Pub Date : 2024-11-20DOI: 10.1088/1475-7516/2024/11/031
Ginevra Braga, Alice Garoffolo, Angelo Ricciardone, Nicola Bartolo and Sabino Matarrese
When gravitational waves travel from their source to an observer, they interact with matter structures along their path, causing distinct deformations in their waveforms. In this study we introduce a novel theoretical framework for wave optics effects in gravitational lensing, addressing the limitations of existing approaches. We achieve this by incorporating the proper time technique, typically used in field theory studies, into gravitational lensing. This approach allows us to extend the standard formalism beyond the eikonal and paraxial approximations, which are traditionally assumed, and to account for polarization effects, which are typically neglected in the literature. We demonstrate that our method provides a robust generalization of conventional approaches, including them as special cases. Our findings enhance our understanding of gravitational wave propagation, which is crucial for accurately interpreting gravitational wave observations and extracting unbiased information about the lenses from the gravitational wave waveforms.
{"title":"Proper time path integrals for gravitational waves: an improved wave optics framework","authors":"Ginevra Braga, Alice Garoffolo, Angelo Ricciardone, Nicola Bartolo and Sabino Matarrese","doi":"10.1088/1475-7516/2024/11/031","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/031","url":null,"abstract":"When gravitational waves travel from their source to an observer, they interact with matter structures along their path, causing distinct deformations in their waveforms. In this study we introduce a novel theoretical framework for wave optics effects in gravitational lensing, addressing the limitations of existing approaches. We achieve this by incorporating the proper time technique, typically used in field theory studies, into gravitational lensing. This approach allows us to extend the standard formalism beyond the eikonal and paraxial approximations, which are traditionally assumed, and to account for polarization effects, which are typically neglected in the literature. We demonstrate that our method provides a robust generalization of conventional approaches, including them as special cases. Our findings enhance our understanding of gravitational wave propagation, which is crucial for accurately interpreting gravitational wave observations and extracting unbiased information about the lenses from the gravitational wave waveforms.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"178 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142673327","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 : 2024-11-19DOI: 10.1088/1475-7516/2024/11/025
Alessio Notari, Michele Redi and Andrea Tesi
We search for physically consistent realizations of evolving dark energy suggested by the cosmological fit of DESI, Planck and Supernovae data. First we note that any lagrangian description of the standard Chevallier-Polarski-Linder (CPL) parametrization for the dark energy equation of state w, allows for the addition of a cosmological constant. We perform the cosmological fit finding new regions of parameter space that however continue to favour dark energy with w < -1 at early times, that is challenging to realize in consistent theories. Next, in the spirit of effective field theories, we consider the effect of higher order terms in the Taylor expansion of the equation of state of dark energy around the present epoch. We find that non-linear corrections of the equation of state are weakly constrained, thus opening the way to scenarios that differ from CPL at early times, possibly with w > -1 at all times. We present indeed scenarios where evolving dark energy can be realized through quintessence models. We introduce in particular the ramp model where dark energy coincides with CPL at late times and approximates to a cosmological constant at early times. The latter model provides a much better fit than ΛCDM, and only slightly worse than w0waCDM, but with the notable advantage of being described by a simple and theoretically consistent lagrangian of a canonical quintessence model.
我们通过对 DESI、普朗克和超新星数据的宇宙学拟合，寻找物理上一致的演化暗能量的实现方式。首先，我们注意到暗能量状态方程 w 的标准切瓦利埃-波兰斯基-林德（CPL）参数的任何拉格朗日描述都允许添加一个宇宙学常数。我们进行了宇宙学拟合，发现了参数空间的新区域，然而这些区域在早期继续倾向于 w < -1 的暗能量，这在一致理论中是难以实现的。接下来，本着有效场理论的精神，我们考虑了暗能量状态方程泰勒扩展中的高阶项在本纪附近的影响。我们发现，状态方程的非线性修正受到弱约束，从而为早期不同于CPL的情景开辟了道路，可能在任何时候w都>-1。我们确实提出了可以通过五重模型实现暗能量演化的情景。我们特别介绍了斜坡模型，即暗能量在晚期与CPL重合，而在早期近似于宇宙常数。后一种模型的拟合效果比ΛCDM好得多，只比w0waCDM稍差一些，但它有一个显著的优点，即可以用一个简单的、理论上一致的经典五元模型的拉格朗日来描述。
{"title":"Consistent theories for the DESI dark energy fit","authors":"Alessio Notari, Michele Redi and Andrea Tesi","doi":"10.1088/1475-7516/2024/11/025","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/025","url":null,"abstract":"We search for physically consistent realizations of evolving dark energy suggested by the cosmological fit of DESI, Planck and Supernovae data. First we note that any lagrangian description of the standard Chevallier-Polarski-Linder (CPL) parametrization for the dark energy equation of state w, allows for the addition of a cosmological constant. We perform the cosmological fit finding new regions of parameter space that however continue to favour dark energy with w < -1 at early times, that is challenging to realize in consistent theories. Next, in the spirit of effective field theories, we consider the effect of higher order terms in the Taylor expansion of the equation of state of dark energy around the present epoch. We find that non-linear corrections of the equation of state are weakly constrained, thus opening the way to scenarios that differ from CPL at early times, possibly with w > -1 at all times. We present indeed scenarios where evolving dark energy can be realized through quintessence models. We introduce in particular the ramp model where dark energy coincides with CPL at late times and approximates to a cosmological constant at early times. The latter model provides a much better fit than ΛCDM, and only slightly worse than w0waCDM, but with the notable advantage of being described by a simple and theoretically consistent lagrangian of a canonical quintessence model.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"106 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142671010","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 : 2024-11-19DOI: 10.1088/1475-7516/2024/11/028
Yi Zhang, Hong Liu, Dan Wen and Hongsheng Zhang
For the first time, we use the Event Horizon Telescope (EHT) data to constrain the parameters of braneworld black holes which constrain ϵ = 0.0285+0.0888+0.1456-0.0895-0.1475 for the anisotropic black hole and q = -0.0305+0.1034+0.1953-0.0895-0.1470 for the tidal Reissner-Nordström (RN) black hole. Based on the fitted data and physical requirement, we calculate the photon deflection, the angular separation and time delay between different relativistic images of the anisotropic black hole and the tidal RN black hole in the ranges -0.1190 < ϵ < 0 and -0.1775 < q < 0. And furthermore, we study the quasinormal modes (QNMs) for the braneworld black holes. The results shed light on existence of extra dimension.
{"title":"Strong lensing as a probe of braneworld","authors":"Yi Zhang, Hong Liu, Dan Wen and Hongsheng Zhang","doi":"10.1088/1475-7516/2024/11/028","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/028","url":null,"abstract":"For the first time, we use the Event Horizon Telescope (EHT) data to constrain the parameters of braneworld black holes which constrain ϵ = 0.0285+0.0888+0.1456-0.0895-0.1475 for the anisotropic black hole and q = -0.0305+0.1034+0.1953-0.0895-0.1470 for the tidal Reissner-Nordström (RN) black hole. Based on the fitted data and physical requirement, we calculate the photon deflection, the angular separation and time delay between different relativistic images of the anisotropic black hole and the tidal RN black hole in the ranges -0.1190 < ϵ < 0 and -0.1775 < q < 0. And furthermore, we study the quasinormal modes (QNMs) for the braneworld black holes. The results shed light on existence of extra dimension.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"54 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142671013","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 : 2024-11-19DOI: 10.1088/1475-7516/2024/11/027
Massimo Giovannini
Stationary processes do not accurately describe the diffuse backgrounds of relic gravitons whose correlations are homogeneous in space (i.e. only dependent upon the distance between the two spatial locations) but not in time. The symmetries of the autocorrelations ultimately reflect the quantum mechanical origin of the diffuse backgrounds and lead to non-stationary observables at late time. In particular, large oscillations are believed to arise in the spectral energy density that is customarily (but approximately) related to the tensor power spectrum. When the full expression of the spectral energy density is employed the amplitudes of oscillation are instead suppressed in the large-scale limit and the non-stationary features of the late-time signal practically disappear. For similar reasons the relations between the spectral energy density and the spectral amplitude are ambiguous in the presence of non-stationary features. While it is debatable if the non-stationary features are (or will be) directly detectable, we argue that the spectral amplitude following from the Wiener-Khintchine theorem is generally inappropriate for a consistent description of the relic signal. Nevertheless the strong oscillatory behaviour of the late-time observables is naturally smeared out provided the spectral energy density is selected as pivotal variable.
{"title":"Relic gravitons and non-stationary processes","authors":"Massimo Giovannini","doi":"10.1088/1475-7516/2024/11/027","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/027","url":null,"abstract":"Stationary processes do not accurately describe the diffuse backgrounds of relic gravitons whose correlations are homogeneous in space (i.e. only dependent upon the distance between the two spatial locations) but not in time. The symmetries of the autocorrelations ultimately reflect the quantum mechanical origin of the diffuse backgrounds and lead to non-stationary observables at late time. In particular, large oscillations are believed to arise in the spectral energy density that is customarily (but approximately) related to the tensor power spectrum. When the full expression of the spectral energy density is employed the amplitudes of oscillation are instead suppressed in the large-scale limit and the non-stationary features of the late-time signal practically disappear. For similar reasons the relations between the spectral energy density and the spectral amplitude are ambiguous in the presence of non-stationary features. While it is debatable if the non-stationary features are (or will be) directly detectable, we argue that the spectral amplitude following from the Wiener-Khintchine theorem is generally inappropriate for a consistent description of the relic signal. Nevertheless the strong oscillatory behaviour of the late-time observables is naturally smeared out provided the spectral energy density is selected as pivotal variable.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"18 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142671018","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 : 2024-11-19DOI: 10.1088/1475-7516/2024/11/026
Shyam Balaji, Guillem Domènech, Gabriele Franciolini, Alexander Ganz and Jan Tränkle
It has been recently proposed that Hawking evaporation might slow down after a black hole has lost about half of its mass. Such an effect, called “memory burden”, is parameterized as a suppression in the mass loss rate by negative powers n of the black hole entropy and could considerably extend the lifetime of a black hole. We study the impact of memory burden on the Primordial Black Hole (PBH) reheating scenario. Modified PBH evaporation leads to a significantly longer PBH dominated stage. Requiring that PBHs evaporate prior enough to Big Bang Nucleosynthesis shrinks the allowed PBH mass range. Indeed, we find that for n > 2.5 the PBH reheating scenario is not viable. The frequency of the Gravitational Waves (GWs) induced by PBH number density fluctuations is bound to be larger than about a Hz, while the amplitude of the GW spectrum is enhanced due to the longer PBH dominated phase. Interestingly, we show that, in some models, the slope of the induced GW spectrum might be sensitive to the modifications to Hawking evaporation, proving it may be possible to test the “memory burden” effect via induced GWs. Lastly, we argue that our results could also apply to general modifications of Hawking evaporation.
{"title":"Probing modified Hawking evaporation with gravitational waves from the primordial black hole dominated universe","authors":"Shyam Balaji, Guillem Domènech, Gabriele Franciolini, Alexander Ganz and Jan Tränkle","doi":"10.1088/1475-7516/2024/11/026","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/026","url":null,"abstract":"It has been recently proposed that Hawking evaporation might slow down after a black hole has lost about half of its mass. Such an effect, called “memory burden”, is parameterized as a suppression in the mass loss rate by negative powers n of the black hole entropy and could considerably extend the lifetime of a black hole. We study the impact of memory burden on the Primordial Black Hole (PBH) reheating scenario. Modified PBH evaporation leads to a significantly longer PBH dominated stage. Requiring that PBHs evaporate prior enough to Big Bang Nucleosynthesis shrinks the allowed PBH mass range. Indeed, we find that for n > 2.5 the PBH reheating scenario is not viable. The frequency of the Gravitational Waves (GWs) induced by PBH number density fluctuations is bound to be larger than about a Hz, while the amplitude of the GW spectrum is enhanced due to the longer PBH dominated phase. Interestingly, we show that, in some models, the slope of the induced GW spectrum might be sensitive to the modifications to Hawking evaporation, proving it may be possible to test the “memory burden” effect via induced GWs. Lastly, we argue that our results could also apply to general modifications of Hawking evaporation.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"63 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670746","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 : 2024-11-19DOI: 10.1088/1475-7516/2024/11/024
Andrew J. Long and Jessica Turner
We study a planar bubble wall that is traveling at an ultrarelativistic speed through a thermal plasma. This situation may arise during a first-order electroweak phase transition in the early universe. As particles cross the wall, it is assumed that their mass grows from ma to mb, and they are decelerated causing them to emit massless radiation (mc = 0). We are interested in the momentum transfer to the wall, the thermal pressure felt by the wall, and the resultant terminal velocity of the wall. We employ the semiclassical current radiation (SCR) formalism to perform these calculations. An incident-charged particle is treated as a point-like classical electromagnetic current, and the spectrum of quantum electromagnetic radiation (photons) is derived by calculating appropriate matrix elements. To understand how the spectrum depends on the thickness of the wall, we explore simplified models for the current corresponding to an abrupt and a gradual deceleration. For the model of abrupt deceleration, we find that the SCR formalism can reproduce the Ptherm ∝ γ0w scaling found in earlier work by assuming that the emission is soft, but if the emission is not soft the SCR formalism can be used to obtain Ptherm ∝ γ2w instead. For the model of gradual deceleration, we find that the wall thickness Lw enters to cutoff the otherwise log-flat radiation spectrum above a momentum of ∼ γ2w / Lw, and we discuss the connections with classical electromagnetic bremsstrahlung.
{"title":"Thermal pressure on ultrarelativistic bubbles from a semiclassical formalism","authors":"Andrew J. Long and Jessica Turner","doi":"10.1088/1475-7516/2024/11/024","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/024","url":null,"abstract":"We study a planar bubble wall that is traveling at an ultrarelativistic speed through a thermal plasma. This situation may arise during a first-order electroweak phase transition in the early universe. As particles cross the wall, it is assumed that their mass grows from ma to mb, and they are decelerated causing them to emit massless radiation (mc = 0). We are interested in the momentum transfer to the wall, the thermal pressure felt by the wall, and the resultant terminal velocity of the wall. We employ the semiclassical current radiation (SCR) formalism to perform these calculations. An incident-charged particle is treated as a point-like classical electromagnetic current, and the spectrum of quantum electromagnetic radiation (photons) is derived by calculating appropriate matrix elements. To understand how the spectrum depends on the thickness of the wall, we explore simplified models for the current corresponding to an abrupt and a gradual deceleration. For the model of abrupt deceleration, we find that the SCR formalism can reproduce the Ptherm ∝ γ0w scaling found in earlier work by assuming that the emission is soft, but if the emission is not soft the SCR formalism can be used to obtain Ptherm ∝ γ2w instead. For the model of gradual deceleration, we find that the wall thickness Lw enters to cutoff the otherwise log-flat radiation spectrum above a momentum of ∼ γ2w / Lw, and we discuss the connections with classical electromagnetic bremsstrahlung.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670975","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 : 2024-11-19DOI: 10.1088/1475-7516/2024/11/023
Rodrigo Guedes Lang
The Telescope Array experiment has recently reported the most energetic event detected in the hybrid technique era, with a reconstructed energy of 240 EeV, which has been named “Amaterasu” after the Shinto deity. Its origin is intriguing since no powerful enough candidate sources are located within the region consistent with its propagation horizon and arrival direction. In this work, we investigate the possibility of describing its origin in a scenario of new physics, specifically under a Lorentz Invariance Violation (LIV) assumption. The kinematics of UHECR propagation under a phenomenological LIV approach is investigated. The total mean free path for a particle with Amaterasu's energy increases from a few Mpc to hundreds of Mpc for -δhad,0 > 10-22, expanding significantly the region from which it could have originated. A combined fit of the spectrum and composition data of Telescope Array under different LIV assumptions was also performed. The data is best fitted with some level of LIV both with and without Amaterasu. Robustness with data from the Pierre Auger Observatory is investigated by exploring an intermediate composition scenario. Similar improvements in the description of the data with LIV are found for that. New physics in the form of LIV could, thus, provide a plausible and robust explanation for the Amaterasu particle.
望远镜阵列实验最近报告了在混合技术时代探测到的能量最高的事件，其重建能量为 240 EeV，并以神道神灵的名字命名为 "天照"。由于在与其传播范围和到达方向一致的区域内没有足够强大的候选源，因此其起源令人好奇。在这项工作中，我们研究了在新物理学情景下描述其起源的可能性，特别是在洛伦兹不变量违反（LIV）假设下。我们研究了 UHECR 在现象学 LIV 方法下的传播运动学。当-δhad,0 > 10-22时，具有天照能量的粒子的总平均自由路径从几Mpc增加到几百Mpc，从而显著扩大了它可能起源的区域。在不同的 LIV 假设下，还对望远镜阵列的光谱和成分数据进行了综合拟合。在有天照和没有天照的情况下，某种程度的 LIV 都能最好地拟合数据。通过探索中间成分情况，研究了与皮埃尔-奥格天文台数据的鲁棒性。结果发现，使用 LIV 对数据的描述也有类似的改进。因此，LIV形式的新物理学可以为天照粒子提供一个合理而稳健的解释。
{"title":"New physics as a possible explanation for the Amaterasu particle","authors":"Rodrigo Guedes Lang","doi":"10.1088/1475-7516/2024/11/023","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/023","url":null,"abstract":"The Telescope Array experiment has recently reported the most energetic event detected in the hybrid technique era, with a reconstructed energy of 240 EeV, which has been named “Amaterasu” after the Shinto deity. Its origin is intriguing since no powerful enough candidate sources are located within the region consistent with its propagation horizon and arrival direction. In this work, we investigate the possibility of describing its origin in a scenario of new physics, specifically under a Lorentz Invariance Violation (LIV) assumption. The kinematics of UHECR propagation under a phenomenological LIV approach is investigated. The total mean free path for a particle with Amaterasu's energy increases from a few Mpc to hundreds of Mpc for -δhad,0 > 10-22, expanding significantly the region from which it could have originated. A combined fit of the spectrum and composition data of Telescope Array under different LIV assumptions was also performed. The data is best fitted with some level of LIV both with and without Amaterasu. Robustness with data from the Pierre Auger Observatory is investigated by exploring an intermediate composition scenario. Similar improvements in the description of the data with LIV are found for that. New physics in the form of LIV could, thus, provide a plausible and robust explanation for the Amaterasu particle.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"52 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670974","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 : 2024-11-19DOI: 10.1088/1475-7516/2024/11/029
U. Bhura, R.A. Battye, J.I. McDonald and S. Srinivasan
Neutron stars provide a powerful probe of axion dark matter, especially in higher frequency ranges where there remain fewer laboratory constraints. Populations of neutron stars near the Galactic Centre have been proposed as a means to place strong constraints on axion dark matter. One downside of this approach is that there are very few direct observations of neutron stars in this region, introducing uncertainties in the total number of neutron stars in this “invisible” population at the Galactic Centre, whose size must be inferred through birth rate modelling. We suggest this number could also be reduced due to stellar dynamics carrying stars away from the Galactic Centre via large kick velocities at birth. We attempt to circumvent the uncertainty on the Galactic Centre population size by modelling the axion signal from better understood populations outside the Galactic Centre using PsrPopPy which is normalised against pulsar observations. We consider lower-frequency, wider-angle searches for this signal via a range of instruments including MeerKAT and SKA-low but find that the sensitivity is not competitive with existing constraints. Finally, returning to the Galactic Centre, we compare populations to single objects as targets for axion detection. Using the latest modelling of axion-photon conversion in the Galactic Centre magnetar, we conclude that within astrophysical uncertainties, the Galactic Centre population and the magnetar could give comparable sensitivities to axion dark matter, suggesting one should continue to search for both signals in future surveys.
{"title":"Axion signals from neutron star populations","authors":"U. Bhura, R.A. Battye, J.I. McDonald and S. Srinivasan","doi":"10.1088/1475-7516/2024/11/029","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/029","url":null,"abstract":"Neutron stars provide a powerful probe of axion dark matter, especially in higher frequency ranges where there remain fewer laboratory constraints. Populations of neutron stars near the Galactic Centre have been proposed as a means to place strong constraints on axion dark matter. One downside of this approach is that there are very few direct observations of neutron stars in this region, introducing uncertainties in the total number of neutron stars in this “invisible” population at the Galactic Centre, whose size must be inferred through birth rate modelling. We suggest this number could also be reduced due to stellar dynamics carrying stars away from the Galactic Centre via large kick velocities at birth. We attempt to circumvent the uncertainty on the Galactic Centre population size by modelling the axion signal from better understood populations outside the Galactic Centre using PsrPopPy which is normalised against pulsar observations. We consider lower-frequency, wider-angle searches for this signal via a range of instruments including MeerKAT and SKA-low but find that the sensitivity is not competitive with existing constraints. Finally, returning to the Galactic Centre, we compare populations to single objects as targets for axion detection. Using the latest modelling of axion-photon conversion in the Galactic Centre magnetar, we conclude that within astrophysical uncertainties, the Galactic Centre population and the magnetar could give comparable sensitivities to axion dark matter, suggesting one should continue to search for both signals in future surveys.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142671017","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 : 2024-11-15DOI: 10.1088/1475-7516/2024/11/022
Sanjay Mandal and Kazuharu Bamba
In this study, we investigate swampland conjectures within the setup of matter and non-metricity nonminimal coupling theories of gravity. We examine how the inflationary solution produced by a single scalar field can be resolved with the swampland criteria in string theory regarding the formation of de Sitter solutions. The new important findings are that the inflationary scenario in our study differs from the one in general relativity because of the presence of a nonminimal coupling term, and that difference gives the correction to general relativity. In addition, we observe that the slow-roll conditions and the swampland conjectures are incompatible with each other for a single scalar field within the framework of nonminimally coupled alternative gravity theories. We predict that these results will hold for a wide range of inflationary scenarios in the context of nonminimal coupling gravitational theories.
{"title":"Theory of gravity with nonminimal matter-nonmetricity coupling and the de-Sitter swampland conjectures","authors":"Sanjay Mandal and Kazuharu Bamba","doi":"10.1088/1475-7516/2024/11/022","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/022","url":null,"abstract":"In this study, we investigate swampland conjectures within the setup of matter and non-metricity nonminimal coupling theories of gravity. We examine how the inflationary solution produced by a single scalar field can be resolved with the swampland criteria in string theory regarding the formation of de Sitter solutions. The new important findings are that the inflationary scenario in our study differs from the one in general relativity because of the presence of a nonminimal coupling term, and that difference gives the correction to general relativity. In addition, we observe that the slow-roll conditions and the swampland conjectures are incompatible with each other for a single scalar field within the framework of nonminimally coupled alternative gravity theories. We predict that these results will hold for a wide range of inflationary scenarios in the context of nonminimal coupling gravitational theories.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"38 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637220","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 : 2024-11-12DOI: 10.1088/1475-7516/2024/11/021
Mattia Pantiri, Matteo Foglieni, Enea Di Dio and Emanuele Castorina
At low redshift, it is possible to combine spectroscopic information of galaxies with their luminosity or angular diameter distance to directly measure the projection of peculiar velocities (PV) along the line-of-sight. A PV survey probing a large fraction of the sky is subject to so-called wide-angle effects, arising from the variation of the line-of-sight across the sky, and other sub-leading projection effects due to the propagation of the photons in a perturbed cosmological background. In this work, for the first time, we provide a complete description, within linear theory and General Relativity, of the power spectrum of luminosity distance fluctuations, clarifying its relation to the observables in a PV survey. We find that wide-angle effects will be detected at high significance by future observations and will have to be included in the cosmological analysis. Other relativistic projections effects could also be detected provided accurate, per object, distances are available.
{"title":"The power spectrum of luminosity distance fluctuations in General Relativity","authors":"Mattia Pantiri, Matteo Foglieni, Enea Di Dio and Emanuele Castorina","doi":"10.1088/1475-7516/2024/11/021","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/11/021","url":null,"abstract":"At low redshift, it is possible to combine spectroscopic information of galaxies with their luminosity or angular diameter distance to directly measure the projection of peculiar velocities (PV) along the line-of-sight. A PV survey probing a large fraction of the sky is subject to so-called wide-angle effects, arising from the variation of the line-of-sight across the sky, and other sub-leading projection effects due to the propagation of the photons in a perturbed cosmological background. In this work, for the first time, we provide a complete description, within linear theory and General Relativity, of the power spectrum of luminosity distance fluctuations, clarifying its relation to the observables in a PV survey. We find that wide-angle effects will be detected at high significance by future observations and will have to be included in the cosmological analysis. Other relativistic projections effects could also be detected provided accurate, per object, distances are available.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"71 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599119","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}
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