Comparative study of black hole transients XTEJ1652-453 and XTEJ1752-223
D. Radhika, M. C. Ramadevi and S. Seetha
ISRO Satellite Centre, Bangalore E-mail: radhikad_isac@yahoo.in

Abstract. Transient sources are seen to undergo a sudden increase in flux to achieve its peak within very few days and then slowly decay over several days or months to the quiescent level. These are binary systems which can be either a LMXB or HMXB. Here we explain the characteristics of two transient sources XTE J1652-453 and XTE 1752-223, both first discovered by PCA on-board RXTE (Rossi X-ray Timing Explorer). XTE J1652-453 was detected during two PCA scans on 28th June, 2009 and 1st July 2009 and is located at an R.A of 16h52m20.33s and Dec of -45ˆ20'39.6'' in the galactic centre region; while XTE J1752-223 was detected on 23-10-2009 in the galactic bulge region at R.A = 17h52m13.2s and Dec = -22ˆ18'30''. XTE J1652-453 is observed to have a faster rise to the peak, while XTE J1752-223 had a very slow rise along with a precursor. The spectral study suggests that both the sources do have thermal and non-thermal emissions and show different characteristic spectral state transitions. From the data analyzed, it is understood that XTE J1752-223 rises from its quiescence to the Low/Hard state, then into the High/Soft state via the intermediate state. Both XTE J1652-453 and XTE J1752-223 remain in the High/Soft state while in the peak, and during decay exhibit intermediate state for a long period of 2 months and enter the Low/Hard state before reaching the quiescence. Spectral study of both the sources also shows the presence of a relativistic Fe Kα emission line. Type C QPO's are seen in the case of XTE J1752-223 while in the intermediate state, but no characteristic features or QPO's are seen in XTE J1652-453. An estimation of the innermost radius of the accretion disc and equivalent mass proves that both the sources are LMXB's and black hole candidates. We would like to present a comparison of both these sources by spectral and timing analysis.