Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-01-14
Astronomy and Astrophysics
Astrophysics
12 pages, 10 figures To be published in the Proceedings of 5th Microquasar Conference (Beijing, 2004)
Scientific paper
A black hole spectrum is known to change from the hard state to the soft state when the energy spectral index $\alpha$ ($F_E \propto E^{-\alpha}$) in, say, 2-20 keV range changes from $\alpha \sim 0.5$ to $\sim 1.5$. However, this `classical' definition which characterizes black holes like Cyg X-1, becomes less useful for many objects such as GRS 1915+105 in which the spectral slope is seen to vary from one to the other in a matter of seconds and depending on whether or not winds form, the spectral slope also changes. The light curves and the colour-colour diagrams may look completely different on different days depending on the frequency and mode of switching from one spectral state to the other. Though RXTE observations have yielded wealth of information on such `variability classes' in GRS 1915+105, very rarely one has been able to observe how the object goes from one class to the other. In the present review, we discuss possible origins of the class transition and present several examples of such transitions. In this context, we use mostly the results of the Indian X-ray Astronomy Experiment (IXAE) which observed GRS 1915+105 more regularly.
No associations
LandOfFree
Class Transitions in Black Holes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Class Transitions in Black Holes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Class Transitions in Black Holes will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-87481