The first detection of Compton Reflection in the Low-Mass X-ray Binary 4U1705-44 with INTEGRAL and BeppoSAX

Abstract

We present data from INTEGRAL and BeppoSAX satellites showing spectral state transitions of the neutron-star, atoll-type, low-mass X-ray binary 1705-44. Its energy spectrum can be described as the sum of one or two blackbody components, a 6.4-keV Fe line, and a component due to thermal Comptonization. In addition, and for the first time in this source, we find a strong signature of Compton reflection, presumably due to illumination of the optically-thick accretion disk by the Comptonization spectrum. The two blackbody components, which the soft-state data require, presumably arise from both the disk and the neutron-star surface. The Comptonization probably takes place in a hot inner flow irradiated by some of the blackbody photons. The spectral transitions are shown to be associated with variations in the bolometric luminosity, most likely proportional to the accretion rate. Indipendentely from the spectral state, we also see changes in the temperature of the Comptonizing electrons and the strength of Compton reflection.

accepted ApJ

References in corpus (23)

• Statistics: Handle with Care, Detecting Multiple Model Components with the Likelihood Ratio Test
• Millisecond Oscillations in X-Ray Binaries
• The INTEGRAL Science Data Centre (ISDC)
• Radiative Processes, Spectral States and Variability of Black-Hole Binaries
• Correlation between Compton reflection and X-ray slope in Seyferts and X-ray binaries
• Simultaneous X-ray and gamma-ray observations of Cyg X-1 in the hard state by Ginga and OSSE
• Hard X-ray Emission From Low Mass X-ray Binaries
• Probing the Inner Region of Cyg X-1 in the Low/Hard State through its X-ray Broad Band Spectrum
• Resolving the Composite Fe K-alpha Emission Line in the Galactic Black Hole Cygnus X-1 with Chandra
• The broad band X-ray/hard X-ray spectra of accreting neutron stars
• The X-ray spectrum of the atoll source 4U 1608-52
• Average hard X-ray emission from NS LMXBs: Observational evidence of different spectral states in NS LMXBs
• The Evolution of the Accretion Disk around 4U 1820-30 During a Superburst
• Phase-resolved X-ray spectroscopy of the millisecond pulsar SAX J1808.4-3658
• A peculiar spectral state transition of 4U1705--44: when an Atoll looks like a Z
• Simultaneous BeppoSAX and RXTE observations of the X-ray burst sources GX 3+1 and Ser X-1
• The X-ray Spectrum of Cyg X-2
• First results from the INTEGRAL Galactic plane scans
• A broad iron line in the Chandra/HETG spectrum of 4U 1705-44
• Discovery of Kilohertz QPOs in the Atoll X-Ray Binary 4U 1705-44
• INTEGRAL spectral variability study of the atoll 4U 1820-30: first detection of hard X-ray emission
• Correlated timing and spectral behavior of 4U 1705-44
• A Compton reflection dominated spectrum in a peculiar accreting neutron star

Cited by in corpus (17)

• Modelling the behaviour of accretion flows in X-ray binaries
• Infrared background signatures of the first black holes
• A self-consistent approach to the hard and soft states of 4U 1705-44
• Testing reflection features in 4U 1705-44 with XMM-Newton, BeppoSAX and RXTE in the hard and soft state
• Suzaku broad-band spectrum of 4U 1705-44: Probing the Reflection component in the hard state
• BeppoSAX observation of 4U 1705-44: detection of hard X-ray emission in the soft state
• NuSTAR and XMM-Newton broad-band spectrum of SAX J1808.4-3658 during its latest outburst in 2015
• Suzaku and BeppoSAX X-ray Spectra of the Persistently Accreting Neutron-Star Binary 4U 1705-44
• Faint progenitors of luminous $z\sim 6$ quasars: why don't we see them?
• The Galactic LMXB Population and the Galactic Centre Region
• Suzaku Studies of Luminosity-Dependent Changes in the Low-Mass X-ray Binary Aquila X-1
• The Chaotic Long-term X-ray Variability of 4U 1705--44
• INTEGRAL and BeppoSAX observations of the transient atoll source 4U 1608-522: from quiescent to hard spectral state
• BEPPOSAX and RXTE spectral study of the low-mass X-ray binary 4u~1705-44. Spectral hardening during the banana branch
• Renewed activity from the X-ray transient SAXJ 1810.8-2609 with INTEGRAL
• Broadband observations of the X-ray burster 4U 1705-44 with BeppoSAX
• Investigating the true nature of three hard X-ray sources