Timing and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst

SRGA J144459.2−604207 is a newly confirmed accreting millisecond X-ray pulsar and type I X-ray burster. We present the broadband X-ray timing and spectral behaviors of SRGA J144459.2−604207 during its 2024 outburst. The data were collected from NICER, Einstein Probe, Imaging X-ray Polarimetry Explor...

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Main Authors: Zhaosheng Li, Lucien Kuiper, Yuanyue Pan, Renxin Xu, Yong Chen, Mingyu Ge, Yue Huang, Shumei Jia, Xiaobo Li, Liming Song, Jinlu Qu, Shu Zhang, Lian Tao, Hua Feng, Shuang-Nan Zhang, Maurizio Falanga
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adf0ff
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author Zhaosheng Li
Lucien Kuiper
Yuanyue Pan
Renxin Xu
Yong Chen
Mingyu Ge
Yue Huang
Shumei Jia
Xiaobo Li
Liming Song
Jinlu Qu
Shu Zhang
Lian Tao
Hua Feng
Shuang-Nan Zhang
Maurizio Falanga
author_facet Zhaosheng Li
Lucien Kuiper
Yuanyue Pan
Renxin Xu
Yong Chen
Mingyu Ge
Yue Huang
Shumei Jia
Xiaobo Li
Liming Song
Jinlu Qu
Shu Zhang
Lian Tao
Hua Feng
Shuang-Nan Zhang
Maurizio Falanga
author_sort Zhaosheng Li
collection DOAJ
description SRGA J144459.2−604207 is a newly confirmed accreting millisecond X-ray pulsar and type I X-ray burster. We present the broadband X-ray timing and spectral behaviors of SRGA J144459.2−604207 during its 2024 outburst. The data were collected from NICER, Einstein Probe, Imaging X-ray Polarimetry Explorer (IXPE), Insight Hard X-ray Modulation Telescope (Insight-HXMT), NuSTAR, and INTEGRAL observations. X-ray pulsations have been detected for the 1.5–90 keV energy range throughout the “ON” phase of the outburst from MJD ∼ 60355–60385. We refined the orbital and spin ephemerides assuming a circular orbit, and found that the pulsar was in a spin-up state during MJD ∼ 60361–60377 showing a significant spin-up rate $\dot{\nu }$ of (3.15 ± 0.36) × 10 ^−13 Hz s ^−1 . Around MJD ∼ 60377 a swing was detected in the spin evolution accompanied by significantly enhanced pulsed emission. We studied the pulse-profile morphology during the X-ray bursts as observed by Insight-HXMT, IXPE, and NuSTAR. During the bursts, pulsations were detected across the 2–60 keV with shapes broadly consistent with those observed for the persistent emission. We found, however, that the “burst” pulse profiles exhibit significant phase offsets relative to the pre- and postburst profiles. These offsets systematically decrease with increasing energy, Δ ϕ ≈ 0.15, 0.11, and 0.02 for IXPE, Insight-HXMT ME, and HE in 2–8, 5–30, and 20–60 keV, respectively, and Δ ϕ ≈ 0.21, 0.10, and 0.07 for NuSTAR in 3–10, 20–35, and 35–60 keV, respectively, compared to the pre- and postburst profiles. We performed a joint spectral analysis of quasi-simultaneous NICER, NuSTAR, and Insight-HXMT data for two epochs. The resulting spectra from both observations were consistent and well described by an absorbed thermal Comptonization model, nthcomp , plus relativistic reflection, relxillCp .
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spelling doaj-art-b43a67d2cac945e3bc5c587e14cc05d72025-08-22T06:19:28ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0199011510.3847/1538-4357/adf0ffTiming and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 OutburstZhaosheng Li0https://orcid.org/0000-0003-2310-8105Lucien Kuiper1https://orcid.org/0000-0002-7889-6586Yuanyue Pan2Renxin Xu3https://orcid.org/0000-0002-9042-3044Yong Chen4https://orcid.org/0000-0001-9834-2196Mingyu Ge5https://orcid.org/0000-0002-2749-6638Yue Huang6Shumei Jia7https://orcid.org/0000-0002-5203-8321Xiaobo Li8Liming Song9https://orcid.org/0000-0003-0274-3396Jinlu Qu10https://orcid.org/0000-0002-9796-2585Shu Zhang11Lian Tao12https://orcid.org/0000-0002-2705-4338Hua Feng13https://orcid.org/0000-0001-7584-6236Shuang-Nan Zhang14https://orcid.org/0000-0001-5586-1017Maurizio Falanga15https://orcid.org/0000-0003-3095-6065Key Laboratory of Stars and Interstellar Medium, Xiangtan University , Xiangtan 411105, Hunan, People’s Republic of China ; lizhaosheng@xtu.edu.cnSRON—Space Research Organisation Netherlands , Niels Bohrweg 4, 2333 CA, Leiden, The NetherlandsKey Laboratory of Stars and Interstellar Medium, Xiangtan University , Xiangtan 411105, Hunan, People’s Republic of China ; lizhaosheng@xtu.edu.cnDepartment of Astronomy, School of Physics, Peking University , Beijing 100871, People’s Republic of China; Kavli Institute for Astronomy and Astrophysics, Peking University , Beijing 100871, People’s Republic of ChinaKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnKey Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences , 19B Yuquan Road, Beijing 100049, People’s Republic of China ; ychen@ihep.ac.cnInternational Space Science Institute (ISSI) , Hallerstrasse 6, 3012 Bern, Switzerland; Physikalisches Institut, University of Bern , Sidlerstrasse 5, 3012 Bern, SwitzerlandSRGA J144459.2−604207 is a newly confirmed accreting millisecond X-ray pulsar and type I X-ray burster. We present the broadband X-ray timing and spectral behaviors of SRGA J144459.2−604207 during its 2024 outburst. The data were collected from NICER, Einstein Probe, Imaging X-ray Polarimetry Explorer (IXPE), Insight Hard X-ray Modulation Telescope (Insight-HXMT), NuSTAR, and INTEGRAL observations. X-ray pulsations have been detected for the 1.5–90 keV energy range throughout the “ON” phase of the outburst from MJD ∼ 60355–60385. We refined the orbital and spin ephemerides assuming a circular orbit, and found that the pulsar was in a spin-up state during MJD ∼ 60361–60377 showing a significant spin-up rate $\dot{\nu }$ of (3.15 ± 0.36) × 10 ^−13 Hz s ^−1 . Around MJD ∼ 60377 a swing was detected in the spin evolution accompanied by significantly enhanced pulsed emission. We studied the pulse-profile morphology during the X-ray bursts as observed by Insight-HXMT, IXPE, and NuSTAR. During the bursts, pulsations were detected across the 2–60 keV with shapes broadly consistent with those observed for the persistent emission. We found, however, that the “burst” pulse profiles exhibit significant phase offsets relative to the pre- and postburst profiles. These offsets systematically decrease with increasing energy, Δ ϕ ≈ 0.15, 0.11, and 0.02 for IXPE, Insight-HXMT ME, and HE in 2–8, 5–30, and 20–60 keV, respectively, and Δ ϕ ≈ 0.21, 0.10, and 0.07 for NuSTAR in 3–10, 20–35, and 35–60 keV, respectively, compared to the pre- and postburst profiles. We performed a joint spectral analysis of quasi-simultaneous NICER, NuSTAR, and Insight-HXMT data for two epochs. The resulting spectra from both observations were consistent and well described by an absorbed thermal Comptonization model, nthcomp , plus relativistic reflection, relxillCp .https://doi.org/10.3847/1538-4357/adf0ffNeutron starsPulsarsLow-mass x-ray binary starsMillisecond pulsars
spellingShingle Zhaosheng Li
Lucien Kuiper
Yuanyue Pan
Renxin Xu
Yong Chen
Mingyu Ge
Yue Huang
Shumei Jia
Xiaobo Li
Liming Song
Jinlu Qu
Shu Zhang
Lian Tao
Hua Feng
Shuang-Nan Zhang
Maurizio Falanga
Timing and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst
The Astrophysical Journal
Neutron stars
Pulsars
Low-mass x-ray binary stars
Millisecond pulsars
title Timing and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst
title_full Timing and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst
title_fullStr Timing and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst
title_full_unstemmed Timing and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst
title_short Timing and Spectral Studies of SRGA J144459.2−604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT, and INTEGRAL During its 2024 Outburst
title_sort timing and spectral studies of srga j144459 2 604207 with nicer einstein probe ixpe nustar insight hxmt and integral during its 2024 outburst
topic Neutron stars
Pulsars
Low-mass x-ray binary stars
Millisecond pulsars
url https://doi.org/10.3847/1538-4357/adf0ff
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