NuSTAR, Swift, and GROND observations of the flaring MeV blazar: PMN J0641$-$0320

TL;DR

This paper reports the discovery and multi-wavelength observations of the MeV blazar PMN J0641-0320, revealing its hard X-ray spectrum and spectral energy distribution consistent with powerful blazars, and models its emission region.

Contribution

The study presents the first detailed multi-wavelength analysis of the new MeV blazar PMN J0641-0320, including its spectral energy distribution and emission region modeling.

Findings

Hard X-ray spectrum with photon index ~1 up to 80 keV.

Spectral energy distribution typical of powerful blazars.

Emission region likely inside broad line region or dusty torus.

Abstract

MeV blazars are a sub--population of the blazar family, exhibiting larger--than--average jet powers, accretion luminosities and black hole masses. Because of their extremely hard X--ray continua, these objects are best studied in the X-ray domain. Here, we report on the discovery by the $Fermi$ Large Area Telescope and subsequent follow-up observations with $NuSTAR$, $Swift$ and GROND of a new member of the MeV blazar family: PMN J0641$-$0320. Our optical spectroscopy provides confirmation that this is a flat--spectrum radio quasar located at a redshift of $z=1.196$. Its very hard $NuSTAR$ spectrum (power--law photon index of $\sim$1 up to $\sim$80 keV) indicates that the emission is produced via inverse Compton scattering off photons coming from outside the jet.The overall spectral energy distribution of PMN J0641$-$0320 is typical of powerful blazars and by reproducing it with a simple one-zone leptonic emission model we find the emission region to be located either inside the broad line region or within the dusty torus.