus and fixed inner and outer radii\, there can exist two
solutions differing in the mass of the torus. This effect can be explained
in geometrical terms—the inner volume of the massive torus can be much
larger than the volume corresponding to the light one. In both cases we in
vestigate the influence of the torus on the location of the innermost stab
le circular orbit (ISCO). The result\, especially for the less massive bra
nch of solutions\, may have astrophysical applications for the estimates o
f the accretion rate\, for example during binary neutron star mergers. We
have also investigated strong field effects appearing for the massive bran
ch of solutions\, in particular the occurrence of ergoregions with spheric
al and toroidal topologies. If time permits\, I will also discuss prelimin
ary results on the stability of the obtained solutions.\n\nhttps://indico.
cern.ch/event/948828/contributions/4025898/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025898/
END:VEVENT
BEGIN:VEVENT
SUMMARY:BiGONLight: a new tool for light propagation in numerical relativi
ty
DTSTART;VALUE=DATE-TIME:20200924T160000Z
DTEND;VALUE=DATE-TIME:20200924T161500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025897@indico.cern.ch
DESCRIPTION:Speakers: Michele Grasso (Center for Theoretical Physics\, PAS
)\nIn the current new era for cosmological observations\, much work is dev
oted in investigating the possibility of measuring new effects like the se
cular changes of optical observables (known as drift effects). In this con
text\, the new bi-local geodesic operators (BGO) formalism of light propag
ation provides a unified framework in which it is possible to describe all
possible optical phenomena like the standard lensing effects as well as t
he drifts effects or the cosmic parallax. I will show how the BGO formalis
m can be used to compute optical observables in numerically simulated spac
etimes through its implementation in the BiGONLight package.\n\nhttps://in
dico.cern.ch/event/948828/contributions/4025897/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025897/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Topology\, coordinates\, and fields in Causal Dynamical Triangulat
ions
DTSTART;VALUE=DATE-TIME:20200926T084500Z
DTEND;VALUE=DATE-TIME:20200926T091500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025519@indico.cern.ch
DESCRIPTION:Speakers: Andrzej Görlich (Jagiellonian University)\nCausal D
ynamical Triangulations (CDT) is a background independent approach to quan
tum gravity which introduces a lattice regularization. The framework uses
only geometric invariants without referring to any coordinate system.\nOne
of its features is the ability to control the topology of the Universe. T
he introduction of toroidal spatial topology allows for a definition of hy
persurfaces which can serve as reference frames used to construct a coordi
nate system.\nIn this talk\, I will discuss how to define coordinates\, vi
a a classical scalar field\, in a way that is invariant under the redefini
tion of the hypersurfaces.\nI will show how the new coordinates give an in
sight into the geometric structure of configurations appearing in four-dim
ensional Causal Dynamical Triangulations.\n\nhttps://indico.cern.ch/event/
948828/contributions/4025519/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025519/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the spectral dimensionality of quantum spacetimes
DTSTART;VALUE=DATE-TIME:20200926T095500Z
DTEND;VALUE=DATE-TIME:20200926T101500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025992@indico.cern.ch
DESCRIPTION:Speakers: Tomasz Trześniewski (Jagiellonian University)\nThe
spectral dimension is one of definitions of the effective dimensionality o
f spacetime that is commonly applied to characterize quantum gravity model
s. A quite universal prediction is the dimensional reduction to 2 in the U
V regime. The notion of spectral dimension can be seen as arising from pro
perties of either a (fictitious) diffusion process or spectral geometry. I
n the latter context\, there also exists the related notion of dimension s
pectrum. The application of both concepts may lead to various pitfalls\; t
hey are actually associated with the heat trace expansion\, which is an im
portant tool in quantum field theory. Furthermore\, quantum spacetime is o
ften described in terms of broadly understood noncommutative geometry\, wh
ich requires even more care. It turns out that the spectral dimension and
dimension spectrum complement each other\, as can be illustrated with the
use of two contrasting examples: the quantum sphere and $\\kappa$-Minkowsk
i spacetime\, with different possible choices of Laplacians that determine
their geometries. In the former case\, we also observe curious oscillatio
ns of dimension in the UV regime (which could leave an imprint on the cosm
ic microwave background).\n\nhttps://indico.cern.ch/event/948828/contribut
ions/4025992/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025992/
END:VEVENT
BEGIN:VEVENT
SUMMARY:3d gravity and quantum groups
DTSTART;VALUE=DATE-TIME:20200926T105500Z
DTEND;VALUE=DATE-TIME:20200926T112500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025517@indico.cern.ch
DESCRIPTION:Speakers: Florian Girelli (University of Waterloo)\nIt is well
-known that quantum groups are relevant to describe the quantum regime of
3d gravity. They encode a deformation of the gauge symmetries (Lorentz sym
metries) parametrized by the value of the cosmological constant. Such def
ormation might be perplexing from a classical picture since the action is
defined in terms of plain/undeformed gauge symmetry. I would like to prese
nt here a novel way to derive/justify such quantum group deformation\, sta
rting from the classical gravity action.\n\nhttps://indico.cern.ch/event/9
48828/contributions/4025517/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025517/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quasi-local energy and Oppenheimer-Snyder collapse
DTSTART;VALUE=DATE-TIME:20200924T083500Z
DTEND;VALUE=DATE-TIME:20200924T090000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025514@indico.cern.ch
DESCRIPTION:Speakers: Naqing Xie (Fudan University)\nIn this talk\, we inv
estigate the gravitational collapse of the Oppenheimer-Snyder dust cloud w
ith spatially constant matter density from a quasi-local perspective. Give
n a closed two-surface within the star\, three versions of the quasi-local
energy are discussed. \nThis talk is based on a recent paper with Xiaokai
He [Class. Quantum Grav. 37(2020)185016\, arXiv:2005.04659].\n\nhttps://i
ndico.cern.ch/event/948828/contributions/4025514/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025514/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamically induced Planck scale and inflation in the Palatini for
mulation
DTSTART;VALUE=DATE-TIME:20200925T144500Z
DTEND;VALUE=DATE-TIME:20200925T151500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025512@indico.cern.ch
DESCRIPTION:Speakers: Antonio Racioppi (National Institute of Chemical Phy
sics and Biophysics\, Tallinn)\nWe study non-minimal Coleman-Weinberg infl
ation in the Palatini formulation of gravity in the presence of an $R^2$ t
erm. The Planck scale is dynamically generated by the vacuum expectation v
alue of the inflaton via its non-minimal coupling to the curvature scalar
$R$. We show that the addition of the $R^2$ term in Palatini gravity makes
non-minimal Coleman-Weinberg inflation again compatible with observationa
l data.\n\nhttps://indico.cern.ch/event/948828/contributions/4025512/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025512/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cosmic String Interpretation of NANOGrav Pulsar Timing Data
DTSTART;VALUE=DATE-TIME:20200925T141500Z
DTEND;VALUE=DATE-TIME:20200925T144500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025511@indico.cern.ch
DESCRIPTION:Speakers: Marek Lewicki (King's College London)\nThe NANOGrav
Collaboration has recently reported strong evidence for a stochastic commo
n-spectrum process\, which we interpret as a SGWB in the framework of cosm
ic strings. The possible NANOGrav signal would correspond to a string tens
ion Gμ∈(4×10^{−11}\,10^{−10}) at the 68% confidence level\, with a
different frequency dependence from supermassive black hole mergers. The
SGWB produced by cosmic strings with such values of Gμ would be beyond th
e reach of LIGO\, but could be measured by other planned and proposed dete
ctors such as SKA\, LISA\, TianQin\, AION-1km\, AEDGE\, Einstein Telescope
and Cosmic Explorer.\n\nhttps://indico.cern.ch/event/948828/contributions
/4025511/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025511/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quantum fate of generic gravitational singularity
DTSTART;VALUE=DATE-TIME:20200926T103500Z
DTEND;VALUE=DATE-TIME:20200926T105500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025706@indico.cern.ch
DESCRIPTION:Speakers: Włodzimierz Piechocki (National Centre for Nuclear
Research)\nI will present quantum model of the dynamics underlying the Bel
inski-Khalatnikov-Lifshitz (BKL) scenario. The classical BKL scenario conc
erns generic singularity of general relativity. The quantum BKL scenario i
ndicates that the gravitational singularity can be avoided by a quantum bo
unce. The latter presents a unitary evolution of considered gravitational
system. It is fairly probable that quantum general relativity\, to be cons
tructed\, would be free from singularities.\n\nhttps://indico.cern.ch/even
t/948828/contributions/4025706/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025706/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Loop quantum Schwarzschild interior and black hole remnant
DTSTART;VALUE=DATE-TIME:20200926T101500Z
DTEND;VALUE=DATE-TIME:20200926T103500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025705@indico.cern.ch
DESCRIPTION:Speakers: Cong Zhang (University of Warsaw)\nThe interior of a
Schwarzschild black hole is quantized by the method of loop quantum gravi
ty. The Hamiltonian constraint is solved and the physical Hilbert space is
obtained in the model. The properties of a Dirac observable corresponding
to the Arnowitt-Deser-Misner mass of the Schwarzschild black hole are stu
died by both analytical and numerical techniques. It turns out that zero i
s not in the discrete spectrum of this Dirac observable. This supports the
existence of a stable remnant after the evaporation of a black hole. Our
conclusion is valid for a general class of schemes adopted for loop quanti
zation of the mode\n\nhttps://indico.cern.ch/event/948828/contributions/40
25705/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025705/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Finite Quantum Gravity
DTSTART;VALUE=DATE-TIME:20200926T093500Z
DTEND;VALUE=DATE-TIME:20200926T095500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025704@indico.cern.ch
DESCRIPTION:Speakers: Lesław Rachwał (Czech Technical University)\nIn th
is talk\, I will present the first construction of the theory of quantum g
ravity completely free of UV divergences. I will show the successful const
ruction in the framework of quantum field theory of gravitational interact
ions. Moreover\, I will relate the enhanced symmetry properties of this th
eory with fixed points of RG flow and ensuing quantum conformal invariance
. The implications for the absence of classical GR-like singularities will
be presented as well.\n\nhttps://indico.cern.ch/event/948828/contribution
s/4025704/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025704/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Space of quantum states built over metrics of fixed signature
DTSTART;VALUE=DATE-TIME:20200926T091500Z
DTEND;VALUE=DATE-TIME:20200926T093500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025703@indico.cern.ch
DESCRIPTION:Speakers: Andrzej Okołów (University of Warsaw)\nA space of
quantum states and an algebra of quantum observables are constructed over
the set of all metrics of arbitrary but fixed signature\, defined on a ma
nifold. The construction is diffeomorphism invariant\, and unique up to na
tural isomorphisms.\n\nhttps://indico.cern.ch/event/948828/contributions/4
025703/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025703/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mutual interaction of binary black hole and misaligned circumbinar
y disk
DTSTART;VALUE=DATE-TIME:20200924T141500Z
DTEND;VALUE=DATE-TIME:20200924T143500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025608@indico.cern.ch
DESCRIPTION:Speakers: Michał Piróg (West Virginia University)\nThe talk
will cover the recent numerical investigation of a system composed of a Su
permassive Black Hole Binary (SMBHB) and a non-self-gravitating\, thin\, l
ocally isothermal\, viscous disk. \n\nThe evolution of such a configuratio
n is relevant not only for the expected gravitational-wave signal\, but al
so for electromagnetic searches for SMBHB candidates. In 2-dimensional\, N
ewtonian\, numerical simulations\, we analyze the influence of the two mod
el parameters: $q$ --- the *mass ratio* of the binary and $\\iota$ --- the
*inclination angle* between the binary and the disk. We found that config
urations with relatively low mass ratio\, composed of central mass and sat
ellite mass\, always settle down in a *quasi steady state*. On the other h
and\, configurations characterized by equal or comparable masses may manif
est an inability to reach quasi steady state for inclinations $\\iota \\in
(20^\\circ\,55^\\circ)$. This problem does not exist for moderately incli
ned or highly inclined configurations\, i.e.\, inclinations $\\iota \\le 2
0^\\circ$ or $\\iota \\ge 55^\\circ$. We try to understand the nature of t
hese phenomena by investigating the binary and viscous torque densities wh
ich determine the disk's final density distribution and\, in particular\,
the size of the *central gap*.\n\nhttps://indico.cern.ch/event/948828/cont
ributions/4025608/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025608/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Curved spacetime Effective Field Theory (cEFT) as a tool to invest
igate vacuum stability
DTSTART;VALUE=DATE-TIME:20200925T153500Z
DTEND;VALUE=DATE-TIME:20200925T155500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025389@indico.cern.ch
DESCRIPTION:Speakers: Łukasz Nakonieczny (University of Warsaw)\nI would
like to present application of the recently proposed curved spacetime Effe
ctive Field Theory (cEFT) to a problem of vacuum stability. To model the m
atter sector we used two scalar fields coupled through the Higgs portal ty
pe of interaction. Additionally\, both of these fields were coupled non-mi
nimally to gravity. This may be considered as a simplified model describi
ng an interaction of the real part of the Higgs doublet with the heavy sca
lar dark matter. To tackle the problem of the false vacuum stability again
st spontaneous creation of the true vacuum bubble we firstly integrated ou
t the heavy scalar and obtained cEFT for the light field. Then we investig
ated the influence of the higher order gravity mediated operators on vacuu
m stability. Results will be discussed in this presentation. \nThe present
ation is based on the paper arXiv:2004.12327\, that was written in collabo
ration with Z. Lalak and A. Nakonieczna.\n\nhttps://indico.cern.ch/event/9
48828/contributions/4025389/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025389/
END:VEVENT
BEGIN:VEVENT
SUMMARY:What happens at the end of the evaporation of a black hole?
DTSTART;VALUE=DATE-TIME:20200926T080000Z
DTEND;VALUE=DATE-TIME:20200926T084500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025516@indico.cern.ch
DESCRIPTION:Speakers: Carlo Rovelli (Centre de Physique Théorique\, CNRS)
\nWhat happens at the evaporation of a black of a black hole is not only s
till unclear\, but also -- contrary to what is sometimes claimed -- releva
nt for the issue of unitarity in blackhole physics. I illustrate what we k
now about this physics. I show that the problem breaks into three distinct
processes\, to some extent independent: the quantum physics of the matter
reaching the black hole center\, the quantum physics of the spacetime reg
ion approaching the singularity itself\, and quantum the physics of the ho
rizon\, as it shrinks towards the Planck scale. We have interesting indica
tions on the first two\, and tools to address the third\, in particular us
ing covariant loop quantum gravity. I describe the possibility of a quantu
m tunnelling across the classical singularity into a white hole region\, t
he matter-bounce at the stage called "Planck star" and the tunnelling of t
he horizon from black to white. I explain why there is no reason to expect
Hawking radiation's entropy to follow a Page curve\, and how information
can be trapped in the large interior volume of a hole and reemitted at the
white-hole/remnant stage.\n\nhttps://indico.cern.ch/event/948828/contribu
tions/4025516/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025516/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nonlinear metric perturbations and their applications
DTSTART;VALUE=DATE-TIME:20200924T090000Z
DTEND;VALUE=DATE-TIME:20200924T092500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025515@indico.cern.ch
DESCRIPTION:Speakers: Andrzej Rostworowski (Jagiellonian University)\nI wi
ll show how to generalize classical results on linear metric perturbations
to any higher orders of perturbation expansion and discuss some possible
applications.\n\nhttps://indico.cern.ch/event/948828/contributions/402551
5/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025515/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the Einstein flow in 2+1 dimensions
DTSTART;VALUE=DATE-TIME:20200924T081000Z
DTEND;VALUE=DATE-TIME:20200924T083500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025513@indico.cern.ch
DESCRIPTION:Speakers: David Fajman (University of Vienna)\nIt is well know
n that the Einstein equations can be interpreted as a system of PDEs descr
ibing a geometric flow - a continuous family of Riemannian metrics on a gi
ven topological manifold. \nIn this perspective the global structure of so
lutions to the Einstein equations is analysed using this geometric flow to
obtain information on the asymptotic behaviour towards future and past. I
n this talk we consider this problem in the context of 2+1-dimensional sol
utions of the Einstein equations and present a result on the future dynami
cs of general initial data on closed hyperbolic surfaces for the vacuum Ei
nstein equations with a cosmological constant.\n\nhttps://indico.cern.ch/e
vent/948828/contributions/4025513/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025513/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Planck scale as a constant of integration
DTSTART;VALUE=DATE-TIME:20200925T133000Z
DTEND;VALUE=DATE-TIME:20200925T141500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025510@indico.cern.ch
DESCRIPTION:Speakers: Alexander Vikman (Czech Academy of Sciences)\nI will
discuss local field theories with global degrees of freedom. The oldest o
f them is the so-called unimodular gravity introduced by Einstein a centur
y ago. In this theory the cosmological constant is not a constant of natur
e\, but merely a constant of integration. This provides an ideal landscape
or ensemble of theories giving a different view on the origin of naturaln
ess issues in modern physics.\n\nhttps://indico.cern.ch/event/948828/contr
ibutions/4025510/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025510/
END:VEVENT
BEGIN:VEVENT
SUMMARY:UNIQUE REGULAR INTERIOR SOLUTION FOR THE SLOWLY ROTATING KERR BLAC
K HOLE
DTSTART;VALUE=DATE-TIME:20200924T105500Z
DTEND;VALUE=DATE-TIME:20200924T111500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025466@indico.cern.ch
DESCRIPTION:Speakers: Pawel Mazur (University of South Carolina)\nI will p
resent the ${\\it No Hair}$ result for the solution of Einstein equations
describing the non-vacuum regular interior and the vacuum exterior of a sp
inning black hole. There are only two parameters characterizing the vacuum
exterior and two parameters for the non-vacuum regular interior of a spin
ning black hole. \nThese two sets of two parameters are connected by the m
atching condition for the interior and the exterior solutions on the appar
ent horizon. The solution depends on two parameters for which one can choo
se the mass $M$ and the angular momentum $J=Ma$ characterizing the vacuum
exterior Kerr metric. The unique regular source of the Kerr gravitational
field rotates rigidly with the angular velocity $\\Omega$ equal to the ang
ular velocity $\\Omega_{_{H}}$ of the Kerr black hole horizon. The exterio
r vacuum solution is given by the well-known Kerr metric while the interio
r metric is completely new. \n\n \nMy result settles the problem posed by
R. P. Kerr in 1963 in the case of slow rotation. This is the ${\\it No Hai
r}$ result for the regular spinning black holes such as those indirectly o
bserved in nature and thus it should have a bearing on the description of
the final states of mergers of binary black holes detected by LIGO and Vir
go gravitational wave detectors.\n\nhttps://indico.cern.ch/event/948828/co
ntributions/4025466/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025466/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Quasi-local mass of weak gravitational field
DTSTART;VALUE=DATE-TIME:20200924T102500Z
DTEND;VALUE=DATE-TIME:20200924T104000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025465@indico.cern.ch
DESCRIPTION:Speakers: Piotr Waluk (Center for Theoretical Physics\, PAS)\n
The widely accepted ADM expression for the energy of an asymptotically fla
t spacetime satisfies a "natural" consistency test - its second variation
is equal to the canonical hamiltonian functional for linearized gravity on
a Minkowski background. A viable quasi-local mass candidate should posses
a similar property\, namely - its second-order approximation should equal
the hamiltonian of the well-understood linearized theory.\nWe show that t
he Hawking quasi-local mass passes this test\, provided that certain gauge
conditions are fulfilled. We believe that these gauge conditions may actu
ally carry a physical meaning - they provide a suggestion about the way th
e problem of quasi-local energy should be posed.\n\nhttps://indico.cern.ch
/event/948828/contributions/4025465/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025465/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-singular Kerr-NUT-(anti-)de Sitter spacetimes with projectivel
y non-singular horizons
DTSTART;VALUE=DATE-TIME:20200924T101000Z
DTEND;VALUE=DATE-TIME:20200924T102500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025464@indico.cern.ch
DESCRIPTION:Speakers: Maciej Ossowski (University of Warsaw)\nSpacetimes w
ith NUT parameter are known to posses a string-like conical singularity. W
e present a method for obtaining non-singular Kerr-NUT spacetimes with an
arbitrary cosmological constant\, via an analogue of the Misner interpreta
tion of Taub-NUT spacetimes. Among the non-singular solution there is a cl
ass for which also one of the horizons is projectively non-singular\, i.e.
its space of null generators is non-singular. The horizon is found to be
always a cosmological one (but possibly with a negative mass) and non-extr
emal. The topology of such non-singular horizon is of a non-trivial bundle
of $U(1)$ over $S^2$ and can be extended onto the spacetime in such way t
hat the global topology is $S^3 \\times \\mathbb{R}$. We provide a geometr
ic interpretation of the non-singular structures on the spacetime\, our ap
proach relies on the space of orbits of the Killing vector field of a part
icular Killing vector field.\n\nhttps://indico.cern.ch/event/948828/contri
butions/4025464/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025464/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conformal fields and integrals of motion in pp waves and electroma
gnetic fields
DTSTART;VALUE=DATE-TIME:20200924T095500Z
DTEND;VALUE=DATE-TIME:20200924T101000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025463@indico.cern.ch
DESCRIPTION:Speakers: Krzysztof Andrzejewski (University of Lodz)\nThe pro
blem of integrals of the motion for the conformal Killing fields in curve
d space-times equipped with electromagnetic backgrounds will be analysed
. In particular\, for the pp-wave spacetimes the explicit form of conserv
ed charges will be presented. Relations between these charges and symmetri
es will be discussed in various Lagrangian and Hamiltonian approaches.\n\
nhttps://indico.cern.ch/event/948828/contributions/4025463/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025463/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The small sphere limits of quasilocal masses in higher dimensions
DTSTART;VALUE=DATE-TIME:20200924T094000Z
DTEND;VALUE=DATE-TIME:20200924T095500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025462@indico.cern.ch
DESCRIPTION:Speakers: Jinzhao Wang (ETH Zurich)\nThe problem of quasilocal
mass has been extensively studied mainly in four dimensions. Here we repo
rt results regarding several quasilocal mass proposals in spacetime dimens
ions $n \\geq 4$. After generalising three distinct quasilocal mass de
finitions to higher dimensions under appropriate assumptions\, we evaluate
their small sphere limits along lightcone cuts shrinking towards the ligh
tcone vertex. The results in vacuum are conveniently represented in terms
of the electromagnetic decompositions of the Weyl tensor. We find that the
limits at presence of matter yield the stress tensor as expected\, but th
e vacuum limits are in general not proportional to the Bel-Robinson supere
nergy $Q$ in dimensions $n > 4$. The result defies the role of the Bel
-Robinson superenergy as characterising the gravitational energy in higher
dimensions\, albeit the fact that it uniquely generalises. Surprisingly\,
the Hawking energy and the Brown-York energy exactly agree upon the small
sphere limits across all dimensions. The new vacuum limit $W$\, however\,
cannot be interpreted as a gravitational energy because of its non-positi
vity. Furthermore\, we also give the small sphere limits of the Kijowski-E
pp-Liu-Yau type energy in higher dimensions\, and again we see $W$ in plac
e of $Q$.\n\nhttps://indico.cern.ch/event/948828/contributions/4025462/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025462/
END:VEVENT
BEGIN:VEVENT
SUMMARY:General Relativistic Shock Waves that Induce Cosmic Acceleration
DTSTART;VALUE=DATE-TIME:20200924T104000Z
DTEND;VALUE=DATE-TIME:20200924T105500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025460@indico.cern.ch
DESCRIPTION:Speakers: Christopher Alexander (University of California\, Da
vis)\nA family of global shock-wave solutions of the Einstein field equati
ons for a perfect fluid are constructed. These shock-wave solutions consis
t of an interior self-similar expanding wave and an exterior self-similar
static wave\, separated by a spherical shock surface. The interior and ext
erior fluids are assumed to have isothermal equations of state of the form
$p = \\sigma\\rho$ and $\\bar{p} = \\bar{\\sigma}\\bar{\\rho}$ respective
ly\, with the strictly positive constants $\\sigma$ and $\\bar{\\sigma}$ r
epresenting a single parameter for each wave. The interior wave has an add
itional parameter\, denoted by $a$\, which represents how perturbed this w
ave is from a Friedmann-Lemaître-Robertson-Walker spacetime with the same
equation of state. The joining of the interior and exterior waves forms a
shock-wave solution when mass and momentum are conserved across the shock
surface\, which places a constraint on the three parameters. The resultin
g shock-wave solution is thus a two-parameter family of solutions. For $\\
sigma = \\bar{\\sigma}$\, the two-parameter family becomes a one-parameter
family and such solutions model the general relativistic version of an ex
plosion within a static\, singular\, isothermal sphere. Interestingly\, th
e two-parameter family of shock waves solve the Einstein field equations i
n the absence of a cosmological constant\, but despite this\, a cosmic acc
eleration is still present in the interior wave\, with the acceleration pa
rameterised by $a$. This fact follows from the pioneering work of Smoller
and Temple. The presence of this acceleration in the absence of a cosmolog
ical constant opens up the question of whether a vast primordial shock-wav
e could give rise to the cosmic acceleration observed today without the ne
ed for dark energy.\n\nhttps://indico.cern.ch/event/948828/contributions/4
025460/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025460/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational dynamics in the Higgs-dark matter sector
DTSTART;VALUE=DATE-TIME:20200924T092500Z
DTEND;VALUE=DATE-TIME:20200924T094000Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025459@indico.cern.ch
DESCRIPTION:Speakers: Anna Nakonieczna (University of Warsaw)\nDuring the
talk the course and results of gravitational collapse within the Higgs-dar
k matter sector using the double null formalism will be presented. The emp
loyed model consists of two scalar fields non-minimally coupled to gravity
\, one of which is charged under a U(1) gauge field and represents a stabl
e dark matter candidate. The uncharged scalar may represent a real part of
the Higgs doublet. There is another U(1) gauge field which can be associa
ted with the dark photon. Two coupling channels among the ordinary matter
and dark sectors\, namely the kinetic mixing among the U(1) gauge fields a
nd the Higgs portal coupling among scalars\, were included in the model.\n
The structures of emerging spacetimes will be analyzed via locations of dy
namically formed horizons and singularities. The dependence of the charact
eristics of forming objects\, precisely dynamical black holes\, on the par
ameters of the model of interest\, will be presented. Additionally\, a set
of spacetime quantities as seen by an observer moving with the medium wil
l be proposed to describe the outcomes of the processes.\n\nhttps://indico
.cern.ch/event/948828/contributions/4025459/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025459/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On Canonical Formalisms in General Relativity
DTSTART;VALUE=DATE-TIME:20200925T094500Z
DTEND;VALUE=DATE-TIME:20200925T101500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025319@indico.cern.ch
DESCRIPTION:Speakers: Gerhard Schaefer (Friedrich Schiller-Universität Je
na)\nThe canonical formalism by Arnowitt\, Deser and Misner has proven ver
y efficient in the derivation of higher order post-Newtonian (PN) dynamics
of compact binaries in general relativity (GR)\, also including bodies wi
th spin. There is ongoing strong impact on the gravitational wave research
\, in particular through its offspring\, the effective-one-body (EOB) appr
oach. The complete 3PN spinless binary dynamics has been obtained in 2001
and the 4PN one in 2014\, each for the first time. However\, there are two
other canonical formalisms in GR\, the somewhat related one by Dirac with
its famous maximal slicing condition and the less known one by Schwinger
with which by Kibble\, and this for the first time\, the Dirac spin-1/2-fi
eld equations had become canonically implemented into GR in fully gauge sy
mmetry-reduced form. In my talk the three canonical formalisms will be pre
sented and compared to each other.\n\nhttps://indico.cern.ch/event/948828/
contributions/4025319/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025319/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Freely falling bodies in standing wave spacetime
DTSTART;VALUE=DATE-TIME:20200925T103500Z
DTEND;VALUE=DATE-TIME:20200925T105500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025318@indico.cern.ch
DESCRIPTION:Speakers: Syed Naqvi (Jagiellonian Universtiy)\nThe phenomena
of standing waves are mostly studied in the context of mechanical or elec
tromagnetic waves. In the context of General Relativity\, the issue of how
to define standing gravitational waves was addressed by Bondi and later b
y Stefani. We investigate an expanding universe filled with standing gravi
tational waves. We study how freely falling particles in this spacetime be
have\, namely\, we investigate the geodesic equation and the geodesic devi
ation equation. We show that antinodes attract freely falling particles.\n
\nhttps://indico.cern.ch/event/948828/contributions/4025318/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025318/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational Waves from a newly born accreting magnetar
DTSTART;VALUE=DATE-TIME:20200925T101500Z
DTEND;VALUE=DATE-TIME:20200925T103500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025317@indico.cern.ch
DESCRIPTION:Speakers: Ankan Sur (Nicolaus Copernicus Astronomical Center\,
PAS)\nWe study the spin-evolution and gravitational-wave luminosity of a
newly-born magnetar with an initial spin period of 1 ms and having an incl
ination α between the magnetic moment axis and the rotation axis. Given a
ny random initial choice for the inclination\, we always find α → 90
◦ in a few milliseconds. As the star rotates under the influence of magn
etic dipole radiation and the escaping neutrinos\, the corotation radius e
xceeds the magnetospheric Alfvén radius and two columns of accreting matt
er are formed at the poles which eventually reach hydrostatic equilibrium
with the outflow and settling matter on the stellar surface. Initially\, t
he spin period is mostly affected by the neutrino luminosity but at later
times\, accretion makes the star spin-up rapidly. This object\, located at
1 Mpc\, emit gravitational waves with a strain h_c ∼ 10^{-24} at kHz fr
equencies. Given the estimated sensitivities for the third generation grav
itational-wave detectors\, we find that such an object would be a potentia
l target.\n\nhttps://indico.cern.ch/event/948828/contributions/4025317/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025317/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Generation of Z bosons in emission processes by neutrinos in early
Universe
DTSTART;VALUE=DATE-TIME:20200925T155500Z
DTEND;VALUE=DATE-TIME:20200925T161500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025392@indico.cern.ch
DESCRIPTION:Speakers: Mihaela Baloi (West University of Timisoara )\nProdu
ction of Z bosons in emission processes by neutrinos in the expanding de S
itter universe is studied. We use perturbative methods to investigate emis
sion processes that are forbidden in flat spacetime electroweak theory by
the energy and momentum conservation. The amplitude and probability for th
e spontaneous emission of a Z boson by a neutrino or an antineutrino are c
omputed analytically\, then we perform a graphical analysis in terms of th
e expansion parameter. Our results prove that this process is possible onl
y for large expansion conditions of the early Universe. The total probabil
ity of the process is analysed and we explore the physical consequences of
our results proving that in the Minkowski limit there is no emission of Z
bosons by neutrinos. The limit of large space expansion when the expansio
n parameter is larger than the mass of the Z boson is also obtained and th
e results prove that in this limit the emission probability increase.\n\nh
ttps://indico.cern.ch/event/948828/contributions/4025392/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025392/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cosmological attractor approximation in Einstein-Gauss-Bonnet grav
ity
DTSTART;VALUE=DATE-TIME:20200925T161500Z
DTEND;VALUE=DATE-TIME:20200925T163500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025390@indico.cern.ch
DESCRIPTION:Speakers: Ekaterina Pozdeeva (SINP MSU)\nWe construct models w
ith the Gauss-Bonnet term multiplied to a function of the scalar field lea
ding to inflationary scenario. The consideration is related with the slow-
roll approximation. The cosmological attractor approach gives the spectral
index of scalar perturbations which is in a good agreement with modern ob
servation and allows variability for tensor-to-scalar ratio. We reconstruc
t models with variability of parameters which allow to reproduce cosmologi
cal attractor predictions for inflationary parameters in the leading order
of 1/N approximation in the Einstein-Gauss-Bonnet gravity. \nThe talk is
based on the paper by E.O. Pozdeeva\, Eur.Phys.J.C 80 (2020) 7\,612 [arXiv
:2005.10133 [gr-qc]].\n\nhttps://indico.cern.ch/event/948828/contributions
/4025390/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025390/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Universe in a black hole with spin and torsion
DTSTART;VALUE=DATE-TIME:20200925T151500Z
DTEND;VALUE=DATE-TIME:20200925T153500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025391@indico.cern.ch
DESCRIPTION:Speakers: Nikodem Popławski (University of New Haven)\nThe co
nservation law for the total (orbital and spin) angular momentum of a Dira
c particle in the presence of gravity requires that spacetime is not only
curved\, but also has a nonzero torsion. The coupling between the spin and
torsion in the Einstein-Cartan theory of gravity generates gravitational
repulsion at extremely high densities. We consider gravitational collapse
of a spin-fluid sphere into a black hole. We show that a singularity is re
placed with a nonsingular bounce if there is no shear. We also show that t
orsion and quantum particle production during contraction avoid a singular
ity even if shear is present. Particle production during expansion can gen
erate a finite period of inflation and produce enormous amounts of matter.
The resulting closed universe on the other side of the event horizon may
have several bounces. Such a universe is oscillatory\, with each cycle lar
ger in size then the previous cycle\, until it reaches the cosmological si
ze and expands indefinitely. Our universe might have therefore originated
from a black hole.\n\nhttps://indico.cern.ch/event/948828/contributions/40
25391/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025391/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Teleparallel version of Horndeski gravity
DTSTART;VALUE=DATE-TIME:20200926T151500Z
DTEND;VALUE=DATE-TIME:20200926T153500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025102@indico.cern.ch
DESCRIPTION:Speakers: Sebastian Bahamonde (University of Tartu)\nHorndeski
gravity is the most general scalar tensor theory\, with a single scalar f
ield\, leading to second-order field equations and after the GW170817 it h
as been severely constrained. In this talk\, I will present an analog of H
orndeski’s theory in the Teleparallel Gravity framework where gravity is
mediated through torsion instead of curvature. It will be shown that\, ev
en though\, many terms are the same as in the curvature case\, we have muc
h richer phenomenology in the teleparallel setting because of the nature o
f the torsion tensor. After this\, I will show that by performing tensoria
l perturbations in this theory in a flat cosmological background\, one is
able to restore the severely constrained terms in standard Horndenski\, cr
eating an interesting way to revive Horndeski gravity. I will finalize my
talk explaining about the PPN analysis of this model.\n\nhttps://indico.ce
rn.ch/event/948828/contributions/4025102/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025102/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Neutrino oscillations in extended theories of gravity
DTSTART;VALUE=DATE-TIME:20200926T145500Z
DTEND;VALUE=DATE-TIME:20200926T151500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025100@indico.cern.ch
DESCRIPTION:Speakers: Luciano Petruzziello (INFN\, Sezione di Napoli)\nIn
this talk\, I summarize the process of investigating neutrino oscillations
within the framework of extended theories of gravity. Based on the covari
ant reformulation of Pontecorvo’s formalism\, the oscillation probabilit
y of neutrinos propagating in static spacetimes described by gravitational
actions quadratic in the curvature invariants is evaluated. For the sake
of simplicity\, calculations are carried out in the two-flavor approximati
on. It is shown that the neutrino phase is sensitive to the violation of t
he strong equivalence principle. By way of illustration\, I specialize the
analysis to various extended models of gravity in order both to quantify
such a violation and to understand how the characteristic free parameters
of these models affect the neutrino phase. The possibility to fix new boun
ds on these parameters and to constrain extended theories of gravity is fi
nally discussed.\n\nhttps://indico.cern.ch/event/948828/contributions/4025
100/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025100/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Canonical variational completion of 4D Gauss-Bonnet gravity
DTSTART;VALUE=DATE-TIME:20200926T143500Z
DTEND;VALUE=DATE-TIME:20200926T145500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025099@indico.cern.ch
DESCRIPTION:Speakers: Manuel Hohmann (University of Tartu)\nWe consider a
recent proposal to obtain a finite contribution of second derivative order
to the gravitational field equations in $D = 4$ dimensions from a renorma
lized Gauss-Bonnet term in the action. In previous works\, it has been sho
wn that the resulting field equations cannot be obtained as the Euler-Lagr
ange equations from a diffeomorphism-invariant action. Here we use techniq
ues from the inverse calculus of variation as an independent confirmation
that the suggested truncated Gauss-Bonnet field equations cannot be variat
ional\, in any dimension. For this purpose\, we employ canonical variation
al completion\, based on the notion of Vainberg-Tonti Lagrangian\, which c
onsists in adding a canonically defined correction term to a given system
of equations\, so as to make them derivable from an action. We find that i
n $D > 4$ the suggested field equations can be variationally completed\, w
hich yields a theory with fourth order field equations. In $D = 4$ the var
iationally completed theory diverges. Our findings are in line with Lovelo
ck's theorem\, which states that\, in 4 dimensions\, the unique second-ord
er Euler-Lagrange equations arising from a scalar density depending on the
metric tensors and its derivatives\, are the Einstein equations with a co
smological constant.\n\nThis contribution is based on [arXiv:2009.05459](h
ttp://export.arxiv.org/abs/2009.05459).\n\nhttps://indico.cern.ch/event/94
8828/contributions/4025099/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025099/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Covariant actions for bouncing cosmology in modified Gauss-Bonnet
gravity theories
DTSTART;VALUE=DATE-TIME:20200926T141500Z
DTEND;VALUE=DATE-TIME:20200926T143500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025097@indico.cern.ch
DESCRIPTION:Speakers: Daniele Vernieri (University of Naples "Federico II"
)\nCyclic universes with bouncing solutions are candidates for solving the
big bang initial singularity problem. Here I will look for bouncing solut
ions in the context of modified Gauss-Bonnet gravity theories whose field
equations contain up to fourth-order derivatives of the metric tensor. In
finding such bouncing solutions I will resort to an order reduction techni
que that reduces the order of the differential equations of the theory to
second-order and thus enables one to find solutions which are perturbative
ly close to general relativity. I will also build the covariant effective
actions of the resulting order reduced theories.\n\nhttps://indico.cern.ch
/event/948828/contributions/4025097/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025097/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aspects of AdS/CFT at finite cut-off
DTSTART;VALUE=DATE-TIME:20200926T134500Z
DTEND;VALUE=DATE-TIME:20200926T141500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025240@indico.cern.ch
DESCRIPTION:Speakers: Paweł Caputa (University of Warsaw)\nI will discuss
the AdS/CFT correspondence with finite cut-off and TT-deformations of hol
ographic conformal field theories. After introduction\, I will present som
e recent results for the deformations of 2d conformal field theories on cu
rved backgrounds and their holographic realization in Anti-de Sitter geome
tries in 3 spacetime dimensions.\n\nhttps://indico.cern.ch/event/948828/co
ntributions/4025240/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025240/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Early evolutionary tracks of low-mass stars in modified gravity
DTSTART;VALUE=DATE-TIME:20200926T131500Z
DTEND;VALUE=DATE-TIME:20200926T134500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025235@indico.cern.ch
DESCRIPTION:Speakers: Aneta Wojnar (University of Tartu)\nI will present h
ow pre-main sequence and low-mass stars' (M\n\nhttps://indico.cern.ch/even
t/948828/contributions/4025235/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025235/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lessons for quantum cosmology from anti-de Sitter black holes
DTSTART;VALUE=DATE-TIME:20200926T123000Z
DTEND;VALUE=DATE-TIME:20200926T131500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025236@indico.cern.ch
DESCRIPTION:Speakers: Michal P. Heller (Max Planck Institute for Gravitati
onal Physics (Albert Einstein Institute))\nGravitational physics is arguab
ly better understood in the presence of a negative cosmological constant t
han a positive one\, yet there exist strong technical similarities between
the two settings. These similarities can be exploited to enhance our unde
rstanding of the more speculative realm of quantum cosmology\, building on
robust results regarding anti-de Sitter black holes describing the thermo
dynamics of holographic quantum field theories. To this end\, we study 4-d
imensional gravitational path integrals in the presence of a negative cosm
ological constant\, and with minisuperspace metrics. We put a special emph
asis on boundary conditions and integration contours. The Hawking-Page tra
nsition is recovered and we find that below the minimum temperature requir
ed for the existence of black holes the corresponding saddle points become
complex. When the asymptotic anti-de Sitter space is cut off at a finite
distance\, additional saddle points contribute to the partition function\,
albeit in a very suppressed manner. These findings have direct consequenc
es for the no-boundary proposal in cosmology\, because the anti-de Sitter
calculation can be brought into one-to-one correspondence with a path inte
gral for de Sitter space with Neumann conditions imposed at the nucleation
of the universe. Our results lend support to recent implementations of th
e no-boundary proposal focusing on momentum conditions at the "big bang".\
n\nhttps://indico.cern.ch/event/948828/contributions/4025236/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025236/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Moving away from the Near-Horizon Attractor of the Extreme Kerr Fo
rce-Free Magnetosphere
DTSTART;VALUE=DATE-TIME:20200924T151500Z
DTEND;VALUE=DATE-TIME:20200924T153500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025233@indico.cern.ch
DESCRIPTION:Speakers: Filippo Camilloni (Niels Bohr Institute & University
of Perugia)\nForce-free electrodynamics is a non-linear regime of Maxwell
's equations capable to provide the minimal non-trivial level of descripti
on for pulsar and black hole magnetospheres. For this system to be hyperbo
lic it is necessary that the field is magnetically dominated\, F^2=B^2-E^2
>0. Despite its crucial role in explaining energy and angular momentum ext
raction from slowly spinning black holes (via the celebrated Blandford & Z
najek mechanism) no force-free analytic solution\, which is also magnetica
lly dominated\, is known in the highly spinning regime.\nAny stationary an
d axisymmetric solution in the extreme Kerr background converges to a forc
e-free attractor when the near-horizon extreme Kerr (NHEK) region is resol
ved. We use this attractor solution as a universal starting point for pert
urbing away from the NHEK region and show that at the second order in pert
urbation theory it is possible to find magnetically dominated magnetospher
es around the extreme Kerr black hole.\nA similar attractor solution emerg
es in the near-horizon near-extreme Kerr (near-NHEK) region of a nearly-ex
treme Kerr spacetime\, thus providing a more sensible model for astrophysi
cal settings.\n\nhttps://indico.cern.ch/event/948828/contributions/4025233
/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025233/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Transonic accretion flow with time-dependent boundary conditions i
n HARM.
DTSTART;VALUE=DATE-TIME:20200924T145500Z
DTEND;VALUE=DATE-TIME:20200924T151500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025035@indico.cern.ch
DESCRIPTION:Speakers: Ishika Palit (Center for Theoretical Physics\, PAS)\
nAccretion disks in High mass X-ray binaries (HMXB's) are mostly fed by th
e stellar wind from there companion star. These winds also affect the obse
rved X-ray spectra arising from the hot coronal flow. \nCygnus X-1 and its
companion star\, HDE-226868 is one of such HMXBs. It is one of the bright
est X-ray sources observed and shows the X-ray intensity variations in bot
h the soft and hard X-rays. I will present my recent work on 2D numerical
modeling using GRMHD code - HARM\, replicating such focused\, clumpy wind
from the binary companion fed for accretion onto the black hole. We model
an inviscid\, non-magnetized\, transonic accretion flow with a low angular
momentum profile. I will discuss my prescribed time-dependent boundary c
onditions in this code and how it affects the hydrodynamics of the flow in
the relativistic framework.\n\nhttps://indico.cern.ch/event/948828/contri
butions/4025035/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025035/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Galactic Center S cluster as a reservoir of strong-gravity probes
DTSTART;VALUE=DATE-TIME:20200924T143500Z
DTEND;VALUE=DATE-TIME:20200924T145500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025034@indico.cern.ch
DESCRIPTION:Speakers: Michal Zajacek (Center for Theoretical Physics\, PAS
)\nRecently\, Peissker\, Eckart\, Zajacek et al. (2020) have reported the
discovery of six faint stars in the innermost cluster of the Galaxy\, so-c
alled S cluster. These stars\, S4711-S4715 and S62\, can be monitored in t
he near-infrared K-band using both photometry and spectroscopy. Their elli
ptical orbits around the supermassive black hole (Sgr A*) break several re
cords. S4711 with the orbital period of 7.6 years is the shortest period s
tar around Sgr A*. S4714 has a large orbital eccentricity of 0.985 and can
potentially reach about 8% of the light speed at its pericenter\, which w
ould make it the fastest star detected so far. We characterize these stars
in terms of the general relativistic parameter. For future monitoring\, w
e will show predictions of the Schwarzschild precession as well as the Len
se-Thirring precession. S62\, S4711\, and S4714 have the potential to exhi
bit the Lense-Thirring precession of their ascending nodes from a fraction
of an arcsecond up to a few arcseconds per year\, depending on the exact
orientation as well as the magnitude of the spin of Sgr A*. These stars ar
e thus unique probes of the space-time around Sgr A* on the scale of a few
100 Schwarzschild radii.\n\nhttps://indico.cern.ch/event/948828/contribut
ions/4025034/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025034/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hydrodynamics of superfluid neutron stars
DTSTART;VALUE=DATE-TIME:20200924T131500Z
DTEND;VALUE=DATE-TIME:20200924T134500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025228@indico.cern.ch
DESCRIPTION:Speakers: Brynmor Haskell (Nicolaus Copernicus Astronomical Ce
nter\, PAS)\nNeutron stars are an extraordinary laboratory in which to stu
dy matter in extreme conditions of density\, magnetic energy and gravity.
Modelling the interior of these objects requires an understanding of high
density physics and phenomena such as superfluidity\, which are well known
in laboratory settings\, but must now be understood in a strong gravity\,
relativistic setting. This issue is particularly crucial now\, as the LIG
O and VIrgo detectors have made their first detections of gravitational wa
ves\, and have opened up an entirely new window to probe the physics of ne
utron stars.\n\nIn this talk I will describe some of the ongoing work at t
he Nicolaus Copernicus Astronomical Center\, and focus on efforts to model
superfluidity in neutron stars\, also in a relativistic setting. I will a
lso discuss how electromagnetic and gravitational wave observations can be
used together to constrain the models and further our understanding of fu
ndamental physics.\n\nhttps://indico.cern.ch/event/948828/contributions/40
25228/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025228/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simulations of Supermassive Black Hole Binaries on their way to Me
rger
DTSTART;VALUE=DATE-TIME:20200924T123000Z
DTEND;VALUE=DATE-TIME:20200924T131500Z
DTSTAMP;VALUE=DATE-TIME:20210417T160752Z
UID:indico-contribution-948828-4025204@indico.cern.ch
DESCRIPTION:Speakers: Manuela Campanelli (Rochester Institute of Technolog
y)\nSupermassive black hole mergers are one of the most dramatic phenomena
in the Universe. For a few hours\, they can emit as much power in gravit
ational waves as all the stars in the Universe produce in light. Moreover
\, they are an important element in determining the mass distribution of t
he entire population of supermassive black holes. However\, none has yet
been caught in the act\, in large part because they are rare\, and no one
knows what sort of light they should emit along with the gravitational wav
es. In this talk\, I will present new simulations aimed at providing deta
iled astrophysical knowledge about the environments close to supermassive
black hole binaries on their way to merger. I will show how gas flows in t
he immediate neighborhoods of these binaries\, especially when both black
holes are spinning\, and present calculations of jet launching and light s
ignals that observers should search for in order to find examples.\n\nhttp
s://indico.cern.ch/event/948828/contributions/4025204/
LOCATION:
URL:https://indico.cern.ch/event/948828/contributions/4025204/
END:VEVENT
END:VCALENDAR