SAX J1810.8−2609: A New Hard X‐Ray Bursting Transient

L. Natalucci, A. Bazzano, M. Cocchi, P. Ubertini, J. Heise, E. Kuulkers, J. J. M. in 't Zand, M. J. S. Smith
2000 Astrophysical Journal  
The transient X-ray source SAX J1810.8-2609 was discovered on 1998, March 10 with the Wide Field Cameras on board the BeppoSAX satellite, while observing the Galactic Bulge in the 2-28 keV energy range. On March 11, a strong type-I X-ray burst was detected with evidence of photospheric radius expansion. A follow-up target of opportunity observation with the Narrow-Field Instruments (NFI) was performed on March 11 and 12, for a total elapsed time of 8.51 x 10^4 s. The wide band spectral data
more » ... -200 keV) obtained with the NFI show a remarkable hard X-ray spectrum detected up to 200 keV, which can be described by a power law with photon spectral index Gamma=1.96±0.04, plus a soft component which is compatible with blackbody radiation of temperature kT 0.5 keV. The detection of the type-I X-ray burst is a strong indication that the compact object is a neutron star in a low mass X-ray binary system. Assuming standard burst parameters and attributing the photospheric radius expansion to near Eddington luminosity, we estimate a distance of 5 kpc. The inferred 2-10 keV X-ray luminosity is 9 x 10^35 erg/s at the time of the discovery.
doi:10.1086/308987 fatcat:s7wt7jowhvarrhkh2e3ldyhvty