Revealing the Focused Companion Wind in Cygnus X-1 with Chandra

Abstract

We have analyzed a Chandra HETGS spectrum of the Galactic black hole Cygnus X-1, obtained at a source flux which is approximately twice that commonly observed in its persistent low-intensity, spectrally-hard state. We find a myriad of absorption lines in the spectrum, including Ly-alpha lines and helium-like resonance lines from Ne, Na, Mg, and Si. We calculate a flux-weighted mean red-shift of ~100 km/s and a flux-weighted mean velocity width of 800 km/s (FWHM) for lines from these elements. We also detect a number of transitions from Fe XVIII-XXIV and Ni XIX-XX in absorption; however, the identification of these lines is less certain and a greater range of shifts and breadth is measured. Our observation occurred at a binary phase of phi = 0.76; the lines observed are consistent with absorption in an ionized region of the supergiant O9.7 Iab companion wind. The spectrum is extremely complicated in that a range of temperatures and densities are implied. Prior Chandra HETGS spectra of Cygnus X-1 were obtained in a similar transition state (at phi = 0.93) and in the low/hard state (at phi= 0.84). Considered together, these spectra provide evidence for a companion wind that is focused as it flows onto the black hole primary in this system.

10 pages, 7 color figures, uses emulateapj.sty and apjfonts.sty. Submitted to ApJ

References in corpus (7)

• Long Term Variability of Cyg X-1 I. X-ray spectral-temporal correlations in the hard state
• Southern Galactic Plane Survey Measurements of the Spatial Power Spectrum of Interstellar H I in the Inner Galaxy
• Resolving the Composite Fe K-alpha Emission Line in the Galactic Black Hole Cygnus X-1 with Chandra
• The First High Resolution X-ray Spectrum of Cyg X-1: Soft X-Ray Ionization and Absorption
• The Ionized Stellar Wind in Vela X-1 During Eclipse
• Variation in Emission and Absorption Lines and Continuum Flux by Orbital Phase in Vela X-1
• The X-ray Spectrum of the Rapid Burster using the Chandra HETGS

Cited by in corpus (34)

• On The Maximum Mass of Stellar Black Holes
• The Reflection Component from Cygnus X-1 in the Soft State Measured by NuSTAR and Suzaku
• On the determination of the spin of the black hole in Cyg X-1 from X-ray reflection spectra
• NuSTAR and Suzaku observations of the hard state in Cygnus X-1: locating the inner accretion disk
• Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State
• The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk
• High-Resolution X-ray Spectroscopy of the Interstellar Medium II: Neon and Iron Absorption Edges
• Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system. I. The non-dip spectrum in the low/hard state
• Stellar Wind Variations During the X-ray High and Low States of Cygnus X-1
• On the Role of the Accretion Disk in Black Hole Disk-Jet Connections
• Long term variability of Cygnus X-1: VII. Orbital variability of the focussed wind in Cyg X-1 / HDE 226868 system
• Chandra X-Ray Spectroscopy of the Focused Wind in the Cygnus X-1 System. II. The Nondip Spectrum in the Low/Hard State - Modulations with Orbital Phase
• A new lepto-hadronic model applied to the first simultaneous multiwavelength data set for Cygnus X--1
• The radio counterpart of the likely TeV binary HESS J0632+057
• Laboratory Measurements of the K-shell transition energies in L-shell ions of Si and S
• Magnesium and silicon in interstellar dust: an X-ray overview
• The INTEGRAL view on Black Hole X-ray Binaries
• The structure of the jet in Cyg X-1 inferred from orbital modulation of the radio emission
• Jet radio emission in Cygnus X-1 and its orbital modulation
• Global Simulations of the Interaction of Microquasar Jets with a Stellar Wind in High-Mass X-ray Binaries
• X-ray luminosity function of high-mass X-ray binaries: Studying the signatures of different physical processes using detailed binary evolution calculations
• Ultraviolet observations of the X-ray photoionized wind of Cygnus X-1 during X-ray soft/high state
• Dramatic Variability of X-ray Absorption Lines in the Black Hole Candidate Cygnus X-1
• Optical Spectroscopic Observations of Cyg X-1=HDE 226868
• Common origin for black holes in both high mass X-ray binaries and gravitational-wave sources
• Comprehensive UV and Optical spectral analysis of Cygnus X-1: Stellar and wind parameters, abundances, and evolutionary implications
• Highly Ionized Fe-K Absorption Line from Cygnus X-1 in the High/Soft State Observed with Suzaku
• X-ray Variations at the Orbital Period from Cygnus X-1 in the High/Soft State
• The X-ray spectral-timing contribution of the stellar wind in the hard state of Cyg X-1
• XRISM High-Resolution X-ray Spectroscopy of Cygnus X-1 -- highly ionized Iron absorption structures
• Low frequency radio spectrum of LS 5039 during periastron and apastron passages
• Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems
• Assessing systematic uncertainties from spectral re-analysis of Cyg X-1 with different coronal geometries
• Conditions for accretion disc formation and observability of wind-accreting X-ray binaries