Spectro-temporal and type I X-ray burst analysis of GX 3+1 using AstroSat observations

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

doi:10.1093/mnras/stad555

Cited by 3 publications

(1 citation statement)

References 46 publications

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“…The details of SXT and LAXPC instruments are given elsewhere (see for e.g. Thomas et al 2022Thomas et al , 2023. The details of data reduction are given in the next subsections.…”

Section: Observation and Data Reductionmentioning

confidence: 99%

NuSTAR and AstroSat observations of GX 9+1: spectral and temporal studies

Thomas

Gudennavar

Bubbly

2023

Monthly Notices of the Royal Astronomical Society

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We have studied the spectro-temporal properties of the neutron star low mass X-ray binary GX 9+1 using data from NuSTAR/FPM and AstroSat/SXT and LAXPC. The hardness-intensity diagram of the source showed it to be in the soft spectral state during both observations. NuSTAR spectral analysis yielded an inclination angle (θ) = 29${^{+3}_{-4}}^{\circ }$ and inner disk radius (Rin) ≤ 19.01 km. Assuming that the accretion disk was truncated at the Alfvén radius during the observation, the upper limit of the magnetic dipole moment (μ) and the magnetic field strength (B) at the poles of the neutron star in GX 9+1 were calculated to be 1.45×1026 G cm3 and 2.08×108 G, respectively (for kA = 1). Flux resolved spectral analysis with AstroSat data showed the source to be in the soft spectral state (Fdisk/Ftotal ∼0.9) with a monotonic increase in mass accretion rate ($\dot{m}$) along the banana branch. The analysis also showed the presence of absorption edges at ∼1.9 and ∼2.4 keV, likely due to Si XIII and S XV, respectively. Temporal analysis with LAXPC-20 data in the 0.02 − 100 Hz range revealed the presence of noise components, which could be characterized with broad Lorentzian components.

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“…The details of SXT and LAXPC instruments are given elsewhere (see for e.g. Thomas et al 2022Thomas et al , 2023. The details of data reduction are given in the next subsections.…”

Section: Observation and Data Reductionmentioning

confidence: 99%

NuSTAR and AstroSat observations of GX 9+1: spectral and temporal studies

Thomas

Gudennavar

Bubbly

2023

Monthly Notices of the Royal Astronomical Society

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Spectral and temporal features of GX 13+1 as revealed by AstroSat

Giridharan,

Thomas,

Gudennavar

et al. 2023

Monthly Notices of the Royal Astronomical Society

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GX 13+1, a neutron star low mass X-ray binary that exhibits the properties of both atoll and Z sources, was studied using data from Soft X-ray Telescope and Large Area X-ray Proportional Counter (LAXPC) onboard AstroSat. The source traced a ν shaped track in its hardness-intensity diagram (HID). Spectral modelling of the data in the 0.7−30.0 keV energy range, with the model - $\mathtt {constant}$ × $\mathtt {tbabs}$ × $\mathtt {thcomp}$ × $\mathtt {bbodyrad}$ + $\mathtt {relxillNS}$, yielded orbital inclination angle (θ) of 77$\substack{+10\\-8}$○. Flux resolved spectral analysis revealed the ν shaped pattern in the plots of spectral parameters kTe, kTbb and Γ versus Fbol, closely resembling the pattern traced in LAXPC HID. This indicates changes in the spectral properties of the corona and the boundary layer/accretion disc. Assuming that the accretion disc was truncated at the Alfvén radius, the upper limit of the magnetic field strength (B) at the poles of neutron star in GX 13+1 was calculated to be 2.55× 108 G (for kA = 1 and η = 0.1), which is close to that of atoll sources. Furthermore, thickness of the boundary layer was estimated to be 5.70 km, which resulted in the neutron star radius value of ≲14.50 km. Quasi-periodic oscillations at 56±4 and 54±4 Hz were detected in Regions D and E of HID, respectively. Their frequencies are similar to the characteristic frequency of horizontal branch oscillation and they do not exhibit a positive correlation with mass accretion rate.

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Spectral and type I X-ray burst studies of 4U 1702−429 using AstroSat observations

Varun,

Thomas,

Gudennavar

et al. 2024

Monthly Notices of the Royal Astronomical Society

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4U 1702−429, an atoll-type neutron star low-mass X-ray binary, was observed twice by AstroSat/Soft X-ray Telescope (SXT) and Large Area X-ray Proportional Counters (LAXPC-20) on 2018 April 27 and 2019 August 8. Persistent emission spectra of the source were well fitted with model combination - $\mathtt {constant \times tbabs (thcomp \times diskbb+powerlaw)}$. The parameters obtained from spectral analysis revealed the source to be in hard spectral state during the observations. Time-resolved spectral analyses were performed on the three type I X-ray bursts detected from the source. Burst analysis showed that the source underwent a photospheric radius expansion. Consequently, radius of the neutron star and distance to the source (with isotropic and anisotropic burst emission) were obtained to be 12.65 $^{+0.90}_{-0.86}$ km, and 6.92 $^{+0.16}_{-0.09}$ and 8.43 $^{+0.20}_{-0.10}$ kpc, respectively.

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Spectro-temporal and type I X-ray burst analysis of GX 3+1 using AstroSat observations

Cited by 3 publications

References 46 publications

NuSTAR and AstroSat observations of GX 9+1: spectral and temporal studies

NuSTAR and AstroSat observations of GX 9+1: spectral and temporal studies

Spectral and temporal features of GX 13+1 as revealed by AstroSat

Spectral and type I X-ray burst studies of 4U 1702−429 using AstroSat observations

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