Hard X-ray Tail Discovered in the Clocked Burster GS 1826-238
arXiv:1512.05514 · doi:10.3847/0004-637X/817/2/101
Abstract
The LMXB NS GS 1826-238 was discovered by Ginga in 1988 September. Due to the presence of quasi-periodicity in the type I X-ray burst rate, the source has been a frequent target of X-ray observations for almost 30 years. Though the bursts were too soft to be detected by INTEGRAL/SPI, the persistent emission from GS 1826-238 was detected over 150 keV during the ~10 years of observations. Spectral analysis found a significant high-energy excess above a Comptonization model that is well fit by a power law, indicating an additional spectral component. Most previously reported spectra with hard tails in LMXB NS have had an electron temperature of a few keV and a hard tail dominating above ~50 keV with an index of Γ~ 2-3. GS 1826-238 was found to have a markedly different spectrum with keV and a hard tail dominating above ~150 keV with an index of Γ~ 1.8, more similar to BHXRB. We report on our search for long-term spectral variability over the 25-370 keV energy range and on a comparison of the GS 1826-238 average spectrum to the spectra of other LMXB NS with hard tails.
References in corpus (9)
- INTEGRAL SPI All-Sky View in Soft Gamma Rays: Study of Point Source and Galactic Diffuse Emissions
- Linking Jet Emission, X-ray States and Hard X-ray Tails in the Neutron Star X-ray Binary GX 17+2
- Broad-band Spectral Evolution of Scorpius X-1 along its Color-Color Diagram
- The hard X-ray shortages prompted by the clock bursts in GS 1826--238
- The nature of the Island and Banana States in Atoll sources and a Unified Model for Low Mass X-ray Binaries
- INTEGRAL spectral variability study of the atoll 4U 1820-30: first detection of hard X-ray emission
- Disc-Jet coupling in the LMXB 4U1636-53 from INTEGRAL
- Hard X-ray emission of Sco X-1
- The hard X-ray continuum of Cen A observed with INTEGRAL SPI