R. Amato, N. La Palombara, M. Imbrogno, G. Israel, P. Esposito, D. de Martino, N. A. Webb, R. Iaria
{"title":"研究 47 Tuc 中周期为 2.4 小时的蚀变大灾变 W2 的性质","authors":"R. Amato, N. La Palombara, M. Imbrogno, G. Israel, P. Esposito, D. de Martino, N. A. Webb, R. Iaria","doi":"10.1051/0004-6361/202450034","DOIUrl":null,"url":null,"abstract":") is a cataclysmic variable (CV) in the Galactic globular cluster 47 Tucanae. Its modulation was discovered within the CATS@BAR project. The source shows all the properties of magnetic CVs, but whether it is a polar or an intermediate polar is still a matter of debate. This paper investigates the spectral and temporal properties of the source, using all archival X-ray data from and Early Data Release, to establish whether the source falls within the category of polars or intermediate polars. We fitted archival spectra with three different models: a power law, a bremsstrahlung and an optically thin thermal plasma. We also explored the temporal properties of the source with searches for pulsations with a power spectral density analysis and a Rayleigh test ($Z_n^2$). displays a mean luminosity of $ over a 20-year span, despite lower values in a few epochs. The source is not detected in the latest observation, taken with in 2022, and we infer an X-ray luminosity $ The source spectral shape does not change over time and can be equally well fitted with each of the three models, with a best-fit photon index of 1.6 for the power law and best-fit temperatures of 10 keV for both the bremsstrahlung and the thermal plasma models. We confirm the previously detected period of 8649 s, ascribed to the binary orbital period, and found a cycle-to-cycle variability associated with this periodicity. No other significant pulsation is detected. Considering the source orbital period, luminosity, spectral characteristics, long-term evolution and strong cycle-to-cycle variability, we suggest that is a magnetic CV of the polar type.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"65 17","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Investigating the nature of the 2.4 hr-period eclipsing cataclysmic variable W2 in 47 Tuc\",\"authors\":\"R. Amato, N. La Palombara, M. Imbrogno, G. Israel, P. Esposito, D. de Martino, N. A. Webb, R. Iaria\",\"doi\":\"10.1051/0004-6361/202450034\",\"DOIUrl\":null,\"url\":null,\"abstract\":\") is a cataclysmic variable (CV) in the Galactic globular cluster 47 Tucanae. Its modulation was discovered within the CATS@BAR project. The source shows all the properties of magnetic CVs, but whether it is a polar or an intermediate polar is still a matter of debate. This paper investigates the spectral and temporal properties of the source, using all archival X-ray data from and Early Data Release, to establish whether the source falls within the category of polars or intermediate polars. We fitted archival spectra with three different models: a power law, a bremsstrahlung and an optically thin thermal plasma. We also explored the temporal properties of the source with searches for pulsations with a power spectral density analysis and a Rayleigh test ($Z_n^2$). displays a mean luminosity of $ over a 20-year span, despite lower values in a few epochs. The source is not detected in the latest observation, taken with in 2022, and we infer an X-ray luminosity $ The source spectral shape does not change over time and can be equally well fitted with each of the three models, with a best-fit photon index of 1.6 for the power law and best-fit temperatures of 10 keV for both the bremsstrahlung and the thermal plasma models. We confirm the previously detected period of 8649 s, ascribed to the binary orbital period, and found a cycle-to-cycle variability associated with this periodicity. No other significant pulsation is detected. Considering the source orbital period, luminosity, spectral characteristics, long-term evolution and strong cycle-to-cycle variability, we suggest that is a magnetic CV of the polar type.\",\"PeriodicalId\":8585,\"journal\":{\"name\":\"Astronomy & Astrophysics\",\"volume\":\"65 17\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-07-24\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Astronomy & Astrophysics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1051/0004-6361/202450034\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astronomy & Astrophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1051/0004-6361/202450034","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
摘要
)是银河系球状星团 47 图卡尼中的一个大灾变(CV)。它的调制是在 CATS@BAR 项目中发现的。该源显示出磁性 CV 的所有特性,但它是极性还是中间极性仍有争议。本文利用来自和早期数据发布的所有档案 X 射线数据,研究了该源的光谱和时间特性,以确定该源属于极性还是中间极性。我们用三种不同的模型拟合了档案光谱:幂律模型、轫致辐射模型和光学稀薄热等离子体模型。我们还通过功率谱密度分析和瑞利测试($Z_n^2$)寻找脉动,探索了该光源的时间特性。在 2022 年进行的最新观测中没有发现该光源,我们推断其 X 射线光度为 $。该光源的光谱形状并没有随着时间的推移而改变,三种模型的拟合效果相当好,幂律模型的最佳拟合光子指数为 1.6,轫致辐射模型和热等离子体模型的最佳拟合温度均为 10 keV。我们确认了之前探测到的 8649 秒的周期,并发现了与这一周期相关的周期间变化。没有检测到其他明显的脉动。考虑到该星源的轨道周期、光度、光谱特征、长期演化和周期间的强烈变化,我们认为这是一个极地类型的磁CV。
Investigating the nature of the 2.4 hr-period eclipsing cataclysmic variable W2 in 47 Tuc
) is a cataclysmic variable (CV) in the Galactic globular cluster 47 Tucanae. Its modulation was discovered within the CATS@BAR project. The source shows all the properties of magnetic CVs, but whether it is a polar or an intermediate polar is still a matter of debate. This paper investigates the spectral and temporal properties of the source, using all archival X-ray data from and Early Data Release, to establish whether the source falls within the category of polars or intermediate polars. We fitted archival spectra with three different models: a power law, a bremsstrahlung and an optically thin thermal plasma. We also explored the temporal properties of the source with searches for pulsations with a power spectral density analysis and a Rayleigh test ($Z_n^2$). displays a mean luminosity of $ over a 20-year span, despite lower values in a few epochs. The source is not detected in the latest observation, taken with in 2022, and we infer an X-ray luminosity $ The source spectral shape does not change over time and can be equally well fitted with each of the three models, with a best-fit photon index of 1.6 for the power law and best-fit temperatures of 10 keV for both the bremsstrahlung and the thermal plasma models. We confirm the previously detected period of 8649 s, ascribed to the binary orbital period, and found a cycle-to-cycle variability associated with this periodicity. No other significant pulsation is detected. Considering the source orbital period, luminosity, spectral characteristics, long-term evolution and strong cycle-to-cycle variability, we suggest that is a magnetic CV of the polar type.