TITLE:
The RXTE/PCA 35-Day X-Ray Lightcurve of Hercules X-1
AUTHORS:
Denis Leahy, Sandra Gonzalez Enriquez
KEYWORDS:
X-Ray Binaries, Light-Curves, Accretion Disks
JOURNAL NAME:
International Journal of Astronomy and Astrophysics,
Vol.13 No.3,
September
7,
2023
ABSTRACT: The archival Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) observations of HZ Her/Her X-1 are analyzed here. The time periods for Anomalous Low States are refined. The 35-day X-ray lightcurve of Her X-1 is produced using 35-day phases determined with RXTE All-Sky Monitor (ASM) and Swift Burst Alert Telescope (BAT) data, with adjustments based on the RXTE/PCA data. As a result, we constructed the best-phased 35-day lightcurve of Her X-1 with the highest sensitivity. The RXTE/PCA data are separated into 8 different substates of the 35-day cycle: Main High (MH) turn-on, MH, MH decline, Low State (LS) 1, Short High (SH) turn-on, SH, SH decline, and LS2. Orbital lightcurves are created for each substate, and they are compared. Eclipse data are extracted for each substate to determine the changes in eclipse shape with 35-day phase. A scattering corona model is fit to the eclipses for the different 35-day substates: this shows that the corona is present with similar intensity at all 35-day phases. We search for previously reported dips without absorption but find none.