Broad-band spectral study of LMXB black hole candidate 4U 1957+11 with NuSTAR

Abstract

We present here the results of broadband spectral analysis of low-mass X-ray binary and a black hole candidate 4U 1957+11. The source was observed nine times with the Nuclear Spectroscopic Telescope Array (NuSTAR) between 2018 September and 2019 November. During these observations, the spectral state of 4U 1957+11 evolved marginally. The disc dominant spectra are well described with a hot, multicolour disc blackbody with disc temperature varying in the range $k{T}_{\mathrm{in}}\sim$ 1.35-1.86 keV and a non-thermal component having a steep slope ($\Gamma =$ 2-3). A broad Fe emission line feature (5-8 keV) was observed in the spectra of all the observations. The relativistic disc model was used to study the effect of distance, inclination, and the black hole mass on its spin. Simulations indicate a higher spin for smaller distances and lower black hole mass. At smaller distances and higher mass, spin is maximum and almost independent of the distance. An inverse correlation exists between the spin and the spectral hardening factor for all the cases. The system prefers a moderate spin of about 0.85 for black hole masses between 4-6 M_sun for a 7 kpc distance.

arXiv comment15 pages, 14 figures, Accepted for publication in Research in Astronomy and Astrophysics

References in corpus (29)

• On the Absorption of X-rays in the Interstellar Medium
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The MAXI Mission on the ISS: Science and Instruments for Monitoring All Sky X-Ray Images
• Broad-band gamma-ray and X-ray spectra of NGC 4151 and their implications for physical processes and geometry
• The May 1989 outburst of the Soft X-ray Transient GS 2023+338 (V404 Cyg)
• The Swift/BAT Hard X-ray Transient Monitor
• The Mass Distribution of Stellar-Mass Black Holes
• Multi-Temperature Blackbody Spectrum of a Thin Accretion Disk around a Kerr Black Hole: Model Computations and Comparison with Observations
• Precessing warped accretion discs in X-ray binaries
• Spectral and temporal properties of Compton scattering by mildly relativistic thermal electrons
• The Discovery of a State Dependent Hard Tail in the X-ray Spectrum of the Luminous Z-source GX 17+2
• No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR
• Discovery of Recurring Soft to Hard State Transitions in LMC X-3
• Suzaku Observations of 4U 1957+11: Potentially the Most Rapidly Spinning Black Hole in (the Halo of) the Galaxy
• Disk Dominated States of 4U 1957+11: Chandra, XMM, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole
• Relativistic Iron Emission and Disk Reflection in Galactic Microquasar XTE J1748-288
• A NICER look at the state transitions of the black hole candidate MAXI J1535-571 during its reflares
• Testing Accretion Disk Structure with Suzaku data of LMC X-3
• 4U 1957+11: a persistent low-mass X-ray binary and black-hole candidate in the high state?
• Studying the Reflection Spectra of the New Black Hole X-ray Binary Candidate MAXI J1631-479 Observed by NuSTAR: A Variable Broad Iron Line Profile
• On the enigmatic X-ray Source V1408 Aql (=4U 1957+11)
• The Case for a Low Mass Black Hole in the Low Mass X-ray Binary V1408 Aquilae (= 4U 1957+115)
• A long-term optical - X-ray correlation in 4U 1957+11
• Results of the Swift Monitoring Campaign of the X-ray Binary 4U 1957+11: Constraints on Binary Parameters
• The Optical Orbital Light Curve of the Low-mass X-ray Binary V1408 Aquilae (= 4U 1957+115)
• The stringent upper limit on jet power in the persistent soft state source 4U~1957+11
• Repeated Short-term Spectral Softening in the Low/Hard State of the Galactic Black-Hole Candidate Swift J1753.5-0127