A Transition Discovered in the Subcritical Regime of 1A 0535+262
We present NICER observations of the accreting X-ray pulsar 1A 0535+262 during its faint state (≲6 × 10 ^36 erg s ^−1 ), observed in several type I and type II outbursts. We discovered a transition of temporal and spectral properties around the luminosity L _t = 3.3 × 10 ^35 erg s ^−1 , below which...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad23cd |
| _version_ | 1827572937177169920 |
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| author | Hua Xiao Long Ji |
| author_facet | Hua Xiao Long Ji |
| author_sort | Hua Xiao |
| collection | DOAJ |
| description | We present NICER observations of the accreting X-ray pulsar 1A 0535+262 during its faint state (≲6 × 10 ^36 erg s ^−1 ), observed in several type I and type II outbursts. We discovered a transition of temporal and spectral properties around the luminosity L _t = 3.3 × 10 ^35 erg s ^−1 , below which spectra are relatively soft and the pulse profiles have only a narrow peak. The spectra are harder and a secondary hump gradually appears in the pulse profiles when L ≳ L _t . We discuss possible physical mechanisms for this transition, including different Comptonization seed photons, the disappearance of gas shocks on the neutron star surface, and the combination of plasma and vacuum polarization effects. |
| first_indexed | 2024-03-07T19:59:53Z |
| format | Article |
| id | doaj.art-2ff9d7a410434a95bf0cf691f5a8e50c |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-07T19:59:53Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-2ff9d7a410434a95bf0cf691f5a8e50c2024-02-28T09:17:32ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-0196314210.3847/1538-4357/ad23cdA Transition Discovered in the Subcritical Regime of 1A 0535+262Hua Xiao0https://orcid.org/0009-0004-1288-4912Long Ji1https://orcid.org/0000-0001-9599-7285School of Physics and Astronomy, Sun Yat-sen University , Zhuhai 519082, People’s Republic of China ; jilong@mail.sysu.edu.cnSchool of Physics and Astronomy, Sun Yat-sen University , Zhuhai 519082, People’s Republic of China ; jilong@mail.sysu.edu.cnWe present NICER observations of the accreting X-ray pulsar 1A 0535+262 during its faint state (≲6 × 10 ^36 erg s ^−1 ), observed in several type I and type II outbursts. We discovered a transition of temporal and spectral properties around the luminosity L _t = 3.3 × 10 ^35 erg s ^−1 , below which spectra are relatively soft and the pulse profiles have only a narrow peak. The spectra are harder and a secondary hump gradually appears in the pulse profiles when L ≳ L _t . We discuss possible physical mechanisms for this transition, including different Comptonization seed photons, the disappearance of gas shocks on the neutron star surface, and the combination of plasma and vacuum polarization effects.https://doi.org/10.3847/1538-4357/ad23cdAccretionHigh mass x-ray binary starsPulsars |
| spellingShingle | Hua Xiao Long Ji A Transition Discovered in the Subcritical Regime of 1A 0535+262 The Astrophysical Journal Accretion High mass x-ray binary stars Pulsars |
| title | A Transition Discovered in the Subcritical Regime of 1A 0535+262 |
| title_full | A Transition Discovered in the Subcritical Regime of 1A 0535+262 |
| title_fullStr | A Transition Discovered in the Subcritical Regime of 1A 0535+262 |
| title_full_unstemmed | A Transition Discovered in the Subcritical Regime of 1A 0535+262 |
| title_short | A Transition Discovered in the Subcritical Regime of 1A 0535+262 |
| title_sort | transition discovered in the subcritical regime of 1a 0535 262 |
| topic | Accretion High mass x-ray binary stars Pulsars |
| url | https://doi.org/10.3847/1538-4357/ad23cd |
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