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Searching for isotropic stochastic gravitational-wave background in the international pulsar timing array second data release

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Communications in Theoretical Physics 2022年第10期74卷 83-88页

作者： Zu-Cheng Chen Yu-Mei Wu Qing-Guo Huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesNo.19A Yuquan RoadBeijing 100049China Department of Astronomy Beijing Normal UniversityBeijing 100875China Advanced Institute of Natural Sciences Beijing Normal UniversityZhuhai 519087China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China

We search for isotropic stochastic gravitational-wave background(SGWB)in the International pulsar timing array second data *** modeling the SGWB as a power-law,we find very strong Bayesian evidence for a common-spectrum process,and further this process has scalar transverse(ST)correlations allowed in general metric theory of gravity as the Bayes factor in favor of the ST-correlated process versus the spatially uncorrelated common-spectrum process is 30±*** median and the 90%equal-tail amplitudes of ST mode are A_(ST)=1.29^(+0.51)_(−0.44)×10^(−15),or equivalently the energy density parameter per logarithm frequency isΩSTGW=2.31^(+2.19)_(−1.30)×10^(−9),at frequency of 1 year−***,we do not find any statistically significant evidence for the tensor transverse(TT)mode and then place the 95%upper limits as A_(TT)<3.95×10^(−15),or equivalentlyΩ^(TT)_(GW)<2.16×10^(−9),at frequency of 1 year^(−1).

关键词： stochastic gravitational-wave background pulsar timing array beyond general relativitiy

Constraints on the primordial curvature power spectrum by pulsar timing array data:a polynomial parameterization approach

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Communications in Theoretical Physics 2024年第1期76卷 96-104页

作者： Qin Fei School of Mathematics and Physics Hubei Polytechnic UniversityHuangshi 435003China

The recent stochastic signal observed jointly by NANOGrav,parkes pulsar timing array,European pulsar timing array,and Chinese pulsar timing array can be accounted for by scalarinduced gravitational waves(SIGWs).The source of the SIGWs is from the primordial curvature perturbations,and the main contribution to the SIGWs is from the peak of the primordial curvature power *** effectively model this peak,we apply the Taylor expansion to parameterize *** the Taylor expansion parameterization,we apply Bayesian methods to constrain the primordial curvature power spectrum based on the NANOGrav 15 year data *** constraint on the primordial curvature power spectrum possesses a degree of generality,as the Taylor expansion can effectively approximate a wide range of function profiles.

关键词： pulsar timing array scalar-induced gravitational waves inflation

Constraints on holographic QCD phase transitions from PTA observations

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 71-78页

作者： Song He Li Li Sai Wang Shao-Jiang Wang Center for Theoretical Physics and College of Physics Jilin University School of Physical Science and Technology Ningbo University Max Planck Institute for Gravitational Physics (Albert Einstein Institute) CAS Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences (UCAS) School of Physical Sciences University of Chinese Academy of Sciences (UCAS) Theoretical Physics Division Institute of High Energy Physics Chinese Academy of Sciences

The underlying physics of QCD phase transition in the early Universe remains largely unknown due to its strong-coupling nature during the quark-gluon plasma/hadron gas transition, yet a holographic model has been proposed to quantitatively fit the lattice QCD data while with its duration of the first-order phase transition(FoPT) left undetermined. At specific baryon chemical potential, the first-order QCD phase transition agrees with the observational constraint of baryon asymmetry. It, therefore, provides a scenario for phase transition gravitational waves(GWs) within the standard model of particle physics. If these background GWs could contribute dominantly to the recently claimed common-spectrum red noise from pulsar timing array(PTA) observations, the duration of this FoPT can be well constrained, and the associated primordial black holes are still allowed by current observations.

关键词： pulsar timing array QCD phase transition gravitational waves primordial black holes

Implications for the supermassive black hole binaries from the NANOGrav 15-year data set

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Science China(Physics,Mechanics & Astronomy) 2023年第12期66卷 3-10页

作者： Yan-Chen Bi Yu-Mei Wu Zu-Cheng Chen Qing-Guo Huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China Department of Astronomy Beijing Normal UniversityBeijing 100875China Advanced Institute of Natural Sciences Beijing Normal UniversityZhuhai 519087China Department of Physics and Synergistic Innovation Center for Quantum Effects and Applications Hunan Normal UniversityChangsha 410081China

Several pulsar timing array(PTA)collaborations,including NANOGrav,EPTA,PPTA,and CPTA,have announced the evidence for a stochastic signal consistent with a stochastic gravitational wave background(SGWB).Supermassive black hole binaries(SMBHBs)are supposed to be the most promising gravitational-wave(GW)sources for this *** this paper,we use the NANOGrav 15-year data set to constrain the parameter space in an astro-informed formation model for *** results prefer a large turn-over eccentricity of the SMBHB orbit when GWs begin to dominate the SMBHB ***,the SGWB spectrum is extrapolated to the space-borne GW detector frequency band by including inspiral-merge-cutoff phases of SMBHBs,indicating that the SGWB from SMBHBs should be detected by LISA,Taiji and Tian Qin in the near future.

关键词： supermassive black hole binary gravitational wave pulsar timing array

NANOGrav hints on planet-mass primordial black holes

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Science China(Physics,Mechanics & Astronomy) 2022年第3期65卷 26-32页

作者： Guillem Domenech Shi Pi INFN Sezione di Padova Padova 1-35131Italy CAS Key'Laboratory of Theoretical Physics.Institute of Theoretical Physics ChinesAcademy of SciencesBeijing 100190China Kavli Institute for the Physics and Mathematics of the Universe(WPI) The University of Tokyo Institutes for Advanced StudyThe University of TokyoKashiwaChiba 277-8583Japan

Recently, the North American Nanohertz Observatory for Gravitational Waves(NANOGrav) claimed the detection of a stochastic common-spectrum process of the pulsar timing array(PTA) time residuals from their 12.5 year data, which might be the first detection of the stochastic background of gravitational waves(GWs). We show that the amplitude and the power index of such waves imply that they could be the secondary GWs induced by the peaked curvature perturbation with a dust-like post inflationary era with-0.091 ≤ w ≤ 0.048. Such stochastic background of GWs naturally predicts substantial existence of planet-mass primordial black holes(PBHs), which can be the lensing objects for the ultrashort-timescale microlensing events observed by the Optical Gravitational Lensing Experiment(OGLE).

关键词： pulsar timing array stochastic gravitational waves the early universe

Non-tensorial gravitational wave background in NANOGrav 12.5-year data set

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Science China(Physics,Mechanics & Astronomy) 2021年第12期64卷 84-89页

作者： Zu-Cheng Chen Chen Yuan Qing-Guo Huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We perform the first search for an isotropic non-tensorial gravitational-wave background(GWB) allowed in general metric theories of gravity in the North American Nanohertz Observatory for Gravitational Waves(NANOGrav) 12.5-year data set. By modeling the GWB as a power-law spectrum, we find strong Bayesian indication for a spatially correlated process with scalar transverse(ST) correlations whose Bayes factor versus the spatially uncorrelated common-spectrum process is 107 ± 7, but no statistically significant evidence for the tensor transverse, vector longitudinal, and scalar longitudinal polarization modes. The median and the 90% equal-tail amplitudes of ST mode are ■ , or equivalently the energy density parameter per logarithm frequency is ■, at frequency of 1/year.

关键词： gravitational wave scalar transverse polarization pulsar timing array

Statistical analyses for NANOGrav 5-year timing residuals

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Research in Astronomy and Astrophysics 2017年第2期17卷 63-76页

作者： Yan Wang James M. Cordes Fredrick A. Jenet Shami Chatterjee Paul B. Demorest Timothy Dolch Justin A. Ellis Michael T. Lam Dustin R. Madison Maura A. McLaughlin Delphine Perrodin Joanna Rankin Xavier Siemens Michele Vallisneri MOE Key Laboratory of Fundamental Physical Quantities Measurements School of Physics Huazhong University of Science and Technology Wuhan 430074 China Center for Advanced Radio Astronomy University of Texas at Brownsville 1 West University Boulevard Brownsville TX 78520 USA Department of Physics and Astronomy University of Texas at Brownsville 1 West University Boulevard Brownsville TX 78520 USA Department of Astronomy Cornell University Ithaca NY 14853 USA National Radio Astronomy Observatory 520 Edgemont Road Charlottesville VA 22903 USA Department of Physics Hillsdale College 33 E. College Street Hillsdale M149242 USA Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive Pasadena CA 91106 USA Department of Physics West Virginia University EO. Box 6315 Morgantown WV 26505 USA INAF-Osservatorio Astronomico di Cagliari Via della Scienza 5 09047 Selargius (CA) Italy Department of Physics University of Vermont Burlington VT 05405 USA Center for Gravitation Cosmology and Astrophysics Department of Physics University of Wisconsin-Milwaukee P.O. Box 413 Milwaukee WI 53201 USA

In pulsar timing, timing residuals are the differences between the observed times of arrival and predictions from the timing model. A comprehensive timing model will produce featureless resid- uals, which are presumably composed of dominating noise and weak physical effects excluded from the timing model （e.g. gravitational waves）. In order to apply optimal statistical methods for detecting weak gravitational wave signals, we need to know the statistical properties of noise components in the residuals. In this paper we utilize a variety of non-parametric statistical tests to analyze the whiteness and Gaussianity of the North American Nanohertz Observatory for Gravitational Waves （NANOGrav） 5- year timing data, which are obtained from Arecibo Observatory and Green Bank Telescope from 2005 to 2010. We find that most of the data are consistent with white noise; many data deviate from Gaussianity at different levels, nevertheless, removing outliers in some pulsars will mitigate the deviations.

关键词： pulsar timing array general -- statistical tests

镜像量子色动力学相变解释纳赫兹随机引力波背景

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Science Bulletin 2024年第6期69卷 741-746页

作者：祖磊张弛李垚钰顾玉超蔡岳霖范一中 Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China

Several pulsar timing array(PTA)Collaborations have recently provided strong evidence for a n Hz Stochastic Gravitational-Wave Background(SGWB).Here we investigate the implications of a firstorder phase transition occurring within the early Universe's dark quantum chromodynamics epoch,specifically within the framework of the mirror twin Higgs dark sector *** analysis indicates a distinguishable SGWB signal originating from this phase transition,which can explain the measurements obtained by ***,a significant portion of the parameter space for the SGWB signal also effectively resolves the existing tensions in both the H_(0) and S_(8) measurements in *** intriguing correlation suggests a possible common origin of these three phenomena for 0.2<ΔN_(eff)<0.5,where the mirror dark matter component constitutes less than 30% of the total dark matter *** CMB experiments such as CMB-S4 can test this parameter region.

关键词： Mirror twin Higgs Dark matter Phase transition Gravitational wave pulsar timing array