Typical X-Ray Outburst Light Curves of Aql X-1
We show that the typical X-ray outburst light curve of Aql X-1 can be reproduced by accretion onto a neutron star in the frame of the disk instability model without invoking partial accretion or the propeller effect. The knee and the subsequent sharp decay in the X-ray light curve can be generated n...
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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/ad1515 |
| _version_ | 1797336230620299264 |
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| author | Ömer Faruk Çoban Ünal Ertan |
| author_facet | Ömer Faruk Çoban Ünal Ertan |
| author_sort | Ömer Faruk Çoban |
| collection | DOAJ |
| description | We show that the typical X-ray outburst light curve of Aql X-1 can be reproduced by accretion onto a neutron star in the frame of the disk instability model without invoking partial accretion or the propeller effect. The knee and the subsequent sharp decay in the X-ray light curve can be generated naturally by taking into account the weak dependence of the disk aspect ratio, h / r , on the disk mass-flow rate, ${\dot{M}}_{\mathrm{in}}$ , in the X-ray irradiation flux calculation. This ${\dot{M}}_{\mathrm{in}}$ dependence of h / r only slightly modifies the irradiation temperature profile along the hot disk in comparison to that obtained with a constant h / r . Nevertheless, this small difference has a significant cumulative effect on the hot disk radius, leading to a much faster decrease in the size of the hot disk and thereby to a sharper decay in the X-ray outburst light curve. The same model also produces the long-term evolution of Aql X-1, consistent with its observed outburst recurrence time and typical light curve. Our results imply that the source accretes matter from the disk in the quiescent state as well. We also estimate that the dipole moment of the source μ ≲ 4 × 10 ^26 G cm ^3 ( B ≲ 4 × 10 ^8 G at the surface). |
| first_indexed | 2024-03-08T08:51:14Z |
| format | Article |
| id | doaj.art-5a27e8110505480ca21e49191967e4ff |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-08T08:51:14Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-5a27e8110505480ca21e49191967e4ff2024-02-01T08:57:41ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01961225210.3847/1538-4357/ad1515Typical X-Ray Outburst Light Curves of Aql X-1Ömer Faruk Çoban0https://orcid.org/0000-0002-5887-6676Ünal Ertan1https://orcid.org/0000-0002-1898-7902Sabancı University , Orhanlı, Tuzla, 34956, İstanbul, TurkeySabancı University , Orhanlı, Tuzla, 34956, İstanbul, TurkeyWe show that the typical X-ray outburst light curve of Aql X-1 can be reproduced by accretion onto a neutron star in the frame of the disk instability model without invoking partial accretion or the propeller effect. The knee and the subsequent sharp decay in the X-ray light curve can be generated naturally by taking into account the weak dependence of the disk aspect ratio, h / r , on the disk mass-flow rate, ${\dot{M}}_{\mathrm{in}}$ , in the X-ray irradiation flux calculation. This ${\dot{M}}_{\mathrm{in}}$ dependence of h / r only slightly modifies the irradiation temperature profile along the hot disk in comparison to that obtained with a constant h / r . Nevertheless, this small difference has a significant cumulative effect on the hot disk radius, leading to a much faster decrease in the size of the hot disk and thereby to a sharper decay in the X-ray outburst light curve. The same model also produces the long-term evolution of Aql X-1, consistent with its observed outburst recurrence time and typical light curve. Our results imply that the source accretes matter from the disk in the quiescent state as well. We also estimate that the dipole moment of the source μ ≲ 4 × 10 ^26 G cm ^3 ( B ≲ 4 × 10 ^8 G at the surface).https://doi.org/10.3847/1538-4357/ad1515AccretionNeutron starsLow-mass x-ray binary starsX-ray burstsX-ray transient sources |
| spellingShingle | Ömer Faruk Çoban Ünal Ertan Typical X-Ray Outburst Light Curves of Aql X-1 The Astrophysical Journal Accretion Neutron stars Low-mass x-ray binary stars X-ray bursts X-ray transient sources |
| title | Typical X-Ray Outburst Light Curves of Aql X-1 |
| title_full | Typical X-Ray Outburst Light Curves of Aql X-1 |
| title_fullStr | Typical X-Ray Outburst Light Curves of Aql X-1 |
| title_full_unstemmed | Typical X-Ray Outburst Light Curves of Aql X-1 |
| title_short | Typical X-Ray Outburst Light Curves of Aql X-1 |
| title_sort | typical x ray outburst light curves of aql x 1 |
| topic | Accretion Neutron stars Low-mass x-ray binary stars X-ray bursts X-ray transient sources |
| url | https://doi.org/10.3847/1538-4357/ad1515 |
| work_keys_str_mv | AT omerfarukcoban typicalxrayoutburstlightcurvesofaqlx1 AT unalertan typicalxrayoutburstlightcurvesofaqlx1 |