X-ray Spectral Analysis of the Steady States of Grs1915+105

Abstract : We report on the X-ray spectral behavior within the steady states of GRS1915+105. Our work is based on the full data set of the source obtained using the Proportional Counter Array (PCA) on the Rossi X-ray Timing Explorer (RXTE) and 15 GHz radio data obtained using the Ryle Telescope. The steady observations within the X-ray data set naturally separated into two regions in the color–color diagram and we refer to these regions as steady-soft and steady-hard. GRS1915+105 displays significant curvature in the coronal component in both the soft and hard data within the RXTE/PCA bandpass. A majority of the steady-soft observations displays a roughly constant inner disk radius (${R}_{{\rm{in}}}$), while the steady-hard observations display an evolving disk truncation which is correlated to the mass accretion rate through the disk. The disk flux and coronal flux are strongly correlated in steady-hard observations and very weakly correlated in the steady-soft observations. Within the steady-hard observations, we observe two particular circumstances when there are correlations between the coronal X-ray flux and the radio flux with log slopes $\eta \sim 0.68\pm 0.35$ and $\eta \sim 1.12\pm 0.13$. They are consistent with the upper and lower tracks of Gallo et al. (2012), respectively. A comparison of the model parameters to the state definitions shows that almost all of the steady-soft observations match the criteria of either a thermal or steep power-law state, while a large portion of the steady-hard observations match the hard-state criteria when the disk fraction constraint is neglected.
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Charith S. Peris, Ronald A. Remillard, James F. Steiner, Saeqa D. Vrtilek, Peggy Varnière, et al.. X-ray Spectral Analysis of the Steady States of Grs1915+105. Astrophys.J., 2016, 822 (2), pp.60. ⟨10.3847/0004-637X/822/2/60⟩. ⟨hal-01554155⟩



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