广义相对论与量子宇宙学学术速递[1.10]
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gr-qc广义相对论与量子宇宙学，共计19篇
【1】 Merger rate of charged black holes from the dynamical capture
标题：动态俘获的带电黑洞合并率
链接：https://arxiv.org/abs/2201.02581
备注：19 pages, 1 figures, Comments are welcome
摘要：We consider the dynamical capture of black holes carrying U(1) charge which
can not only correspond to electric or magnetic charge but also have other
physical interpretations such as dark or hidden charge. In the low-velocity and
weak-field regime, we study gravitational and electromagnetic radiations from
point masses with U(1) charges in a hyperbolic orbit, and we develop a
formalism to derive the merger rate of charged black holes from the dynamical
capture. We apply the formalism to find the effects of the charge-to-mass ratio
on the merger rate for possible different cases and discover that the effects
depend on the models.
【2】 Constraints on Einstein-dilation-Gauss-Bonnet gravity from Black Hole-Neutron Star Gravitational Wave Events
标题：黑洞-中子星引力波事件对爱因斯坦膨胀高斯引力帽引力的制约
链接：https://arxiv.org/abs/2201.02543
备注：11 pages, 5 figures
摘要：Recent gravitational wave observations allow us to probe gravity in the
strong and dynamical field regime. In this paper, we focus on testing
Einstein-dilation Gauss-Bonnet gravity which is motivated by string theory. In
particular, we use two new neutron star black hole binaries (GW200105 and
GW200115). We also consider GW190814 which is consistent with both a binary
black hole and a neutron star black hole binary. Adopting the leading
post-Newtonian correction and carrying out a Bayesian Markov-chain Monte Carlo
analyses, we derive the 90\% credible upper bound on the coupling constant of
the theory as $\sqrt{\alpha_{GB}} \lesssim 1.33\,\rm km$, whose consistency is
checked with an independent Fisher analysis. This bound is stronger than the
bound obtained in previous literature by combining selected binary black hole
events in GWTC-1 and GWTC-2 catalogs. We also derive a combined bound of
$\sqrt{\alpha_{GB}} \lesssim 1.18\,\rm km$ by stacking GW200105, GW200115,
GW190814, and selected binary black hole events. In order to check the validity
of the effect of higher post-Newtonian terms, we derive corrections to the
waveform phase up to second post Newtonian order by mapping results in
scalar-tensor theories to Einstein-dilation Gauss-Bonnet gravity. We find that
such higher-order terms improve the bounds by $14.5\%$ for GW200105 and $6.9\%$
for GW200115 respectively.
【3】 Are Parametrized Tests of General Relativity with Gravitational Waves Robust to Unknown Higher Post-Newtonian Order Effects?
标题：引力波广义相对论的参数化检验对未知的高阶后牛顿效应是稳健的吗？
链接：https://arxiv.org/abs/2201.02542
备注：18 pages, 11 plots, and 7 figures
摘要：Gravitational wave observations have great potential to reveal new
information about the fundamental nature of gravity, but extracting that
information can be difficult. One popular technique is the parametrized
inspiral test of general relativity (a realization of the parametrized
post-Einsteinian framework), where the gravitational waveform, as calculated in
Einstein's theory as a series expansion in the orbital velocity, is
parametrically deformed at a given set of orders in velocity. However, most
current approaches usually only analyze the data while considering a single,
specific modification at a time. Are then constraints placed with a single
modification robust to our ignorance of higher post-Newtonian order
corrections? We show here that for a wide class of theories, specifically those
that admit a post-Newtonian expansion, single-parameter tests are indeed
robust. In particular, through a series of full Bayesian parameter estimation
studies on several different sets of synthetic data, we show that
single-parameter constraints are not degraded but rather are improved by the
inclusion of multiple parameters, provided one includes information about the
mathematical structure of the series. We then exemplify this with a specific
theory of gravity, shift-symmetric scalar Gauss-Bonnet theory, where the
waveform has been calculated to higher post-Newtonian orders than leading. We
show that the inclusion of these higher order terms strengthens
single-parameter constraints, instead of weakening them, and that the
strengthening is very mild. This analysis therefore provides strong evidence
that single-parameter post-Einsteinian tests of general relativity are robust
to ignorance of high post-Newtonian order terms in the general relativistic
deformations.
【4】 Inflation -- a Comparative Study Amongst Different Modified Gravity Theories
标题：膨胀--不同修正引力理论的比较研究
链接：https://arxiv.org/abs/2201.02473
备注：None
摘要：In the recent years, a host of modified gravity models have been proposed as
alternatives to the dark energy. A quantum theory of gravity also requires to
modify `General Theory of Relativity'. In the present article, we consider five
different modified theories of gravity, and compare inflationary parameters
with recent data sets released by two Planck collaboration teams. Our analysis
reveals that the scalar-tensor theory of gravity is the best alternative.
【5】 How fundamental is entropy? From non-extensive statistics and black hole physics to the holographic dark universe
标题：熵有多基本？从非泛泛统计和黑洞物理到全息暗宇宙
链接：https://arxiv.org/abs/2201.02424
备注：13 pages, no figures
摘要：We propose a new entropy construct that generalizes the Tsallis, R\'enyi,
Sharma-Mittal, Barrow, Kaniadakis, and Loop Quantum Gravity entropies and
reduces to the Bekenstein-Hawking entropy in a certain limit. This proposal is
applied to the Schwarzschild black hole and to spatially homogeneous and
isotropic cosmology, where it is shown that it can potentially describe
inflation and/or holographic dark energy.
【6】 Ghost instability in the teleparallel gravity model with parity violations
标题：具有宇称破缺的遥平行引力模型中的鬼不稳定性
链接：https://arxiv.org/abs/2201.02357
备注：9 pages, 0 figure, teleparallel gravity, parity violation
摘要：In this paper we consider the parity violating gravity model within the
framework of teleparallel gravity. The parity violations are caused by the
couplings of a scalar field to the scalar invariants which are parity-odd and
quadratic in the torsion tensor. Totally there are two such type independent
invariants, and one of them is the Nieh-Yan density. Through investigations on
the cosmological perturbations of this model, we find that in general it
suffers from the difficulties of ghost instability in the scalar and vector
perturbations. But in the special case only the coupling to the Nieh-Yan
density exists, this model is ghost free and reduces to the Nieh-Yan modified
Teleparallel Gravity model.
【7】 On the role of magnetic fields into the dynamics and gravitational wave emission of binary neutron stars
标题：磁场在双星中子星动力学和引力波发射中的作用
链接：https://arxiv.org/abs/2201.02287
备注：19 pages, 10 figures
摘要：Modelling as a dipole the magnetic interaction of a binary system of neutron
stars, we are able to include the magnetic effects in the Newtonian and in the
inspiral dynamics of the system using an equivalent one-body description.
Furthermore, in the inspiral stage we determine the role of the magnetic
interaction in the waveforms generated by the system and obtain explicit
formulas for the decrease in the separation of the stars, the time to reach a
minimal radius, the gravitational luminosity and the change of gravitational
wave frequency, all this within the quadrupole approximation. For the magnitude
of the magnetic field that is consider to exist in these binaries $\sim 10^{16}
{\rm G}$ we are able to show that its effect on the observable quantities is of
the order of the 2PN correction, already close to the detection range of the
gravitational waves observatories. %} We also discuss cases in which the
magnetic field could have a more significant influence.
【8】 Dynamical evolution of dark matter admixed neutron stars
标题：暗物质混合中子星的动力学演化
链接：https://arxiv.org/abs/2201.02274
备注：None
摘要：We dynamically evolve for the first time dark matter admixed neutron stars
with fermionic dark matter. These systems are mixtures of the ordinary nuclear
matter of a neutron star and dark matter. To perform our dynamical evolutions,
we derive the equations of motion, in conservation form, for spherically
symmetric systems with an arbitrary number of perfect fluids. Using finite
volume and high-resolution shock-capturing methods, we dynamically evolve the
two-fluid case, with the first fluid modeling ordinary matter and the second
fluid modeling dark matter. We use our dynamical solutions to study nonlinear
stability, radial oscillation frequencies, and a dynamical formation process.
【9】 Perturbations of a Schwarzschild black hole in torsion bigravity
标题：扭转双引力下Schwarzschild黑洞的微扰
链接：https://arxiv.org/abs/2201.02259
摘要：In this paper we pursue the study of linear perturbations around a
Schwarzschild black hole in a generalized Einstein-Cartan theory of gravity,
called torsion bigravity. This theory contains both massless and massive spin-2
excitations. Here we consider non spherically-symmetric perturbations with
generic multipolarity $L \geq 1$. We extend the conclusion of linear stability,
previously obtained for $L=0$ [Phys. Rev. D 104, 024032], to the generic $L
\geq 1$ case. We prove that the mass $\kappa$ of the massive spin-2 excitation
must be large enough, namely $\kappa r_h > \sqrt{1+\eta}$, to avoid the
presence of singularities in the perturbation equations. The perturbation
equations are shown to have a triangular structure, where massive spin-2
excitations satisfy decoupled equations, while the Einstein-like massless
spin-2 ones satisfy inhomogeneous equations sourced by the massive spin-2
sector. We study quasi-bound states, and exhibit some explicit complex
quasi-bound frequencies. We briefly discuss the issue of superradiance
instabilities.
【10】 Swiss-cheese cosmologies with variable $G$ and $Λ$ from the renormalization group
标题：重整化群中具有变量$G$和$Λ$的瑞士奶酪宇宙论
链接：https://arxiv.org/abs/2201.02251
备注：15 pages, 3 figures
摘要：A convincing explanation for the nature of the dark energy and dark matter is
still missing. In recent works a RG-improved swiss-cheese cosmology with an
evolving cosmological constant dependent on the \sch radius has been proven to
be a promising model to explain the observed cosmic acceleration. In this work
we extend this model to consider the combined scaling of the Newton constant
$G$ and the cosmological constant $\Lambda$ according to the IR-fixed point
hypothesis. We shall show that our model easily generates the observed recent
passage from deceleration to acceleration without need of extra energy scales,
exotic fields or fine tuning. In order to check the generality of the concept,
two different scaling relations have been analysed and we proved that both are
in very good agreement with $\Lambda$CDM cosmology. We also show that our model
satisfies the observational local constraints on $\dot{G}/G$.
【11】 Black Hole Superradiance in Dynamical Chern-Simons Gravity
标题：动力Chern-Simons引力中的黑洞超辐射
链接：https://arxiv.org/abs/2201.02220
备注：19 pages, 4 figures
摘要：Black hole superradiance provides a window into the dynamics of light scalar
fields and their interactions close to a rotating black hole. Due to the
rotation of the black hole, the amplitude of the scalar field becomes
magnified, leading to a "black hole bomb" effect. Recent work has demonstrated
that rotating black holes in dynamical Chern-Simons gravity possess unique
structures, the "Chern-Simons caps," which may influence the behavior of matter
near the black hole. Motivated by the presence of these caps, we study
superradiance in dynamical Chern-Simons gravity in the context of a slowly
rotating black hole. We find that additional modes are excited and contribute
to the superradiance beyond what is expected for a Kerr black hole. Studying
the superradiant spectrum of perturbations, we find that the Chern-Simons
contributions give rise to small corrections to the angular dependence of the
resulting scalar cloud. Finally, we comment on potential observable
consequences and future avenues for investigation.
【12】 Well Tempered Cosmology: Scales
标题：温文尔雅的宇宙学：尺度
链接：https://arxiv.org/abs/2201.02211
备注：6 pages
摘要：Well tempered cosmology provides a well defined path for obtaining cosmology
with a low energy cosmic acceleration despite a high (Planck) energy
cosmological constant $\Lambda$, through a scalar field dynamically canceling
$\Lambda$. We explore relations between the mass scales entering the various
Horndeski gravity terms, and focus on the cases of only one or only two mass
scales, obtaining general solutions for the form of the action. The resulting
cosmology can be natural and viable, and as one of the only paths to dealing
with the cosmological constant problem it has a rationale to be a benchmark
cosmology.
【13】 Bubble universes and traversable wormholes
标题：泡沫宇宙和可穿越的虫洞
链接：https://arxiv.org/abs/2201.02203
备注：24 pages, 8 figures
摘要：Bubble universes and traversable wormholes in general relativity can be
realized as two sides of the same concept. To exemplify, we find, display, and
study in a unified manner a Minkowski-Minkowski closed universe and a
Minkowski-Minkowski traversable wormhole. By joining two 3-dimensional flat
balls along a thin shell two-sphere of matter, i.e., a spherical domain wall,
into a single spacetime one gets a Minkowski-Minkowski static closed universe,
i.e., a bubble universe. By joining two 3-dimensional complements of flat balls
along a thin shell two-sphere of matter, i.e., a spherical throat, into a
single spacetime one gets a Minkowski-Minkowski static open universe which is a
traversable wormhole. Thus, Minkowski-Minkowski bubble universes and wormholes
can be seen as complementary. It is also striking that these two spacetimes
have resemblances with two well-known static universes. The Minkowski-Minkowski
static closed universe resembles the Einstein universe, a static closed
spherical universe homogeneously filled with dust matter and with a
cosmological constant. The Minkowski-Minkowski static open universe resembles
the Friedmann static universe, a static open hyperbolic universe homogeneously
filled with negative energy density dust and with a negative cosmological, a
universe with two disjoint branes that can be considered a failed wormhole. In
this light, the Einstein and Friedmann universes are also two sides of the same
concept. A linear stability analysis for all these spacetimes is performed. The
complementarity between bubble universes and traversable wormholes, that exists
for these static spacetimes, can be can carried out for dynamical spacetimes,
indicating that such a complementarity is general. The study suggests that
bubble universes and traversable wormholes can be seen as coming out of the
same concept, and thus, if ones exist the others should also exist.
【14】 The spatial Functional Renormalization Group and Hadamard states on cosmological spacetimes
标题：宇宙时空中的空间泛函重整化群和Hadamard态
链接：https://arxiv.org/abs/2201.02575
备注：59 pages, 1 figure
摘要：A spatial variant of the Functional Renormalization Group (FRG) is introduced
on (Lorentzian signature) globally hyperbolic spacetimes. Through its
perturbative expansion it is argued that such a FRG must inevitably be state
dependent and that it should be based on a Hadamard state. A concrete
implementation is presented for scalar quantum fields on flat
Friedmann-Lema\^{i}tre spacetimes. The universal ultraviolet behavior of
Hadamard states allows the flow to be matched to the one-loop renormalized flow
(where strict removal of the ultraviolet cutoff requires a tower of potentials,
one for each power of the Ricci scalar). The state-dependent infrared behavior
of the flow is investigated for States of Low Energy, which are Hadamard states
deemed to be viable vacua for a pre-inflationary period. A simple
time-dependent infrared fixed point equation (resembling that in Minkowski
space) arises for any scale factor, with analytically computable corrections
coding the non-perturbative ramifications of the Hadamard property in the
infrared.
【15】 Microlensing constraints on clustered primordial black holes
标题：簇状原始黑洞的微透镜约束
链接：https://arxiv.org/abs/2201.02521
备注：9 pages, 1 figure. Comments are welcome!
摘要：The discovery of black-hole-binary mergers through their gravitational wave
(GW) emission has reopened the exciting possibility that dark matter is made,
at least partly, of primordial black holes (PBHs). However, this scenario is
challenged by many observational probes that set bounds on the relative PBH
abundance across a broad range of viable PBH masses. Among these bounds, the
ones coming from microlensing surveys are particularly severe in the mass range
from $\sim 10^{-10}$ to a few M$_{\odot}$. The upper part of this range
precisely corresponds to the mass window inside which the formation of PBHs
should be boosted due to the QCD phase transition in the early Universe, which
makes the microlensing probes particularly important. However, it has been
argued that taking into account the inevitable clustering of PBH on small
scales can significantly relax or entirely remove these bounds. While the
impact of PBH clustering on the GW event rate has been studied in detail, its
impact on the microlensing event rate has not yet been fully assessed. In this
Letter, we address this issue, and show that clusters arising from PBH formed
from Gaussian initial curvature perturbations do not alter the current
microlensing constraints, as they are not sufficiently dense nor massive.
【16】 Gravitational Reheating
标题：重力加热
链接：https://arxiv.org/abs/2201.02348
备注：5 pages, 4 figures
摘要：In this letter, we show for the first time that the perfect state of our
present universe can be obtained through gravitational interaction between
inflaton and all fundamental fields during reheating without invoking new
physics. Our analysis revealed that gravitational reheating is consistent for a
very restricted class of inflation models and narrow ranges of reheating
temperature and dark matter mass.
【17】 Genuine tripartite nonlocality and entanglement in curved spacetime
标题：弯曲时空中的真三体非定域性和纠缠
链接：https://arxiv.org/abs/2201.02333
备注：None
摘要：We study the genuine tripartite nonlocality (GTN) and the genuine tripartite
entanglement (GTE) of Dirac fields in the background of a Schwarzschild black
hole. We find that the Hawking radiation degrades both the physically
accessible GTN and the physically accessible GTE. The former suffers from
"sudden death" at some critical Hawking temperature, and the latter approaches
to the nonzero asymptotic value in the limit of infinite Hawking temperature.
We also find that the Hawking effect cannot generate the physically
inaccessible GTN, but can generate the physically inaccessible GTE for fermion
fields in curved spacetime. These results show that on the one hand the GTN
cannot pass through the event horizon of black hole, but the GTE do can, and on
the other hand the surviving physically accessible GTE and the generated
physically inaccessible GTE for fermions in curved spacetime are all not
nonlocal. Some monogamy relations between the physically accessible GTE and the
physically inaccessible GTE are found.
【18】 New binary black hole mergers in the LIGO--Virgo O3a data
标题：LIGO中新的双星黑洞合并--室女座O3a数据
链接：https://arxiv.org/abs/2201.02252
备注：13 pages, 6 figures, 2 tables, 4 appendices (15 pages, 15 figures)
摘要：We report the detection of ten new binary black hole (BBH) merger signals in
the publicly released data from the the first half of the third observing run
(O3a) of advanced LIGO and advanced Virgo. Candidates are identified using an
updated version of the IAS pipeline (Venumadhav et al.), and events are
declared according to criteria similar to those in the GWTC-2.1 catalog (Abbott
et al.). The updated search is sensitive to a larger region of parameter space,
applies a template prior that accounts for different search volume as a
function of intrinsic parameters, and uses an improved coherent detection
statistic that optimally combines data from the Hanford and Livingston
detectors. Among the ten new events, we find interesting astrophysical
scenarios including sources with confidently large effective spin in both the
positive and negative directions, high-mass black holes that are difficult to
form in stellar collapse models due to (pulsational) pair instability, and
low-mass mergers bridging the gap between neutron stars and the lightest
observed black holes. We detect events populating the upper and lower black
hole mass gaps with both extreme and near-unity mass ratios, and one of the
possible neutron star--black hole mergers is well localized for electromagnetic
counterpart searches. We see a substantial increase in significance for many of
the events previously reported by other pipelines, and we detect all of the
GWTC-2.1 BBH mergers with coincident data in Hanford and Livingston except for
three loud events that get vetoed (compatible with the false-positive rate of
our veto procedure) and three that fall below the detection threshold. We also
return to significance the event GW190909_114149, which was reduced to a
sub-threshold trigger in GWTC-2.1. This makes a total of 42 BBH mergers
detected by our pipeline's Hanford--Livingston coincident search of the O3a
data.
【19】 A $p$-Adic Matter in a Closed Universe
标题：a$p$-封闭宇宙中的阿迪克物质
链接：https://arxiv.org/abs/2201.02200
备注：None
摘要：In this paper, we introduce a new type of matter that has origin in $p$-adic
strings, i.e., strings with a $p$-adic worldsheet. We investigate some
properties of this $p$-adic matter, in particular its cosmological aspects. We
start with crossing symmetric scattering amplitudes for $p$-adic open strings
and related effective nonlocal and nonlinear Lagrangian which describes tachyon
dynamics at the tree level. Then, we make a slight modification of this
Lagrangian and obtain a new Lagrangian for non-tachyonic scalar field. {Using
this new Lagrangian in the weak field approximation as a matter in Einstein
gravity with the cosmological constant, one obtains an exponentially expanding
FLRW closed universe.} At the end, we discuss the obtained results, i.e.,
computed mass of the scalar $p$-adic particle, estimated radius of related
closed universe and noted $p$-adic matter as a possible candidate for dark
matter.
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