A Distinctive Disk-Jet Coupling in the Lowest-Mass Seyfert, NGC 4395

TL;DR

This study investigates the relationship between X-ray and radio emissions in the lowest-mass Seyfert galaxy NGC 4395, revealing a potential universal disk-jet coupling mechanism across black hole mass scales.

Contribution

It provides the first simultaneous X-ray and radio observations of NGC 4395, demonstrating that SMBHs may follow two distinct L_X-L_R tracks similar to stellar-mass black holes.

Findings

Weak or tentative coupling between X-ray and radio fluxes.

NGC 4395 and NGC 4051 lie on the steeper L_X-L_R track.

Supports universal disk-jet coupling mechanisms across mass scales.

Abstract

Simultaneous observations of X-rays and radio luminosities have been well studied in accreting stellar-mass black holes. These observations are performed in order to understand how mass accretion rates and jetted outflows are linked in these individual systems. Such contemporaneous studies in supermassive black holes (SMBH) are harder to perform, as viscous times scale linearly with mass. However, as NGC 4395 is the lowest known mass Seyfert galaxy, we have used it to examine the simultaneous X-ray (Swift) and radio (VLA) correlation in a SMBH in a reasonably timed observing campaign. We find that the intrinsic X-ray variability is stronger than the radio variability, and that the fluxes are only weakly or tentatively coupled, similar to prior results obtained in NGC 4051. If the corona and the base of the jet are one and the same, this may suggest that the corona in radio-quiet AGN filters disk variations, only transferring the strongest and/or most sustained variations into the jet. Further, when both NGC 4395 and NGC 4051 are placed on the stellar-mass L_X-L_R plane, they appear to reside on the steeper L_X-L_R track. This suggests that SMBHs also follow two distinct tracks just as stellar-mass black holes do, and supports the idea that the same physical disk-jet mechanisms are at play across the mass scale.