QPO Frequency - Color Radius Connection in GRS 1915+105: a Possible Turnover supporting AEI predictions

TL;DR

This study supports the AEI model's prediction of a turnover in the QPO frequency versus color radius relationship in GRS 1915+105, showing multiple correlation types within a single source.

Contribution

It provides new observational evidence of a possible inversion in the QPO frequency-color radius relationship in GRS 1915+105, aligning with AEI model predictions.

Findings

Observation of positive, negative, and null correlations within the same source.

First evidence of a possible turnover in the QPO frequency-radius curve in GRS 1915+105.

Supports the relativistic AEI model predictions.

Abstract

It is widely believed that the low frequency quasi-periodic X-ray oscillations observed in microquasars are correlated to, but do not originate at, the physical radius of the inner edge of the accretion disk. Models relating the QPO frequency and color radius are hindered by observations showing contradicting trend correlations between the microquasars GRO 1655-40, XTE J1550-564 and GRS 1915+105. The first shows a negative correlation and the latter two a positive one. By taking into account relativistic rotation in the accretion disk, the Accretion-Ejection Instability (AEI) model predicts a turnover in the frequency-radius relationship, and has been successfully compared with observations of GRO J1655-40 and GRS 1915+105. We present further evidence supporting the AEI model prediction by using observations of the microquasar GRS 1915+105. By combining a data set including $\theta$-, $\beta$- and $\alpha$-class X-ray light curves, we observe positive, negative and null correlations in the frequency-radius relationship. This is the first time a single source has shown a possible inversion in the QPO frequency-color radius curve predicted by the AEI model.