The Square Kilometre Array (SKA)

Abstract:

We have analyzed in detail a set of Rossi X-ray Timing Explorer (RXTE) observations of the galactic microquasar GRS 1915+105 corresponding to times when quasi-periodic oscillations in the infrared have been reported. From time-resolved spectral analysis, we have estimated the mass accretion rate through the (variable) inner edge of the accretion disk. We compare this accretion rate to an estimate of the mass/energy outflow rate in the jet. We discuss the possible implications of these results in terms of disk-instability and jet ejection, and in particular note an apparent anti-correlation between the accretion and ejection rates, implying that the gas expelled in the jet must leave the accretion disk before reaching its innermost radius.

Abstract:

In this paper we present high spatial resolution radio images of the puzzling binary system β Lyrae obtained with MERLIN at 5 GHz. We find a nebula surrounding the binary with a brightness temperature of (11000 ± 700) K approximately 40 AU across. This definitively confirms the thermal origin of the radio emission, which is consistent with emission from the wind of the B6-8 II component (mass loss of order of 10^-7 M⊙yr^-1), ionized by the radiation field of the hotter companion. This nebula, surrounding the binary, is the proof that β Lyrae evolved in a non-conservative way, i. e. not all the mass lost by the primary is accretted by the secondary, and present measurements indicate that almost 0.015 M⊙ had been lost from the system since the onset of the Roche lobe overflow phase. Moreover, the nebula is aligned with the jet-like structures inferred from recent optical measurements, indicating a possible connection among them.