Dense matter in neutron stars with eXTP

Ang Li; Anna L. Watts; Guobao Zhang; Sebastien Guillot; Yanjun Xu; Andrea Santangelo; Silvia Zane; Hua Feng; Shuang Nan Zhang; Mingyu Ge; Liqiang Qi; Tuomo Salmi; Bas Dorsman; Zhiqiang Miao; Zhonghao Tu; Yuri Cavecchi; Xia Zhou; Xiaoping Zheng; Weihua Wang; Quan Cheng; Xuezhi Liu; Yining Wei; Wei Wang; Yujing Xu; Shanshan Weng; Weiwei Zhu; Zhaosheng Li; Lijing Shao; Youli Tuo; Akira Dohi; Ming Lyu; Peng Liu; Jianping Yuan; Mingyang Wang; Wenda Zhang; Zexi Li; Lian Tao; Liang Zhang; Hong Shen; Constança Providência; Laura Tolos; Alessandro Patruno; Li Li; Guozhu Liu; Kai Zhou; Lie Wen Chen; Yizhong Fan; Toshitaka Kajino; Dong Lai; Xiangdong Li; Jie Meng; Xiaodong Tang; Zhigang Xiao; Shaolin Xiong; Renxin Xu; Shan Gui Zhou; David R. Ballantyne; G. Fiorella Burgio; Jérôme Chenevez; Devarshi Choudhury; Anthea F. Fantina; Duncan K. Galloway; Francesca Gulminelli; Kai Hebeler; Mariska Hoogkamer; Jorge E. Horvath; Yves Kini; Aleksi Kurkela; Manuel Linares; Jérôme Margueron; Melissa Mendes; Micaela Oertel; Alessandro Papitto; Juri Poutanen; Nanda Rea; Achim Schwenk; Xin Ying Song; Isak Svensson; David Tsang; Aleksi Vuorinen; Nils Andersson; M. Coleman Miller; Luciano Rezzolla; Jirina R. Stone; Anthony W. Thomas

doi:10.1007/s11433-025-2761-4

Dense matter in neutron stars with eXTP

Ang Li, Anna L. Watts, Guobao Zhang, Sebastien Guillot, Yanjun Xu, Andrea Santangelo, Silvia Zane, Hua Feng, Shuang Nan Zhang, Mingyu Ge, Liqiang Qi, Tuomo Salmi, Bas Dorsman, Zhiqiang Miao, Zhonghao Tu, Yuri Cavecchi, Xia Zhou, Xiaoping Zheng, Weihua Wang, Quan ChengXuezhi Liu, Yining Wei, Wei Wang, Yujing Xu, Shanshan Weng, Weiwei Zhu, Zhaosheng Li, Lijing Shao, Youli Tuo, Akira Dohi, Ming Lyu, Peng Liu, Jianping Yuan, Mingyang Wang, Wenda Zhang, Zexi Li, Lian Tao, Liang Zhang, Hong Shen, Constança Providência, Laura Tolos, Alessandro Patruno, Li Li, Guozhu Liu, Kai Zhou, Lie Wen Chen, Yizhong Fan, Toshitaka Kajino, Dong Lai, Xiangdong Li, Jie Meng, Xiaodong Tang, Zhigang Xiao, Shaolin Xiong, Renxin Xu, Shan Gui Zhou, David R. Ballantyne, G. Fiorella Burgio, Jérôme Chenevez, Devarshi Choudhury, Anthea F. Fantina, Duncan K. Galloway, Francesca Gulminelli, Kai Hebeler, Mariska Hoogkamer, Jorge E. Horvath, Yves Kini, Aleksi Kurkela, Manuel Linares, Jérôme Margueron, Melissa Mendes, Micaela Oertel, Alessandro Papitto, Juri Poutanen, Nanda Rea, Achim Schwenk, Xin Ying Song, Isak Svensson, David Tsang, Aleksi Vuorinen, Nils Andersson, M. Coleman Miller, Luciano Rezzolla, Jirina R. Stone, Anthony W. Thomas

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Abstract

In this white paper, we present the potential of the enhanced X-ray timing and polarimetry (eXTP) mission to constrain the equation of state of dense matter in neutron stars, exploring regimes not directly accessible to terrestrial experiments. By observing a diverse population of neutron stars—including isolated objects, X-ray bursters, and accreting systems—eXTP’s unique combination of timing, spectroscopy, and polarimetry enables high-precision measurements of compactness, spin, surface temperature, polarimetric signals, and timing irregularity. These multifaceted observations, combined with advances in theoretical modeling, pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is planned to be launched in early 2030.

Original language	English
Article number	119503
Journal	Science China Physics, Mechanics & Astronomy
Volume	68
Issue number	11
Early online date	18 Sept 2025
DOIs	https://doi.org/10.1007/s11433-025-2761-4
Publication status	Published - 30 Nov 2025

Funding

This work was supported by China’s Space Origins Exploration Program. Ang Li was supported by the National Natural Science Foundation of China (Grant No. 12273028). Anna L. Watts, Bas Dorsman, and Tuomo Salmi acknowledged support from ERC Consolidator (Grant No. 865768) AEONS. Anna L. Watts also acknowledged support from NWO grant ENW-XL OCENW.XL21.XL21.038. Sebastien Guillot acknowledged the support of the CNES. Shuang-Nan Zhang was supported by the National Natural Science Foundation of China (Grant No. 12333007), the International Partnership Program of Chinese Academy of Sciences (Grant No. 113111KYSB20190020), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA15020100). Zhiqiang Miao was supported by the China National Postdoctoral Program for Innovation Talents (Grant No. BX20240223), and the China Postdoctoral Science Foundation Funded Project (Grant No. 2024M761948). Yuri Cavecchi acknowledged support from a Ramon y Cajal fellowship (Grant No. RYC2021-032718-1) financed by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. Xia Zhou was supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region (Grant No. 2023D01E20), and the National SKA Program of China (Grant No. 2020SKA0120300). Xiaoping Zheng and Xuezhi Liu were supported by the National Natural Science Foundation of China (Grant Nos. 12033001, and 12473039), and Weihua Wang was supported by Zhejiang Provincial Natural Science Foundation of China (Grant No. LQ24A030002). Quan Cheng was supported by the National Natural Science Foundation of China (Grant No. 12003009). Weiwei Zhu was supported by the National SKA Program of China (Grant No. 2020SKA0120200), and the National Natural Science Foundation of China (Grant No. 12041303). Zhaosheng Li was supported by the National Natural Science Foundation of China (Grant No. 1227303). Lijing Shao was supported by the National SKA Program of China (Grant No. 2020SKA0120300), the Beijing Natural Science Foundation (Grant No. 1242018), and the Max Planck Partner Group Program funded by the Max Planck Society. Akira Dohi was supported by JSPS KAKENHI (the Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research) (Grant Nos. 23K19056, and 25K17403). Hong Shen was supported by the National Natural Science Foundation of China (Grant No. 12175109). Constançã Providência acknowledged support from FCT (Fundação para a Ciência e a Tecnologia, I.P., Portugal) (Grant Nos. UIDB/04564/2020, and 2022.06460.PTDC). Laura Tolos was supported from the program Unidad de Excelencia María de Maeztu CEX2020-001058-M, from the project PID2022-139427NB-I00 financed by the Spanish MCIN/AEI/10.13039/501100011033/FEDER, UE (FSE+), and by the CRC-TR 211 “Strong-interaction matter under extreme conditions”–project Nr. 315477589–TRR 211. Alessandro Patruno acknowledged support from grant PID2021-124581OB-I0, PID2024-155316NB-I00, and 2021SGR00426. Li Li was supported by the National Natural Science Foundation of China (Grant No. 12122513). The work of Kai Hebeler, Melissa Mendes, Achim Schwenk, and Isak Svensson was supported in part by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant No. 101020842), and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)–Project-ID 279384907–SFB 1245. Manuel Linares acknowledged support from the ERC Consolidator ( Grant No. 101002352) (LOVENEST). Nanda Rea was supported by the European Research Council (ERC) via the Consolidator Grant “MAGNESIA” (Grant No. 817661) and the Proof of Concept “DeepSpacePulse” (Grant No. 101189496), the Catalan grant SGR2021-01269, the Spanish grant ID2023-153099NA-I00, and the program Unidad de Excelencia Maria de Maeztu CEX2020-001058-M. Aleksi Vuorinen was supported by the Research Council of Finland (Grant No. 354533).

Funders	Funder number
PRTR
Max-Planck-Gesellschaft
European Commission
European Research Council
Unidad de Excelencia Maria de Maeztu CEX2020-001058-M
National SKA Program of China	12033001, 2020SKA0120300, 12473039
Centre National d’Etudes Spatiales	12333007
Natural Science Foundation of Xinjiang Uygur Autonomous Region	2023D01E20
Fundação para a Ciência e a Tecnologia	12122513, PID2024-155316NB-I00, 2022.06460, 315477589, PID2021-124581OB-I0, UIDB/04564/2020, 2021SGR00426, PID2022-139427NB-I00
Japan Society for the Promotion of Science	12175109, 25K17403, 23K19056
Chinese Academy of Sciences	113111KYSB20190020, XDA15020100
Natural Science Foundation of Zhejiang Province	LQ24A030002, 12003009, 12041303, 2020SKA0120200, 1227303
Horizon 2020 Framework Programme	101020842
Deutsche Forschungsgemeinschaft	101189496, 101002352, 817661, 279384907–SFB 1245, ID2023-153099NA-I00, SGR2021-01269
Natural Science Foundation of Beijing Municipality	1242018
China Postdoctoral Science Foundation	MCIN/AEI/10.13039/501100011033, RYC2021-032718-1, 2024M761948
China National Postdoctoral Program for Innovation Talents	BX20240223
Research Council of Finland	354533
NWO	ENW-XL OCENW.XL21.XL21.038
National Natural Science Foundation of China	865768, 12273028

Keywords

dense matter
equation of state
neutron stars
X-rays

ASJC Scopus subject areas

General Physics and Astronomy

Access to Document

10.1007/s11433-025-2761-4

2506.08104v1

https://arxiv.org/abs/2506.08104

Cite this

Li, A., Watts, A. L., Zhang, G., Guillot, S., Xu, Y., Santangelo, A., Zane, S., Feng, H., Zhang, S. N., Ge, M., Qi, L., Salmi, T., Dorsman, B., Miao, Z., Tu, Z., Cavecchi, Y., Zhou, X., Zheng, X., Wang, W., ... Thomas, A. W. (2025). Dense matter in neutron stars with eXTP. Science China Physics, Mechanics & Astronomy, 68(11), Article 119503. https://doi.org/10.1007/s11433-025-2761-4

Li, A, Watts, AL, Zhang, G, Guillot, S, Xu, Y, Santangelo, A, Zane, S, Feng, H, Zhang, SN, Ge, M, Qi, L, Salmi, T, Dorsman, B, Miao, Z, Tu, Z, Cavecchi, Y, Zhou, X, Zheng, X, Wang, W, Cheng, Q, Liu, X, Wei, Y, Wang, W, Xu, Y, Weng, S, Zhu, W, Li, Z, Shao, L, Tuo, Y, Dohi, A, Lyu, M, Liu, P, Yuan, J, Wang, M, Zhang, W, Li, Z, Tao, L, Zhang, L, Shen, H, Providência, C, Tolos, L, Patruno, A, Li, L, Liu, G, Zhou, K, Chen, LW, Fan, Y, Kajino, T, Lai, D, Li, X, Meng, J, Tang, X, Xiao, Z, Xiong, S, Xu, R, Zhou, SG, Ballantyne, DR, Burgio, GF, Chenevez, J, Choudhury, D, Fantina, AF, Galloway, DK, Gulminelli, F, Hebeler, K, Hoogkamer, M, Horvath, JE, Kini, Y, Kurkela, A, Linares, M, Margueron, J, Mendes, M, Oertel, M, Papitto, A, Poutanen, J, Rea, N, Schwenk, A, Song, XY, Svensson, I, Tsang, D, Vuorinen, A, Andersson, N, Miller, MC, Rezzolla, L, Stone, JR & Thomas, AW 2025, 'Dense matter in neutron stars with eXTP', Science China Physics, Mechanics & Astronomy, vol. 68, no. 11, 119503. https://doi.org/10.1007/s11433-025-2761-4

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title = "Dense matter in neutron stars with eXTP",

abstract = "In this white paper, we present the potential of the enhanced X-ray timing and polarimetry (eXTP) mission to constrain the equation of state of dense matter in neutron stars, exploring regimes not directly accessible to terrestrial experiments. By observing a diverse population of neutron stars—including isolated objects, X-ray bursters, and accreting systems—eXTP{\textquoteright}s unique combination of timing, spectroscopy, and polarimetry enables high-precision measurements of compactness, spin, surface temperature, polarimetric signals, and timing irregularity. These multifaceted observations, combined with advances in theoretical modeling, pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is planned to be launched in early 2030.",

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author = "Ang Li and Watts, \{Anna L.\} and Guobao Zhang and Sebastien Guillot and Yanjun Xu and Andrea Santangelo and Silvia Zane and Hua Feng and Zhang, \{Shuang Nan\} and Mingyu Ge and Liqiang Qi and Tuomo Salmi and Bas Dorsman and Zhiqiang Miao and Zhonghao Tu and Yuri Cavecchi and Xia Zhou and Xiaoping Zheng and Weihua Wang and Quan Cheng and Xuezhi Liu and Yining Wei and Wei Wang and Yujing Xu and Shanshan Weng and Weiwei Zhu and Zhaosheng Li and Lijing Shao and Youli Tuo and Akira Dohi and Ming Lyu and Peng Liu and Jianping Yuan and Mingyang Wang and Wenda Zhang and Zexi Li and Lian Tao and Liang Zhang and Hong Shen and Constan{\c c}a Provid{\^e}ncia and Laura Tolos and Alessandro Patruno and Li Li and Guozhu Liu and Kai Zhou and Chen, \{Lie Wen\} and Yizhong Fan and Toshitaka Kajino and Dong Lai and Xiangdong Li and Jie Meng and Xiaodong Tang and Zhigang Xiao and Shaolin Xiong and Renxin Xu and Zhou, \{Shan Gui\} and Ballantyne, \{David R.\} and Burgio, \{G. Fiorella\} and J{\'e}r{\^o}me Chenevez and Devarshi Choudhury and Fantina, \{Anthea F.\} and Galloway, \{Duncan K.\} and Francesca Gulminelli and Kai Hebeler and Mariska Hoogkamer and Horvath, \{Jorge E.\} and Yves Kini and Aleksi Kurkela and Manuel Linares and J{\'e}r{\^o}me Margueron and Melissa Mendes and Micaela Oertel and Alessandro Papitto and Juri Poutanen and Nanda Rea and Achim Schwenk and Song, \{Xin Ying\} and Isak Svensson and David Tsang and Aleksi Vuorinen and Nils Andersson and Miller, \{M. Coleman\} and Luciano Rezzolla and Stone, \{Jirina R.\} and Thomas, \{Anthony W.\}",

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AU - Watts, Anna L.

AU - Zhang, Guobao

AU - Guillot, Sebastien

AU - Xu, Yanjun

AU - Santangelo, Andrea

AU - Zane, Silvia

AU - Feng, Hua

AU - Zhang, Shuang Nan

AU - Ge, Mingyu

AU - Qi, Liqiang

AU - Salmi, Tuomo

AU - Dorsman, Bas

AU - Miao, Zhiqiang

AU - Tu, Zhonghao

AU - Cavecchi, Yuri

AU - Zhou, Xia

AU - Zheng, Xiaoping

AU - Wang, Weihua

AU - Cheng, Quan

AU - Liu, Xuezhi

AU - Wei, Yining

AU - Wang, Wei

AU - Xu, Yujing

AU - Weng, Shanshan

AU - Zhu, Weiwei

AU - Li, Zhaosheng

AU - Shao, Lijing

AU - Tuo, Youli

AU - Dohi, Akira

AU - Lyu, Ming

AU - Liu, Peng

AU - Yuan, Jianping

AU - Wang, Mingyang

AU - Zhang, Wenda

AU - Li, Zexi

AU - Tao, Lian

AU - Zhang, Liang

AU - Shen, Hong

AU - Providência, Constança

AU - Tolos, Laura

AU - Patruno, Alessandro

AU - Li, Li

AU - Liu, Guozhu

AU - Zhou, Kai

AU - Chen, Lie Wen

AU - Fan, Yizhong

AU - Kajino, Toshitaka

AU - Lai, Dong

AU - Li, Xiangdong

AU - Meng, Jie

AU - Tang, Xiaodong

AU - Xiao, Zhigang

AU - Xiong, Shaolin

AU - Xu, Renxin

AU - Zhou, Shan Gui

AU - Ballantyne, David R.

AU - Burgio, G. Fiorella

AU - Chenevez, Jérôme

AU - Choudhury, Devarshi

AU - Fantina, Anthea F.

AU - Galloway, Duncan K.

AU - Gulminelli, Francesca

AU - Hebeler, Kai

AU - Hoogkamer, Mariska

AU - Horvath, Jorge E.

AU - Kini, Yves

AU - Kurkela, Aleksi

AU - Linares, Manuel

AU - Margueron, Jérôme

AU - Mendes, Melissa

AU - Oertel, Micaela

AU - Papitto, Alessandro

AU - Poutanen, Juri

AU - Rea, Nanda

AU - Schwenk, Achim

AU - Song, Xin Ying

AU - Svensson, Isak

AU - Tsang, David

AU - Vuorinen, Aleksi

AU - Andersson, Nils

AU - Miller, M. Coleman

AU - Rezzolla, Luciano

AU - Stone, Jirina R.

AU - Thomas, Anthony W.

PY - 2025/11/30

Y1 - 2025/11/30

N2 - In this white paper, we present the potential of the enhanced X-ray timing and polarimetry (eXTP) mission to constrain the equation of state of dense matter in neutron stars, exploring regimes not directly accessible to terrestrial experiments. By observing a diverse population of neutron stars—including isolated objects, X-ray bursters, and accreting systems—eXTP’s unique combination of timing, spectroscopy, and polarimetry enables high-precision measurements of compactness, spin, surface temperature, polarimetric signals, and timing irregularity. These multifaceted observations, combined with advances in theoretical modeling, pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is planned to be launched in early 2030.

AB - In this white paper, we present the potential of the enhanced X-ray timing and polarimetry (eXTP) mission to constrain the equation of state of dense matter in neutron stars, exploring regimes not directly accessible to terrestrial experiments. By observing a diverse population of neutron stars—including isolated objects, X-ray bursters, and accreting systems—eXTP’s unique combination of timing, spectroscopy, and polarimetry enables high-precision measurements of compactness, spin, surface temperature, polarimetric signals, and timing irregularity. These multifaceted observations, combined with advances in theoretical modeling, pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is planned to be launched in early 2030.

KW - dense matter

KW - equation of state

KW - neutron stars

KW - X-rays

UR - https://www.scopus.com/pages/publications/105018093148

U2 - 10.1007/s11433-025-2761-4

DO - 10.1007/s11433-025-2761-4

M3 - Review article

AN - SCOPUS:105018093148

SN - 1674-7348

VL - 68

JO - Science China Physics, Mechanics & Astronomy

JF - Science China Physics, Mechanics & Astronomy

IS - 11

M1 - 119503

ER -

Dense matter in neutron stars with eXTP

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