1. Taiji Laboratory for Gravitational Wave Universe, University of Chinese Academy of Sciences (UCAS), Beijing 100049, China 2. Peng Cheng Laboratory, Shenzhen 518055, China 3. Department of Astronomy, Beijing Normal University, Beijing 100875, China 4. School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China 5. CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China 6. School of Physical Sciences, UCAS, Beijing 100049, China 7. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China 8. School of Astronomy and Space Science, UCAS, Beijing 100049, China 9. International Centre for Theoretical Physics Asia-Pacific (ICTP-AP, UNESCO), UCAS, Beijing 100190, China 10. Shanghai Frontiers Science Center for Gravitational Wave Detection, Shanghai 200240, China 11. Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Beijing 100101, China
The direct observation of gravitational waves (GWs) opens a new window for exploring new physics from quanta to cosmos and provides a new tool for probing the evolution of universe. GWs detection in space covers a broad spectrum ranging over more than four orders of magnitude and enables us to study rich physical and astronomical phenomena. Taiji is a proposed space-based gravitational wave (GW) detection mission that will be launched in the 2030s. Taiji will be exposed to numerous overlapping and persistent GW signals buried in the foreground and background, posing various data analysis challenges. In order to empower potential scientific discoveries, the Mock Laser Interferometer Space Antenna (LISA) data challenge and the LISA data challenge (LDC) were developed. While LDC provides a baseline framework, the first LDC needs to be updated with more realistic simulations and adjusted detector responses for Taiji’s constellation. In this paper, we review the scientific objectives and the roadmap for Taiji, as well as the technical difficulties in data analysis and the data generation strategy, and present the associated data challenges. In contrast to LDC, we utilize second-order Keplerian orbit and second-generation time delay interferometry techniques. Additionally, we employ a new model for the extreme-mass-ratio inspiral waveform and stochastic GW background spectrum, which enables us to test general relativity and measure the non-Gaussianity of curvature perturbations. Furthermore, we present a comprehensive showcase of parameter estimation using a toy dataset. This showcase not only demonstrates the scientific potential of the Taiji data challenge (TDC) but also serves to validate the effectiveness of the pipeline. As the first data challenge for Taiji, we aim to build an open ground for data analysis related to Taiji sources and sciences. More details can be found on the official website (taiji-tdc.ictp-ap.org).
Dynamical evolution and population of MBHBs, study the birth and growth of MBHs, and the astrophysical environment of the host galaxy
2
Precisely estimate parameters of MBH, reveals the physical nature of BHs, probe dynamics of galactic nuclei, and the astrophysical environment at the galaxy center by EMRI
3
Formation evolution and population of Galaxy binaries
4
Study SOBHB formation, environment, population, and joint observation with LIGO
5
Test GR, study the properties of GW propagation
6
GW cosmology, i.e., measurement of the Hubble constant and cosmology constant
7
PSD shape and upper limit of SGWB signals
8
Detect unmodeled signals
9
New physics and cosmology beyond GR
Tab.1
No.
Technical challenges
1
Foreground GB signals separation
2
SOBBH signals separation
3
Others signal with non-Gaussian GB noise
4
Overlapping MBHB signals
5
Instrumental glitches
6
Data gap due to maintenance, telescope re-alignment, and communication issue
7
TDI technique to suppress laser frequency noise
Tab.2
Fig.1
Fig.2
No.
(Gpc)
1
0.3
0.1
0.2
53.39
1
2
0.8
0.14
0.12
16.02
0.05
3
0.4
0.18
0.08
21.36
0.1
4
0.7
0.14
0.8
53.39
0.15
5
0.5
0.2
0.4
53.39
0.5
6
0.6
0.1
0.6
106.78
0.35
7
0.1
0.22
0.48
16.02
0.45
8
0.05
0.16
0.28
26.69
1
9
0.5
0.02
0.08
32.03
0.4
10
1
0.06
0.08
10.68
0.5
Tab.3
Name
Scientific objective
Technical challenge
Signals
Waveform model
TDC-1
1, 5, 6
7
1 MBHB signal
SEOBNRv4_opt
TDC-2-1
2, 5, 6
7
1 EMRI signal
PN5AAK
TDC-2-2
2, 5, 6
7
1 EMRI signal
XSPEG
TDC-3
3, 5, 6
7
43 VGB signals
Sinusoidal
TDC-4
3, 5, 6
1, 7
GB signals
Sinusoidal
TDC-5
4, 5, 6
2, 7
SOBBH signals
IMRPhenomD
TDC-6-1
5, 6, 7
7
SGWB
Power-law
TDC-6-2
5, 6, 7
7
SGWB
Non-Gaussian curvature perturbations
TDC-7
1, 3, 5, 6
1, 3, 7
10 MBHBs, 43 VGBs,
SEOBNRv4_opt, Sinusoidal
Tab.4
Fig.3
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