We present an investigation into how well the properties of the accretion flow onto a supermassive black hole may be coupled to those of the overlying hot corona. To do so, we specifically measure the characteristic spectral index, Γ, of a power-law energy distribution, over an energy range of 2 to 10 keV, for X-ray selected, broad-lined radio-quiet active galactic nuclei (AGN) up to z∼2 in COSMOS and E-CDF-S. We test the previously reported dependence between Γ and black hole mass, FWHM and Eddington ratio using a sample of AGN covering a broad range in these parameters based on both the Mg ii and Hα emission lines with the later afforded by recent near infrared spectroscopic observations using Subaru/FMOS. We calculate the Eddington ratios, λ Edd , for sources where a bolometric luminosity (L Bol ) has been presented in the literature, based on SED fitting, or, for sources where these data do not exist, we calculate L Bol using a bolometric correction to the X-ray luminosity, derived from a relationship between the bolometric correction, and L X /L 3000 . From a sample of 69 X-ray bright sources (> 250 counts), where Γ can be measured with greatest precision, with an estimate of L Bol , we find a statistically significant correlation between Γ and λ Edd , which is highly significant with a chance probability of 6.59×10 −8 . A statistically significant correlation between Γ and the FWHM of the optical lines is confirmed, but at lower significance than with λ Edd indicating that λ Edd is the key parameter driving conditions in the corona. Linear regression analysis reveals that Γ = (0.32 ± 0.05)log 10 λ Edd +(2.27 ± 0.06) and Γ = (−0.69 ± 0.11)log 10 (FWHM/km s −1 )+(4.44 ± 0.42). Our results on Γ-λ Edd are in very good agreement with previous results. While the Γ-λ Edd relationship means that X-ray spectroscopy may be used to estimate black hole accretion rate, considerable dispersion in the correlation does not make this viable for single sources, however could be valuable however for large X-ray spectral samples, such as those to be produced by eROSITA.

We present new deep optical spectra of 9 high-z radio galaxies (HzRGs) at z > 2.7 obtained with FORS2 on VLT. These rest-frame ultraviolet spectra are used to infer the metallicity of the narrow-line regions (NLRs) in order to investigate the chemical evolution of galaxies in high-z universe. We focus mainly on the C iv/He ii and C iii]/C iv flux ratios that are sensitive to gas metallicity and ionization parameter. Although the N v emission has been widely used to infer the gas metallicity, it is often too weak to be measured accurately for NLRs. By combining our new spectra with data from the literature, we examine the possible redshift evolution of the NLR metallicity for 57 HzRGs at 1 < ∼ z < ∼ 4. Based on the comparison between the observed emission-line flux ratios and the results of our photoionization model calculations, we find no significant metallicity evolution in NLRs of HzRGs, up to z ∼ 4. Our results imply that massive galaxies had almost completed their chemical evolution at much higher redshift (z > 5). Finally, although we detect strong N v emission lines in 5 HzRGs at z > 2.7, we point out that high N v/He ii ratios are not indicative of high metallicities but correspond to high ionization parameters of gas clouds in NLRs.

We searched for quasars that are ∼ 3 mag fainter than the SDSS quasars in the redshift range 3.7 z 4.7 in the COSMOS field to constrain the faint end of the quasar luminosity function. Using optical photometric data, we selected

We systematically investigate the near-(NIR) to far-infrared (FIR) photometric properties of a nearly complete sample of local active galactic nuclei (AGN) detected in the Swift/Burst Alert Telescope (BAT) all-sky ultra hard X-ray (14-195 keV) survey. Out of 606 non-blazar AGN in the Swift/BAT 70-month catalog at high galactic latitude of |b| > 10• , we obtain IR photometric data of 604 objects by cross-matching the AGN positions with catalogs from the WISE, AKARI, IRAS, and Herschel infrared observatories. We find a good correlation between the ultra-hard X-ray and mid-IR (MIR) luminosities over five orders of magnitude (41 < log(L 14−195 /erg s −1 ) < 46). Informed by previous measures of the intrinsic spectral energy distribution of AGN, we find FIR pure-AGN candidates whose FIR emission is thought to be AGN-dominated with low starformation activity. We demonstrate that the dust covering factor decreases with the bolometric AGN luminosity, confirming the luminositydependent unified scheme. We also show that the completeness of the WISE color-color cut in selecting Swift/BAT AGN increases strongly with 14-195 keV luminosity.