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Complete and Simultaneous Spectral Observations of the Black Hole X‐Ray Nova XTE J1118+480

2001; IOP Publishing; Volume: 555; Issue: 1 Linguagem: Inglês

10.1086/321449

1538-4357

Jeffrey E. McClintock, C. A. Haswell, M. R. Garcia, J. J. Drake, R. I. Hynes, H. L. Marshall, M. P. Muno, S. Chaty, P. Garnavich, P. Groot, W. H. G. Lewin, Christopher W. Mauche, J. M. Mïller, G. G. Pooley, C. R. Shrader, S. D. Vrtilek,

Astrophysics and Cosmic Phenomena

The X-ray nova XTE J1118+480 suffers minimal extinction (b = 62 degrees) and therefore represents an outstanding opportunity for multiwavelength studies. Hynes et al. (2000) conducted the first such study, which was centered on 2000 April 8 using UKIRT, EUVE, HST and RXTE. On 2000 April 18, the Chandra X-ray Observatory obtained data coincident with a second set of observations using all of these same observatories. A 30 ks grating observation using Chandra yielded a spectrum with high resolution and sensitivity covering the range 0.24-7 keV. Our near-simultaneous observations cover approximately 80% of the electromagnetic spectrum from the infrared to hard X-rays. The UV/X-ray spectrum of XTE J1118+480 consists of two principal components. The first of these is an approximately 24 eV thermal component which is due to an accretion disk with a large inner disk radius: > 35 Schwarzschild radii. The second is a quasi power-law component that was recorded with complete spectral coverage from 0.4-160 keV. A model for this two-component spectrum is presented in a companion paper by Esin et al. (2001).