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您选择的条件: Tao Yang
  • Parameter estimation of eccentric gravitational waves with a decihertz observatory and its cosmological implications

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Eccentricity of compact binaries can improve the parameter estimation of gravitational waves (GWs). In this paper, we first investigate the parameter estimation of eccentric GWs with decihertz observatory. We consider two scenarios for the configuration of DECIGO, i.e., the one cluster of DECIGO with its design sensitivity and B-DECIGO which also has one cluster but with inferior sensitivity as a comparison. We adopt the Fisher matrix to estimate the parameter errors. By mocking up the typical binaries in GWTC-3, we find a nonvanishing eccentricity can significantly improve the estimation for almost all waveform parameters. In particular, the localization of typical binary black holes (BBH) can achieve $\mathcal{O}(10-10^{3.5})$ factors of improvement when the initial eccentricity $e_0=0.4$ at 0.1 Hz. The precise localization of binary neutron stars (BNS) and neutron star--black hole binaries (NSBH), together with the large improvement of localization of BBH from eccentricity in the mid-band, inspire us to construct the catalogs of golden dark sirens whose host galaxies can be uniquely identified. We find that with only one cluster of DECIGO running 1 year in its design sensitivity, hundreds of golden dark BNS, NSBH, and tens of golden dark BBH can be observed. Eccentricity can greatly increase the population of golden dark BBH from $\sim 7~(e_0=0)$ to $\sim 65~(e_0=0.2)$. Such an increase of population of golden dark BBH events can improve the precision of Hubble constant measurement from 2.06\% to 0.68\%, matter density parameter from 64\% to 16\% in $\Lambda$CDM model. Through the phenomenological parameterization of GW propagation, the constraints of modified gravity can be improved from 6.2\% to 1.6\%. Our results show the remarkable significance of eccentricity for the detection and parameter estimation of GW events, allowing us to probe the Universe precisely.

  • Space-borne atom interferometric gravitational wave detections. Part I. The forecast of bright sirens on cosmology

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Atom interferometers (AIs) as gravitational-wave (GW) detectors have been proposed a decade ago. Both ground and space-based projects will be in construction and preparation in the near future. In this paper, for the first time, we investigate the potential of the space-borne AIs on detecting GW standard sirens and hence the applications on cosmology. We consider AEDGE as our fiducial AI GW detector and estimate the number of bright sirens that would be obtained within a 5-years data-taking period of GW and with the follow-up observation of electromagnetic (EM) counterparts. We then construct the mock catalogue of bright sirens and predict their ability on constraining cosmological parameters such as the Hubble constant, dynamics of dark energy, and modified gravity theory. Our preliminary results show around order $\mathcal{O} (30)$ bright sirens can be obtained from a 5-years operation time of AEDGE and the follow-up observation of EM counterparts. The bright sirens alone can measure $H_0$ with a precision of 2.1\%, which is sufficient to arbitrate the Hubble tension. Combining current most precise electromagnetic experiments, the inclusion of AEDGE bright sirens can improve the measurement of the equation of state of dark energy, though marginally. Moreover, by modifying GW propagation on cosmological scales, the deviations from general relativity (modified gravity theory effects) can be constrained at 5.7\% precision level.

  • Space-borne atom interferometric gravitational wave detections. Part II. Dark sirens and finding the one

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: In this paper, we investigate the potential of dark sirens by the space-borne atom interferometric gravitational-wave detectors to probe the Hubble constant. In the mid-frequency band, the sources live a long time. The motion of a detector around the Sun as well as in Earth orbit would induce large Doppler and reorientation effects, providing a precise angular resolution. Such precise localization for the GW sources makes it possible to observe the dark sirens with only one potential host galaxy, which are dubbed "golden dark sirens". We construct the catalogs of golden dark sirens and estimate that there are around 79 and 35 golden dark sirens of binary neutron stars (BNS) and binary black holes (BBH) that would be pass the detection threshold of AEDGE in 5 years. Our results show that with 5, 10, and all 79 golden dark BNS tracked by AEDGE one can constrain $H_0$ at 5.5\%, 4.1\%, and 1.8\% precision levels. With 5, 10, and all 35 golden dark BBH one can constrain $H_0$ at 2.2\%, 1.8\%, and 1.5\% precision levels, respectively. It suggests that only 5-10 golden dark BBH by AEDGE are sufficient to arbitrate the current tension between local and high-$z$ measurements of $H_0$.

  • Gravitational-Wave Detector Networks: Standard Sirens on Cosmology and Modified Gravity Theory

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: 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 detections of LISA+Taiji, which we estimate would be available and released in the 2030s. Thus we construct a combined Hubble diagram from these ground and spaced-based detector networks to explore the expansion history of our Universe from redshift 0 to 7. We give a conservative and realistic estimation of the catalogue and Hubble diagram of GW standard sirens and their potential on studying cosmology and modified gravity theory in the 2030s. We adopt two strategies for the forecasts. One is the traditional model-fitting Markov-Chain Monte-Carlo method (MCMC). The results show that the combined StS alone can constrain the Hubble constant at the precision level of $0.34\%$, 1.76 times more tightly than the current most precise measurement from \textit{Planck}+BAO+Pantheon. The joint StS with current EM experiments will improve the constraints of cosmological parameters significantly. The modified gravity theory can be constrained with $0.46\%$ error from the GW propagation. In the second strategy, we use the machine-learning nonparametric reconstruction techniques, i.e., the Gaussian process (GP) with the Artificial Neural Networks (ANN) as a comparison. GP reconstructions can give comparable results with MCMC. We anticipate more works and research on these topics.

  • The Gravitational-Wave Physics II: Progress

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: It has been a half-decade since the first direct detection of gravitational waves, which signifies the coming of the era of the gravitational-wave astronomy and gravitational-wave cosmology. The increasing number of the detected gravitational-wave events has revealed the promising capability of constraining various aspects of cosmology, astronomy, and gravity. Due to the limited space in this review article, we will briefly summarize the recent progress over the past five years, but with a special focus on some of our own work for the Key Project ``Physics associated with the gravitational waves'' supported by the National Natural Science Foundation of China. In particular, (1) we have presented the mechanism of the gravitational-wave production during some physical processes of the early Universe, such as inflation, preheating and phase transition, and the cosmological implications of gravitational-wave measurements; (2) we have put constraints on the neutron star maximum mass according to GW170817 observations; (3) we have developed a numerical relativity algorithm based on the finite element method and a waveform model for the binary black hole coalescence along an eccentric orbit.

  • Space-borne atom interferometric gravitational wave detections. Part III. Eccentricity on dark sirens

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Eccentricity of the inspiraling compact binaries can greatly improve the distance inference and source localization of dark sirens. In this paper, we continue the research for the space-borne atom interferometric gravitational-wave detector AEDGE and investigate the effects of eccentricity on the dark sirens observed by AEDGE in the mid-band. We simulate five types of typical compact binaries with component mass ranging from $1-100~M_{\odot}$. The largest improvement for both distance inference and localization can be as much as 1.5--3 orders of magnitude. We then construct the catalogs of dark sirens observed by AEDGE in five years. We find eccentricity is crucial to the detection of golden binary black holes (BBH) whose host galaxy can be uniquely identified. With only 5--10 golden dark BBHs one can obtain a 2 percent precision measurement of $H_0$ which is sufficient to arbitrate the Hubble tension. Regardless of eccentricity, AEDGE can also observe tens of golden binary neutron stars (BNS) and neutron star--black hole binaries (NSBH) with unique host galaxies. These golden dark sirens can serve as early warnings for the follow-up observations of gravitational waves in the high frequency band as well as the search of their electromagnetic counterparts. Our results show eccentricity is a crucial factor in the detection, data analysis, and application of GWs with the atom interferometers in the mid-band.

  • Eccentricity of Long Inspiraling Compact Binaries Sheds Light on Dark Sirens

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The localization and distance inference of gravitational waves are two crucial factors for dark sirens as precise probes of cosmology, astrophysics, and fundamental physics. In this Letter, for the first time we investigate the parameter estimation of gravitational waves emitted by the eccentric compact binaries in the mid-frequency (0.1--10 Hz) band. Based on the configuration of one cluster of DECIGO (B-DECIGO), we simulate five types of typical compact binaries in GWTC-3 with component mass ranging from $\mathcal{O}(1\sim100)~M_{\odot}$. For each type of binaries, we assign discrete eccentricities from 0 to 0.4 at 0.1 Hz in $10^3$ random orientations. The multiple harmonics induced by eccentricity can break the degeneracy between parameters. We find that with eccentricity $e_0=0.4$, these typical binaries can achieve $\mathcal{O}(10^2-10^4)$ improvement for the distance inference in the near face-on orientations, compared to the circular case. More importantly, a nonvanishing eccentricity ($0.01\sim0.4$) can significantly improve the source localization of the typical binary black holes, most by $1.5\sim{3.5}$ orders of magnitude. Our result shows the remarkable significance of eccentricity for dark sirens in the mid-band as precise probes of the Universe.

  • Development and Evaluation of a Narrow Linewidth Laser System for 171Yb+ E2 Transition

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: We report the construction and characterization of a narrow-linewidth laser system to interrogate the E2 clock transitions at 436 nm of ytterbium ions trapped in end-cap traps. The 871 nm seed laser at the fundamental frequency is referenced to a 10 cm long notched ULE cavity. The output of the laser system is delivered to a narrow-linewidth femtosecond fiber comb, which has been referenced to an ultrastable 698 nm laser, with a phase noise-canceled fiber link. The beat between the laser and the comb shows a sub-Hz linewidth, and with a stability better than 2E-15@1~100 s. The performance of the self-developed wavelength extension ports at 871 nm of the narrow linewidth erbium-doped fiber comb with single-point frequency-doubling technique is also verified.

  • The Gravitational-Wave Physics

    分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-09-27

    摘要: The direct detection of gravitational wave by Laser Interferometer Gravitational-Wave Observatory indicates the coming of the era of gravitational-wave astronomy and gravitational-wave cosmology. It is expected that more and more gravitational-wave events will be detected by currently existing and planned gravitational-wave detectors. The gravitational waves open a new window to explore the Universe and various mysteries will be disclosed through the gravitational-wave detection, combined with other cosmological probes. The gravitational-wave physics is not only related to gravitation theory, but also is closely tied to fundamental physics, cosmology and astrophysics. In this review article, three kinds of sources of gravitational waves and relevant physics will be discussed, namely gravitational waves produced during the inflation and preheating phases of the Universe,the gravitational waves produced during the first-order phase transition as the Universe cools down and the gravitational waves from the three phases: inspiral, merger and ringdown of a compact binary system, respectively. We will also discuss the gravitational waves as a standard siren to explore the evolution of the Universe.

  • Dodging the cosmic curvature toprobe the constancy of the speed oflight

    分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-09-27

    摘要: We develop a new model-independent method to probe the constancy of the speed of light c. In our method, the degeneracy between the cosmic curvature and the speed of light can be eliminated, which makes the test more natural and general. Combining the independent observations of Hubble parameter H(z) and luminosity distance dL(z), we use the model-independent smoothing technique, Gaussian processes, to reconstruct them and then detect variation of the speed of light. We find no signal of deviation from the present value of the speed of light c0. Moreover, to demonstrate the improvement in probing the constancy of the speed of light from future experiments, we produce a series of simulated data. The Dark Energy Survey will be able to detect #1;c/c0 #24; 1% at #24; 1.5σ confidencelevel and #1;c/c0 #24; 2% at #24; 3σ confidence level. If the errors are reduced to one-tenth of the expected DES ones, it can detect a #1;c/c0 #24; 0.1% variation at #24; 2σ confidence level.

  • Null test of the cosmic curvature using H(z) and supernovae data

    分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-09-27

    摘要: We introduce a model-independent approach to the null test of the cosmic curvature which is geometrically related to the Hubble parameter H(z) and luminosity distance dL(z). Combining the independent observations of H(z) and dL(z), we use the model-independent smoothing technique,Gaussian processes, to reconstruct them and determine the cosmic curvature (0)K in the null test relation. The null test is totally geometrical and does not assume any cosmological model. We show that the cosmic curvature (0)K = 0 is consistent with current observational data sets, falling within the 1#27; limit. To demonstrate the effect on the precision of the null test, we produce a series of simulated data of the models with different (0) K . Future observations in better quality can provide a greater improvement to constrain or refute the flat universe with (0)K = 0.