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164 results on '"Heindl, W. A"'

154. RXTE observations of a new X-ray transient: GRS 1737-31

Author

Wei Cui, Heindl, W. A., Swank, J. H., Smith, D. M., Morgan, E. H., Remillard, R., and Marshall, F. E.

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics
Abstract

We present the results from RXTE observations of a new X-ray transient, GRS 1737-31, near the Galactic center during an outburst. Over a span of two weeks, the source was seen to vary significantly on time scales down to a few seconds. The rapid flares in the light curves bear resemblance to those observed for Cygnus X-1, a well-known black hole candidate (BHC). The power-density spectrum is also very typical of BHCs in the HARD (or LOW) state: it is flat below a characteristic break frequency of ~0.03 Hz, and becomes roughly a 1/f power law above. The observed X-ray spectrum can be characterized by a simple power law with a photon index of ~1.7 over a broad energy range 2-200 keV, which is remarkably similar to that of Cyg X-1 in the HARD state. The similarities to Cyg X-1 make GRS 1737-31 a likely BHC. However, unlike most transient BHCs, GRS 1737-31 does not seem to reach a ``soft state'' even during an outburst. We discuss this phenomenon in light of the comparison to a class of hard X--ray BHCs including transients GRO J0422+32, V404Cyg and GRO J1719-24, and persistent sources 1E1740.7-2942 and GRS 1758-258., 12 pages, including 4 figures. To appear in ApJ Letters

157. RXTE observations of AGN

Author

Rothschild, R. E., Heindl, W. A., Blanco, P. R., Gruber, D. E., Marsden, D. C., Pelling, M. R., Jahoda, K., Madejski, G., Swank, J. H., Andrzej Zdziarski, Gierliński, M., and Hink, P. L.

163. RXTE monitoring of centaurus A.

Author

Benlloch, S., Rothschild, R. E., Wilms, J., Reynolds, C. S., Heindl, W. A., Pottschmidt, K., Orr, A., Kreykenbohm, I., and Staubert, R.

Subjects
*GALAXIES, *X-ray spectroscopy
Abstract

We analyze a 75 ksec observation of the active galaxy Centaurus A carried out with RXTE in 1998 August. The joint PCA/HEXTE broad band X-ray spectrum can be well described by a heavily absorbed (NH λ 7 x 10[sup 22] cm[sup -2]) power law with a photon index of γ = 1.8. We present the interpretation of this spectrum in terms of Monte Carlo computations. No significant temporal variability was found during this observation. [ABSTRACT FROM AUTHOR]

Published
2001

164. Multifrequency observations of the Virgo blazars 3C 273 and 3C 279 in CGRO cycle 8.

Author

Collmar, W., Benlloch, S., Grove, J. E., Hartman, R. C., Heindl, W. A., Kraus, A., Tera¨sranta, H., Villata, M., Bennett, K., Bloemen, H., Johnson, W. N., Krichbaum, T. P., Raiteri, C. M., Ryan, J., Sobrito, G., Scho¨nfelder, V., Williams, O. R., and Wilms, J.

Subjects
*VIRGO (Astrology), *BL Lacertae objects
Abstract

We report first observational results of multifrequency campaigns on the prominent Virgo blazars 3C 273 and 3C 279 which were carried out in January and February 1999. Both blazars are detected from radio to γ-ray energies. We present the measured X- to γ-ray spectra of both sources, and for 3C 279 we compare the 1999 broad-band (radio to γ-ray) spectrum to measured previous ones. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

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