An Empirical Method for Improving the Quality of RXTE HEXTE Spectra

Abstract

We have developed a correction tool to improve the quality of RXTE HEXTE spectra by employing the same method we used earlier to improve the quality of RXTE PCA spectra. We fit all of the hundreds of HEXTE spectra of the Crab individually to a simple power-law model, some 37 million counts in total for Cluster A and 39 million counts for Cluster B, and we create for each cluster a combined spectrum of residuals. We find that the residual spectrum of Cluster A is free of instrumental artifacts while that of Cluster B contains significant features with amplitudes ~1%; the most prominent is in the energy range 30-50 keV, which coincides with the iodine K edge. Starting with the residual spectrum for Cluster B, via an iterative procedure we created the calibration tool hexBcorr for correcting any Cluster B spectrum of interest. We demonstrate the efficacy of the tool by applying it to Cluster B spectra of two bright black holes, which contain several million counts apiece. For these spectra, application of the tool significantly improves the goodness of fit, while affecting only slightly the broadband fit parameters. The tool may be important for the study of spectral features, such as cyclotron lines, a topic that is beyond the scope of this paper.

Accepted in ApJ. 8 pages, 9 figures

References in corpus (4)

• X-ray Reflection Spectroscopy of the Black Hole GX 339-4: Exploring the Hard State with Unprecedented Sensitivity
• When A Standard Candle Flickers
• An Empirical Method for Improving the Quality of RXTE PCA Spectra
• The first cyclotron harmonic of 4U 1538-52

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• Reflection Spectroscopy of the Black Hole Binary XTE J1752-223 in its Long-Stable Hard State
• Evidence for Returning Disk Radiation in the Black Hole X-ray Binary XTE J1550-564
• Does the disk in the hard state of XTE J1752-223 extend to the innermost stable circular orbit?
• Conflicting disk inclination estimates for the black hole X-ray binary XTE J1550-564
• Combining timing characteristics with physical broadband spectral modelling of black hole X-ray binary GX~339$-$4
• Plasma-environment effects on K lines of astrophysical interest III. IPs, K thresholds, radiative rates, and Auger widths in Fe ix - Fe xvi
• The Goodness of Simultaneous Fits in ISIS
• The long-stable hard state of XTE J1752-223 and the disk truncation dilemma