Fast optical variability in Supergiant X-ray binaries

Abstract

The main goal of this work is to investigate the fast photometric variability of the optical counterparts to supergiant X-ray binaries and to compare the general patterns of such variability with the Galactic population of other early-type stars. We analyzed a sample of 14 high-mass X-ray binaries with supergiant companions observed by the Transiting Exoplanet Survey Satellite (TESS) and 4 Be/X-ray binaries with persistent X-ray emission for comparison. All sources exhibit fast aperiodic light variations. The shape of the periodogram is well described by a red noise component at intermediate frequencies ($\sim 1-10$ d${}^{-1}$). At lower frequencies the noise level flattens while at higher frequencies the periodogram is dominated by white noise. We find that the patterns of variability of the massive companions in supergiant X-ray binaries agree with that of single early-type evolved stars in terms of the general shape of the periodograms. However, they exhibit higher amplitude at low frequencies and lower characteristic frequencies than Be/X-ray binaries. Unlike Be/X-ray binaries, supergiant X-ray binaries exhibit a total lack of coherent signals at high frequencies. Most sources have been analyzed over multiple TESS sectors, spanning a duration of 4 years. We do not find any significant variation over time in the low-frequency variability characteristics. This study reveals that stochastic low-frequency variability is a very common, if not ubiquitous, feature intrinsic to supergiant optical companions in X-ray binaries.

References in corpus (42)

• The Transiting Exoplanet Survey Satellite
• Kepler Mission Design, Realized Photometric Performance, and Early Science
• Be/X-ray binaries
• Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
• Catalogue of high-mass X-ray binaries in the Galaxy ($4^{th}$ edition)
• Probing the interior physics of stars through asteroseismology
• Internal Gravity Waves in Massive Stars: Angular Momentum Transport
• Low-frequency gravity waves in blue supergiants revealed by high-precision space photometry
• Towards a unified view of inhomogeneous stellar winds in isolated supergiant stars and supergiant high mass X-ray binaries
• Variability of OB stars from TESS southern Sectors 1-13 and high-resolution IACOB and OWN spectroscopy
• Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150 and HD 46966
• Three-Dimensional Simulations of Massive Stars: I. Wave Generation and Propagation
• Photometric detection of internal gravity waves in upper main-sequence stars. II. Combined TESS photometry and high-resolution spectroscopy
• On the photometric detection of Internal Gravity Waves in upper main-sequence stars I. Methodology and application to CoRoT targets
• A catalogue of high-mass X-ray binaries in the Galaxy: from the INTEGRAL to the Gaia era
• Short-term variability and mass loss in Be stars I. BRITE satellite photometry of $\eta$ and $\mu$ Centauri
• Advances in Understanding High-Mass X-ray Binaries with INTEGRAL and Future Directions
• A new method for the spectroscopic identification of stellar non-radial pulsation modes. I. The method and numerical tests
• The eccentric massive binary V380 Cyg: revised orbital elements and interpretation of the intrinsic variability of the primary component
• The Observational Signatures of Convectively Excited Internal Gravity Modes in Main Sequence Stars
• Low-frequency variability in massive stars: Core generation or surface phenomenon?
• Kepler sheds new and unprecedented light on the variability of a blue supergiant: gravity waves in the O9.5Iab star HD 188209
• Revisiting the archetypical wind accretor Vela X-1 in depth -- A case study of a well-known X-ray binary and the limits of our knowledge
• PX Andromedae: Superhumps and variable eclipse depth
• Short-term variability and mass loss in Be stars II. Physical taxonomy of photometric variability observed by the Kepler spacecraft
• Two-Dimensional Simulations of Internal Gravity Waves in The Radiation Zones of Intermediate-Mass Stars
• TESS observations of Be stars: a new interpretation
• The M Supergiant High Mass X-Ray Binary 4U 1954+31
• 3D hydrodynamic simulations of massive main-sequence stars. I. Dynamics and mixing of convection and internal gravity waves
• Low-frequency photospheric and wind variability in the early-B supergiant HD 2905
• Stochastic light variations in hot stars from wind instability: Finding photometric signatures and testing against the TESS data
• The photometric variability of massive stars due to gravity waves excited by core convection
• Red noise and pulsations in evolved massive stars
• Short Term Variability of Evolved Massive Stars with TESS II: A New Class of Cool, Pulsating Supergiants
• Short Term Variability of Evolved Massive Stars with TESS
• Short-term variability and mass loss in Be stars IV. Two groups of closely spaced, approximately equidistant frequencies in three decades of space photometry of $\nu$ Puppis (B7-8 IIIe)
• Photometric detection of internal gravity waves in upper main-sequence stars. III. Comparison of amplitude spectrum fitting and Gaussian process regression using celerite2
• Internal Gravity Waves in Massive Stars II: Frequency Analysis Across Stellar Mass
• Three-Dimensional Simulations of Massive Stars: II. Age Dependence
• Catalog of the Galactic population of X-ray pulsars in High-mass X-ray binary systems
• Fast time optical variability in Be/X-ray binaries. Pulsation and rotation
• Multiwavelength study of the fast rotating supergiant high-mass X-ray binary IGR J16465-4507