by jsendak | Jan 20, 2024 | GR & QC Articles
Extreme mass-ratio inspirals, a target source for the space-based
gravitational wave detector LISA, are a sensitive probe of fundamental scalar
fields coupled to gravity. We assess the capability of LISA to detect whether
the secondary compact object is endowed with a scalar field, in the case of
inclined orbits. We show that the imprint of the scalar field depends on the
orbital inclination, and is significantly larger for prograde orbits.
Conclusions:
- Extreme mass-ratio inspirals (EMRIs) are a target source for the space-based gravitational wave detector LISA.
- EMRIs can provide valuable information about fundamental scalar fields coupled to gravity.
- The presence of a scalar field can be detected by LISA, particularly in the case of inclined orbits.
- The imprint of the scalar field is larger for prograde (forward-moving) orbits compared to retrograde (backward-moving) orbits.
Roadmap for Readers:
1. Introduction
The introduction provides an overview of the significance of extreme mass-ratio inspirals as a target source for the LISA gravitational wave detector, emphasizing their potential to probe fundamental scalar fields coupled to gravity.
2. Background
This section explains the concepts of extreme mass-ratio inspirals and scalar fields coupled to gravity, ensuring readers have a clear understanding of the topic before delving into the analysis.
3. Methodology
This section describes the approach used to assess the capability of LISA in detecting the presence of scalar fields in EMRIs with inclined orbits. It outlines the calculations and simulations performed to study the imprint of scalar fields on the gravitational wave signals.
4. Results
This section presents the findings of the study. It highlights that the imprint of scalar fields depends on the orbital inclination and is more pronounced for prograde orbits compared to retrograde orbits.
5. Discussion
In this section, the authors analyze and interpret the results obtained. They explore the implications of their findings and discuss the significance of detecting scalar fields in EMRIs.
6. Future Challenges
This section identifies potential challenges that need to be addressed in future research. It could include limitations of the current study, computational complexities, and uncertainties in the detection process.
7. Opportunities on the Horizon
This section explores potential opportunities for further investigation. It could discuss areas for improvement in data analysis techniques, advancements in gravitational wave detectors, or the possibility of conducting observational studies.
8. Conclusion
A summary of the key findings and their implications is provided in the conclusion section. It reinforces the importance of studying extreme mass-ratio inspirals to probe fundamental scalar fields coupled to gravity.
Format:
Extreme mass-ratio inspirals, a target source for the space-based gravitational wave detector LISA, are a sensitive probe of fundamental scalar fields coupled to gravity. We assess the capability of LISA to detect whether the secondary compact object is endowed with a scalar field, in the case of inclined orbits. We show that the imprint of the scalar field depends on the orbital inclination, and is significantly larger for prograde orbits.
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by jsendak | Jan 19, 2024 | GR & QC Articles
We study the holographic dual of a topological symmetry operator in the
context of the AdS/CFT correspondence. Symmetry operators arise from
topological field theories localized on a subspace of the boundary CFT
spacetime. We use bottom up considerations to construct the topological sector
associated with their bulk counterparts. In particular, by exploiting the
structure of entanglement wedge reconstruction we argue that the bulk
counterpart has a non-topological worldvolume action, i.e., it describes a
dynamical object. As a consequence, we find that there are no global $p$-form
symmetries for $p geq 0$ in asymptotically AdS spacetimes, which includes the
case of non-invertible symmetries. Provided one has a suitable notion of
subregion-subregion duality, our argument for the absence of bulk global
symmetries applies to more general spacetimes. These considerations also
motivate us to consider for general QFTs (holographic or not) the notion of
lower-form symmetries, namely, $(-m)$-form symmetries for $m geq 2$.
According to the article, the holographic dual of a topological symmetry operator in the AdS/CFT correspondence can be studied. These symmetry operators come from topological field theories localized on a subspace of the boundary CFT spacetime. The article uses bottom-up considerations to construct the topological sector associated with their bulk counterparts.
By analyzing the structure of entanglement wedge reconstruction, the article argues that the bulk counterpart of the topological symmetry operator has a non-topological worldvolume action. This means that it describes a dynamic object rather than a purely topological one.
As a result of this analysis, the article concludes that there are no global p-form symmetries for p greater than or equal to 0 in asymptotically AdS spacetimes, even for non-invertible symmetries. This conclusion holds true for a wider range of spacetimes if a suitable notion of subregion-subregion duality is considered.
Based on these conclusions, the article suggests considering the notion of lower-form symmetries, specifically (-m)-form symmetries for m greater than or equal to 2, for general quantum field theories, whether holographic or not.
Future Roadmap
Potential Challenges:
- Developing a suitable notion of subregion-subregion duality for more general spacetimes
- Investigating the implications of the absence of global p-form symmetries in asymptotically AdS spacetimes
- Understanding the behavior and properties of dynamical objects associated with topological symmetry operators
- Exploring the implications and applications of lower-form symmetries in general quantum field theories
Potential Opportunities:
- Advancing our understanding of the AdS/CFT correspondence and its implications for symmetry operators
- Expanding the knowledge of entanglement wedge reconstruction and its connection to the bulk dynamics
- Exploring new avenues in quantum field theories by considering lower-form symmetries
- Applying the findings to various areas of physics, such as condensed matter systems, high-energy physics, and quantum gravity
Conclusion:
The article emphasizes the study of the holographic dual of a topological symmetry operator in relation to the AdS/CFT correspondence. It argues that the bulk counterpart of this operator has a non-topological worldvolume action and, as a result, there are no global p-form symmetries for p greater than or equal to 0 in asymptotically AdS spacetimes. The conclusions apply to a wider range of spacetimes if subregion-subregion duality is considered. The article suggests exploring lower-form symmetries for general quantum field theories as a potential future direction.
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by jsendak | Jan 19, 2024 | GR & QC Articles
The species scale is a field-dependent UV cut-off for any effective field
theory weakly coupled to gravity. In this letter we show that, in the context
of inflationary cosmology, a detection of primordial gravitational waves will
set an upper bound on the decay rate $|Lambda’_s/Lambda_s|$ of the species
scale. Specifically, we derive this in terms of the tensor-to-scalar ratio $r$
of power spectra of primordial perturbations. Given the targets of current and
next generation experiments, we show that any successful detection would
signify that this upper limit is of the order of unity, which is consistent
with recent discussions in the literature.
The Roadmap for Inflationary Cosmology and Primordial Gravitational Waves
In the context of inflationary cosmology, the detection of primordial gravitational waves has important implications for our understanding of the early universe. In this letter, we present a new insight into the relationship between the detection of these gravitational waves and the decay rate of the species scale, denoted as $|Lambda’_s/Lambda_s|$.
Understanding the Species Scale
The species scale is a concept that characterizes the UV cut-off limit for any effective field theory weakly coupled to gravity. It provides a boundary beyond which our current theoretical frameworks may no longer hold. By investigating the relationship between the decay rate of the species scale and the detection of primordial gravitational waves, we can gain valuable insights into the fundamental laws governing our universe.
Exploring the Tensor-to-Scalar Ratio
In our analysis, we leverage the tensor-to-scalar ratio, denoted as $r$, which quantifies the power spectra of primordial perturbations. By studying the connection between $r$ and the decay rate $|Lambda’_s/Lambda_s|$, we can establish an upper bound for this rate based on the detection or non-detection of primordial gravitational waves.
Potential Challenges
As with any scientific endeavor, there are challenges that need to be overcome in this research. First and foremost, detecting primordial gravitational waves is an intricate task that requires advanced observational techniques and precise measurements. Current and next-generation experiments are striving to achieve this goal, but it remains a complicated endeavor.
Additionally, establishing a robust upper limit on the decay rate $|Lambda’_s/Lambda_s|$ based on the detection of gravitational waves involves significant theoretical and experimental considerations. Our understanding of inflationary cosmology and the species scale is continuously evolving, and further research and analysis are necessary to refine our findings.
Potential Opportunities
The successful detection of primordial gravitational waves and the establishment of an upper limit on the decay rate $|Lambda’_s/Lambda_s|$ would have far-reaching implications. It would validate and refine our current understanding of inflationary cosmology, providing concrete evidence for the validity of our theoretical frameworks.
Moreover, this detection would open up new avenues for exploring the fundamental laws of the universe beyond our current theoretical constraints. It would prompt further investigations into the interplay between gravity, quantum field theories, and the early universe, potentially revolutionizing our understanding of the cosmos.
The Journey Ahead
In conclusion, the road ahead in the study of inflationary cosmology and primordial gravitational waves is both challenging and promising. The detection of these waves and the establishment of an upper limit on the decay rate of the species scale hold immense potential for advancing our knowledge of the early universe.
However, it is essential to acknowledge the complexities involved in detecting gravitational waves and accurately determining the decay rate. Continuing advancements in observational techniques and theoretical understanding are vital to overcoming these challenges.
As we progress on this journey, it is crucial to remain open to new insights and to nurture interdisciplinary collaborations. By persisting in our pursuit, we stand to uncover profound truths about the cosmos and our place within it.
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by jsendak | Jan 19, 2024 | GR & QC Articles
Recent works have uncovered an excess signal in the parity-odd four-point
correlation function measured from the BOSS spectroscopic galaxy survey. If
physical in origin, this could indicate evidence for new parity-breaking
processes in the scalar sector, most likely from inflation. At heart, these
studies compare the observed four-point correlator to the distribution obtained
from parity-conserving mock galaxy surveys; if the simulations underestimate
the covariance of the data, noise fluctuations may be misinterpreted as a
signal. To test this, we reanalyse the BOSS CMASS + LOWZ parity-odd dataset
with the noise distribution modeled using the newly developed GLAM-Uchuu suite
of mocks. These comprise full N-body simulations that follow the evolution of
$2000^3$ dark matter particles in a $Lambda$CDM universe, and represent a
significant upgrade compared to the formerly MultiDark-Patchy mocks, which were
based on an alternative (non N-body) gravity solver. We find no significant
evidence for parity-violation in the BOSS dataset (with a baseline detection
significance of $1.4sigma$), suggesting that the former signal ($>3.5sigma$
with our data cuts) could be caused by an underestimation of the covariance in
MultiDark-Patchy. The significant differences between results obtained with the
two sets of BOSS-calibrated galaxy catalogs showcases the heightened
sensitivity of beyond-two-point analyses to the treatment of non-linear effects
and indicates that previous constraints may suffer from large systematic
uncertainties.
Recent studies have found an excess signal in the parity-odd four-point correlation function measured from the BOSS spectroscopic galaxy survey. This excess signal could be evidence of new parity-breaking processes in the scalar sector, possibly caused by inflation.
To determine if this signal is physical or if it could be due to noise fluctuations, the BOSS CMASS + LOWZ parity-odd dataset is reanalyzed. The noise distribution in this analysis is modeled using the newly developed GLAM-Uchuu suite of mocks, which are full N-body simulations that follow the evolution of dark matter particles in a $Lambda$CDM universe.
This reanalysis finds no significant evidence for parity-violation in the BOSS dataset, with a baseline detection significance of .4sigma$. This suggests that the previous signal ($>3.5sigma$ with data cuts) may have been caused by an underestimation of the covariance in the MultiDark-Patchy mocks.
The significant differences between the results obtained with the two sets of BOSS-calibrated galaxy catalogs highlight the importance of properly accounting for non-linear effects in beyond-two-point analyses. These differences also indicate that previous constraints may have large systematic uncertainties.
Future Roadmap
Looking ahead, there are several challenges and opportunities on the horizon:
1. Further Analysis
Additional analysis and investigations should be conducted to confirm these findings and verify the robustness of the conclusions. This includes exploring other datasets and performing independent analyses to validate the absence of parity-violation.
2. Improving Covariance Estimation
The underestimation of covariance in the MultiDark-Patchy mocks underscores the need for more accurate and reliable methods of estimating covariance. Developing improved covariance estimation techniques can help prevent the misinterpretation of noise fluctuations as signals, leading to more accurate and reliable measurements.
3. Refining Non-linear Effects Treatment
Beyond-two-point analyses are highly sensitive to the treatment of non-linear effects. Ongoing efforts should focus on refining and enhancing the methods used to account for these non-linear effects. This will improve the accuracy of future measurements and reduce systematic uncertainties.
4. Expanding Mock Catalogs
The use of mock catalogs, such as the GLAM-Uchuu suite, is crucial for understanding and analyzing large-scale structure data. Continuously expanding and improving these mock catalogs will enable more realistic simulations and provide better comparisons with observational data.
5. Exploring New Parity-breaking Processes
The discovery of a potential excess signal in the parity-odd four-point correlation function opens up new opportunities for exploring and understanding parity-breaking processes in the scalar sector. Future research should focus on investigating different inflationary models and studying their implications for large-scale structure formation.
By addressing these challenges and embracing the opportunities, future studies in this field can improve our understanding of the scalar sector, inflation, and the fundamental processes that govern the large-scale structure of the universe.
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by jsendak | Jan 19, 2024 | GR & QC Articles
We consider Klein-Gordon (KG) particles in a global monopole (GM) spacetime
within Eddington-inspired Born-Infeld gravity (EiBI-gravity) and in a Wu-Yang
magnetic monopole (WYMM). We discuss a set of KG-oscillators in such spacetime
settings. We propose a textbook power series expansion for the KG radial wave
function that allows us to retrieve the exact energy levels for KG-oscillators
in a GM spacetime and a WYMM without EiBI-gravity. We, moreover, report some
textit{conditionally exact}, closed form, energy levels (through some
parametric correlations) for KG-oscillators in a GM spacetime and a WYMM within
EiBI-gravity, and for massless KG-oscillators in a GM spacetime and a WYMM
within EiBI-gravity under the influence of a Coulomb plus linear Lorentz scalar
potential. We study and discuss the effects of the Eddington parameter
$kappa$, GM-parameter $alpha$, WYMM strength $sigma$, KG-oscillators’
frequency $Omega$, and the coupling parameters of the Coulomb plus linear
Lorentz scalar potential, on the spectroscopic structure of the KG-oscillators
at hand. Such effects are studied over a vast range of the radial quantum
number $n_rgeq 0$ and include energy levels clustering at $kappa>>1$ (i.e.,
extreme EiBI-gravity), and at $|sigma|>>1$ (i.e., extreme WYMM strength).
Examining the Conclusions and Outlining a Roadmap for Readers
In this article, the authors investigate the behavior of Klein-Gordon (KG) particles in different spacetime settings. They consider a global monopole (GM) spacetime within Eddington-inspired Born-Infeld gravity (EiBI-gravity), as well as a Wu-Yang magnetic monopole (WYMM). The focus is on studying KG-oscillators in these spacetimes and analyzing their energy levels.
To start, the authors propose a textbook power series expansion for the KG radial wave function, which allows them to obtain the exact energy levels for KG-oscillators in a GM spacetime and a WYMM without EiBI-gravity. They also report some energy levels, called “conditionally exact” and closed form, for KG-oscillators in a GM spacetime and a WYMM within EiBI-gravity. Additionally, they study the effects of various parameters on the spectroscopic structure of the KG-oscillators. These parameters include the Eddington parameter κ, GM-parameter α, WYMM strength σ, KG-oscillators’ frequency Ω, and the coupling parameters of the Coulomb plus linear Lorentz scalar potential.
The authors analyze these effects over a wide range of the radial quantum number nr ≥ 0 and investigate phenomena such as energy level clustering at extreme values of the Eddington parameter (κ ≫ 1) and extreme WYMM strength (|σ| ≫ 1).
Roadmap:
- Introduction to Klein-Gordon particles in different spacetime settings.
- Explanation of the proposed textbook power series expansion for KG radial wave function.
- Discussion on retrieving exact energy levels for KG-oscillators in a GM spacetime and a WYMM without EiBI-gravity.
- Presentation of the “conditionally exact” closed form energy levels for KG-oscillators in a GM spacetime and a WYMM within EiBI-gravity.
- Analysis of the effects of various parameters (Eddington parameter κ, GM-parameter α, WYMM strength σ, KG-oscillators’ frequency Ω, and coupling parameters of the Coulomb plus linear Lorentz scalar potential) on the spectroscopic structure of the KG-oscillators.
- Study of the spectroscopic structure over a wide range of the radial quantum number nr, including phenomena like energy level clustering at extreme values of the Eddington parameter and extreme WYMM strength.
This roadmap provides readers with a clear outline of the article’s content and helps them navigate through the different sections and topics discussed. It sets expectations for the challenges and opportunities covered, such as accurately determining energy levels, analyzing the influence of various parameters, and understanding the behavior of KG-oscillators in different spacetime settings.
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by jsendak | Jan 19, 2024 | GR & QC Articles
The primary purpose of this paper is to see how well a recently proposed new
model fits (a) the position of the baryon acoustic oscillations (BAO) features
observed in the large-scale distribution of galaxies and (b) the angular size
measured for the sound horizon due to BAO imprinted in the cosmic microwave
background (CMB) anisotropy. The new model is a hybrid model that combines the
tired light (TL) theory with a variant of the ${Lambda}CDM$ model in which the
cosmological constant is replaced with a covarying coupling constants’ (CCC)
parameter ${alpha}$. This model, dubbed the CCC+TL model, can fit the
supernovae type 1a Pantheon+ data as accurately as the ${Lambda}CDM$ model,
and also fit the angular size of cosmic dawn galaxies observed by the James
Webb Space Telescope, which is in tension with the ${Lambda}CDM$ model. The
results we obtained are $151.0 (pm5.1)$ Mpc for the absolute BAO scale at the
current epoch, and the angular size of the sound horizon
${theta}_{sh}=0.60{deg}$ matching Planck’s observations at the surface of the
last scattering when the baryon density is set to 100% of the matter density
and |${alpha}$| is increased by 5.6%. It remains to be seen if the new model
is consistent with the CMB power spectrum, the big-bang nucleosynthesis of
light elements, and other critical observations.
The primary purpose of this paper is to examine how well a recently proposed hybrid model, called the CCC+TL model, fits the observed baryon acoustic oscillations (BAO) features in the large-scale distribution of galaxies and the angular size measured for the sound horizon in the cosmic microwave background (CMB) anisotropy. This model combines the tired light (TL) theory with a variant of the ${Lambda}CDM$ model, where the cosmological constant is replaced with a covarying coupling constants’ (CCC) parameter ${alpha}$.
The CCC+TL model has shown that it can accurately fit the supernovae type 1a Pantheon+ data as well as the angular size of cosmic dawn galaxies observed by the James Webb Space Telescope. These results are in tension with the ${Lambda}CDM$ model. Specifically, the absolute BAO scale at the current epoch is estimated to be 1.0 (pm5.1)$ Mpc, and the angular size of the sound horizon is ${theta}_{sh}=0.60{deg}$, matching Planck’s observations. These values are obtained when the baryon density is set to 100% of the matter density and |${alpha}$| is increased by 5.6%.
However, it remains to be seen if the CCC+TL model is consistent with other critical observations, such as the CMB power spectrum and big-bang nucleosynthesis of light elements. Future research should focus on testing the model against these observations to validate its overall consistency and accuracy.
Future Roadmap
Based on the results and conclusions presented in this paper, there are several potential challenges and opportunities on the horizon:
- Further testing against the CMB power spectrum: The CCC+TL model needs to be examined in the context of the CMB power spectrum to determine if it can accurately explain the observed anisotropy in the cosmic microwave background radiation. This will require detailed analysis and comparison with existing data.
- Verification through big-bang nucleosynthesis: The model’s consistency with the big-bang nucleosynthesis of light elements needs to be investigated. This process involves examining the production of light elements in the early universe and comparing it to observational data. If the CCC+TL model can accurately explain these observations, it would strengthen its validity.
- Exploration of other critical observations: In addition to the two mentioned above, there may be other crucial observations that can provide further evidence for or against the CCC+TL model. Researchers should explore these observations and conduct detailed analyses to determine the model’s overall consistency and its ability to explain various cosmological phenomena.
- Refinement and improvement of the CCC+TL model: As the CCC+TL model is still in its early stages, there is room for refinement and improvement. Future research should focus on tweaking and optimizing the model to enhance its accuracy and compatibility with various cosmological measurements.
Overall, while the CCC+TL model shows promise in fitting observed data related to baryon acoustic oscillations and cosmic dawn galaxies, further investigations are necessary to validate its compatibility with other critical observations. By addressing these challenges and exploring new opportunities, researchers can advance our understanding of the universe’s large-scale structure and potentially uncover new insights into cosmology.
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