分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2024-02-01 合作期刊: 《Research in Astronomy and Astrophysics》
摘要: In this paper, new light curves (LCs) of contact eclipsing binary (CEB) systems LX Lyn and V0853 Aur are presented and analyzed by using the 2015 version of the Wilson–Devinney (W-D) code. In order to explain their asymmetric LCs, cool starspots on the components were employed. It is suggested that their fill-out degrees are f = 12.0% (LX Lyn) and f = 26.3% (V0853 Aur). At the same time, we found that LX Lyn is a W-type eclipsing binary (EB) with an orbital inclination of i = 8488 and a mass ratio of q = 2.31. V0853 Aur is also a W-type CEB with a mass ratio of q = 2.77 and an orbital inclination of i = 7926. Based on all available times of light minimum, their orbital period changes are studied by using the O − C method. The O − C diagram of LX Lyn reveals a cyclic oscillation with a period of about 14.84 yr and an amplitude of 0.0019 days, which can be explained by the light-travel time effect (LTTE) due to the presence of a third body with a minimum mass of 0.06M⊙. For V0853 Aur, it is discovered that the O − C diagram of the system also shows a cyclic oscillation with a period of 9.64 yr and an amplitude of 0.03365 days. The cyclic oscillation of V0853 Aur can be attributed to the LTTE by means of a third body with a mass no less than 3.77M⊙. The third body may play an important role in the formation and evolution of these systems.
分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2024-01-09 合作期刊: 《Research in Astronomy and Astrophysics》
摘要: Gamma-ray bursts (GRBs) exhibit powerful radiation and relativistic jets similar to blazars. However, the central engine of GRBs remains unknown. In this paper, we use the fundamental plane to analyze a sample of GRBs with measured mass. We extend, over ∼12 orders of magnitude, the correlation analysis and fundamental plane with a sample of X-ray binaries, active galactic nuclei (AGNs) including blazars, and brightest cluster galaxies. The fundamental plane of our de-beamed sample, with a measured mass (= (0.60 ± 0.03)+(0.78 ± 0.02)+7.23 ± 0.95), closely aligns with the findings of previous work on AGNs. This finding suggests that GRBs adhere to the fundamental plane of AGNs and supports the theory proposed in previous work that the central engine of GRBs may be black holes. This observation provides a plausible explanation for the striking similarities between GRBs and AGNs.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Monitoring and stabilizing the power ratio of laser pairs is significant to high-precision atom interferometers, especially as the compact electro-optic modulated all-fiber laser system prevails. In this Letter, we demonstrate a novel method to in-situ probe the relative power of laser pairs and to stabilize the power ratio of two Raman lasers using a high-dispersion virtually imaged phased array (VIPA) etalon. Sub-microsecond resolution on probing laser power transformation during atom interferometer sequence is achieved and the power ratio of two Raman lasers (PRTR) is tightly locked with high bandwidth despite of environmental disturbances, showing an Allan deviation of $4.39\times 10^{-5}$ at 1000 s averaging time. This method provides a novel way to stabilize the PRTR and diagnose the multi-frequency laser systems for atom interferometers and could find potential application in broad quantum sensing scenarios.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Low-phase-noise and pure-spectrum Raman light is vital for high-precision atom interferometry by two-photon Raman transition. A preferred and prevalent solution for Raman light generation is electro-optic phase modulation. However, phase modulation inherently brings in double sidebands, resulting in residual sideband effects of multiple laser pairs beside Raman light in atom interferometry. Based on a well-designed rectangular fiber Bragg grating and an electro-optic modulator, optical single-sideband modulation has been realized at 1560 nm with a stable suppression ratio better than -25 dB despite of intense temperature variations. After optical filtration and frequency doubling, a robust phase-coherent Raman light at 780 nm is generated with a stable SNR of better than -19 dB and facilitates measuring the local gravity successfully. This proposed all-fiber single-sideband-modulated Raman light source, characterized as robust, compact and low-priced, is practical and potential for field applications of portable atom interferometry.
分类: 天文学 >> 天文学 提交时间: 2023-12-29
摘要: Globular clusters harbor numerous millisecond pulsars; however, the detection of long-period pulsars within these clusters has been notably scarce. The search for long-period pulsars encounters significant challenges due to pronounced red noise interference, necessitating the crucial step of red noise removal in the data preprocessing. In this study, we use running median filtering to mitigate red noise in multiple globular cluster datasets obtained through observations with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Additionally, we estimated the minimum detectable flux density of pulsars ($S_{ rm min}$) considering this processing step, resulting in a function depicting how $S_{ rm min}$ varies with different duty cycles and periods. Subsequently, a systematic search for long-period pulsars was conducted on the globular cluster datasets after red noise elimination. Ultimately, two isolated long-period pulsars were discovered in the M15 globular cluster, with periods of approximately 1.928451 seconds and 3.960716 seconds, both exhibiting remarkably low pulse duty cycles of around 1 %. Using archived data, we obtained timing solutions for these pulsars. Based on the timing results, their positions are found to be close to the center of the M15 cluster. On the $P- dot{P}$ diagram, they both lie below the spin-up line, suggesting that their recycling process was likely interrupted, leading them to become isolated pulsars. Moreover, in our current search, these very faint long-period pulsars are exclusively identified in M15, and one possible reason for this could be the relatively close proximity and extremely high stellar formation rate of M15. As observational data accumulate and search algorithms undergo iterative enhancements, the prospect of discovering additional long-period pulsars within globular clusters, such as M15, becomes increasingly promising.