Study of the reflection spectrum of the LMXB 4U 1702-429

Abstract

The source 4U 1702-429 (Ara X-1) is a low-mass X-ray binary system hosting a neutron star. Albeit the source is quite bright ( $\sim 10^{37}$ erg s${}^{-1}$) its broadband spectrum has never been studied. Neither dips nor eclipses have been observed in the light curve suggesting that its inclination angle is smaller than 60${}^{\circ }$.We analysed the broadband spectrum of 4U 1702-429 in the 0.3-60 keV energy range, using XMM-Newton and INTEGRAL data, to constrain its Compton reflection component if it is present. After excluding the three time intervals in which three type-I X-ray bursts occurred, we fitted the joint XMM-Newton and INTEGRAL spectra obtained from simultaneous observations. A broad emission line at 6.7 keV and two absorption edges at 0.87 and 8.82 keV were detected. We found that a self-consistent reflection model fits the 0.3-60 keV spectrum well. The broadband continuum is composed of an emission component originating from the inner region of the accretion disc, a Comptonised direct emission coming from a corona with an electron temperature of $2.63\pm 0.06$ keV and an optical depth $\tau =13.6\pm 0.2$, and, finally, a reflection component. The best-fit indicates that the broad emission line and the absorption edge at 8.82 keV, both associated with the presence of \ion{Fe}{xxv} ions, are produced by reflection in the region above the disc with a ionisation parameter of $Log(\xi )\simeq 2.7$. We have inferred that the inner radius, where the broad emission line originates, is $64_{-15}^{+52}$ km, and the inner radius of the accretion disc is $39_{-8}^{+6}$ km. (Abridged)

9 pages, 9 figures, accepted for publication by A&A

References in corpus (8)

• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Interstellar Extinction Law toward the Galactic Center II: V, J, H, and Ks Bands
• X-ray reflection in accreting stellar-mass black hole systems
• A relativistically smeared spectrum in the neutron star X-ray Binary 4U 1705-44: Looking at the inner accretion disc with X-ray spectroscopy
• Disk reflection signatures in the spectrum of the bright Z-source GX 340+0
• Suzaku broad-band spectrum of 4U 1705-44: Probing the Reflection component in the hard state
• Study of the reflection spectrum of the accreting neutron star GX 3+1 using XMM-Newton and INTEGRAL
• On the Non-relativistic Origin of Red-skewed Iron Lines in CV, Neutron Star and Black Hole Sources

Cited by in corpus (16)

• NuSTAR Observations of the Accreting Atolls GX 3+1, 4U 1702-429, 4U 0614+091, and 4U 1746-371
• Accretion geometry of the neutron star low mass X-ray binary Cyg X-2 from X-ray polarization measurements
• X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143
• Dust absorption and scattering in the silicon K-edge
• First detection of X-ray polarization from the accreting neutron star 4U 1820-303
• NuSTAR view of the Z-type neutron star low-mass X-ray binary Cygnus~X--2
• The Galactic LMXB Population and the Galactic Centre Region
• Reflection component in the Bright Atoll Source GX 9+9
• High-frequency variability in neutron-star low-mass X-ray binaries
• Spectral analysis of the dipping LMXB system XB 1916-053
• Quasi-simultaneous Integral, Swift, And Nustar Observations Of The New X-ray Clocked Burster 1rxsj180408.9-342058
• Fe K$\alpha$ and Fe K$\beta$ line detection in the NuSTAR spectrum of the ultra-bright Z-source Scorpius X-1
• Evidence of hard power-law spectral cutoff and disc reflection features from the X-ray transient XTE J1739-285
• Probing the accretion geometry of the atoll source 4U 1702-429 in different spectral states with NICER, NuSTAR, and AstroSat
• Spectral study of neutron star low mass X-ray binary source 1A 1744-361
• Spectro-temporal evolution of 4U 1702-429 using AstroSat-NICER