Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei
We present our X-ray and optical observations performed by NICER, NuSTAR, and Tomo-e Gozen during the 2023 outburst in the intermediate polar GK Persei. The X-ray spectrum consisted of three components: blackbody (BB) emission of several tens of eVs from the irradiated white dwarf (WD) surface, a so...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/adcf27 |
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| author | Mariko Kimura Takayuki Hayashi Yuuki Wada Wataru Iwakiri Shigeyuki Sako Martina Veresvarska Simone Scaringi Noel Castro-Segura Christian Knigge Keith C. Gendreau Zaven Arzoumanian |
| author_facet | Mariko Kimura Takayuki Hayashi Yuuki Wada Wataru Iwakiri Shigeyuki Sako Martina Veresvarska Simone Scaringi Noel Castro-Segura Christian Knigge Keith C. Gendreau Zaven Arzoumanian |
| author_sort | Mariko Kimura |
| collection | DOAJ |
| description | We present our X-ray and optical observations performed by NICER, NuSTAR, and Tomo-e Gozen during the 2023 outburst in the intermediate polar GK Persei. The X-ray spectrum consisted of three components: blackbody (BB) emission of several tens of eVs from the irradiated white dwarf (WD) surface, a source possibly including several emission lines around 1 keV, and multitemperature bremsstrahlung emission from the accretion column. The 351.3 s WD spin pulse was detected in X-rays, and the observable X-ray flux from the column drastically decreased at the off-pulse phase, which suggests that the absorption of the column by the accreting gas, called the curtain, was the major cause of the pulse. As the system became brighter in the optical, the column became fainter, the pulse amplitude became higher, and the energy dependence of pulses became weaker at <8 keV. These phenomena could be explained by the column’s more pronounced absorption by the denser curtain as mass-accretion rates increased. The BB and line fluxes rapidly decreased at the optical decline, which suggests the expansion of the innermost disk edge with decreasing accretion rates. The electron scattering or the column geometry may be associated with the almost no energy dependence of high-energy pulses. The irradiated vertically thick structure at the disk may generate optical quasi-periodic oscillations with a period of ∼5700 s. |
| format | Article |
| id | doaj-art-a38d22b6621c4da4bbdd4c92777bf8f4 |
| institution | DOAJ |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-a38d22b6621c4da4bbdd4c92777bf8f42025-08-20T03:12:39ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01985224010.3847/1538-4357/adcf27Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK PerseiMariko Kimura0https://orcid.org/0009-0002-1729-8416Takayuki Hayashi1https://orcid.org/0000-0001-6665-2499Yuuki Wada2Wataru Iwakiri3https://orcid.org/0000-0002-0207-9010Shigeyuki Sako4Martina Veresvarska5https://orcid.org/0000-0002-0146-3096Simone Scaringi6https://orcid.org/0000-0001-5387-7189Noel Castro-Segura7https://orcid.org/0000-0002-5870-0443Christian Knigge8https://orcid.org/0000-0002-1116-2553Keith C. Gendreau9https://orcid.org/0000-0001-7115-2819Zaven Arzoumanian10https://orcid.org/0009-0008-6187-8753Advanced Research Center for Space Science and Technology, College of Science and Engineering, Kanazawa University , Kakuma, Kanazawa, Ishikawa 920-1192, Japan; Cluster for Pioneering Research, Institute of Physical and Chemical Research (RIKEN) , 2-1 Hirosawa, Wako, Saitama 351-0198, JapanCenter for Research and Exploration in Space Science and Technology (CRESST II) , Greenbelt, MD 20771, USA; Department of Physics, University of Maryland , Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA; X-ray Astrophysics Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USAGraduate School of Engineering, Osaka University , 2-1 Yamadaoka, Suita, Osaka, 565-0871, JapanInternational Center for Hadron Astrophysics, Chiba University , Chiba 263-8522, JapanInstitute of Astronomy, Graduate School of Science, The University of Tokyo , 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan; The Collaborative Research Organization for Space Science and Technology, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, JapanCentre for Extragalactic Astronomy, Department of Physics, Durham University , South Road, Durham, DH1 3LE, UKCentre for Extragalactic Astronomy, Department of Physics, Durham University , South Road, Durham, DH1 3LE, UKDepartment of Physics, University of Warwick , Gibbet Hill Road, Coventry, CV 4 7AL, UK; Department of Physics and Astronomy. University of Southampton , Southampton, SO17 1BJ, UKDepartment of Physics and Astronomy. University of Southampton , Southampton, SO17 1BJ, UKAstrophysics Science Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USAAstrophysics Science Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USAWe present our X-ray and optical observations performed by NICER, NuSTAR, and Tomo-e Gozen during the 2023 outburst in the intermediate polar GK Persei. The X-ray spectrum consisted of three components: blackbody (BB) emission of several tens of eVs from the irradiated white dwarf (WD) surface, a source possibly including several emission lines around 1 keV, and multitemperature bremsstrahlung emission from the accretion column. The 351.3 s WD spin pulse was detected in X-rays, and the observable X-ray flux from the column drastically decreased at the off-pulse phase, which suggests that the absorption of the column by the accreting gas, called the curtain, was the major cause of the pulse. As the system became brighter in the optical, the column became fainter, the pulse amplitude became higher, and the energy dependence of pulses became weaker at <8 keV. These phenomena could be explained by the column’s more pronounced absorption by the denser curtain as mass-accretion rates increased. The BB and line fluxes rapidly decreased at the optical decline, which suggests the expansion of the innermost disk edge with decreasing accretion rates. The electron scattering or the column geometry may be associated with the almost no energy dependence of high-energy pulses. The irradiated vertically thick structure at the disk may generate optical quasi-periodic oscillations with a period of ∼5700 s.https://doi.org/10.3847/1538-4357/adcf27Cataclysmic variable starsDwarf novaeDQ Herculis starsX-ray sourcesStellar accretion disks |
| spellingShingle | Mariko Kimura Takayuki Hayashi Yuuki Wada Wataru Iwakiri Shigeyuki Sako Martina Veresvarska Simone Scaringi Noel Castro-Segura Christian Knigge Keith C. Gendreau Zaven Arzoumanian Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei The Astrophysical Journal Cataclysmic variable stars Dwarf novae DQ Herculis stars X-ray sources Stellar accretion disks |
| title | Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei |
| title_full | Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei |
| title_fullStr | Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei |
| title_full_unstemmed | Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei |
| title_short | Evolution of the Inner Accretion Flow and the White Dwarf Spin Pulse during the 2023 Outburst in GK Persei |
| title_sort | evolution of the inner accretion flow and the white dwarf spin pulse during the 2023 outburst in gk persei |
| topic | Cataclysmic variable stars Dwarf novae DQ Herculis stars X-ray sources Stellar accretion disks |
| url | https://doi.org/10.3847/1538-4357/adcf27 |
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