Parity violation is a powerful observable to distinguish a cosmological background of Gravitational Waves (GWs) from an astrophysical one. Planar single GW interferometers, both on ground and in space, are unable to measure the net circular polarization of an isotropic Stochastic Gravitational Wave Background (SGWB). In this paper, we explore the possibility of detecting circular polarization of an isotropic SGWB by cross-correlating two space-based detectors planned to be launched around 2034: LISA and Taiji. We compute the response of such a network to chirality and we perform a Fisher forecast analysis on the $I$ and $V$ Stokes parameters for the SGWB. We find that a clear measurement of chirality can be claimed for a maximally chiral signal with $h^2 \, Ω_{\rm GW} \simeq 10^{-12}$.
LISA and Taiji are expected to form a space-based gravitational-wave (GW) detection network in the future. In this work, we make a forecast for the cosmological parameter estimation with the standard siren observation from the LISA-Taiji network. We simulate the standard siren data based on a scenario with configuration angle of $40^{\circ}$ between LISA and Taiji. Three models for the population of massive black hole binary (MBHB), i.e., pop III, Q3d, and Q3nod, are considered to predict the events of MBHB mergers. We find that, based on the LISA-Taiji network, the number of electromagnetic (…
A space-based gravitational-wave detector, LISA, consists of a triangle of three spacecrafts with a separation distance of 2.5 million kilometers in a heliocentric orbit behind the Earth. Like LISA, Taiji is compose of a triangle of three spacecrafts with a separation distance of 3 million kilometers in a heliocentric orbit ahead of the Earth. They are expected to launch in 2030-2035. Assuming a one-year overlap, we propose the LISA-Taiji network in space to fast and accurately localize the gravitational-wave sources. We use the Fisher information matrix approach to analyze the sky localizatio…
The vector and scalar polarization modes of gravitational waves do not exist in General Relativity, and their detection would have significant impacts on fundamental physics. In this paper, we explored the detectability of these anomalous polarization modes in a gravitational wave background around 1 mHz with the future LISA-Taiji network. The inherent geometrical symmetry of the network largely simplifies the correlation analysis. By taking a suitable linear combination of the correlated outputs, the contribution of the standard tensor modes can be canceled algebraically, and the anomalous mo…
The Hubble parameter is one of the central parameters in modern cosmology, which describes the present expansion rate of the universe. Their values inferred from the late-time observations are systematically higher than those from the early-time measurements by about $10\%$. To come to a robust conclusion, independent probes with accuracy at percent levels are crucial. Gravitational waves from compact binary coalescence events can be formulated into the standard siren approach to provide an independent Hubble parameter measurement. The future space-borne gravitational wave observatory network,…
PTA-Compatible Domain Walls at LISA and Taiji: Bayesian Reconstruction and Multiband Inference
Nanjing Normal University（南京师范大学）；Scuola Superiore Meridionale, Università degli studi di Napoli “Federico II”（那不勒斯费德里科二世大学南方高等学院）；INFN - Sezione di Napoli（意大利国家核物理研究所那不勒斯分部）
Construction of Sensitivity Curves for Dynamic LISA and Taiji
School of Astronomy and Space Science, University of Chinese Academy of Sciences (UCAS)（中国科学院大学天文与空间科学学院）；School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, UCAS（中国科学院大学杭州高等研究院基础物理与数学学院）；International Centre for Theoretical Physics Asia-Pacific, UCAS（中国科学院大学亚太理论物理中心）
Identifying Monochromatic Signals in LISA and Taiji via Spectral Split: Gravitational Waves versus Ultralight Dark Matter
University of Chinese Academy of Sciences (UCAS)（中国科学院大学）；Hangzhou Institute for Advanced Study, UCAS（杭州高等研究院，中国科学院大学）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；International Center for Theoretical Physics Asia-Pacific（亚太理论物理中心）；School of Astronomy and Space Science, UCAS（天文学与空间科学学院，中国科学院大学）
Distinguishing Monochromatic Signals in LISA and Taiji: Ultralight Dark Matter versus Gravitational Waves
School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, UCAS（杭州高等研究院基础物理与数学学院）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；University of Chinese Academy of Sciences (UCAS)（中国科学院大学）；International Center for Theoretical Physics Asia-Pacific（亚太理论物理中心）
We discuss exploration for isotropic gravitational wave backgrounds around 1 mHz by correlation analysis, targeting both parity odd and even polarization modes. Even though the space interferometer LISA alone cannot probe the two modes due to cancellations, the outlook is being changed drastically by the strong development of other space detectors such as Taiji. In fact, a heliocentric interferometer network holds a preferable geometrical symmetry {illuminated by a virtual sphere off-center from the Sun}. By utilizing an internal symmetry of data streams, we can optimally decompose the odd and…
With the recent strong developments of TianQin and Taiji, we now have an increasing chance to make a correlation analysis in the mHz band by operating them together with LISA. Assuming two LISA-like triangular detectors at general geometrical configurations, we develop a simple formulation to evaluate the network sensitivity to an isotropic gravitational wave background. In our formulation, we fully use the symmetry of data channels within each triangular detector and provide tractable expressions without directly employing cumbersome detector tensors. We concretely evaluate the expected netwo…
An Opacity-Free Test of the Cosmic Distance Duality Relation Using Strongly Lensed Gravitational Wave Signals with Space-Based Detector Networks
Center for Gravitational Wave Experiment, National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences（中国科学院力学研究所微重力实验室引力波实验中心）；Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台暗物质与空间天文重点实验室）；School of Astronomy and Space Science, University of Science and Technology of China（中国科学技术大学天文与空间科学学院）；Department of Astronomy, Beijing Normal University（北京师范大学天文系）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；Taiji Laboratory for Gravitational Wave Universe (Beijing/Hangzhou), University of Chinese Academy of Sciences（中国科学院大学太极引力波宇宙实验室（北京/杭州））；Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences（中国科学院大学杭州高等研究院）；School of Physics Science And Technology, Wuhan Un（武汉大物理学科学与技术学院）
We investigate gravitational waves (GWs) generated in a two-field inflationary model with a non-canonical kinetic term, in which the gravitational Chern-Simons term is coupled to a heavy dynamical field. In such a model, primordial GWs experience a period of resonant amplification for some modes. In addition, isocurvature perturbations suffer from a temporary tachyonic instability due to an effective negative mass, which source curvature perturbations, resulting in large induced GWs. These two stochastic gravitational wave backgrounds correspond to different frequency bands, which are expected…
We study the inflationary implications of a novel parity-violating gravity model, which modifies the teleparallel equivalent of general relativity by introducing the Nieh-Yan term coupled to an axion-like field. The parity-violating Nieh-Yan term results in the velocity birefringence of gravitational waves (GWs) and triggers the tachyonic instability only for one of the two circular polarization states. We consider that the inflaton is identified as the coupled axion-like field with a wiggly potential characterized by steep cliffs connected by smooth plateaus. During inflation, the temporary f…
Gravitational wave (GW) detection in space is aimed at low frequency band (100 nHz - 100 mHz) and middle frequency band (100 mHz - 10 Hz). The science goals are the detection of GWs from (i) Supermassive Black Holes; (ii) Extreme-Mass-Ratio Black Hole Inspirals; (iii) Intermediate-Mass Black Holes; (iv) Galactic Compact Binaries and (v) Relic GW Background. In this paper, we present an overview on the sensitivity, orbit design, basic orbit configuration, angular resolution, orbit optimization, deployment, time-delay interferometry and payload concept of the current proposed GW detectors in spa…
We construct the catalogues of standard sirens (StS) based on the future gravitational wave (GW) detector networks, i.e., the second-generation ground-based advanced LIGO+advanced Virgo+KAGRA+LIGO-India (HLVKI), the third-generation ground-based Einstein Telescope+two Cosmic Explorer (ET+2CE), and the space-based LISA+Taiji. From the corresponding electromagnetic (EM) counterpart detectors for each networks, we sample the joint GW+EM detections from the probability to construct the Hubble diagram of standard sirens for 10 years detections of HLVKI, 5 years detections of ET+2CE, and 5 years of …
We use direct numerical simulations of decaying primordial hydromagnetic turbulence with helicity to compute the resulting gravitational wave (GW) production and its degree of circular polarization. We find a clear dependence of the polarization of the resulting GWs on the fractional helicity of the turbulent source and we show that driven magnetic fields produce GWs more efficiently than magnetic fields that are initially present, leading to larger spectral amplitudes. The helicity does not have a huge impact on the maximum spectral amplitude in any of the two types of turbulence considered. …
Distinguishing gravity theories with networks of space-based gravitational-wave detectors
International Centre for Theoretical Physics Asia-Pacific, University of Chinese Academy of Sciences（国际理论物理中心亚太分 centre，中国科学院大学）；Taiji Laboratory for Gravitational Wave Universe, University of Chinese Academy of Sciences（引力波宇宙太极实验室，中国科学院大学）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences（中国科学院大学杭州高等研究院基础物理与数学学院）
We investigate the potential stochastic gravitational waves from first-order electroweak phase transitions in a model with pseudo-Nambu-Goldstone dark matter and two Higgs doublets. The dark matter candidate can naturally evade direct detection bounds, and can achieve the observed relic abundance via the thermal mechanism. Three scalar fields in the model obtain vacuum expectation values, related to phase transitions at the early Universe. We search for the parameter points that can cause first-order phase transitions, taking into account the existed experimental constraints. The resulting gra…
In this paper, we propose a model in which a spectator field non-minimally couples to an inflaton field and the power spectrum of the perturbation of the spectator field at small scales is dramatically enhanced by the sharp feature in the form of non-minimal coupling. At or after the end of inflation, the perturbation of the spectator field is converted into curvature perturbation and leads to the formation of primordial black holes (PBHs). Furthermore, for example, we consider three phenomenological models for generating PBHs with mass function peaked at $\sim10^{-12}M_\odot$ and representing…
We investigate the enhancement of the curvature perturbations in a single-field slow-roll inflation with a spectator scalar field kinetically coupled to the inflaton. The coupling term with a periodic function of inflaton triggers the exponential growth of the spectator field perturbations, which indirectly amplifies the curvature perturbations to produce a sizable abundance of primordial black holes (PBHs). This scenario is found to be insensitive to the inflationary background. We study two distinct populations of the stochastic gravitational wave background (SGWB) produced in this scenario,…
We explore the Gravitational Waves (GW) phenomenology of a simple class of supergravity models that can explain and unify inflation and Primordial Black Holes (PBH) as Dark Matter (DM). Our (modified) supergravity models naturally lead to a two-field attractor-type double inflation, whose first stage is driven by Starobinsky scalaron and the second stage is driven by another scalar belonging to a supergravity multiplet. The PBHs formation in our supergravity models is efficient, compatible with all observational constraints, and predicts a stochastic GW background. We compute the PBH-induced G…
Measuring the Hubble constant with strongly lensed gravitational waves from space-based detector networks
Center for Gravitational Wave Experiment, National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences（中国科学院力学研究所微重力实验室引力波实验中心）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学天体物理与天文卡尔弗利研究所）；Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台暗物质与空间天文重点实验室）；School of Astronomy and Space Science, University of Science and Technology of China（中国科学技术大学天文与空间科学学院）；International Centre for Theoretical Physics Asia-Pacific, University of Chinese Academy of Sciences（中国科学院大学亚太理论物理中心）；Taiji Laboratory for Gravitational Wave Universe (Beijing/Hangzhou), University of Chinese Academy of Sciences（中国科学院大学太极引力波宇宙实验室（北京/杭州））
The nonattractor evolution in ultra-slow-roll (USR) inflation results in the amplification of superhorizon curvature perturbations and then induces a strong and detectable stochastic gravitational wave background. In this letter, we search for such a stochastic gravitational wave background in data from the third LIGO-Virgo observing run and place constraints on the USR inflationary models. The $e$-folding number of the USR phase are constrained to be $ΔN \lesssim 2.9$ at the 95% confidence level and the power spectrum of curvature perturbations amplified during the USR phase is constrained to…
In the minimal supersymmetric standard model (MSSM) extended by a singlet superfield, when the coupling between the singlet sector and the MSSM sector is tiny, the singlet sector can be a quasi dark sector with supersymmetry (SUSY). We investigate the cosmological phenomena in this scenario and obtain the following observations: (i) In the parameter space solving the small cosmological scale anomalies via self-interacting singlino dark matter (SIDM), a first-order phase transition (FOPT) can readily happen but requires rather light dark matter below MeV; (ii) The corresponding parameter space …
The exact properties of dark matter remain largely unknown despite the accumulating evidence. If dark matter is composed of weakly interacting massive particles, it would be accreted by the black hole in the galactic center and form a dense, cuspy spike. Dynamical friction from this spike may have observable effects in a binary system. We consider extreme-mass-ratio inspiral (EMRI) binaries comprising massive black holes harbored in dark matter spikes and stellar mass objects in elliptic orbits. We find that the gravitational-wave waveforms in the frequency domain can be substantially modified…
We investigate the gravitational wave production induced by the primordial magnetic fields in a parity-violating magnetogenesis model. It is shown that the gravitational waves detectable by LISA, DECIGO or BBO and the magnetic fields strong enough to explain the blazar observation can be simultaneously produced. The magnetic fields and the gravitational waves have the same chirality and their amplitudes are related, which may also be tested by future observations.
