핵심 개념
This research paper presents an analysis of the long-term X-ray behavior of XTE J1829−098, a transient X-ray pulsar, revealing distinct active and inactive states, and refining our understanding of its orbital characteristics and outburst behavior.
초록
Bibliographic Information: Corbet, R. H. D., et al. "Sharp Periodic Flares and Long-Term Variability in the High-Mass X-ray Binary XTE J1829-098 from RXTE PCA, Swift BAT and MAXI Observations." Astrophysical Journal, Accepted October 3, 2024. arXiv:2410.03500v1 [astro-ph.HE] 4 Oct 2024.
Research Objective: This study aims to characterize the long-term X-ray variability of XTE J1829−098, a transient X-ray pulsar and candidate Be star system, using data spanning two decades from RXTE PCA, Swift BAT, and MAXI.
Methodology: The researchers analyzed X-ray light curves from three different instruments: RXTE PCA, Swift BAT, and MAXI. They calculated power spectra to identify periodicities and fitted a triangular profile to the light curves to characterize the periodic outbursts and refine the orbital period. The study also compared the properties of XTE J1829−098 with other similar systems.
Key Findings:
XTE J1829−098 exhibits distinct active (Epochs I and III) and inactive (Epoch II) states, with strong periodic flares only observed during active periods.
The orbital period is refined to 243.95 ± 0.04 days, with outbursts confined to a narrow phase range (∼0.05 Porb).
The mean outburst profile is symmetric, lasting approximately 34 days, but significant cycle-to-cycle variability is observed.
The system's location on the spin-period versus orbital-period diagram supports its classification as a Be star system.
XTE J1829−098 shares similarities with other Be star systems exhibiting sharp flares, such as A 0538-66 and AX J0049.4-7323, and GS 1843-02, which has a similar orbital period but a longer spin period and a highly eccentric orbit.
Main Conclusions:
The long-term X-ray variability of XTE J1829−098, with its alternating active and inactive states, is typical of Be X-ray binary systems.
The short duration of the outbursts, relative to the orbital period, suggests a high orbital eccentricity or a mechanism that disrupts the Be star's decretion disk near periastron passage.
Further observations are needed to determine the precise nature of the companion star and the mechanism responsible for the observed X-ray variability.
Significance: This research enhances our understanding of the long-term behavior of Be X-ray binary systems and the mechanisms driving their X-ray emission. The study highlights the importance of continuous monitoring of these systems to capture their diverse variability patterns and refine our knowledge of their orbital and accretion processes.
Limitations and Future Research: The study acknowledges the limitations posed by the limited number of pulse period measurements and the unknown behavior of the system during its inactive state. Future research could focus on obtaining more precise and frequent pulse period measurements, conducting multi-wavelength observations to characterize the companion star and its environment, and exploring theoretical models to explain the observed outburst behavior and the transition between active and inactive states.
통계
XTE J1829−098 is a transient X-ray pulsar with a period of ∼7.8 s.
The orbital period of the system is refined to 243.95 ± 0.04 days.
The mean outburst profile has a total phase duration of 0.140 ± 0.007.
The system was in an inactive state between approximately December 2008 and April 2018.
A cyclotron resonance scattering feature (CRSF) was reported at ∼18 keV.
Shtykovsky et al. (2019) determined a magnetic field of 1.7 × 10^12 G.
Distance estimates for the source range from 4.5 to 18 kpc.
인용구
"XTE J1829−098 is a transient X-ray pulsar with a period of ∼7.8 s. It is a candidate Be star system, although the evidence for this is not yet definitive."
"We investigated the twenty-year long X-ray light curve using the Rossi X-ray Timing Explorer Proportional Counter Array (PCA), Neil Gehrels Swift Observatory Burst Alert Telescope (BAT), and the Monitor of All-sky X-ray Image (MAXI)."
"We find that all three light curves are clearly modulated on the ∼244 day orbital period previously reported from PCA monitoring observations, with outbursts confined to a narrow phase range."
"The light curves also show that XTE J1829−098 was in an inactive state between approximately December 2008 and April 2018 and no strong outbursts occurred."
"Such behavior is typical of Be X-ray binary systems, with the absence of outbursts likely related to the dissipation of the Be star’s decretion disk."