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Title: SPECTRAL ANALYSIS IN ORBITAL/SUPERORBITAL PHASE SPACE AND HINTS OF SUPERORBITAL VARIABILITY IN THE HARD X-RAYS OF LS I +61°303

We present an INTEGRAL spectral analysis in the orbital/superorbital phase space of LS I +61°303. A hard X-ray spectrum with no cutoff is observed at all orbital/superorbital phases. The hard X-ray index is found to be uncorrelated with the radio index (non-simultaneously) measured at the same orbital and superorbital phases. In particular, the absence of an X-ray spectrum softening during periods of negative radio index does not favor a simple interpretation of the radio index variations in terms of a microquasar's changes of state. We uncover hints of superorbital variability in the hard X-ray flux, in phase with the superorbital modulation in soft X-rays. An orbital phase drift of the radio peak flux and index along the superorbital period is observed in the radio data. We explore its influence on a previously reported double-peak structure of a radio orbital light curve, and present it as a plausible explanation.
Authors:
;  [1] ;  [2]
  1. Institute of Space Sciences (IEEC-CSIC), Campus UAB, Torre C5, 2a planta, E-08193 Barcelona (Spain)
  2. Laboratory for Particle Astrophysics, Institute of High Energy Physics, Beijing 100049 (China)
Publication Date:
OSTI Identifier:
22365904
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 785; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COSMIC X-RAY SOURCES; DIAGRAMS; HARD X RADIATION; INDEXES; MODULATION; ORBITS; PHASE SPACE; QUASARS; VARIATIONS; VISIBLE RADIATION; X-RAY SPECTRA