EDP Sciences
Free access
Volume 431, Number 3, March I 2005
Page(s) 825 - 830
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20041662

A&A 431, 825-830 (2005)
DOI: 10.1051/0004-6361:20041662

Class transitions and two component accretion flow in GRS 1915+105

S. K. Chakrabarti1, 2, A. Nandi1, A. K. Chatterjee3, A. K. Choudhury3 and U. Chatterjee3

1  S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700098, India
2  Centre for Space Physics, Chalantika 43, Garia Station Rd., Kolkata, 700084, India
3  Centre for Space Physics (Malda Branch), Atul Market, Malda 732101, India
    e-mail: chakraba@bose.res.in; space_phys@vsnl.com

(Received 14 July 2004 / Accepted 14 October 2004 )

The light curve of the galactic micro-quasar GRS 1915+105 changes in at least thirteen different ways which are called classes. We present examples of the transitions from one class to another as observed by the IXAE instrument aboard the Indian Satellite IRS-P3. We find that the transitions are associated with changes in photon counts over a time-scale of only a few hours and they take place through unknown classes. Assuming that the transitions are caused by variation of the accretion rates, this implies that a significant fraction of the matter must be nearly freely falling in order to have such dramatic changes in such a short time.

Key words: black hole physics -- X-rays: binaries -- radiation mechanisms: general -- X-rays: individuals: GRS 1915+105

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