Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/008
Alan B.H. Nguyen, Marco Bonici, Glen McGee and Will J. Percival
With the advent of the next generation of astrophysics experiments, the volume of data available to researchers will be greater than ever. As these projects will significantly drive down statistical uncertainties in measurements, it is crucial to develop novel tools to assess the ability of our models to fit these data within the specified errors. We introduce to astronomy the Leave One Out-Probability Integral Transform (LOO-PIT) technique. This first estimates the LOO posterior predictive distributions based on the model and likelihood distribution specified, then evaluates the quality of the match between the model and data by applying the PIT to each estimated distribution and data point, outputting a LOO-PIT distribution. Deviations between this output distribution and that expected can be characterised visually and with a standard Kolmogorov-Smirnov distribution test. We compare LOO-PIT and the more common χ2 test using both a simplified model and a more realistic astrophysics problem, where we consider fitting Baryon Acoustic Oscillations in galaxy survey data with contamination from emission line interlopers. LOO-PIT and χ2 tend to find different signals from the contaminants, and using these tests in conjunction increases the statistical power compared to using either test alone. We also show that LOO-PIT outperforms χ2 in certain realistic test cases.
{"title":"LOO-PIT: A sensitive posterior test","authors":"Alan B.H. Nguyen, Marco Bonici, Glen McGee and Will J. Percival","doi":"10.1088/1475-7516/2025/01/008","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/008","url":null,"abstract":"With the advent of the next generation of astrophysics experiments, the volume of data available to researchers will be greater than ever. As these projects will significantly drive down statistical uncertainties in measurements, it is crucial to develop novel tools to assess the ability of our models to fit these data within the specified errors. We introduce to astronomy the Leave One Out-Probability Integral Transform (LOO-PIT) technique. This first estimates the LOO posterior predictive distributions based on the model and likelihood distribution specified, then evaluates the quality of the match between the model and data by applying the PIT to each estimated distribution and data point, outputting a LOO-PIT distribution. Deviations between this output distribution and that expected can be characterised visually and with a standard Kolmogorov-Smirnov distribution test. We compare LOO-PIT and the more common χ2 test using both a simplified model and a more realistic astrophysics problem, where we consider fitting Baryon Acoustic Oscillations in galaxy survey data with contamination from emission line interlopers. LOO-PIT and χ2 tend to find different signals from the contaminants, and using these tests in conjunction increases the statistical power compared to using either test alone. We also show that LOO-PIT outperforms χ2 in certain realistic test cases.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/005
Ananda F. Smith, Craig J. Copi and Glenn D. Starkman
Much of modern cosmology relies on the Cosmological Principle, the assumption that the Universe is isotropic and homogeneous on sufficiently large scales, but it remains worthwhile to examine cosmological models that violate this principle slightly. We examine a class of such spacetimes that maintain homogeneity but break isotropy through their underlying local spatial geometries. These spacetimes are endowed with one of five anisotropic model geometries of Thurston's geometrization theorem, and their evolution is sourced with perfect fluid dust and cosmological constant. We show that the background evolution of these spacetimes induces fluctuations in the observed cosmic microwave background (CMB) temperature with amplitudes coupled to the curvature parameter ΩK. In order for these fluctuations to be compatible with the observed CMB angular power spectrum, we find |ΩK| ≲ 10-5. This strongly limits the cosmological consequences of these models.
{"title":"Cosmological constraints on anisotropic Thurston geometries","authors":"Ananda F. Smith, Craig J. Copi and Glenn D. Starkman","doi":"10.1088/1475-7516/2025/01/005","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/005","url":null,"abstract":"Much of modern cosmology relies on the Cosmological Principle, the assumption that the Universe is isotropic and homogeneous on sufficiently large scales, but it remains worthwhile to examine cosmological models that violate this principle slightly. We examine a class of such spacetimes that maintain homogeneity but break isotropy through their underlying local spatial geometries. These spacetimes are endowed with one of five anisotropic model geometries of Thurston's geometrization theorem, and their evolution is sourced with perfect fluid dust and cosmological constant. We show that the background evolution of these spacetimes induces fluctuations in the observed cosmic microwave background (CMB) temperature with amplitudes coupled to the curvature parameter ΩK. In order for these fluctuations to be compatible with the observed CMB angular power spectrum, we find |ΩK| ≲ 10-5. This strongly limits the cosmological consequences of these models.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"80 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/014
M. Ullmo and E. Moulin
An intriguing challenge in observational astronomy is the separation signals in areas where multiple signals intersect. A typical instance of this in very-high-energy (VHE, E ≳ 100 GeV) gamma-ray astronomy is the issue of residual background in observations. This background arises when cosmic-ray protons are mistakenly identified as gamma-rays from sources of interest, thereby blending with signals from astrophysical sources of interest. We introduce a deep ensemble approach to determine a non-parametric estimation of source and background signals in VHE gamma observations, as well as a likelihood-derived epistemic uncertainty on these estimations. We rely on minimal assumptions, exploiting the separability of space and energy components in the signals, and defining a small region in coordinate space where the source signal is assumed to be negligible compared to background signal. The model is applied both on mock observations, including a simple toy case and a realistic simulation of dark matter annihilation in the Galactic center, as well as true observations from the public H.E.S.S. data release, specifically datasets of the Crab nebula and the pulsar wind nebula MSH 15-52. Our method performs well in mock cases, where the ground truth is known, and compares favorably against conventional physical analysis approaches when applied to true observations. In the case of the mock dark matter signal in the Galactic center, our work opens new avenues for component separation in this complex region of the VHE sky.
{"title":"Nonparametric signal separation in very-high-energy gamma ray observations with probabilistic neural networks","authors":"M. Ullmo and E. Moulin","doi":"10.1088/1475-7516/2025/01/014","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/014","url":null,"abstract":"An intriguing challenge in observational astronomy is the separation signals in areas where multiple signals intersect. A typical instance of this in very-high-energy (VHE, E ≳ 100 GeV) gamma-ray astronomy is the issue of residual background in observations. This background arises when cosmic-ray protons are mistakenly identified as gamma-rays from sources of interest, thereby blending with signals from astrophysical sources of interest. We introduce a deep ensemble approach to determine a non-parametric estimation of source and background signals in VHE gamma observations, as well as a likelihood-derived epistemic uncertainty on these estimations. We rely on minimal assumptions, exploiting the separability of space and energy components in the signals, and defining a small region in coordinate space where the source signal is assumed to be negligible compared to background signal. The model is applied both on mock observations, including a simple toy case and a realistic simulation of dark matter annihilation in the Galactic center, as well as true observations from the public H.E.S.S. data release, specifically datasets of the Crab nebula and the pulsar wind nebula MSH 15-52. Our method performs well in mock cases, where the ground truth is known, and compares favorably against conventional physical analysis approaches when applied to true observations. In the case of the mock dark matter signal in the Galactic center, our work opens new avenues for component separation in this complex region of the VHE sky.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/004
Samanta Saha, Craig J. Copi, Glenn D. Starkman, Stefano Anselmi, Javier Carrón Duque, Mikel Martin Barandiaran, Yashar Akrami, Fernando Cornet-Gomez, Andrew H. Jaffe, Arthur Kosowsky, Deyan P. Mihaylov, Thiago S. Pereira, Amirhossein Samandar, Andrius Tamosiunas and The COMPACT collaboration
Cosmic microwave background (CMB) temperature and polarization observations indicate that in the best-fit Λ Cold Dark Matter model of the Universe, the local geometry is consistent with at most a small amount of positive or negative curvature, i.e., |ΩK| ≪ 1. However, whether the geometry is flat (E3), positively curved (S3) or negatively curved (H3), there are many possible topologies. Among the topologies of S3 geometry, the lens spaces L(p,q), where p and q (p > 1 and 0 < q < p) are positive integers, are quotients of the covering space of S3 (the three-sphere) by ℤp, the cyclic group of order p. We use the absence of any pair of circles on the CMB sky with matching patterns of temperature fluctuations to establish constraints on p and q as a function of the curvature scale that are considerably stronger than those previously asserted for most values of p and q. The smaller the value of |ΩK|, i.e., the larger the curvature radius, the larger the maximum allowed value of p. For example, if |ΩK| ≃ 0.05 then p ≤ 9, while if |ΩK| ≃ 0.02, p can be as high as 24. Future work will extend these constraints to a wider set of S3 topologies.
{"title":"Cosmic topology. Part Ic. Limits on lens spaces from circle searches","authors":"Samanta Saha, Craig J. Copi, Glenn D. Starkman, Stefano Anselmi, Javier Carrón Duque, Mikel Martin Barandiaran, Yashar Akrami, Fernando Cornet-Gomez, Andrew H. Jaffe, Arthur Kosowsky, Deyan P. Mihaylov, Thiago S. Pereira, Amirhossein Samandar, Andrius Tamosiunas and The COMPACT collaboration","doi":"10.1088/1475-7516/2025/01/004","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/004","url":null,"abstract":"Cosmic microwave background (CMB) temperature and polarization observations indicate that in the best-fit Λ Cold Dark Matter model of the Universe, the local geometry is consistent with at most a small amount of positive or negative curvature, i.e., |ΩK| ≪ 1. However, whether the geometry is flat (E3), positively curved (S3) or negatively curved (H3), there are many possible topologies. Among the topologies of S3 geometry, the lens spaces L(p,q), where p and q (p > 1 and 0 < q < p) are positive integers, are quotients of the covering space of S3 (the three-sphere) by ℤp, the cyclic group of order p. We use the absence of any pair of circles on the CMB sky with matching patterns of temperature fluctuations to establish constraints on p and q as a function of the curvature scale that are considerably stronger than those previously asserted for most values of p and q. The smaller the value of |ΩK|, i.e., the larger the curvature radius, the larger the maximum allowed value of p. For example, if |ΩK| ≃ 0.05 then p ≤ 9, while if |ΩK| ≃ 0.02, p can be as high as 24. Future work will extend these constraints to a wider set of S3 topologies.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"23 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/013
Chia-Min Lin, Harish Dhananjay Nalla, Chen-Pin Yeh and Da-Shin Lee
We analytically compute the power spectrum of primordial curvature perturbations in Type III hilltop inflation models under the slow-roll approximation. The model parameters are constrained using current Cosmic Microwave Background (CMB) data. The curvature perturbations that exit the horizon at small scales show sufficiently large amplitudes to produce primordial black holes (PBHs). We then consider the quantum one-loop corrections in these models from both the self-interaction of the inflaton and its interaction with the waterfall field. We show the loop corrections in both cases for 60 e-folds of inflation are negligible, ensuring the tree-level results are reliable within the chosen parameter regime.
{"title":"Primordial perturbations in Type III hilltop inflation models","authors":"Chia-Min Lin, Harish Dhananjay Nalla, Chen-Pin Yeh and Da-Shin Lee","doi":"10.1088/1475-7516/2025/01/013","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/013","url":null,"abstract":"We analytically compute the power spectrum of primordial curvature perturbations in Type III hilltop inflation models under the slow-roll approximation. The model parameters are constrained using current Cosmic Microwave Background (CMB) data. The curvature perturbations that exit the horizon at small scales show sufficiently large amplitudes to produce primordial black holes (PBHs). We then consider the quantum one-loop corrections in these models from both the self-interaction of the inflaton and its interaction with the waterfall field. We show the loop corrections in both cases for 60 e-folds of inflation are negligible, ensuring the tree-level results are reliable within the chosen parameter regime.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"30 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/016
Cristian Erices and Mohsen Fathi
In this paper, we find that unlike in General Relativity, the shift-symmetric subclass of Beyond Horndeski theories permits black holes with primary hair that are thermodynamically stable and align with current Event Horizon Telescope observations of the M87* and Sgr A* black holes. This work begins by investigating thermodynamic properties, analyzing how primary hair influences thermodynamic quantities and local stability, which imposes strict constraints on the allowed range of primary hair values. The null geodesics near this black hole are then examined, demonstrating how scalar hair affects the shadow diameter. Specifically, when the parameter of the Beyond Horndeski function F4 is negative, increasing scalar hair enlarges the shadow; in contrast, when this parameter is positive, greater scalar hair reduces the shadow size. Further constraints on the scalar hair are derived using observational data, highlighting its sensitivity to other black hole parameters. To explore additional observational features, face-on two-dimensional images of spherically infalling accretion disks are simulated, revealing how primary scalar hair shapes the black hole's shadow. Finally, all relevant constraints are combined to identify black holes that are both stable and consistent with observational data.
{"title":"Thermodynamic and observational constraints on black holes with primary hair in Beyond Horndeski gravity: Stability and shadows","authors":"Cristian Erices and Mohsen Fathi","doi":"10.1088/1475-7516/2025/01/016","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/016","url":null,"abstract":"In this paper, we find that unlike in General Relativity, the shift-symmetric subclass of Beyond Horndeski theories permits black holes with primary hair that are thermodynamically stable and align with current Event Horizon Telescope observations of the M87* and Sgr A* black holes. This work begins by investigating thermodynamic properties, analyzing how primary hair influences thermodynamic quantities and local stability, which imposes strict constraints on the allowed range of primary hair values. The null geodesics near this black hole are then examined, demonstrating how scalar hair affects the shadow diameter. Specifically, when the parameter of the Beyond Horndeski function F4 is negative, increasing scalar hair enlarges the shadow; in contrast, when this parameter is positive, greater scalar hair reduces the shadow size. Further constraints on the scalar hair are derived using observational data, highlighting its sensitivity to other black hole parameters. To explore additional observational features, face-on two-dimensional images of spherically infalling accretion disks are simulated, revealing how primary scalar hair shapes the black hole's shadow. Finally, all relevant constraints are combined to identify black holes that are both stable and consistent with observational data.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"85 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/021
Sung Hak Lim, Eric Putney, Matthew R. Buckley and David Shih
We present a novel, data-driven analysis of Galactic dynamics, using unsupervised machine learning — in the form of density estimation with normalizing flows — to learn the underlying phase space distribution of 6 million nearby stars from the Gaia DR3 catalog. Solving the equilibrium collisionless Boltzmann equation, we calculate — for the first time ever — a model-free, unbinned estimate of the local acceleration and mass density fields within a 3 kpc sphere around the Sun. As our approach makes no assumptions about symmetries, we can test for signs of disequilibrium in our results. We find our results are consistent with equilibrium at the 10% level, limited by the current precision of the normalizing flows. After subtracting the known contribution of stars and gas from the calculated mass density, we find clear evidence for dark matter throughout the analyzed volume. Assuming spherical symmetry and averaging mass density measurements, we find a local dark matter density of 0.47± 0.05 GeV/cm3. We compute the dark matter density at four radii in the stellar halo and fit to a generalized NFW profile. Although the uncertainties are large, we find a profile broadly consistent with recent analyses.
{"title":"Mapping dark matter in the Milky Way using normalizing flows and Gaia DR3","authors":"Sung Hak Lim, Eric Putney, Matthew R. Buckley and David Shih","doi":"10.1088/1475-7516/2025/01/021","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/021","url":null,"abstract":"We present a novel, data-driven analysis of Galactic dynamics, using unsupervised machine learning — in the form of density estimation with normalizing flows — to learn the underlying phase space distribution of 6 million nearby stars from the Gaia DR3 catalog. Solving the equilibrium collisionless Boltzmann equation, we calculate — for the first time ever — a model-free, unbinned estimate of the local acceleration and mass density fields within a 3 kpc sphere around the Sun. As our approach makes no assumptions about symmetries, we can test for signs of disequilibrium in our results. We find our results are consistent with equilibrium at the 10% level, limited by the current precision of the normalizing flows. After subtracting the known contribution of stars and gas from the calculated mass density, we find clear evidence for dark matter throughout the analyzed volume. Assuming spherical symmetry and averaging mass density measurements, we find a local dark matter density of 0.47± 0.05 GeV/cm3. We compute the dark matter density at four radii in the stellar halo and fit to a generalized NFW profile. Although the uncertainties are large, we find a profile broadly consistent with recent analyses.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"10 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/017
Reginald Christian Bernardo, Stephen Appleby and Kin-Wang Ng
The degree of Gaussianity of a field offers insights into its cosmological nature, and its statistical properties serve as indicators of its Gaussianity. In this work, we examine the signatures of Gaussianity in a gravitational wave background (GWB) by analyzing the cumulants of the one- and two-point functions of the relevant observable, using pulsar timing array (PTA) simulations as a proof-of-principle. This appeals to the ongoing debate about the source of the spatially-correlated common-spectrum process observed in PTAs, which is likely associated with a nanohertz stochastic GWB. We investigate the distribution of the sample statistics of the one-point function in the presence of a Gaussian GWB. Our results indicate that, within PTAs, one-point statistics are impractical for constraining the Gaussianity of the nanohertz GWB due to dominant pulsar noises. However, our analysis of two-point statistics shows promise, suggesting that it may be possible to constrain the Gaussianity of the nanohertz GWB using PTA data. We also emphasize that the Gaussian signatures identified in the one- and two-point functions in this work are expected to be applicable to any gravitational wave background.
{"title":"Toward a test of Gaussianity of a gravitational wave background","authors":"Reginald Christian Bernardo, Stephen Appleby and Kin-Wang Ng","doi":"10.1088/1475-7516/2025/01/017","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/017","url":null,"abstract":"The degree of Gaussianity of a field offers insights into its cosmological nature, and its statistical properties serve as indicators of its Gaussianity. In this work, we examine the signatures of Gaussianity in a gravitational wave background (GWB) by analyzing the cumulants of the one- and two-point functions of the relevant observable, using pulsar timing array (PTA) simulations as a proof-of-principle. This appeals to the ongoing debate about the source of the spatially-correlated common-spectrum process observed in PTAs, which is likely associated with a nanohertz stochastic GWB. We investigate the distribution of the sample statistics of the one-point function in the presence of a Gaussian GWB. Our results indicate that, within PTAs, one-point statistics are impractical for constraining the Gaussianity of the nanohertz GWB due to dominant pulsar noises. However, our analysis of two-point statistics shows promise, suggesting that it may be possible to constrain the Gaussianity of the nanohertz GWB using PTA data. We also emphasize that the Gaussian signatures identified in the one- and two-point functions in this work are expected to be applicable to any gravitational wave background.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"75 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/015
Pablo Navarro Moreno, Aneta Wojnar and Felipe J. Llanes-Estrada
The Seidov limit is a bound on the maximum latent heat that a presumed first-order phase transition of neutron-star matter can have before its excess energy density, not compensated by additional pressure, results in gravitational collapse. Because latent heat forces an apparent nonanalytic behaviour in plots correlating physical quantities (kinks in two-dimensional, ridges in three-dimensional ones), it can be constrained by data. As the onset of collapse depends on the intensity of gravity, testing for sudden derivative changes and, if they are large, breaching the Seidov limit would reward with two successive discoveries: such a phase transition (which could stem from hadron matter but also from a gravitational phase transition), and a modification of General Relativity (thus breaking the matter/gravity degeneracy). We illustrate the point with f(R) = R + αR2 metric gravity.
{"title":"Testing gravity with the latent heat of neutron star matter","authors":"Pablo Navarro Moreno, Aneta Wojnar and Felipe J. Llanes-Estrada","doi":"10.1088/1475-7516/2025/01/015","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/015","url":null,"abstract":"The Seidov limit is a bound on the maximum latent heat that a presumed first-order phase transition of neutron-star matter can have before its excess energy density, not compensated by additional pressure, results in gravitational collapse. Because latent heat forces an apparent nonanalytic behaviour in plots correlating physical quantities (kinks in two-dimensional, ridges in three-dimensional ones), it can be constrained by data. As the onset of collapse depends on the intensity of gravity, testing for sudden derivative changes and, if they are large, breaching the Seidov limit would reward with two successive discoveries: such a phase transition (which could stem from hadron matter but also from a gravitational phase transition), and a modification of General Relativity (thus breaking the matter/gravity degeneracy). We illustrate the point with f(R) = R + αR2 metric gravity.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"22 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1088/1475-7516/2025/01/006
Sihao Cheng, 思浩 程, Gabriela A. Marques, Daniela Grandón, Leander Thiele, Masato Shirasaki, Brice Ménard and Jia Liu
As weak lensing surveys go deeper, there is an increasing need for reliable characterization of non-Gaussian structures at small angular scales. Here we present the first cosmological constraints with weak lensing scattering transform, a statistical estimator that combines efficiency, robustness, and interpretability. With the Hyper Suprime-Cam survey (HSC) year 1 data, we obtain Ωm = 0.29-0.03+0.04, SS8 ≡ σ8(Ωm/0.3)0.5 = 0.83±0.02, and intrinsic alignment strength AIA = 1.0±0.4 through simulation-based forward modeling. Our constraints are consistent with those derived from Planck. The error bar of Ωm is 2 times tighter than that obtained from the power spectrum when the same scale range is used. This constraining power is on par with that of convolutional neural networks, suggesting that further investment in spatial information extraction may not yield substantial benefits. We also point out an internal tension of S8 estimates linked to a redshift bin around z ∼ 1 in the HSC data. We found that discarding that bin leads to a consistent decrease of S8 from 0.83 to 0.79, for all statistical estimators. We argue that photometric redshift estimation is now the main limitation in the estimation of S8 using HSC. This limitation is likely to affect other ground-based weak lensing surveys reaching redshifts greater than one. Alternative redshift estimation techniques, like clustering redshifts, may help alleviate this limitation.
{"title":"Cosmological constraints from weak lensing scattering transform using HSC Y1 data","authors":"Sihao Cheng, 思浩 程, Gabriela A. Marques, Daniela Grandón, Leander Thiele, Masato Shirasaki, Brice Ménard and Jia Liu","doi":"10.1088/1475-7516/2025/01/006","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/01/006","url":null,"abstract":"As weak lensing surveys go deeper, there is an increasing need for reliable characterization of non-Gaussian structures at small angular scales. Here we present the first cosmological constraints with weak lensing scattering transform, a statistical estimator that combines efficiency, robustness, and interpretability. With the Hyper Suprime-Cam survey (HSC) year 1 data, we obtain Ωm = 0.29-0.03+0.04, SS8 ≡ σ8(Ωm/0.3)0.5 = 0.83±0.02, and intrinsic alignment strength AIA = 1.0±0.4 through simulation-based forward modeling. Our constraints are consistent with those derived from Planck. The error bar of Ωm is 2 times tighter than that obtained from the power spectrum when the same scale range is used. This constraining power is on par with that of convolutional neural networks, suggesting that further investment in spatial information extraction may not yield substantial benefits. We also point out an internal tension of S8 estimates linked to a redshift bin around z ∼ 1 in the HSC data. We found that discarding that bin leads to a consistent decrease of S8 from 0.83 to 0.79, for all statistical estimators. We argue that photometric redshift estimation is now the main limitation in the estimation of S8 using HSC. This limitation is likely to affect other ground-based weak lensing surveys reaching redshifts greater than one. Alternative redshift estimation techniques, like clustering redshifts, may help alleviate this limitation.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"19 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}