2 research outputs found
A long hard look at MCG-6-20-15 with XMM-Newton
We present the first results from a 325-ks observation of the Seyfert 1 galaxy MCG–6-30-15 with XMM-Newton and BeppoSAX. The strong, broad, skewed iron line is clearly detected and is well characterized by a steep emissivity profile within 6rg (i.e. 6GM/c2) and a flatter profile beyond. The inner radius of the emission appears to lie at about 2rg, consistent with results reported from both an earlier XMM-Newton observation of MCG–6-30-15 by Wilms et al. and part of an ASCA observation by Iwasawa et al. when the source was in a lower flux state. The radius and steep emissivity profile do depend however on an assumed incident power-law continuum and a lack of complex absorption above 2.5 keV. The blue wing of the line profile is indented, either by absorption at about 6.7 keV or by a hydrogenic iron emission line. The broad iron line flux does not follow the continuum variations in a simple manner
NuSTAR OBSERVATIONS OF WISE J1036+0449, A GALAXY AT z similar to 1 OBSCURED BY HOT DUST
Hot dust-obscured galaxies (hot DOGs), selected from Wide-Field Infrared Survey Explorer’s all-sky infrared
survey, host some of the most powerful active galactic nuclei known and may represent an important stage in the
evolution of galaxies. Most known hot DOGs are located at z > 1.5, due in part to a strong bias against identifying
them at lower redshift related to the selection criteria. We present a new selection method that identifies 153 hot
DOG candidates at z ~ 1, where they are significantly brighter and easier to study. We validate this approach by
measuring a redshift z = 1.009 and finding a spectral energy distribution similar to that of higher-redshift hot
DOGs for one of these objects, WISE J1036+0449 ( LBol ~= 8 x 10^46 erg s^-1). We find evidence of a broadened
component in Mg II, which would imply a black hole mass of MBH ~= 2 x 10^8 M(solar) and an Eddington ratio of
LambdaEdd ~= 2.7. WISE J1036+0449 is the first hot DOG detected by the Nuclear Spectroscopic Telescope Array, and
observations show that the source is heavily obscured, with a column density of NH = 2-15 x 10^23 cm^-2 . The
source has an intrinsic 2–10 keV luminosity of ~ 6 x 10^44 erg s^-1, a value significantly lower than that expected
from the mid-infrared/X-ray correlation. We also find that other hot DOGs observed by X-ray facilities show a
similar deficiency of X-ray flux. We discuss the origin of the X-ray weakness and the absorption properties of hot
DOGs. Hot DOGs at z ~< 1 could be excellent laboratories to probe the characteristics of the accretion flow and of
the X-ray emitting plasma at extreme values of the Eddington ratio