A search for evidence of irradiation in Centaurus X-4 during quiescence

Abstract

We present a study of the neutron star X-Ray Transient Cen X-4. Our aim is to look for any evidence of irradiation of the companion with a detailed analysis of its radial velocity curve, relative contribution of the donor star and Doppler tomography of the main emission lines. To improve our study all our data are compared with a set of simulations that consider different physical parameters of the system, like the disc aperture angle and the mass ratio. We conclude that neither the radial velocity curve nor the orbital variation of the relative donor's contribution to the total flux are affected by irradiation. On the other hand, we do see emission from the donor star at H$\alpha$ and HeI 5876 which we tentatively attribute to irradiation effects. In particular, the H$\alpha$ emission from the companion is clearly asymmetric and we suggest is produced by irradiation from the hot-spot. Finally, from the velocity of the HeI 5876 spot we constrain the disc opening angle to alpha=7-14 deg.

arXiv comment4 pages, 5 figures, accepted for publication in A&A as a RN

References in corpus (7)

• The Neutron Stars of Soft X-Ray Transients
• The "K-Correction" for Irradiated Emission Lines in LMXBs: Evidence for a Massive Neutron Star in X1822-371 (V691 CrA)
• The variable quiescence of Cen X-4
• Rotational Broadening and Doppler Tomography of the Quiescent X-Ray Nova Centaurus X-4
• Doppler tomography of the transient X-ray binary Centaurus X-4 in quiescence
• Irradiation of the secondary star in X-ray Nova Scorpii 1994 (=GRO J1655--40)
• Optical spectroscopy of the dwarf nova U Geminorum

Cited by in corpus (7)

• Dynamical constraints on the neutron star mass in EXO 0748-676
• The spotty donor star in the X-ray transient Cen X-4
• The long-term evolution of the X-ray pulsar XTE J1814-338: a receding jet contribution to the quiescent optical emission?
• A correlation between Ha trough depth and inclination in quiescent X-ray transients: evidence for a low-mass black hole in GRO J0422+32
• A misfired outburst in the neutron star X-ray binary Centaurus X-4
• Bowen emission from Aquila X-1: evidence for multiple components and constraint on the accretion disc vertical structure
• Measuring interacting binary mass functions with X-ray fluorescence