Comprehensive spectro-temporal studies of GX 17+2 using AstroSat observations

IF 10.2 4区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Journal of High Energy Astrophysics Pub Date : 2024-12-20 DOI:10.1016/j.jheap.2024.12.007

Neal Titus Thomas, S. Lavanya, S.B. Gudennavar, S.G. Bubbly

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引用次数: 0

Abstract

We performed a comprehensive spectro-temporal study of the Z-type neutron star low-mass X-ray binary GX 17+2 using long term data from the AstroSat/Soft X-ray Telescope (SXT) and Large Area X-ray Proportional Counter (LAXPC). The hardness–intensity diagrams (HIDs) of the source revealed a positive correlation between the hardness and intensity, characteristic of soft spectral state. Additionally, the LAXPC-20 HID showed the presence of secular shifts in both hardness and intensity. Time-averaged spectral modelling in the 0.7 − 30.0 keV energy range indicated that the spectra could be well fitted with the model combination: constant × edge × edge × tbabs × thcomp × bbodyrad. This analysis yielded a blackbody radius (

R_{b b}

) of ∼59 km, photon index (Γ) of ∼2.84 and electron temperature (

k T_{e}

) of ∼4.84 keV. Time-averaged temporal analysis revealed normal branch oscillations (NBOs) at ∼ 7 Hz in Observations 1 and 3, flaring branch oscillation (FBO) at ∼15 Hz in Observation 2, and horizontal branch oscillation (HBO) at ∼36 Hz in Observation 5. Flux resolved spectro-temporal analysis indicated that the source remained in the soft spectral state throughout all observations. A positive correlation was observed between

k T_{b b}

F_{b b}

and

F_{b o l}

, whereas an anti-correlation was noted between

k T_{e}

and

F_{b o l}

. The constant frequency of NBOs with an increase in

F_{b o l}

suggests that their origin lies in a region strongly influenced by the corona, as explained by the radiation-hydrodynamic model. The origin of FBOs may be attributed to the damped radiation-hydrodynamic mode of radial flow, while the origin of HBOs is supported by the beat-frequency model.

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来源期刊

Journal of High Energy Astrophysics Earth and Planetary Sciences-Space and Planetary Science

CiteScore

9.70

自引率

5.30%

发文量

审稿时长

65 days

期刊介绍： The journal welcomes manuscripts on theoretical models, simulations, and observations of highly energetic astrophysical objects both in our Galaxy and beyond. Among those, black holes at all scales, neutron stars, pulsars and their nebula, binaries, novae and supernovae, their remnants, active galaxies, and clusters are just a few examples. The journal will consider research across the whole electromagnetic spectrum, as well as research using various messengers, such as gravitational waves or neutrinos. Effects of high-energy phenomena on cosmology and star-formation, results from dedicated surveys expanding the knowledge of extreme environments, and astrophysical implications of dark matter are also welcomed topics.