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We report on the NuSTAR observations of two bright Seyfert 1 galaxies, namely MCG +8-11-11 (100 ks) and NGC 6814 (150 ks). The main goal of these observations was to investigate the Comptonization mechanisms acting in the innermost regions of AGN which are believed to be responsible for the UV/X-ray emission. The spectroscopic analysis of the NuSTAR spectra of these two sources revealed that although they had different properties overall (black hole masses, luminosity and Eddington ratios) they had very similar coronal properties. Both presented a power law spectrum with a high-energy cutoff at $sim 150-200$ keV, a relativistically broadened Fe K$alpha$ line and the associated disk reflection component, plus a narrow iron line likely emitted in Compton thin and distant matter. The intrinsic continuum was well described by Comptonization models that show for MCG +8-11-11 a temperature of the coronal plasma of kT$_{rm e} sim$ 60 keV and an extrapolated optical depth $tau$=1.8; for NGC 6814 the coronal temperature was kT$_{rm e} sim$ 45 keV with an extrapolated optical depth of $tau$=2.5. We compare and discuss these values to some most common Comptonization models which aim at explaining the energy production and stability of coronae in active galactic nuclei.
We present preliminary results on the hard X-ray emission properties of the Seyfert 1.5 galaxy MCG+8-11-11 as observed by INTEGRAL and SWIFT. All the INTEGRAL IBIS/ISGRI data available up to October 2009 have been analyzed together with two SWIFT/XRT
Though S0 galaxies are usually thought to be `red and dead, they often demonstrate star formation organized in ring structures. We try to clarify the nature of this phenomenon and its difference from star formation in spiral galaxies. Two early-type
In the optical sky, minutes-duration transients from cosmological distances are rare. Known objects that give rise to such transients include gamma-ray bursts (GRBs), the most luminous explosions in the universe that have been detected at redshift as
We report the analysis of 5 NuSTAR observations of SGR 1806-20 spread over a year from April 2015 to April 2016, more than 11 years following its Giant Flare (GF) of 2004. The source spin frequency during the NuSTAR observations follows a linear tren
MCG-6-30-15, at a distance of 37 Mpc (z=0.008), is the archetypical Seyfert 1 galaxy showing very broad Fe K$alpha$ emission. We present results from a joint NuSTAR and XMM-Newton observational campaign that, for the first time, allows a sensitive, t