EDP Sciences
Free access
Volume 434, Number 1, April IV 2005
Page(s) L5 - L8
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200500096

A&A 434, L5-L8 (2005)
DOI: 10.1051/0004-6361:200500096


A simple model for the complex lag structure of microquasars

P. Varnière

Department of Physics & Astronomy, Rochester University, Rochester NY 14627-0171, USA
    e-mail: pvarni@pas.rochester.edu

(Received 2 December 2004 / Accepted 6 March 2005 )

The phase lag structure between the hard and soft X-ray photons observed in GRS 1915+105 and XTE J1550-564 has been said to be "complex" because the phase of the Quasi-Periodic Oscillation fundamental Fourier mode changes with time and because the even and odd harmonics signs behave differently. From simultaneous X-ray and radio observations this seems to be related to the presence of a jet (level of radio emission). We propose a simple idea where a partial absorption of the signal can shift the phases of the Fourier modes and account for the phase lag reversal. We also briefly discuss a possible physical mechanism that could lead to such an absorption of the quasi-periodic oscillation modulation.

Key words: X-rays: binaries -- stars: individual: GRS 1915+105, XTE J1550-564 -- accretion disks

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