Joint XMM-Newton and NuSTAR observations of the reflection spectrum of III Zw 2

Abstract

Detecting and modelling the reprocessed hard X-ray emission component in the accretion flow, so-called reflection spectrum is a main tool to estimate black hole spins in a wide range of astrophysical black holes regardless of their mass or distance. In this work, we studied the X-ray spectra of the Seyfert I galaxy III Zw 2 using multi-epoch XMM-Newton, NuSTAR and Suzaku observations. The X-ray spectra exhibit a soft-excess below 1 keV and a prominent excess at the location of the broad Fe Kα line at 6.4 keV. To account for these spectral features, we have fitted the spectra with multiple models including an ionized partially covering absorber and an accretion disk reflection model. To fully resolve the reflection component, we analyzed jointly the XMM-Newton and NuSTAR observations taken in 2017 and archival XMM-Newton data from 2000. Assuming the reflection scenario, the resulting model fits support a rapidly spinning black hole (a 0.98) in this radio-intermediate source. The X-ray spectra in 2000 and 2017 are remarkably similar with the only difference in the reflection fraction, possibly due to a change in the geometry of the accretion flow. However, the Suzaku observation is markedly different, and we suggest this could be an effect of a jet contribution in the X-ray band, which is supported by the elevated radio flux during this observation.

Testing the magnetic flux paradigm for AGN radio loudness with a radio-intermediate quasar

“…We conclude by noting that we have here and in Chamani et al (2020) demonstrated a new method for testing the magnetic flux paradigm by combining BH spin measurements from X-ray reflection spectroscopy with jet magnetic field measurements from sub-milliarcsecond multi-frequency VLBI astrometry. We have shown for one particular RIQ source that its measured BH spin and jet magnetic flux are in a good agreement with the Sikora & Begelman (2013) model, in which the amount of magnetic flux threading the BH is the parameter controlling the AGN jet production efficiency.…”

“…There is some evidence that the jet in III Zw 2 could be of intermittent nature. First, the source exhibits highly fluctuating radio flux density at 37 GHz (more than a factor of ten peak-to-through ratio; Chamani et al 2020), which could be due to variable jet power. It undergoes a recurrent activity roughly every five years (Li et al 2010) with a detected variable gamma-ray emission in the short term (Liao et al 2016).…”

“…Errors were estimated by fitting 5000 realisations of the spectrum; in each round a set of flux densities were drawn from a set of Gaussian distributions with means corresponding to the measured flux densities and the standard deviations corresponding to the flux density measurement uncertainties at each frequency. We complemented the VLBA flux density measurements with 37 GHz single-dish data from Metsähovi Radio Observatory monitoring programme (Chamani et al 2020;Teräsranta et al 1998). Metsähovi observations were made on November 2 and November 16, 2017 and we interpolated the measured flux densities to the date of the VLBA observations, November 8, 2017.…”

“…A good example of such an RIQ is III Zw 2, also known as Mrk 1501 and PG 0007+106. Its observed radio loudness (R = L 5 GHz /L B , where L 5 GHz is the radio luminosity at 5 GHz and L B is the optical B-band luminosity of the nucleus) ranges from 150 to 200 (Falcke et al 1996a;Sikora et al 2007) and, accounting for the bulk Lorentz factor, places the source in or near the radio-quiet group with intrinsic radio loudness ranging from 2 to 35 (Chamani et al 2020). This source has a compact, Snellen et al (2002).…”

“…core-dominated, low-power jet, and it harbours a rapidly spinning BH (Chamani et al 2020) with a mass of 1.8 × 10 8 M (Grier et al 2012). The parsec-scale jet was ejected towards the north-western direction as observed at 43 GHz in the late 1990s (Brunthaler et al 2000(Brunthaler et al , 2005.…”