Monitoring the Violent Activity from the Inner Accretion Disk of the Seyfert 1.9 Galaxy NGC 2992 with RXTE

TL;DR

This study monitored the Seyfert 1.9 galaxy NGC 2992 over a year with RXTE, revealing that its X-ray flux varies across its entire historical range, with evidence of inner disk activity during flares, and a stable spectral index despite large flux changes.

Contribution

First detailed year-long X-ray monitoring of NGC 2992 showing flux variability and inner disk activity, challenging previous ideas about accretion state changes.

Findings

Flux covered the entire historical range.

Redshifted Fe K line appeared during flares.

Spectral index remained constant despite flux variability.

Abstract

We present the results of a one year monitoring campaign of the Seyfert 1.9 galaxy NGC 2992 with RXTE. Historically, the source has been shown to vary dramatically in 2-10 keV flux over timescales of years and was thought to be slowly transitioning between periods of quiescence and active accretion. Our results show that in one year the source continuum flux covered almost the entire historical range, making it unlikely that the low-luminosity states correspond to the accretion mechanism switching off. During flaring episodes we found that a highly redshifted Fe K line appears, implying that the violent activity is occurring in the inner accretion disk, within ~100 gravitational radii of the central black hole. We also found that the spectral index of the X-ray continuum remained approximately constant during the large amplitude variability. These observations make NGC 2992 well-suited for future multi-waveband monitoring, as a test-bed for constraining accretion models.