X-ray study of bow shocks in runaway stars

Abstract

Massive runaway stars produce bow shocks through the interaction of their winds with the interstellar medium, with the prospect for particle acceleration by the shocks. These objects are consequently candidates for non-thermal emission. Our aim is to investigate the X-ray emission from these sources. We observed with XMM-Newton a sample of 5 bow shock runaways, which constitutes a significant improvement of the sample of bow shock runaways studied in X-rays so far. A careful analysis of the data did not reveal any X-ray emission related to the bow shocks. However, X-ray emission from the stars is detected, in agreement with the expected thermal emission from stellar winds. On the basis of background measurements we derive conservative upper limits between 0.3 and 10 keV on the bow shocks emission. Using a simple radiation model, these limits together with radio upper limits allow us to constrain some of the main physical quantities involved in the non-thermal emission processes, such as the magnetic field strength and the amount of incident infrared photons. The reasons likely responsible for the non-detection of non-thermal radiation are discussed. Finally, using energy budget arguments, we investigate the detectability of inverse Compton X-rays in a more extended sample of catalogued runaway star bow shocks. From our analysis we conclude that a clear identification of non-thermal X-rays from massive runaway bow shocks requires one order of magnitude (or higher) sensitivity improvement with respect to present observatories.

arXiv comment15 pages, 6 figures and 9 tables, accepted for publication in MNRAS

References in corpus (28)

• A new calibration of stellar parameters of Galactic O stars
• The Second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• Mass loss from hot massive stars
• X-ray background measurements with XMM-Newton EPIC
• The XMM-Newton serendipitous survey. VII. The third XMM-Newton serendipitous source catalogue
• The Disk Population of the Upper Scorpius Association
• Radio, X-ray, and gamma-ray Emission Models of the Colliding Winds Binary WR 140
• Catalogue of particle-accelerating colliding-wind binaries
• Masses and Luminosities of O and B - type stars and red super giants
• Non-thermal emission processes in massive binaries
• E-BOSS: an Extensive stellar BOw Shock Survey. I: Methods and First Catalogue
• Detection of nonthermal emission from the bow shock of a massive runaway star
• E-BOSS: An Extensive stellar BOw Shock Survey. II. Catalogue second release
• Thin-shell mixing in radiative wind-shocks and the Lx-Lbol scaling of O-star X-rays
• Resolved astrometric orbits of ten O-type binaries
• Non-thermal processes in bowshocks of runaway stars. Application to Zeta Oph
• AE Aurigae: first detection of non-thermal X-ray emission from a bow shock produced by a runaway star
• Modeling broadband X-ray absorption of massive star winds
• A new determination of the orbit and masses of the Be binary system delta Scorpii
• The binary Be star δ Sco at high spectral and spatial resolution: Disk geometry and kinematics before the 2011 periastron
• Systematic search for high-energy gamma-ray emission from bow shocks of runaway stars
• X-ray Observations of Bow Shocks around Runaway O Stars. The case of $\zeta$ Oph and BD+43${}^{\circ }$3654
• The Orbit of the Binary Star Delta Scorpii
• On the Absence of Non-thermal X-ray emission around Runaway O stars
• Turbulence-induced magnetic fields in shock precursors
• Is the bowshock of the runaway massive star HD 195592 a Fermi source?
• The X-ray under-luminosity of the O-type supergiants HD16691 and HD14947 revealed by XMM-Newton
• Long-term XMM-Newton investigation of two particle-accelerating colliding-wind binaries in NGC6604: HD168112 and HD167971

Cited by in corpus (14)

• MHD-shock structures of astrospheres: $\lambda$ Cephei-like astrospheres
• Wind nebulae and supernova remnants of very massive stars
• 3D MHD astrospheres: applications to IRC-10414 and Betelgeuse
• Non-thermal emission from stellar bow shocks
• Multi-zone non-thermal radiative model for stellar bowshocks
• MeerKAT discovery of radio emission from the Vela X-1 bow shock
• Possible Association of Two Stellar Bowshocks with Unidentified Fermi Sources
• Mixing of materials in magnetised core-collapse supernova remnants
• High-sensitivity radio study of the non-thermal stellar bow shock EB27
• The Bubble Nebula NGC 7635 -- testing the wind-blown bubble theory
• Searching for Faint X-ray Emission from Galactic Stellar Wind Bow Shocks
• The long-period massive binary HD~54662 revisited
• Radio detections of IR-selected runaway stellar bow shocks
• Radio polarization from runaway star bowshocks-I. The general case