Disk–jet Connection in the Radio Galaxy 3c 120

Abstract

We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 120 between 2002 and 2007 at X-ray (2-10 keV), optical (R and V band), and radio (14.5 and 37 GHz) wave bands, as well as imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Over the 5 yr of observation, significant dips in the X-ray light curve are followed by ejections of bright superluminal knots in the VLBA images. Consistent with this, the X-ray flux and 37 GHz flux are anti-correlated with X-ray leading the radio variations. Furthermore, the total radiative output of a radio flare is related to the equivalent width of the corresponding X-ray dip. This implies that, in this radio galaxy, the radiative state of accretion disk plus corona system, where the X-rays are produced, has a direct effect on the events in the jet, where the radio emission originates. The X-ray power spectral density of 3C 120 shows a break, with steeper slope at shorter timescale and the break timescale is commensurate with the mass of the central black hole based on observations of Seyfert galaxies and black hole X-ray binaries. These findings provide support for the paradigm that black hole X-ray binaries and both radio-loud and radio-quiet active galactic nuclei are fundamentally similar systems, with characteristic time and size scales linearly proportional to the mass of the central black hole. The X-ray and optical variations are strongly correlated in 3C 120, which implies that the optical emission in this object arises from the same general region as the X-rays, i.e., in the accretion diskcorona system. We numerically model multi-wavelength light curves of 3C 120 from such a system with the optical-UV emission produced in the disk and the X-rays generated by scattering of thermal photons by hot electrons in the corona. From the comparison of the temporal properties of the model light curves to that of the observed variability, we constrain the physical size of the corona and the distances of the emitting regions from the central BH. In addition, we discus physical scenarios for the disk-jet connection that are consistent with our observations.

Constraints on Black Hole Masses With Timescales of Variations in Blazars

“…Observations show that dips in the X-ray emission generated in the central engines are followed by ejections of bright superluminal radio knots in the jets of AGNs and microquasars (e.g., Marscher et al 2002;Chatterjee et al 2009Chatterjee et al , 2011Arshakian et al 2010). The dips in the Xray emission are well correlated with the ejections of bright superluminal knots in the radio jets of 3C 120 (Chatterjee et al 2009) and 3C 111 (Chatterjee et al 2011). An instability in the accretion flow may cause a section of the inner disk to break off, and the loss of this section leads to a decrease in the soft X-ray flux, observed as a dip in the X-ray emission.…”

Resolving Doppler-Factor Crisis in Active Galactic Nuclei: Non-Steady Magnetized Outflows

“…Observationally, the connection of the disk and jet activities is well established in the case of Galactic microquasars (Mirabel & Rodríguez 1999). In AGNs, the data are controversial (Chatterjee et al 2009). …”

The Complex Circumnuclear Environment of the Broad-Line Radio Galaxy 3c 390.3 Revealed by Chandra Hetg

“…The presence of accretion disks, winds, and jets in radio galaxies makes them ideal objects for studying the The Astrophysical Journal, 830:98 (7pp), 2016 October 20 doi:10.3847/0004-637X/830/2/98 interplay among these components (e.g., Marscher et al 2002;Chatterjee et al 2009Chatterjee et al , 2011Tombesi et al 2011Tombesi et al , 2012Tombesi et al , 2013bLohfink et al 2013). Moreover, spectral features indicating reflection from the inner accretion disk and the parsec-scale torus or broad-line region have been identified in some high signal-to-noise ratio spectra of radio galaxies.…”