Pub Date : 2021-10-13DOI: 10.13097/ARCHIVE-OUVERTE/UNIGE:156136
G. Franciolini
Primordial Black Holes (PBH) can form in the early universe and might comprise a significant fraction of the dark matter. Interestingly, they are accompanied by the generation of Gravitational Wave (GW) signals and they could contribute to the merger events currently observed by the LIGO/Virgo Collaboration (LVC). In this thesis, we study the PBH scenario, addressing various properties at the formation epoch and the computation of abundance beyond the Gaussian paradigm, while also developing the theoretical description of PBH evolution through accretion and mergers, with particular focus on modelling their GW signatures. In a second part, we compare the primordial scenario with current GW data, seizing the possible contribution of PBH binaries to LVC signals and forecasting the potential of future GW detectors, such as Einstein Telescope and LISA, to detect mergers of primordial binaries and the stochastic GW background induced at second order by the PBH formation mechanism.
{"title":"Primordial Black Holes: from Theory to Gravitational Wave Observations","authors":"G. Franciolini","doi":"10.13097/ARCHIVE-OUVERTE/UNIGE:156136","DOIUrl":"https://doi.org/10.13097/ARCHIVE-OUVERTE/UNIGE:156136","url":null,"abstract":"Primordial Black Holes (PBH) can form in the early universe and might comprise a significant fraction of the dark matter. Interestingly, they are accompanied by the generation of Gravitational Wave (GW) signals and they could contribute to the merger events currently observed by the LIGO/Virgo Collaboration (LVC). In this thesis, we study the PBH scenario, addressing various properties at the formation epoch and the computation of abundance beyond the Gaussian paradigm, while also developing the theoretical description of PBH evolution through accretion and mergers, with particular focus on modelling their GW signatures. In a second part, we compare the primordial scenario with current GW data, seizing the possible contribution of PBH binaries to LVC signals and forecasting the potential of future GW detectors, such as Einstein Telescope and LISA, to detect mergers of primordial binaries and the stochastic GW background induced at second order by the PBH formation mechanism.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"117 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83183455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yongda Zhu, G. Becker, S. Bosman, L. Keating, H. Christenson, E. Bañados, F. Bian, F. Davies, V. D’Odorico, A. Eilers, Xiaohui Fan, M. Haehnelt, Girish Kulkarni, A. Pallottini, Y. Qin, Feige Wang, Jinyi Yang
We present a new investigation of the intergalactic medium (IGM) near the end of reionization using "dark gaps" in the Lyman-alpha (Ly$alpha$) forest. Using spectra of 55 QSOs at $z_{rm em}>5.5$, including new data from the XQR-30 VLT Large Programme, we identify gaps in the Ly$alpha$ forest where the transmission averaged over 1 comoving $h^{-1},{rm Mpc}$ bins falls below 5%. Nine ultra-long ($L > 80~h^{-1},{rm Mpc}$) dark gaps are identified at $z<6$. In addition, we quantify the fraction of QSO spectra exhibiting gaps longer than $30~h^{-1},{rm Mpc}$, $F_{30}$, as a function of redshift. We measure $F_{30} simeq 0.9$, 0.6, and 0.15 at $z = 6.0$, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to $z simeq 5.3$. Comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six. Models wherein the IGM is essentially fully reionized that retain large-scale fluctuations in the ionizing UV background at $z lesssim 6$ are also potentially consistent with the data. Overall, our results suggest that signature of reionization in the form of islands of neutral hydrogen and/or large-scale fluctuations in the ionizing background remain present in the IGM until at least $z simeq 5.3$.
我们提出了利用莱曼α (Ly $alpha$)森林中的“暗隙”对再电离结束附近的星系间介质(IGM)的新研究。利用$z_{rm em}>5.5$上55个qso的光谱，包括来自XQR-30 VLT大项目的新数据，我们确定了Ly $alpha$森林中的间隙，其中1个移动$h^{-1},{rm Mpc}$箱的平均传输低于5个%. Nine ultra-long ($L > 80~h^{-1},{rm Mpc}$) dark gaps are identified at $z<6$. In addition, we quantify the fraction of QSO spectra exhibiting gaps longer than $30~h^{-1},{rm Mpc}$, $F_{30}$, as a function of redshift. We measure $F_{30} simeq 0.9$, 0.6, and 0.15 at $z = 6.0$, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to $z simeq 5.3$. Comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six. Models wherein the IGM is essentially fully reionized that retain large-scale fluctuations in the ionizing UV background at $z lesssim 6$ are also potentially consistent with the data. Overall, our results suggest that signature of reionization in the form of islands of neutral hydrogen and/or large-scale fluctuations in the ionizing background remain present in the IGM until at least $z simeq 5.3$.
{"title":"Chasing the Tail of Cosmic Reionization with Dark Gap Statistics in the Ly$α$ Forest over $5 < z < 6$","authors":"Yongda Zhu, G. Becker, S. Bosman, L. Keating, H. Christenson, E. Bañados, F. Bian, F. Davies, V. D’Odorico, A. Eilers, Xiaohui Fan, M. Haehnelt, Girish Kulkarni, A. Pallottini, Y. Qin, Feige Wang, Jinyi Yang","doi":"10.17863/CAM.75772","DOIUrl":"https://doi.org/10.17863/CAM.75772","url":null,"abstract":"We present a new investigation of the intergalactic medium (IGM) near the end of reionization using \"dark gaps\" in the Lyman-alpha (Ly$alpha$) forest. Using spectra of 55 QSOs at $z_{rm em}>5.5$, including new data from the XQR-30 VLT Large Programme, we identify gaps in the Ly$alpha$ forest where the transmission averaged over 1 comoving $h^{-1},{rm Mpc}$ bins falls below 5%. Nine ultra-long ($L > 80~h^{-1},{rm Mpc}$) dark gaps are identified at $z<6$. In addition, we quantify the fraction of QSO spectra exhibiting gaps longer than $30~h^{-1},{rm Mpc}$, $F_{30}$, as a function of redshift. We measure $F_{30} simeq 0.9$, 0.6, and 0.15 at $z = 6.0$, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to $z simeq 5.3$. Comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six. Models wherein the IGM is essentially fully reionized that retain large-scale fluctuations in the ionizing UV background at $z lesssim 6$ are also potentially consistent with the data. Overall, our results suggest that signature of reionization in the form of islands of neutral hydrogen and/or large-scale fluctuations in the ionizing background remain present in the IGM until at least $z simeq 5.3$.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"96 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79916241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-17DOI: 10.1103/PhysRevD.105.103534
Georgios Valogiannis, C. Dvorkin
Optimal extraction of the non-Gaussian information encoded in the Large-Scale Structure (LSS) of the universe lies at the forefront of modern precision cosmology. We propose achieving this task through the use of the Wavelet Scattering Transform (WST), which subjects an input field to a layer of non-linear transformations that are sensitive to non-Gaussianity in spatial density distributions through a generated set of WST coefficients. In order to assess its applicability in the context of LSS surveys, we apply the WST on the 3D overdensity field obtained by the Quijote simulations, out of which we extract the Fisher information in 6 cosmological parameters. It is subsequently found to deliver a large improvement in the marginalized errors on all parameters, ranging between $1.2-4times$ tighter than the corresponding ones obtained from the regular 3D cold dark matter + baryon power spectrum, as well as a $50 %$ improvement over the neutrino mass constraint given by the marked power spectrum. Through this first application on 3D cosmological fields, we demonstrate the great promise held by this novel statistic and set the stage for its future application to actual galaxy observations.
{"title":"Towards an Optimal Estimation of Cosmological Parameters with the Wavelet Scattering Transform","authors":"Georgios Valogiannis, C. Dvorkin","doi":"10.1103/PhysRevD.105.103534","DOIUrl":"https://doi.org/10.1103/PhysRevD.105.103534","url":null,"abstract":"Optimal extraction of the non-Gaussian information encoded in the Large-Scale Structure (LSS) of the universe lies at the forefront of modern precision cosmology. We propose achieving this task through the use of the Wavelet Scattering Transform (WST), which subjects an input field to a layer of non-linear transformations that are sensitive to non-Gaussianity in spatial density distributions through a generated set of WST coefficients. In order to assess its applicability in the context of LSS surveys, we apply the WST on the 3D overdensity field obtained by the Quijote simulations, out of which we extract the Fisher information in 6 cosmological parameters. It is subsequently found to deliver a large improvement in the marginalized errors on all parameters, ranging between $1.2-4times$ tighter than the corresponding ones obtained from the regular 3D cold dark matter + baryon power spectrum, as well as a $50 %$ improvement over the neutrino mass constraint given by the marked power spectrum. Through this first application on 3D cosmological fields, we demonstrate the great promise held by this novel statistic and set the stage for its future application to actual galaxy observations.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86467955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-17DOI: 10.1051/0004-6361/202141736
V. Gurzadyan, A. Stepanian
It is shown that, from the two independent approaches of McCrea-Milne and of Zeldovich, one can fully recover the set equations corresponding to relativistic equations of the expanding universe of Friedmann-Lemaitre-Robertson-Walker geometry. Although similar, the Newtonian and relativistic set of equations, have principal difference in the content and hence define two flows, local and global ones, thus naturally exposing the Hubble tension at presence of the cosmological constant Lambda. From that, we obtain "absolute" constraints on the lower and upper values for the local Hubble parameter, sqrt{Lambda c^2/3} simeq 56.2 and sqrt{Lambda c^2} simeq 97.3$ (km/sec Mpc^{-1}), respectively. The link to the so-called "maximum force/tension" issue in cosmological models is revealed.
{"title":"Hubble tension and absolute constraints on the local Hubble parameter.","authors":"V. Gurzadyan, A. Stepanian","doi":"10.1051/0004-6361/202141736","DOIUrl":"https://doi.org/10.1051/0004-6361/202141736","url":null,"abstract":"It is shown that, from the two independent approaches of McCrea-Milne and of Zeldovich, one can fully recover the set equations corresponding to relativistic equations of the expanding universe of Friedmann-Lemaitre-Robertson-Walker geometry. Although similar, the Newtonian and relativistic set of equations, have principal difference in the content and hence define two flows, local and global ones, thus naturally exposing the Hubble tension at presence of the cosmological constant Lambda. From that, we obtain \"absolute\" constraints on the lower and upper values for the local Hubble parameter, sqrt{Lambda c^2/3} simeq 56.2 and sqrt{Lambda c^2} simeq 97.3$ (km/sec Mpc^{-1}), respectively. The link to the so-called \"maximum force/tension\" issue in cosmological models is revealed.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83160546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two types of distance measurement are important in cosmological observations, the angular diameter distance $d_A$ and the luminosity distance $d_L$. In the present work, we carried out an assessment of the theoretical relation between these two distance measurements, namely the cosmic distance duality relation, from type Ia supernovae (SN-Ia) data, the Cosmic Chronometer (CC) Hubble parameter data, and baryon acoustic oscillation (BAO) data using Gaussian Process. The luminosity distance curve and the angular diameter distance curve are extracted from the SN-Ia data and the combination of BAO and CC data respectively using the Gaussian Process. The distance duality relation is checked by a non-parametric reconstruction using the reconstructed $H$, $d_L$, and the volume-averaged distance $D_v$. We compare the results obtained for different choices of the covariance function employed in the Gaussian Process. It is observed that the theoretical distance duality relation is in well agreement with the present analysis in 2$sigma$ for the overlapping redshift domain $0 leq z leq 2$ of the reconstruction.
在宇宙学观测中有两种重要的距离测量，角直径距离$d_A$和光度距离$d_L$。本文利用高斯过程对Ia型超新星(SN-Ia)数据、cosmic Chronometer (CC)哈勃参数数据和重子声学振荡(BAO)数据进行了宇宙距离对偶关系的理论评价。利用高斯过程分别从SN-Ia数据和结合BAO和CC数据提取光度距离曲线和角直径距离曲线。距离对偶关系通过使用重建的$H$, $d_L$和体积平均距离$D_v$进行非参数重建来检查。我们比较了高斯过程中不同选择的协方差函数所得到的结果。观察到，对于重建的重叠红移域$0 leq z leq 2$，理论距离对偶关系与本文2 $sigma$的分析很好地吻合。
{"title":"Assessment of the cosmic distance duality relation using Gaussian process","authors":"P. Mukherjee, Ankan Mukherjee","doi":"10.1093/mnras/stab1054","DOIUrl":"https://doi.org/10.1093/mnras/stab1054","url":null,"abstract":"Two types of distance measurement are important in cosmological observations, the angular diameter distance $d_A$ and the luminosity distance $d_L$. In the present work, we carried out an assessment of the theoretical relation between these two distance measurements, namely the cosmic distance duality relation, from type Ia supernovae (SN-Ia) data, the Cosmic Chronometer (CC) Hubble parameter data, and baryon acoustic oscillation (BAO) data using Gaussian Process. The luminosity distance curve and the angular diameter distance curve are extracted from the SN-Ia data and the combination of BAO and CC data respectively using the Gaussian Process. The distance duality relation is checked by a non-parametric reconstruction using the reconstructed $H$, $d_L$, and the volume-averaged distance $D_v$. We compare the results obtained for different choices of the covariance function employed in the Gaussian Process. It is observed that the theoretical distance duality relation is in well agreement with the present analysis in 2$sigma$ for the overlapping redshift domain $0 leq z leq 2$ of the reconstruction.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86482334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-07DOI: 10.21203/RS.3.RS-298059/V1
S. Afach, B. Buchler, D. Budker, C. Dailey, A. Derevianko, V. Dumont, N. L. Figueroa, I. Gerhardt, Z. Gruji'c, Hong Guo, Chuanpeng Hao, P. Hamilton, M. Hedges, D. F. Kimball, Dongok Kim, Sami Khamis, T. Kornack, V. Lebedev, Zheng‐Tian Lu, H. Masia-Roig, M. Monroy, M. Padniuk, C. Palm, Sun Yool Park, Karun V. Paul, A. Penaflor, Xiang Peng, M. Pospelov, Rayshaun Preston, S. Pustelny, T. Scholtes, P. Segura, Y. Semertzidis, D. Sheng, Y. Shin, Joseph A. Smiga, J. Stalnaker, I. Sulai, Dhruv Tandon, Tao Wang, A. Weis, A. Wickenbrock, T. Wilson, Teng Wu, D. Wurm, Wei Xiao, Yucheng Yang, Dongrui Yu, Jianwei Zhang
Results are reported from the first full-scale search for transient signals from exotic fields of astrophysical origin using data from a newly constructed Earth-scale detector: the Global Network of Optical Magnetometers for Exotic physics searches (GNOME). Data collected by the GNOME consist of correlated measurements from optical atomic magnetometers located in laboratories all over the world. GNOME data are searched for patterns of signals propagating through the network consistent with exotic fields composed of ultralight bosons such as axion-like particles (ALPs). Analysis of data from a continuous month-long operation of the GNOME finds no statistically significant signals consistent with those expected due to encounters with topological defects (axion domain walls), placing new experimental constraints on such dark matter scenarios.
{"title":"Search for topological defect dark matter using the global network of optical magnetometers for exotic physics searches (GNOME)","authors":"S. Afach, B. Buchler, D. Budker, C. Dailey, A. Derevianko, V. Dumont, N. L. Figueroa, I. Gerhardt, Z. Gruji'c, Hong Guo, Chuanpeng Hao, P. Hamilton, M. Hedges, D. F. Kimball, Dongok Kim, Sami Khamis, T. Kornack, V. Lebedev, Zheng‐Tian Lu, H. Masia-Roig, M. Monroy, M. Padniuk, C. Palm, Sun Yool Park, Karun V. Paul, A. Penaflor, Xiang Peng, M. Pospelov, Rayshaun Preston, S. Pustelny, T. Scholtes, P. Segura, Y. Semertzidis, D. Sheng, Y. Shin, Joseph A. Smiga, J. Stalnaker, I. Sulai, Dhruv Tandon, Tao Wang, A. Weis, A. Wickenbrock, T. Wilson, Teng Wu, D. Wurm, Wei Xiao, Yucheng Yang, Dongrui Yu, Jianwei Zhang","doi":"10.21203/RS.3.RS-298059/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-298059/V1","url":null,"abstract":"\u0000 Results are reported from the first full-scale search for transient signals from exotic fields of astrophysical origin using data from a newly constructed Earth-scale detector: the Global Network of Optical Magnetometers for Exotic physics searches (GNOME). Data collected by the GNOME consist of correlated measurements from optical atomic magnetometers located in laboratories all over the world. GNOME data are searched for patterns of signals propagating through the network consistent with exotic fields composed of ultralight bosons such as axion-like particles (ALPs). Analysis of data from a continuous month-long operation of the GNOME finds no statistically significant signals consistent with those expected due to encounters with topological defects (axion domain walls), placing new experimental constraints on such dark matter scenarios.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81829045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-08DOI: 10.1051/0004-6361/202140515
A. Gorce, A. Hutter, J. Pritchard
Intensity mapping of the 21cm signal of neutral hydrogen will yield exciting insights into the Epoch of Reionisation and the nature of the first galaxies. However, the large amount of data that will be generated by the next generation of radio telescopes, such as the Square Kilometre Array (SKA), as well as the numerous observational obstacles to overcome, require analysis techniques tuned to extract the reionisation history and morphology. In this context, we introduce a one-point statistic, to which we refer as the local variance, $sigma_mathrm{loc}$, that describes the distribution of the mean differential 21cm brightness temperatures measured in two-dimensional maps along the frequency direction of a light-cone. The local variance takes advantage of what is usually considered an observational bias, the sample variance. We find the redshift-evolution of the local variance to not only probe the reionisation history of the observed patches of the sky, but also trace the ionisation morphology. This estimator provides a promising tool to constrain the midpoint of reionisation as well as gaining insight into the ionising properties of early galaxies.
{"title":"Using the sample variance of 21cm maps as a tracer of the ionisation topology","authors":"A. Gorce, A. Hutter, J. Pritchard","doi":"10.1051/0004-6361/202140515","DOIUrl":"https://doi.org/10.1051/0004-6361/202140515","url":null,"abstract":"Intensity mapping of the 21cm signal of neutral hydrogen will yield exciting insights into the Epoch of Reionisation and the nature of the first galaxies. However, the large amount of data that will be generated by the next generation of radio telescopes, such as the Square Kilometre Array (SKA), as well as the numerous observational obstacles to overcome, require analysis techniques tuned to extract the reionisation history and morphology. In this context, we introduce a one-point statistic, to which we refer as the local variance, $sigma_mathrm{loc}$, that describes the distribution of the mean differential 21cm brightness temperatures measured in two-dimensional maps along the frequency direction of a light-cone. The local variance takes advantage of what is usually considered an observational bias, the sample variance. We find the redshift-evolution of the local variance to not only probe the reionisation history of the observed patches of the sky, but also trace the ionisation morphology. This estimator provides a promising tool to constrain the midpoint of reionisation as well as gaining insight into the ionising properties of early galaxies.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85568577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A dark-energy which behaves as the cosmological constant until a sudden phantom transition at very-low redshift ($z 4$sigma$ disagreement between the local and high-redshift determinations of the Hubble constant, while maintaining the phenomenological success of the $Lambda$CDM model with respect to the other observables. Here, we show that such a hockey-stick dark energy cannot solve the $H_0$ crisis. The basic reason is that the supernova absolute magnitude $M_B$ that is used to derive the local $H_0$ constraint is not compatible with the $M_B$ that is necessary to fit supernova, BAO and CMB data, and this disagreement is not solved by a sudden phantom transition at very-low redshift. We make use of this example to show why it is preferable to adopt in the statistical analyses the prior on $M_B$ as an alternative to the prior on $H_0$. The three reasons are: i) one avoids potential double counting of low-redshift supernovae, ii) one avoids assuming the validity of cosmography, in particular fixing the deceleration parameter to the standard model value $q_0=-0.55$, iii) one includes in the analysis the fact that $M_B$ is constrained by local calibration, an information which would otherwise be neglected in the analysis, biasing both model selection and parameter constraints. We provide the priors on $M_B$ relative to the recent Pantheon and DES-SN3YR supernova catalogs. We also provide a Gaussian joint prior on $H_0$ and $q_0$ that generalizes the prior on $H_0$ by SH0ES.
{"title":"On the use of the local prior on the absolute magnitude of Type Ia supernovae in cosmological inference","authors":"D. Camarena, V. Marra","doi":"10.1093/mnras/stab1200","DOIUrl":"https://doi.org/10.1093/mnras/stab1200","url":null,"abstract":"A dark-energy which behaves as the cosmological constant until a sudden phantom transition at very-low redshift ($z 4$sigma$ disagreement between the local and high-redshift determinations of the Hubble constant, while maintaining the phenomenological success of the $Lambda$CDM model with respect to the other observables. Here, we show that such a hockey-stick dark energy cannot solve the $H_0$ crisis. The basic reason is that the supernova absolute magnitude $M_B$ that is used to derive the local $H_0$ constraint is not compatible with the $M_B$ that is necessary to fit supernova, BAO and CMB data, and this disagreement is not solved by a sudden phantom transition at very-low redshift. We make use of this example to show why it is preferable to adopt in the statistical analyses the prior on $M_B$ as an alternative to the prior on $H_0$. The three reasons are: i) one avoids potential double counting of low-redshift supernovae, ii) one avoids assuming the validity of cosmography, in particular fixing the deceleration parameter to the standard model value $q_0=-0.55$, iii) one includes in the analysis the fact that $M_B$ is constrained by local calibration, an information which would otherwise be neglected in the analysis, biasing both model selection and parameter constraints. We provide the priors on $M_B$ relative to the recent Pantheon and DES-SN3YR supernova catalogs. We also provide a Gaussian joint prior on $H_0$ and $q_0$ that generalizes the prior on $H_0$ by SH0ES.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90216406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-17DOI: 10.1103/PhysRevD.103.103504
O. Philcox
Conventional algorithms for galaxy power spectrum estimation measure the true spectrum convolved with a survey window function, which, for parameter inference, must be compared with a similarly convolved theory model. In this work, we directly estimate the unwindowed power spectrum multipoles using quadratic estimators akin to those introduced in the late 1990s. Under Gaussian assumptions, these are optimal and free from the leading-order effects of pixellization and non-Poissonian shot-noise. They may be straightforwardly computed given the survey data-set and a suite of simulations of known cosmology. We implement the pixel-based maximum-likelihood estimator and a simplification based on the FKP weighting scheme, both of which can be computed via FFTs and conjugate gradient descent methods. Furthermore, the estimators allow direct computation of spectrum coefficients in an arbitrary linear compression scheme, without needing to first bin the statistico. Applying the technique to a subset of the BOSS DR12 galaxies, we find that the pixel-based quadratic estimators give statistically consistent power spectra, compressed coefficients, and cosmological parameters to those obtained with the usual windowed approaches. Due to the sample's low number density and compact window function, the optimal weighting scheme gives little improvement over the simplified form; this may change for dense surveys or those focusing on primordial non-Gaussianity. The technique is shown to be efficient and robust, and shows significant potential for measuring the windowless power spectrum and bispectrum in the presence of weak non-Gaussianity.
{"title":"Cosmology without window functions: Quadratic estimators for the galaxy power spectrum","authors":"O. Philcox","doi":"10.1103/PhysRevD.103.103504","DOIUrl":"https://doi.org/10.1103/PhysRevD.103.103504","url":null,"abstract":"Conventional algorithms for galaxy power spectrum estimation measure the true spectrum convolved with a survey window function, which, for parameter inference, must be compared with a similarly convolved theory model. In this work, we directly estimate the unwindowed power spectrum multipoles using quadratic estimators akin to those introduced in the late 1990s. Under Gaussian assumptions, these are optimal and free from the leading-order effects of pixellization and non-Poissonian shot-noise. They may be straightforwardly computed given the survey data-set and a suite of simulations of known cosmology. We implement the pixel-based maximum-likelihood estimator and a simplification based on the FKP weighting scheme, both of which can be computed via FFTs and conjugate gradient descent methods. Furthermore, the estimators allow direct computation of spectrum coefficients in an arbitrary linear compression scheme, without needing to first bin the statistico. Applying the technique to a subset of the BOSS DR12 galaxies, we find that the pixel-based quadratic estimators give statistically consistent power spectra, compressed coefficients, and cosmological parameters to those obtained with the usual windowed approaches. Due to the sample's low number density and compact window function, the optimal weighting scheme gives little improvement over the simplified form; this may change for dense surveys or those focusing on primordial non-Gaussianity. The technique is shown to be efficient and robust, and shows significant potential for measuring the windowless power spectrum and bispectrum in the presence of weak non-Gaussianity.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76354076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-15DOI: 10.1103/PhysRevD.103.123539
R. Cai, Jiajian Ding, Zongkuan Guo, Shao-Jiang Wang, Wang-Wei Yu
The increasing tension between the different local direct measurements of the Hubble expansion rate and that inferred from the Cosmic Microwave Background observation by $Lambda$-Cold-Dark-Matter model could be a smoking gun of new physics, if not caused by either observational systematics or local bias. We complete previous investigation on the local bias from a local void by globally fitting the Pantheon sample over all parameters in the radial profile function of a local void described by an inhomogeneous but isotropic Lema^{i}tre-Tolman-Bondi metric with a cosmological constant. Our conclusion strengths the previous studies that the current tension on Hubble constant cannot be saved by a local void alone.
{"title":"Do the observational data favor a local void?","authors":"R. Cai, Jiajian Ding, Zongkuan Guo, Shao-Jiang Wang, Wang-Wei Yu","doi":"10.1103/PhysRevD.103.123539","DOIUrl":"https://doi.org/10.1103/PhysRevD.103.123539","url":null,"abstract":"The increasing tension between the different local direct measurements of the Hubble expansion rate and that inferred from the Cosmic Microwave Background observation by $Lambda$-Cold-Dark-Matter model could be a smoking gun of new physics, if not caused by either observational systematics or local bias. We complete previous investigation on the local bias from a local void by globally fitting the Pantheon sample over all parameters in the radial profile function of a local void described by an inhomogeneous but isotropic Lema^{i}tre-Tolman-Bondi metric with a cosmological constant. Our conclusion strengths the previous studies that the current tension on Hubble constant cannot be saved by a local void alone.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83125713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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