Engine-fed Kilonovae (Mergernovae). II. Radiation
The radioactive power generated by materials within the ejecta of a binary-neutron-star (BNS) merger powers an optical transient known as a kilonova. When the central remnant of a BNS merger is a long-lived magnetar, it continuously produces a highly magnetized wind, altering both the dynamics and t...
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IOP Publishing
2024-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad93b4 |
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| author | Shunke Ai He Gao Bing Zhang |
| author_facet | Shunke Ai He Gao Bing Zhang |
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| description | The radioactive power generated by materials within the ejecta of a binary-neutron-star (BNS) merger powers an optical transient known as a kilonova. When the central remnant of a BNS merger is a long-lived magnetar, it continuously produces a highly magnetized wind, altering both the dynamics and temperature of the ejecta, leading to the expected emergence of an engine-fed kilonova. In the first paper of this series, we conducted a detailed study of the dynamics of wind-ejecta interaction and the efficiency of energy injection through shocks. In this work, we combine this dynamical evolution with both shock-heating and additional X-ray irradiation to model photon diffusion within a constant-opacity ejecta. By calculating the radiation, we obtain the light curve and spectral energy distribution (SED). Our findings reveal that, with energy injection, a blue bump typically appears in the early stages (≲1 day). Furthermore, if the magnetar has not spun down by that time, a brightening in the later stages occurs. Despite this, in a large parameter space, the expected luminosity of the engine-fed kilonova is not significantly higher than the typical r -process kilonova due to limited heating efficiency. The SED of engine-fed kilonovae peaks in the relatively blue band in the early stages and evolves toward the red, but at a slower rate compared to the typical r -process kilonova. |
| format | Article |
| id | doaj-art-7371e65b68b04aab95d590f81eb08d91 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-7371e65b68b04aab95d590f81eb08d912024-12-24T09:26:28ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-0197815210.3847/1538-4357/ad93b4Engine-fed Kilonovae (Mergernovae). II. RadiationShunke Ai0https://orcid.org/0000-0002-9165-8312He Gao1https://orcid.org/0000-0003-2516-6288Bing Zhang2https://orcid.org/0000-0002-9725-2524Department of Astronomy, School of Physics and Technology, Wuhan University , Wuhan 430072, People's Republic of China ; shunke.ai@whu.edu.cnInstitute for Frontier in Astronomy and Astrophysics, Beijing Normal University , Beijing 102206, People's Republic of China ; gaohe@bnu.edu.cn; School of Physics and Astronomy, Beijing Normal University , Beijing 100875, People's Republic of ChinaNevada Center for Astrophysics, University of Nevada Las Vegas , Las Vegas, NV 89154, USA ; bing.zhang@unlv.edu; Department of Physics and Astronomy, University of Nevada Las Vegas , Las Vegas, NV 89154, USAThe radioactive power generated by materials within the ejecta of a binary-neutron-star (BNS) merger powers an optical transient known as a kilonova. When the central remnant of a BNS merger is a long-lived magnetar, it continuously produces a highly magnetized wind, altering both the dynamics and temperature of the ejecta, leading to the expected emergence of an engine-fed kilonova. In the first paper of this series, we conducted a detailed study of the dynamics of wind-ejecta interaction and the efficiency of energy injection through shocks. In this work, we combine this dynamical evolution with both shock-heating and additional X-ray irradiation to model photon diffusion within a constant-opacity ejecta. By calculating the radiation, we obtain the light curve and spectral energy distribution (SED). Our findings reveal that, with energy injection, a blue bump typically appears in the early stages (≲1 day). Furthermore, if the magnetar has not spun down by that time, a brightening in the later stages occurs. Despite this, in a large parameter space, the expected luminosity of the engine-fed kilonova is not significantly higher than the typical r -process kilonova due to limited heating efficiency. The SED of engine-fed kilonovae peaks in the relatively blue band in the early stages and evolves toward the red, but at a slower rate compared to the typical r -process kilonova.https://doi.org/10.3847/1538-4357/ad93b4Transient sourcesGamma-ray burstsMagnetars |
| spellingShingle | Shunke Ai He Gao Bing Zhang Engine-fed Kilonovae (Mergernovae). II. Radiation The Astrophysical Journal Transient sources Gamma-ray bursts Magnetars |
| title | Engine-fed Kilonovae (Mergernovae). II. Radiation |
| title_full | Engine-fed Kilonovae (Mergernovae). II. Radiation |
| title_fullStr | Engine-fed Kilonovae (Mergernovae). II. Radiation |
| title_full_unstemmed | Engine-fed Kilonovae (Mergernovae). II. Radiation |
| title_short | Engine-fed Kilonovae (Mergernovae). II. Radiation |
| title_sort | engine fed kilonovae mergernovae ii radiation |
| topic | Transient sources Gamma-ray bursts Magnetars |
| url | https://doi.org/10.3847/1538-4357/ad93b4 |
| work_keys_str_mv | AT shunkeai enginefedkilonovaemergernovaeiiradiation AT hegao enginefedkilonovaemergernovaeiiradiation AT bingzhang enginefedkilonovaemergernovaeiiradiation |