Query : 2002A&A...386..271R

2002A&A...386..271R - Astronomy and Astrophysics, volume 386, 271-279 (2002/4-4)

Energy dependence of a low frequency QPO in GRS 1915+105.


Abstract (from CDS):

We analyze a set of three RXTE Target of Opportunity observations of the Galactic microquasar GRS 1915+105, observed on April 2000, during a multi-wavelength campaign. During the three observations, a strong, variable low frequency (2-9Hz) quasi periodic oscillation (hereafter QPO), often referred to as the ubiquitous QPO, is detected together with its first harmonic. We study the spectral properties of both features, and show that: 1) their frequency variations are better correlated with the soft X-ray flux (2-5keV), favoring thus the location of the QPO in the accretion disk; 2) the QPO affects more the hard X-rays, usually taken as the signature of an inverse Compton scattering of the soft photons in a corona; 3) the fundamental and its harmonic do not behave in the same manner: the fundamental sees its power increase with the energy up to 40keV, whereas the harmonic increases up to ∼10keV. The results presented here could find an explanation in the context of the Accretion-Ejection Instability, which could appear as a rotating spiral or hot point located in the disk, between its innermost edge and the co-rotation radius. The presence of the harmonic could then be a signature of the non-linear behavior of the instability. The high-energy (>40keV) decrease of the fundamental would favor an interpretation where most or all of the quasi-periodic modulation at high energies comes not from the comptonized corona as usually assumed, but from a hot point in the optically thick disk.

Abstract Copyright:

Journal keyword(s): stars: individual: GRS 1915+105 - X-rays: binaries

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* V381 Nor HXB 15 50 58.6637920704 -56 28 35.258385000   17.95 16.6     K3III 1135 0
2 V* V1033 Sco HXB 16 54 00.137 -39 50 44.90   15.20 14.2 16.14   F5IV 1837 1
3 Granat 1915+105 HXB 19 15 11.55576 +10 56 44.9052           ~ 2530 0

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